MCB 244: Exam II Study Guide
MCB 244: Exam II Study Guide MCB 244
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This 42 page Study Guide was uploaded by Laura Kunigonis on Wednesday October 14, 2015. The Study Guide belongs to MCB 244 at University of Illinois at Urbana-Champaign taught by Dr, Chester Brown in Fall 2015. Since its upload, it has received 242 views. For similar materials see Human Anatomy and Physiology I in Biology at University of Illinois at Urbana-Champaign.
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Date Created: 10/14/15
MCB 244 Exam Chapter 6 Osseous Tissue and Bone Structure Osteogenesis Bonefonna on Ossification Process of replacing other tissues with bone 2 types intramembranous and endochondral Calcification Process of depositing calcium salts Occurs during bone ossification and in other tissues Endochondral Ossification Ossifies bone that originates as hyaline cartilage most bones originate as hyaline cartilage 6 main steps Step 1 of Endochondral Ossification Cartilage enlarges and chondrocytes increase in size reducing the matrix to a series of struts that begin to calcify Chondrocytes then die leaving cavities within the canHage Step 2 of Endochondral Ossification Blood vessels grow around edges of cartilage Cells of perichondrium convert to osteoblasts Shaft of cartilage becomes ensheathed in superficial layerofbone Step 3 of Endochondral Ossification Blood vessels penetrate cartilage and invade central region Fibroblasts migrating with the blood vessels differentiate into osteoblasts and begin producing spongy bone at primary ossification center Bone formation then spreads along shaft toward both ends Step 4 of Endochondral Ossification Remodeling osteoclasts break down matrix to make medullary cavity Osseus tissue of shaft becomes thicker Cartilage near each epiphysis is replaced by shafts of bone Further growth involves increases in length and diameter Step 5 of Endochondral Ossification Capillaries and osteoblasts migrate into epiphysis creating secondary ossification centers Step 6 of Endochondral Ossification Bone lengthening head is pushed away from diaphysis Replacing cartilage with bone Cartilage forms and moves that area away from diaphysis Osteoblasts replace it with bone Epiphyseal Plates Sites in our long bones where bone lengthening occurs occurs from birth til early 20s Contain epiphyseal cartilage Epiphyseal Lines Occur when epiphyseal cartilage disappears when bone stops growing after puberty Visible on xray Can show how old someone is Intramembranous Ossification Occurs in the dermis Produces dermal bones flat bones mandible clavicle etc 3 main steps Step 1 of Intramembranous Ossification Mesenchymal cells aggregate differentiate into osteoblasts and begin forming bone tissue Bone expands as a series of spicules that spread into surrounding tissue Step 2 of Intramembranous Ossification As spicules interconnect they trap blood vessels within the bone Step 3 of Intramembranous Ossifcation Over time the bone assumes the structure of spongy bone Areas of spongy bone may later be removed creating medullary cavities Through remodeling spongy bone formed in this way can be converted to compact bone Diaphysis The shaft A heavy wall of compact bone or dense bone Epiphysis Wide part at each end Articulation with other bones Mostly spongy cancellous bone Covered with compact bone cortex Metaphysis Where diaphysis and epiphysis meet Spongy Bone Does not have osteons The matrix forms an open network of trabeculae Trabeculae have no blood vessels The space between trabeculae is filled with red bone marrow Which has blood vessels Forms red blood cells Supplies nutrients to osteocytes In some bones spongy bone holds yellow bone marrow Appositional Growth Bone widening Occurs in longcompact bones Compact bone develops via increase in diameter at outer surface grows from inside outward Osteoblasts from periosteum deposit bone matrix and become osteocytes Layers of circumferential ameae are added increasing the strength of bone and create compact bone like tree bark Bone Resorption A process of bone remodeling Removal of matrix components Breakdown of bones Bone Deposition A process of bone remodeling Depositing material into bone matrix Bone Remodeling Purpose In adults the skeleton uses the activities of osteocytes osteoblasts and osteoclasts to maintain itself replace mineral reserves recycle and renew bone matrix Factors that Influence Bone Growth and Remodeling Exercise stress Nutrition Hormones Effects of Exercise on Bone quotUse it or lose itquot Heavily stressed bones become thicker and stronger Because bone degenerates quickly bones which don39t see any activity quickly lose strength 13 of bone mass can be lost in a few weeks of inactivity Nutrition Needed for Bone Growth and Development Normal bone growth and maintenance requires calcium and phosphates salts plus small amounts of Mg F Fe and Mn Vitamin C Vitamin A Vitamins K and B12 Vitamin C Required for collagen synthesis and stimulation of osteoblast differentiation Vitamin A Stimulates osteoblast activity Vitamins K and B12 Help synthesize bone proteins Calcium most abundant mineral in body vital to neurons and muscle cells especially heart cells various processes ca signaling blood clotting Hormones involved in Bone Growth and Maintenance Calcitriol Growth Hormone and Thyroxine Estrogens and Androgens Calcitonin and Parathyroid Hormone Calcitriol source and effects Source kidneys Effects helps absorb Ca and Phosphorous from digestive tract lts synthesis requires Vitamin D3 cholecalciferol Growth Hormone Source pituitary gland Effects stimulates osteoblast activity and the synthesis of bone matrix Thyroxine Source thyroid gland follicle cells Effects with growth hormone stimulates osteoblast activity and the synthesis of bone matrix Sex Hormones Source ovaries estrogens testes androgens Effects stimulate osteoblast activity and the synthesis of bone matrix estrogens stimulate epiphyseal closure earlier than androgens Parathyroid Hormone source and effects Source parathyroid glands Effects stimulates osteoclast and osteoblast activity elevates Ca ion concentrations in body fluids Calcitonin source and effects Source thyroid gland C cells Effects inhibits osteoclast activity promotes Ca loss by kidneys reduces Ca ion concentration in body fluids 3 Hormones which Regulate Calcium Homeostasis Calcitonin Parathyroid Hormone most