Unit 2, Week 6 Notes
Unit 2, Week 6 Notes PET3322
Popular in Functional Anatomy and Physiology I
Popular in Anatomy and Physiology
This 8 page Class Notes was uploaded by mak15k on Thursday October 6, 2016. The Class Notes belongs to PET3322 at Florida State University taught by Arturo Figueroa-Galvez in Summer 2016. Since its upload, it has received 16 views. For similar materials see Functional Anatomy and Physiology I in Anatomy and Physiology at Florida State University.
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Date Created: 10/06/16
10/4/2016 TUESDAY UNIT 2- NERVOUS SYSTEM (LECTURE 3) CHAPTER 15- SENSORY, MOTOR, NAD INTEGRATIVE SYSTEMS (CNS PP) Nerves contain several notable connective tissue layers: o endoneurium- around each axon (propagation of the neuron) o perineurium- around each fasicle (group of axons) o epineurium- around entire nerve Nerves are located in various systems: o PNS = nerve o CNS = tracts same thing! just different location, so different name...in class, Dr. Figueroa vs. at home, dad Sensory nervous systems respond to stimuli by sending signals to the CNS integrative systems (within CNS) process and evaluate that sensory information in a process called integration Motor systems carry signals from the CNS to effectors, and makes sure that motor output is coordinated for efficient responses sensory neurons are supposed to carry information from CNS to PNS...in the distal end, there is a receptor, and in the proximal end, there is am axon terminals (neurotransmitters are here and synapse) Nociceptors are free nerve endings found everywhere in the body (except the brain). Nociceptors have several unusual properties o Nociceptors are activated by multiple types on stimuli o Many chemicals can stimulate nociceptors, and/or sensitize them to other stimuli - in this way pain plays a major role in inflammation o Nociceptors adapt poorly, allowing pain to continue o don't need to know the process specifically we know where our various body parts are, but we don't know (without anatomy class) where these organs are just based on what we feel inside...we feel pain from different organs in places that the organs are not located; referred pain in left arm when myocardial infarction occurs and many people don't recognize the symptoms something enters skin painfully...neuron transports to dorsal (back) spinal cord...peripheral neurons in between sensory and motor...soma dendrites of peripheral motor neurons go to the muscle after ACh stimulates it to move away somatosensory cortex- most external area in the brain; "somato" = body Know how to identify the origin and insertion of the spinal tracts o somatic sensory pathways carry information from the body to the somatosensory cortex o second-order = central sensory neuron o first- order = peripheral sensory neuron o third-order = sensory; conducts impulse into somatosensory cortex o example: direct flight from Tallahassee to NYC, get two tickets...one says "TAL, NY" and the other says "NY, TAL" which tells you the origin and the destination...neurons are similar "spinothalamic tract" ---> from the spine to the thalamus in the CNS o see picture on next page (the picture below is the only pathway that matters in terms of the information on the test) There are areas in our body that are more sensitive than others; most sensitive areas are the hands (mainly fingers) and the lips because they have more receptors in the brain postcentral gyrus- separates anterior is motor, posterior is somatosensory your face has more control over contraction than the muscles of the legs because of the amount of neurons in the brain of the respective areas o the face has small motor units the allow for more precise movements stimulation of motor neurons in CNS will bring action potentials to the spinal cord know the identification of the meaning of the names (lateral corticospinal tract...cortex to spinal cord in CNS) not their function or any details like that 80% of left brain refers to the right side of the body, and 20% remains referred to the left side (opposite is true of the right brain); the crossing over sections of the left and right axons is called decussation of pyramids in the brain stem, medulla oblongata cervical spinal cord = muscles of the arm lumbar area = muscles of the legs Reflexes: involuntary movement with the spinal cord as the integrative center o is someone has a spinal cord injury, they cannot produce voluntary contraction of the lower body muscles, but only involuntary (disconnection between the brain and the muscles) Reflexes are rapid, involuntary responses to stimuli. Reflexes are predictable: a specific stimulus always gives the same response o Cranial reflexes are integrated in the brainstem o Spinal reflexes are integrated in the spinal cord o Somatic reflexes have responses involving skeletal muscles o Autonomic reflexes involve internal processes, and are usually not consciously perceived o Many reflexes are tested clinically because they provide us with functional information about the health of the nervous system Hypothalamus- middle of the thalamus; controls the pituitary, and therefore is the main controller of the endocrine system; controls the medulla, and therefore is the main controller of the cardiovascular system o Regulates ANS activity by controlling centers in the brain stem and spinal cord o Regulates blood pressure, rate and force of heartbeat, digestive tract motility, rate and depth of breathing, and many other visceral activities pituitary gland- below the hypothalamus; probably the most important pure endocrine gland in the body medulla- cardiovascular center of control; cells here are neurons to control the heart and the blood vessels (autonomic nervous system); also the respiratory center with neuron cells o hypothalamus controls the body temperature by vasodilatation (skin turns red) when hot, and vasorestriction (skin turns blue) when cold brain stem- beginning of the spinal cord that contains the cranial nerves o three areas: mid-brain at top, pons in between, and medulla on the bottom 10/6/2016 THURSDAY UNIT 2- MUSCULAR SYSTEM (LECTURE 4) Exam 2 is on the 18th- covers nervous and muscular systems only PROPERTIES OF MUSCLE contractility (lifting weights), excitability (stimulus response with nerves), extensibility (stretching), and elasticity (recoil to homeostasis after a stretch) o reduced physical ability as we age leads to reduced elasticity; immobilization after injury...use it or lose it striated = banded; appearance of muscle (under microscope) due to light and dark banding; smooth muscle doesn't have striations Connective tissue membranes: (prefixes are the same as neurons...