important with regards to every day Ca regulations Calcitriol 3 Systems that Calcitonin and PTH Affect Skeletal system bones Digestive system digestive tract Renal System kidneys Parathyroid Hormone Functions Increases plasma Ca levels by Stimulating osteoclasts Increasing intestinal absorption of Ca requires Vit D3 Decreases Ca excretion at kidneys Calcitonin Functions Decreases plasma Ca ion levels by Inhibiting osteoclast activity Reducing intestinal Ca absorption Increasing excretion at kidneys Fractures Cracks or breaks in bones caused by physical stress 4 Major Steps in Fracture Repair Hematoma Formation First step in fracture repair Produces a clot fracture hematoma Establishes a fibrous network Bone cells in the area die Callus Formation 2nd step in fracture repair quotTemporary Repairquot formation of soft callus Cells of endosteum and periosteum divide and migrate into fracture zone Calluses form to stabilize the break 2 Types of Calluses Formed in Fracture Repair External Callus made of cartilage and bone surrounds break lnternal Callus develops in medullary cavity Bone Formation 3rd step in fracture repair Osteoblast activity increases Replace central cartilage of internal callus with spongy bone External callus replaced with compact bone Bone Remodeling 4th step in fracture repair quotclean up phasequot Osteoblasts and osteocytes remodel the fracture for up to a year Reduces bone calluses Types of Fractures Transverse Fracture break a bone shaft across its long axis Displaced Fracture produce new and abnormal bone arrangements nondisplaced fractures retain the normal alignment of the bones or fragments Compression Fracture occur in vertebrae subjected to extreme stresses such as those produced by the forces that arise when you land on your seat in a fall Spiral Fracture produced by twisting stresses that spread along the length of the bone Epiphyseal Fracture tend to occur where the bone matrix is undergoing calcification and chondrocytes are dying A clean transverse fracture along this line generally heals well Unless carefully treated fractures between the epiphysis and the epiphyseal cartilage can permanently stop growth at this site Comminuted Fracture shatter the affected area into a multitude of bony fragments Greenstick Fracture only one side of the shaft is broken the other is bent generally occurs in children whose long bones have yet to ossify fully Colles Fracture a break in the distal portion of the radius typically result of reaching out to cushion a fall Pott39s Fracture occurs at the ankle and affects both bones of the leg Bones Most Affected by Aging epiphysis vertebrae and jaw fragile limbs reductions in height and tooth loss Two Disorders Classified by Severe Bone Loss Osteopenia Osteoporosis Osteopenia Characteristics Begins between ages 30s and 40s Women lose 8 of bone mass per decade men 3 Osteopenia Treatments Treatments are controversial No specific medications for treatment of osteopenia lf deemed necessary medications for osteopenia can be given but it usually avoided due to their side effects Osteoporosis Characteristics Severe bone loss Affects normal function Begins over age 45 Occurs in 29 of women and 18 of men Osteoporosis Causes Hormones estrogens and androgens help maintain bone mass inhibit osteoclast activity bone loss in women accelerates after menopause Cancer cancerous tissue release osteoclastactivating factor that stimulate osteoclasts and produces severe osteoporosis Osteoporosis Treatments estrogenhormone replacement therapy ERTHRT drugs that mimic estrogen39s effects calcitonin administration physical therapy Chapter 7 The Axial Skeleton Skull Protects the brain contains entrances to the respiratory system and digestive system Contains 28 bones and 1 associated bone Cranial Bones 8 Occipital 1 Parietal 2 Frontal 1 Temporal 2 Sphenoid 1 Ethmoid 1 Facial Bones 15 Maxillae 2 Palatine 2 Nasal 2 Vomer 1 Inferior Nasal Conchae 2 Zygomatic 2 Lacrimal 2 Mandible 1 Hyoid 1 Cranial Bones Occipital Bone Forms the posterior and inferior surfaces of the cranium Articulates with parietal temporal sphenoid and atlas External Occipital Protuberance Inferior to the foramen magnum At the base of the occipital bone External Occipital Crest Attaches ligaments Leads from foramen magnum to the external occipital protuberance Occipital Condyles Articulates with the neck Large structures surrounding the foramen magnum Foramen Magnum Connects cranial and spinal cavities Big hole on bottom of skull Jugular Foramen Passage forjugular vein Bottom holes lateral to the foramen magnum Inferior to carotid canal Hypoglossal Canal Allows for passage of the hypoglossal cranial nerve CN Xll Canal in the foramen magnum Frontal Bone Forms the anterior cranium and upper eye sockets Contains frontal sinuses Articulates with parietal sphenoid ethmoid metopic suture nasal lacrimal maxillary and zygomatic Frons Frontal Squama Forehead Flat portion superior to eye sockets In line with metopic suture Supra Orbital Margin Protects the eye Ridge of the eyebrow Lacrimal Fossa For the tear ducts In the eye sockets Frontal Sinuses Sinuses in the nasal area Supra Orbital Foramen For blood vessels of eyebrows eyelids and frontal sinuses Parietal Bones Forms part of the superior and lateral surfaces of the cranium Articulates with the other parietal occipital temporal frontal sphenoid Superior Temporal Line Vague line on the parietal bone above the temporal bone Inferior Temporal Line Other vague line on the parietal bone above the temporal bone Temporal Bone Part of the lateral walls of the cranium and zygomatic arches Surrounds and protects the inner ear Attaches muscles ofjaws and head Articulates with zygomatic sphenoid parietal occipital and mandible Squamous Part Flat part of the temporal bone that borders the squamous suture Mandibular Fossa Articulates with the mandible Between the zygomatic process and the external acoustic meatus Zygomatic Process Inferior to the squamous part Articulates with the temporal process of zygomatic bone Forms zygomatic arch cheekbone Mastoid Process For muscle attachment Contains mastoid air cells connected to middle ear Behind the external acoustic meatus Styloid Process Attaches tendons and ligaments of the hyoid tongue and pharynx Pointy process between mastoid and mandible Petrous Part Encloses structures of the inner ear Auditory Ossicles Three tiny bones in middle ear that transfer sound from eardrum to inner ear Malleus lncus and Stapes External Acoustic Meatus Holes in temporal bones for ear canal Ends at tympanic membrane Internal Acoustic Meatus For blood vessels and nerves of the inner ear Carotid Canal Allows for passageway of the carotid artery Superior to the jugular foramen Top hole that is lateral to the foramen magnum Ethmoid Forms anterior medial floor of cranium Roof of the nasal cavity Part of the nasal septum and medial orbital wall Contains ethmoidal air cells Articulates with frontal sphenoid nasal lacrimal palatine maxillary inferior nasal conchae and vomer Cribriform Plate Roof of the nasal cavity Contains crista galli and olfactory foramina Crista Galli Ridge on the Cribriform plate Nasal Conchae Middle and lnferior are the bulbs seen through the nose cavity on skull Superior conchae are not visible Perpendicular Plate The plate seen in the nose cavity on the skull Sphenoid Bone Part of the floor of the cranium Unites cranial and facial bones Strengthens sides of the skull Contains sphenoidal sinuses Articulates with ethmoid frontal occipital parietal temporal palatine zygomatic maxillae and vomer Shaped like a bat Lesser Wings Anterior to the sella turcica Smaller wings Greater Wings Form part of the cranial floor Posterior wall of the orbit Larger wings Paranasal Sinuses Air filled chambers connected to nasal cavities Lightens skull bones and provides mucous Infections can induce inflammation leading to excessive fluid build up Facial Bones Maxilla Support upper teeth Forms inferior orbital rim upperjaw and hard palate Contains maxillary sinuses Articulates with Frontal ethmoid maxilla all other facial bones except mandible Orbital Rim Protects eye and orbit Anterior Nasal Spine Attaches cartilaginous anterior nasal septum Alveolar Processes Borders the mouth and supports upper teeth Palatine Processes Forms the hard palate Roof of the mouth Inferior Orbital Fissure For cranial nerves and blood vessels Infra Orbital Foramen For sensory nerve to brain Connects with foramen rotundum Incisive Foramen Supplies blood vessels and nerves to the superior oral mucosa of hard palate Right behind front teeth Palatine Bone Forms posterior portion of the hard palate Contributes to the floors of the orbits Articulates with other palatine maxillae sphenoid ethmoid inferior nasal conchae and vomer Palatine Markings Horizontal Plate Perpendicular Plate and Orbital Process Vomer Supports the bridge of the nose Connects to cartilages of the nose external nares Articulates with other nasal bone ethmoid frontal maxillae palatine bones sphenoid Inferior Nasal Conchae Creates air turbulence increases epithelial surface area and warms air Articulates with ethmoid maxillae palatine bones and lacrimal bones Lacrimal Bones Smallest facial bone that forms part of the medial wall of the orbit Articulates with frontal bone maxillae and ethmoid Zygomatic Bones Contributes to the rim and lateral wall of the orbit Forms zygomatic arch Articulates with sphenoid frontal temporal and maxillae Temporal Process Part of the zygomatic bone that meets the temporal bone to form the zygomatic arch Mandible Forms the lowerjaw Articulates with temporal bone at the mandibular fossae Body of Mandible Horizontal portion thats not the point of the chin Jaw line Mental Protuberance Attaches facial muscles Pointy part in middle of chin Ramus of Mandible Ascending from the mandibular angle on either side Vertical part at sides ofjaw Mandibular Angle Pointy part at sides ofjaw Condylar Process Articulates with temporal bone at temporomandibularjoint Directly above the mandibular angle Across from coronoid process towards the back Coronoid Process Mandible Insertion point for temporalis muscle Across from the condylar process towards the front Alveolar Processes Holds the teeth Mandibular Notch depression separating the condylar and coronoid processes Submandibular Fossa Depression for submandibular gland On the inside of the mandible beneath teeth and mylohyoid line Mylohyoid Line Origin for mylohyoid muscle Inside of the mandible beneath teeth above submandibular fossa Mental Foramen Allows for passage of blood vessels to cheek and teeth Hole in the mandible beneath teeth Articular Surface for Temporomandibular Joint Articulation between temporal bone and mandible Condylar process on mandible fits into mandibular fossa on temporal bone Hyoid Bone Supports the larynx and attaches muscles of the larynx pharynx and tongue Indirectly articulates with styloid processes at the lesser horns Body of Hyoid Horizontal portion Attaches muscles of larynx tongue and pharynx Greater Horns of Hyoid Supports larynx and attaches muscles of the tongue Lesser Horns of Hyoid Attaches to stylohyoid ligaments Supports hyoid and larynx Vertebral Column Composed of 7 cervical vertebrae 12 thoracic vertebrae 5 lumbarl ertebra sacrum and coccyx Pedicles Walls of the vertebral arch Connects the vertebral body Laminae Roof of the vertebral arch Connects to spinous process Spinous Process Projection where vertebral laminae fuse Across from vertebral body Transverse Processes Projection where laminae join pedicles On either side of the vertebrae Superior Articular Process Above the spinous process Inferior Articular Process Below spinous process Have articular facets Intervertebral Foramina Gaps between pedicles that allow nerve connections to spinal cord Vertebral Canal Formed by vertebral foramina and enclose the spinal cord Intervertebral Discs Pads of fibrous cartilage that separate vertebrae and absorb shock Cervical Vertebrae C1C7 Contain transverse foramen next to the transverse processes Can appear to look like a fox Spinous process is bifurcated Smallest vertebrae W Articulates with occipital condyles on skull No body or spinous process Extra large foramen to accommodate the dens of the Axis Anterior arch articulates with dens m Supports the atlas Has an enlarged spinous process to attach muscles of head and neck The dens of the axis fuses with the atlas Thoracic Vertebrae T1T12 Larger than the cervical Smaller foramen with long slender spinous processes Looks like a giraffe Costal facets articulate with ribs Superior Costal Facet Part of thoracic vertebrae that articulates with head of rib T1T8 have two sets Inferior Costal Facet Part of thoracic vertebrae that articulates with head of rib T1T8 have two sets Lumbar Vertebrae L1L5 Largest and thickest vertebrae No costal