-mysium = muscle) o epimysium- connective tissue that covers and surrounds the whole muscle o perimysium- denser; surrounds a group of muscle fibers (fasciculus) o endomysium- loose connective tissue with reticular fibers myocytes = muscle cells...more usually called "muscle fiber" Muscular fascia (surrounds individual muscles and groups Epimysiums) Artery (surrounds muscles) Vein Perimysium Nerve (surrounds fasciculi) Endomysium (surrounds muscle fibers) Muscle fiber Artery Nerve Vein Fasciculus Capillary Axon of motor neuron Synapse or neuromuscular junction neuromuscular junction: the contact between an axon terminal and a muscular fiber; the presynaptic terminal releases ACh into the synaptic cleft after an action potential so that the postsynaptic terminal can cause a response in the muscle sarcolemma: membrane of skeletal muscle mitochondria of skeletal muscle: mitochondria (: myoglobin: a cytoplasmic protein that binds oxygen...a globin in the muscle = myo- vs. a globin in the blood = hemoglobin (stores oxygen for exercise) sarcoplasmic reticulum: a network of membranous sacs around the myofibrils; the SR stores calcium ions. myofibril- muscles can be broken down to this level; it is made of myofilaments: o actin or thin filaments (smaller); 2 of them; attached to the z-disk; allows the muscle to contract and become stronger o myosin (bigger); 1 of them; located in the center of the sacomere when muscle is relaxed o know this slide (#11): function of the sarcomere (between the z-disks that together make up striations of myofibrils) is to contract the muscle and become shorter (move actin to the center of the muscle, taking along with it the z-disk) and its length is shortened the dark and light band colors are caused by density of proteins/ filaments o since myosin is bigger, it is more dense; in the region of the sarcomere where we have more myosin, it will look darker o the opposite is true- actin is smaller and therefore less dense, so it appears lighter; 1/2 of the light band belongs to one sarcomere, and the other half belong to the band adjacent to it Actin filaments: has three components... o most important is called G or F-actin (looks like blueberries on the slide) because it has active sites (yellow dots on slide) which are a kind of receptor for the heads of the myosin filaments o tropomyosin- another stranded protein that covers the active site of the G-actin during a relaxed state; to uncover the active sites and remove the tropomyosin we need troponin o troponin- only globular/ bulbous protein; has 3 subunits- one os attached to the G-actin, one is attached to the tropomyosin, and one free one on the top that is the receptor for Ca TnI: attached to the G-actin TnC: receptor for Calcium TnT: attached to tropomyosin Myosin filaments o myosin heads are the most important because there is an enzyme (ATPase) that helps to release the energy from ATP that is important for muscle contraction during exercise Calcium in the stored in the skeletal muscle- sarcoplasmic reticulum (thin and porous and thicker at the ends) in the cisterna transverse tubule: where the sarcomere enters into the membrane so that the action potential can propagate itself to release Ca from the SR to the sarcoplasm so it can bind to troponin-C, move tropomyosin, allowing myosin to bind to the active sites, producing a muscle contraction The T tubules penetrate into the cell’s interior (continuation of the sarcolemma) o T tubules associate with the paired terminal cisternae to form triads Striated appearance o I bands: from Z disks to ends of thick filaments o A bands: length of thick filaments o H zone: region in A band where actin and myosin do not overlap 6 actins surround one myosin o the more myosin heads binding to the actin heads, the more powerful the contraction of the muscle Sliding Filament Model/Theory- myosin moves the actins because the z-disk is attached and the length of the sacomere decreases as does the length of the muscle fiber & the whole muscle o actin slides over the myosin to create movement (the picture below explains this visually) Z H Z I A I (a) Relaxed sarcomere In a relaxed muscle, the actin and myosin myofilaments overlap slightly, and the H zone is visible. The sarcomere length is at its normal resting length. As a muscle contraction is initiated, actin myofilaments slide past the myosin myofilaments, the z disks are brought closer together, and the sarcomere begins to shorten. Z Z I A I (b) Fully contracted sarcomere In a contracted muscle, the A bands, which are equal to the length of the myosin myofilaments, do not narrow because the length of the myosin myofilaments does not change, nor does the length of the actin myofilaments. In addition, the ends of the actin myofilaments are pulled to and overlap in the center of the sarcomere, shortening it and the H zone disappears. Length of the A-band is not changing because this is the myosin...the I-bond shortens because this is the actin moving over the myosin
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