facets Spinous process is short and heavy Appear to look like a moose Sacrum Protects reproductive urinary and digestive organs Curved more in males than in females Attaches the axial skeleton to the pelvic girdle The adult sacrum consists of five fused vertebrae that fuses between puberty and 30 Coccyx Consists of 35 fused coccygeal vertebrae quotTail Bonequot Thoracic Cage Protects organs of thoracic cavity Attaches muscles for respiration vertebral column pectoral girdle and upper limbs Composed of ribs and sternum True Ribs Ribs 17 Vertebrosternal ribs Connected to the sternum by costal cartilages False Ribs Ribs 812 Do not attach directly to the sternum Vertebrochondral Ribs Ribs 810 Fuse together and merge with cartilage before reaching the sternum Floating Ribs Ribs 1112 Vertebral ribs Connect only to the vertebrae and back muscles No connection to the sternum Sternum Flat bone in the midline of the thoracic cage Composed of manubrium sternal body and xiphoid process Chapter 8 The Appendicular Skeleton 126 bones Allows us to move and manipulate objects Limbs and supportive girdles Girdles Bones of the appendicular skeleton attach to the axial skeleton via the girdles Pectoral Girdle quotShoulder Girdlequot Connects the arms to the body Consists of clavicles and scapulae Connects with the axial skeleton only at the manubrium Clavicles quotCollarbonesquot Long SShaped bones Originate at the manubrium sternal end and articulate with the scapulae acromial end Scapulae quotShoulder Bladequot Broad flat triangles Articulates with arm and collarbone The hooked parts connect to the arm Subscapular Fossa Anterior surface of the scapula Just beneath the superior border Scapular Body Superior Border Medial Border is on the vertebral side and Lateral Border is closest to arms Glenoid Cavity Depression in the head of the scapula towards the arms Articulates with humerus and forms shoulderjoint Coracoid Process Smaller anterior process that is part of the glenoid cavity Acromion Larger posterior process that articulates with the clavicle Forms the acromioclavicularjoint Scapular Spine Ridge across the posterior surface of scapula Separates into the supraspinous fossa and the infraspinous fossa Humerus Long upper arm bone Brachium Articulates with pectoral girdle Humerus Head Rounded articulating surface contained within the shoulderjoint Proximal Greater Tubercle Lateral and forms tip of shoulder Lesser Tubercle Medial part of shoulder Distal Epiphysis of Humerus Medial and lateral epicondyles for muscle attachment Also contains the condyle that articulates with ulna and radius Humerus Conder Articulates with ulna and radius Contains the trochlea and capitulum Humerus Trochlea Articulates with ulna HookPulley shaped Fits into the trochlear notch on ulna Humerus Capitulum Rounded area that articulates with radius Forearm Antebrachium Consists of Ulna and Radius Ulna Medial bone Has the big projection on proximal end Olecranon Superior end of ulna Articulates with trochlea of humerus Point of elbow Higher projection on the proximal head of ulna Forearm Extended Olecranon ulna enters olecranon fossa humerus Forearm Flexed Coronoid process ulna enters coronoid fossa humerus Coronoid Process Ulna Lower projection on the proximal head of ulna Radial Notch Articulates with the head of the radius Forms Proximal radioulnar joint Ulnar Head Prominent styloid process that attaches to articular disc between forearm and wrist lnterosseous membrane RadioUlnar A fibrous sheet that connects lateral margin of ulnar shaft to radius Radius Lateral bone of the forearm Radial Head Disk shaped projection that fits into the radial notch on the ulna Radial Tuberosity Attaches the bicep Below the radial head Ulnar Notch Distal end that articulates with wrist and radius Bones of the Wrist and Hand carpals metacarpals phalanges Carpals 8 bones in the wrist Four proximal Four distal Allow wrist to bend and twist Four Distal Carpals Trapezium Lateral Trapezoid Medial Capitate Medialer Largest Hamate Medialest LateralMedial Try To Catch Her Four Proximal Carpals Scaphoid Lateral Lunate Medial Pisiform Medialest Triquetrum Posterior LateralMedial She Looks Too Pretty Metacarpals 5 long bones of hand Numbered 15 1thumb Make up the palm Phalanges 14 finger bones The thumb pollex has two phalanges proximal and distal The fingers have three phalanges proximal middle and distal Pelvic Girdle Made up of two hip bones Bears body weight and stress of movement Part of the pelvis Coxal Bones quotHip Bonesquot Made up of three fused bones llium lschium and Pubis Acetabulum quotHip Socketquot Meeting point of ilium ischium and pubis Articulates with head of femur Lateral surface of coxal bones Ilium Upper most portion of coxal bone Largest Contains Greater sciatic notch iliac crest and iliac fossa Greater Sciatic Notch For the sciatic nerve Big notch on medial side of coxal bone liac Crest Upper rim of coxal bone lliac Fossa Depression between iliac crest and arcuate line Above the greater sciatic notch Arcuate Line Line on the coxal bone above the greater sciatic notch lschium Lower posterior portion of the coxal bone Contains ischial spine ischial tuberosity lesser sciatic notch and ischial ramus lschial Spine Projection beneath the greater sciatic notch Above the lesser sciatic notch lschial Tuberosity Posterior projection that bears weight when you sit Beneath the lesser sciatic notch lschial Ramus Lower portion of the obturator foramen Pubis Lower anterior portion of coxal bone Contains the pubic symphysis pubic tubercles obturator foramen pectineal line and superior ramus Pubic Symphysis Padding of fibrous cartilage that connects two coxal bones at the pubis Obturator Foramen Formed by ischial and pubic rami Attaches hip muscles Big hole on coxalbones Pubic Ramus Superior portion of the obturator foramen Pectineal Line Ridge of the pubic ramus Pelvis Consist of two coxal bones sacrum and the coccyx Coxal bones connected by pubic symphysis Sacrum fits into the iliac portion of the coxalbones True Pelvis Encloses the pelvic cavity Everything below the arcuate line Contains Pelvic Brim and Perineum region Pelvic Brim The top portion of the pelvis contains the pelvic inlet lnlet is wider than outlet Perineum Region Lower portion of the pelvis contains pelvic outlet Outlet is narrower than inlet False Pelvis Blades of ilium above the arcuate line Female Pelvis Smoother and lighter Less prominent muscles and ligaments Modifications for childbirth include enlarged pelvic outlet shallow iliac fossa broad pubic angle less curvature of sacrum wide circular pelvic inlet coccyx points interiorly and broad and low pelvis Femur Thigh bone Proximal Head of Femur Articulates with pelvis at acetabulum Separated from shaft by a neck Femoral Trochanters Greater trochanter and lesser trochanter on either sides of femoral neck at the proximal end Area of tendon attachment Linea Aspera Prominent ridge on the shaft of the femur Attaches hip muscles and joins epicondyles Distal Femoral Epiphysis Contains medial and lateral epicondyles and condyles above the knee joint Separated by intercondylar fossa Patella quotKneecapquot Formed within tendon of quadriceps femoris Base attaches quadriceps femoris Apex attaches patellar ligament Tibia quotShin Bonequot Supports body weight Larger leg bone medial to fibula Tibia Proximal Epiphysis Medial and Lateral Condyles separated by intercondylar eminence Articulate with condyles of femur Tibial Tuberosity Attaches patellar ligament Tibial Shaft Anterior margin is the sharp ridge of the shinbone Distal Epiphysis of Tibia Contains medial malleolus which is the medial projection at the ankle Fibula Attaches muscles of feet and toes Smaller than and lateral to tibia Superior Tibiofibular Joint Proximal articulation point of tibia and fibula Lateral Malleolus Lateral projection on the distal head of fibula Interosseous Membrane TibioFibular Binds fibula to tibia Tarsal Bones Seven ankle bones Talus Calcaneus Navicular Medial cuneiform intermediate cuneiform lateral cuneiform and cuboid Calcaneus quotHeel Bonequot Transfers weight from talus to the ground Attaches the calcaneal Achilles tendon Talus Tarsal bone that carries weight from tibia across trochlea Navicular Tarsal bone that articulates with talus and cuneiform bones Cuboid Articulates with calcaneus Cancer Takes No More Interesting Little Clowns Clockwise locations of the tarsal bones from a superior view Longitudinal Arch Calcaneal portion lateral and talar portion medial Transfer weight from one part of the foot to another Transverse Arch Formed by a difference in curvatures between medial and lateral border of the foot Metatarsals Five long bones of foot Numbered 15 starting with big toe Hallux Phalanges of Foot 14 bones Hallux has two phalanges distal and proximal Others have three phalanges distal medial and proximal Muscle primary tissue type divided into Skeletal Muscle voluntary striated muscle controlled by nerves of the central nervous system Cardiac Muscle involuntary striated muscle Smooth Muscle involuntary nonstriated muscle 5 Characteristics of all muscle tissues Specialized Cells elongated high density of myofilaments cytoplasmic microfilaments of actin amp myosin Excitability receive amp respond to stimulus Contractility shorten amp produce force upon stimulation Extensibility can be stretched Elasticity recoil after stretch Skeletal Muscles 44 of body mass attached to the skeletal system allow us to move organs composed of skeletal muscle cells fibers connective tissue nerves amp blood vessels muscular system includes only skeletal muscles 6 Functions of Skeletal Muscle Tissue produce skeletal movement maintain posture amp body position support soft tissues guard entrances amp exits maintain body temperature store nutrient reserves starvation only Muscles 3 layers of connective tissue epimysium perimysium amp endomysium Epimysium covers the muscle exterior colleen layer and separates it from other tissues composed of collagen connects to deep fascia Perimysium composed of collagen amp elasin has associated blood vessels and nerves bundles of muscle fibers in groups called fascicles covered by perimysium Endomysium composed of reticular fibers contains capillaries nerve fibers and myosatellite cells stem cellsgt repair surrounds individual muscle fibers Skeletal Muscle lConnective Tissue endomysium perimysium and epimysium come together at ends of muscles to form connective tissue attachment to bone matrix tendon bundle aponeurosis sheet Skeletal Muscle Nerves skeletal muscles are voluntary muscles controlled by nerves of the central nervous system nerves branch extensively as every muscle fiber must be innervated Skeletal Muscle Blood Vessels muscles have an extensive capillary system that supplies large amounts of oxygen and nutrients amp carries away wastes metabolic end products Skeletal Muscle Cells large and multinucleate formed but fusion of 100s of myoblasts nuclei of each myoblast retained to provide enough mRNA for protein synthesis in large fiber unfused myoblasts in adult myosatellite cells myosatellite cells are capable of division and fusion to existing fibers for repair but cannot generate new fibers de novo sarcolemma cell membrane maintains separation of electrical charges results in transmembrane potential NaKATPase pump maintains cell excitability Resting membrane potential ca 85 mV negative charge inside cell primarily from proteins if membrane permeability is altered Na will flow in causing a change in membrane potential Cytoplasm sarcoplasm rich in glycosides glycogengranules amp myoglobin intracellularOZ carrier Skeletal muscle fiber internal organization Transverse Tubules T tubules invaginations of sarcolemma that reach deep inside the cell to transmit changes in transmembrane potential to structures inside the cell transmit action potential through entire cell facilitates the contraction to the entire muscle fiber simultaneously by carrying depolarization deep into cell Myofibrils lengthwise subdivisions within muscle fiber hundreds to thousands in each fiber made up of bundles of protein filaments myofilaments myofilaments are responsible for muscle contraction 80 of cell volume thick actin thin myosin Sarcoplasmic Reticulum SR a membranous structure surrounding each myofibril similar in structure to smooth endoplasmic reticulum Function store calcium and help transmit action potential to myofibril Forms chambers terminal cisternae attached to T tubules Cisternae concentrate Ca2 via ion pumps ReleaseCa2 intosarco meres to begin muscle contraction SR has high density of Ca2 pumps SR Ca2 1000x gt than sarcoplasm T ads located repeatedly alone the length of myofilaments ttubule wrapped around a myofibril sandwiched between two terminal cistern of SR formed by 1 T tubule and 2 terminal cistern of SR located at both ends of a sarcomere Sarcomere smallest functional unit of a myofibril contractile units of muscle structural units of myofibrils form visible patterns within myofibrils composed of 1 Thick filaments myosin 2 Thin filaments actin 3 Stabilizing proteins hold thick amp thin filaments in place 4 Regulatory proteins contol interactions of thin amp thick filaments organization of thin amp thick filaments striated appearance Striated appearance of skeletal muscle alternating dark thick myosin filaments and the light thin actin filaments found in portions of the A band A Anisotropic polarizes light thin filaments are also found in l band l Isotropic does not polarize light 6 components of the Sarcomere Aband M line Hband Zone of overlap lband Z linesdiscs Aband whole width of thick myosin filaments looks dark microscopically M line at midline fo sarcomere center of each thick filament middle of Aband attaches neighboring thick filaments Hband lighter region on either side of the m line contains thick filaments only Zone of overlap triads encircle zones of overlap ends of Abands place where thin filaments intercalate between thick filaments Lband contains thin filaments outside zone of overlap not whole width of thin filament Z linesdiscs centers of the l bands constructed of activins anchor thin filaments and bind neighboring sarcomeres and titin proteins bind thick filaments to Zline stabilize the filament Sarcomere Function Triads transverse tubule 2 terminal cisternae of SR encircle the sarcomere near zones of overlap Ca2 from SR causes thin and thick filaments to interact Muscle Contraction Caused by interactions of thick and thin filaments Structures of protein molecules determine interactions Thin Filament StructureFunction Filamentous Factin Composed of 2 twisted rows of globular Gactin The active sites on strands of Gactin bind to myosin Nebulin Holds Factin strands together Tropomyosin Double stranded protein that covers the active sites on Gactin thereby preventing actinmyosin interaction Troponin binds tropomyosin to Gactin Also has receptor for Ca2 when Ca2 binds to the troponin C it exposes the active sites on Factin for myosin binding thereby initiating the muscle contraction Thick Filament StructureFunction Each contains about 300 twisted myosin subunits Titin anchors filaments to Zdisk and provides recoil Each myosin molecule is composed of 3 parts Tail Many tails bundled together to make length of thick filament Hinge Flexible region allows for movement in contraction Head Made of two globular protein subunits Reaches the nearest thin filament Binds to actin in active site to form actinmyosin crossbridges Sliding Filament Theory of Muscle Contraction Contraction of skeletal muscle is due to thick filaments and thin filament sliding past each other not compression of filaments Thin filaments of sarcomere slide toward M line alongside thick filaments Sliding causes shortening of every sarcomere in every myofibril in every fiber shortening of whole skeletal muscle 1 Hband and lband width decreases during contraction 2 Zones of overlap increase width 3 Zlines move closer together 4 Aband width remains constant Skeletal Muscle ExcitationContraction 1 Neural Stimulation results in the release of acetylcholine ACh at the neuromuscularjunction 2 ExcitationContraction Couplingthat is the coupling of the neural excitation with muscle contraction via a series of molecular events involving Ca2 3 Muscle Contraction and the shortening of the sarcomeres and that of the muscles involved followed by 4 Relaxation of the Muscle once the neural stimulation has ended and all Ca2 has been resequestered by the sarcoplasmic reticulum SR Neuromuscular Junction NMJ Special intercellular connection between the nervous system and skeletal muscle fiber Couples neural excitation with skeletal muscle excitation in seven steps Muscle Contraction Cycle 6 Steps of the Contraction Cycle 1 Contraction Cycle Begins 2 ActiveSite Exposure 3 CrossBridge Formation 4 Myosin Head Pivoting 5 CrossBridge Detachment 6 Myosin Reactivation IMPORTANT 1 Action potential a transient allor none change depolarization in membrane potential travels down a motor neuron and reaches the nerve terminal at the neuromuscularjunction NMJ 2 The transient depolarization at the synaptic terminal opens Ca2 channels and the influx of Ca2 into the synaptic terminal causes the release of acetylcholine ACh into the synaptic cleft via exocytosis of synaptic vesicles 3 ACh diffuses across the cleft and binds to receptors nicotinic on the motor end plate sarcolemma membrane resulting in a transient opening of nonselective cation channels 4 Cations primarily Na rush into the sarcoplasm resulting in a transient depolarization of the sarcolemma The depolarization spreads across the entire sarcolemma and is transmitted deep into the muscle via the T Tubule system 5 The depolarization affects dihydropyridine receptors DHPRs voltagesensitive calcium channels of the Ttubule system resulting in the release of a small amount of Ca2 into the sarcoplasm This release along with the mechanical link known as triadic feet which spans the sarcoplasmic gap between the Ttubule and the SR transmits the signal to calcium channels in the SR known as ryanodine receptors RyRs Opening of these channels results in the release of a relatively large amount of Ca2 into the sarcoplasma known as the calcium transient 107 gt106 M 6 Ca2 binds to troponin specifically troponin C on the thin filaments which leads to a conformational change in the troponintropomyosin complex and the tropomyosin physically moving aside to uncover binding sites for myosin binding on the actin filament known as the active site 7 The myosin head binds to actin thereby forming a crossbridge The myosin head pivots at the hinge towards the Mline as it undergoes a conformational shift known as the power stroke pulling the actin toward the center of the sarcomere and thereby shortening the sarcomere by O5 for each stroke 8 As soon as Ca2 is released into the sarcoplasm it is actively taken up by Ca2ATPase pumps in the SR Similarly as soon as ACh is released at the NMJ acetylcholinesterase degrades it Both mechanisms minimize the latency period before another excitationcontraction coupling can occur 9 With Ca2 no longer bound to troponin C tropomyosin slips back to its blocking position over the active sites on actin for myosin biding Contraction ends and actin slides back to its original resting position 10 ATP is not only required for the SR Ca2ATPase pumps but primarily for the release of the myosin head from actin and thus breakage of the crossbridge As ATP is hydrolyzed by the myosin ATPase the myosin head recocks making it ready for another power stroke Key Concepts in Skeletal Muscle Contraction amp Relaxation Cycle Skeletal muscle fibers shorten as thin filaments slide between thick filaments Free Ca2 in the sarcoplasm triggers contraction SR releases Ca2 when a motor neuron stimulates the muscle fiber Contraction is an active process Relaxation and return to resting length are passive Tension in a single muscle fiber depends on The number of pivoting crossbridges The fiber39s resting length at the time of stimulation The frequency of stimulation Tension in a group of muscle fibers depends on The number of motor units involved and the tension generated both internally and externally against elastic components Tension Production by Muscle Fibers As a whole a muscle fiber is either contracted or relaxed allor none LengthTension Relationshipj 1 Number of pivoting crossbridges depends on amount of overlap between thick and thin fibers 2 Optimum overlap produces greatest amount of tension too much or too little reduces efficiency 3 Normal resting sarcomere length is 75 to 130 of optimal length 3 Phases of a Twitch Latent period 2 msec Delay before Ca2 release as action potential moves through sarcolemma Contraction phase 2 1039s of msec Calcium ions bind to troponin Tension builds to peak Relaxation phase 25 msec Sarcoplasmic Ca2 levels fall Active sites are covered tension falls Frequency of Stimulatiod A single neural stimulation produces a single contraction or twitch 7100 msec Sustained muscular contractions require repeated stimuli A single twitch will not produce normal movement requires many cumulative twitches Repeated stimulations result in higher tensions due to some Ca2 remaining in the sarcoplasm from previous twitch 2 Types of Frequency Stimulation Treppe A stairstep increase in twitch tension Repeated stimulations im mediately after relaxation phase stimulus frequency lt50second Causes a series of contractions with increasing tension Resting tension reached between each twitch MOST SKELETAL MUSCLES DO NOT EXHIBIT TREPPE CARDIAC MUSCLE DOES Wave Summation Increasing tension or summation of twitches Repeated stimulations before the end of relaxation phase stimulus frequency gt50sec Next twitch arrives while some crossbridges still intact and some Ca2 remains in sarcoplasm resulting in increasing tension or summation of subsequent twitches upon previous This is what typical skeletal muscle contractions looks like Incomplete Tentanus Stimuli arrive at a frequency that prevents complete relaxation Ca2 reabsorption so that tension builds upon the previous twitch Not complete tetanus because some relaxation occurs between twitches A type of wave summation that reaches a plateau in tension that is stimulus frequency dependent Complete Tetanus lf stimulation frequency is high enough muscle never begins to relax and is in continuous contraction Produces 4x more tension than max treppe Stimulus frequency higher than Ca2 pumps can work amp thus no relaxation only summation Fatigues easily at this rate of stimulation After a long period of tetanus tension will fall off below max tension Tension Produced By A Whole Skeletal Muscle Depends On 1 Internal tension produced by sarcomeres Not all tension is transferred to the loadsome of it is lost due to the elasticity of muscle tissues 2 External tension exerted by muscle fibers on elastic extracellular fibers Tension applied to the load 3 Total number of muscle fibers stimulated Motor Unit All fibers controlled by a single motor neuron avon branches to contact each fiber each skeletal muscle has thousand of fibers organized into motor units number of fibers in a motor unit depends on the function fine control 4unit gross control ZOOunit fibers from different units are intermingled in the muscle so that the activation of one unit will produce equal tension across the whole muscle Recruitment multiple motor unit summation In a whole muscle or group of muscles smooth motion and increasing tension are produced by slowly increasing the size or number of motor units stimulated Order of activation of motor units is important Slower weaker units activated first stronger units are added to produce steady increases in tension as required Maximum tension achieved when all motor units reach tetanus can be sustained only a very short time Sustained Tension Typically less than maximum tension Allows motor units rest in rotation Force is increased by increasing the number of motor units recruitment Muscle Tone Resting tension Maintains shapedefinitionsome units always contracting Braces skeleton amp acts as shock absorber accelerates recruitment Exercise increases the number of contractual units gtincreases metabolic rate even at rest gt increases speed of recruitment better tone Contractions are classified based on pattern of tension production Isotonic Contraction Skeletal muscle changes length resulting in motion If muscle tension gt load muscle shortens concentric contraction If muscle tension lt load muscle lengthens eccentric contraction Isometric Contraction Skeletal muscle develops tension but is prevented from changing length eg postural muscles Load resistance amp Contractile Speed Are inversely related The heavier the load on a muscle the longer it takes for shortening to begin and the less the muscle will shorten As load T speed of crossbridge pivoting l Muscle Relaxation passively returns to resting length Elastic recoil The pull of elastic elements tendons and ligaments Expands the sarcomeres to resting length Opposing muscle contractions Reverse the direction of the original motion eg bicep vs tricep brachii Gravity Opposes muscle contraction to return a muscle to its resting state Muscles fatigue when they can no longer perform a required activity due to 1 Depletion of reserves glycogen ATP CrP 2 Decreased pH due to lactic acid accumulation this decreases calcium binding to troponin and alters enzyme activities 3 Damage to sarcolemma and sarcoplasmic reticulum 4 Sense of weariness and decreased desire to continue as a result of pain The higher the degree of fatigue the longer the recovery time replenishment nutrients include ATP CrP glycogen oxygen and Cori cycle in liver lactate gt pyruvate gt glucose repair of damage Force amount of tension produced Power amount of tension produced per unit time Endurance amount of time an activity can be sustained Force Power and Endurance Depend On 1 the types of skeletal muscle fibers 2 physical conditioning Fast Glycolytic Fibers Fast twitch Type llb Myosin ATPase works quickly fast cycling ATP production via glucose fermentation anaerobic glycolysis Large diameter fibers Many myofilaments and high glycogen supply Few mitochondria Fast to act powerful but quick to fatigue Slow Oxidative Fibers Slow twitchType l Myosin ATPases work slowly Specialized for aerobic respiration many mitochondria extensive blood supply capillarity amp myoglobin red pigment binds oxygen Smaller fibers for better diffusion Slow to contract produce lower tension but resist fatigue Catabolize lipids glucose and amino acids Intermediate or Fast OxidativeGlycolytic Fibers Intermediate twitch Type lla Qualities of both fast glycolytic and slow oxidative fibers Fast acting but perform aerobic respiration so slow to fatigue Intermediate levels of myoglobin and capillarity Physical conditioning can convert some fast fibers into intermediate fibers for stamina Extra Chapter 10 Details White Muscles mostly fast fibers pale chicken breast Red Muscles mostly slow fibers dark chicken legs Most human muscles are pink and contain a mix of fibers Muscle Hypertrophy Muscle growth from activity eg training especially when repeatedly near maximal tension May increase diameter of muscle fibers number of myofibrils andor mitochondria number myoglobin content capillary density glycogen reserves Does NOT increase number of muscle fibers Muscle Atrophy Muscle loss due to inactivity Reduced muscle size tone and power Aerobic Activities Endurance training prolonged activity is supported by mitochondrial metabolism amp requires oxygen and bloodborne nutrients Improves endurance by training fast fibers to be more like intermediate fibers Improves cardiovascular performance Does NOT result in muscle hypertrophy Training Increases Aerobic EnduranceEfficiency by Increasing capillary density as well as mitochondria and myoglobin content Anaerobic Activities Uses fast fibers which fatigue quickly with strenuous activity weightlifting Improved by frequent brief intensive workouts Training causes hypertrophy fibers increase in diameter NOT NUMBER increase number of myofibrils amp myofiIaments thereby increasing the tension that can be generated Training Increases Anaerobic Endurance Efficiency by Increasing glycogen supply amount of ATP and CrP available and tolerance to lactic acid generation amp increases power output and sustainable anaerobic duration Exercise is important because What you don39t use you lose Muscle tone indicates base activity in motor units of skeletal muscles Muscles become flaccid when inactive for days or weeks Muscle fibers break down proteins become smaller and weaker With prolonged inactivity fibrous tissue may replace muscle fibers Crosstraining that is training by alternating aerobic and anaerobic activities enhances health by increasing both muscle mass and aerobic endurance Cardiac Muscle Tissue Cells are striated and only found in the heart Striations are similar to that of skeletal muscle because the internal myofilament arrangement is similar 7 Characteristics of Cardiomyocytes 1 Are small Have a single nucleus typicallysometimes 2 Have short wide T tubules that surround Zline Have no triads Have SR with no terminal cisternae Are highly aerobic high in myoglobin amp mitochondria lCDO lPOON Have intercalated discs gap junctions and desomosomes which enhances molecular and electrical AP connections lntercalated discs link cardiocytes mechanically chemically amp electrically Heart functions like a single fused mass of cells lntercalated Discs Are specialized contact points between cardiomtocytes Join cell membranes of adjacent cardiomyocytes gap junctions desmosomes Maintain structure enhance molecular and electrical connections amp conduct action potentials Coordination of cardiomyocytes because intercalated discs link heart cells mechanically chemically and electrically the heart functions like a single fused mass of cells Functional Characteristics of Cardiac Muscle Tissue 1 Automaticity Contraction without neural stimulation Controlled by pacemaker cells cells that generate action potentials spontaneously found in the sinoatrial and atrioventricular nodes and Purkinje fibers 2 Variable contraction tension and pace Controlled by nervous system 3 Extended contraction time Ten times as long as skeletal muscle 4 Prevention of wave summation and tetanic contractions by cell membranes Long refractory period only twitches Smooth Muscle Tissue nonstriated muscle tissue with different internal organization of actin and myosin and different functional characteristics than that of striated muscle lines hollow organs and regulates blood flow and movement of materials in organs organized in 2 layers circular amp longitudinal Characteristics of Smooth Muscle Tissue Long slender and spindle shaped Have a single central nucleus Have no T tubules myofibrils or sarcomeres Have no tendons or aponeuroses Have scattered myosin fibers Myosin fibers have more heads per thick filament Have thin filaments attached to dense bodies Dense bodies transmit contractions from cell to cell Structurally different than striated muscle no troponin active sites on actin are always exposed Smooth Muscle Contraction Events 1 Stimulation causes Ca release from SR 2 Ca2 binds to calmodulin in the sarcoplasm Calmodulin CALcium MODULated protelN 3 Calmodulin activates myosin light chain MLC kinase this complex phosphorylates myosin 4 MLC Kinase converts ATP gt ADP to cock myosin head 5 Cross bridge form gt contraction cells pull toward center Length Tension Relationships Smooth Muscle Tissue Thick and thin filaments are scattered Resting length not related to tension development Functions over a wide range of lengths plasticity Control of Contractions Smooth Muscle Tissue Multiunit smooth muscle cells that are connected to motor neurons Visceral single unit smooth muscle cells that are not connected to motor neurons and produce rhythmic cycles of activity controlled by pacese er Modified by neural hormonal or chemical factors
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