Chapter 7 Muscle System and Chapter 8 Nervous System
Chapter 7 Muscle System and Chapter 8 Nervous System BIO 1004
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Date Created: 02/14/16
Chapter 7 Muscle: Smooth: elliptical in shape; one nucleus per cell; no striations; it is not as strong as the other muscle types because it lacks striations; involuntary control; found in digestive track, circulatory system, reproductive systems; it is found in other areas but large concentrations are in those areas; it can contract and relax; contract=shorten; to contract a muscle requires calcium, potassium, electrical impulse (nervous system) and ATP (energy); fatigues slowly but recovers quickly Cardiac: deep striations indicate strength; is the strongest; found in the heart; cardiac muscle: the electrical stimulation is not from the nervous system(Originates in the heart);branched structure; each cell is fused with several other cells; it allows an electrical impulse to travel between muscle cells; one nuclei per cell; ***nonfatiguing*** Skeletal: multiple nuclei per cell; mild striations (moderately strong); physical activity influences the striations; cells are no longer fused together; in the past, they may have been fused together which could explain the multiple nuclei; cylindrical in shape; quick to fatigue and slow to recover; voluntary control; can either relax or contract All muscles: contain muscle tissue, blood vessels, connective tissue, nervous tissue Terms: o Myoglobin (chemical that is similar to hemoglobin) chemical stored in muscle that carries oxygen; oxygen is required in muscle contraction; gives muscle a reddish color; the more conditioned a muscle, the darker the muscle tissue due to increased concentration of myoglobin. o Hemoglobin: Found in blood and carries oxygen; dark red o Antagonistic pairs: most muscles occur in antagonistic pairs; relax and contract; in the relaxed state you can lengthen the muscle through force; in antagonistic pairs, one set of the pair contracts while the other relaxes. This allows for opposing actions; o Synengists: smaller muscles that work with a larger muscle group; they provide additional strength o Origin: the origin of the muscle is where it is attached to a stationary bone o Insertion: the point of attachment to the moving bone Biceps the origin in on the humerus; the insertion is on the radius and ulna. Functions of Skeletal muscles: o supports the body against gravity o moves bones o generally it moves the bone below the attachment point o maintain body temperature; protects internal organs o stabilizes joints o moves blood in veins o moves lymph in lymphatic vessels (Last 2 mechanisms are the exact same type) Look up and learn locations o Trapezius o Deltoid o pectoralis major o triceps/biceps brachii o latissimus dorsi o abdominal muscles o gluteus maximus o sartorius o biceps femoris o rectus femoris o gastrocnemius Structure Largest to smallest: Muscle: covered by connective tissue (fascia) which eventually forms tissues; fascia thickens towards the ends of the muscle, forming the tendons. Muscle bundle: bundles of fibers, each of which are enclosed in connective tissue Muscle fiber: groups of myofibrils Myofibrils: functional unit of the muscle (part that gets shorter) Myofibril: functional unit of the muscle; contains protein actin and myosin. They (actin and myosin) slide past one another which cause the myofibril to shorten(contract). This requires ATP, calcium, potassium, electrical charges. You can control the number of myofibrils that contract at any given time, which allows you to control the strength of the muscle. Muscle contractions o The contraction of numerous myofibrils o Requires electrical stimulation from nervous tissue o Requires calcium o Requires ATP to force actin to slide past myosin o Glycogen: provides glucose for ATP production o Creatine Phosphate: aids in regeneration of ATP (fast) o Fermentation: production of ATP without the use of oxygen/leads to a buildup of lactic acid in tissue; Fermentation powers quick explosive movements; this lactic acid accumulates near the joints; stimulates the nerve endings in those areas causing pain Atropy: the shrinkage of muscles due to nonuse; muscle tissue is slowly replaced with connective tissue and adipose tissue; if atrophy continues over long periods of time, it may lead to contortion of body parts Hypertrophy: enlargement of muscles due to increased number of myofibrils; must be worked to 75% of maximum on a continuous basis Steroids: specific group of hormones produced by males that allow for faster muscle recovery o The good: they are commonly used to treat injuries and also abused; the group that abuses steriods the worst are men between the age of 4050; 2nd worst is female athletes o The bad: abused quite often which can lead to injuries; not necessarily muscle tissue; they can cause the testicles to shrink, which may be irreversible in some; can cause hair to fall out; cause acne; can cause severe mood swings. in most cases, males who abuse steroids, symptoms may disappear with the discontinued use of steroids o The sometimes really ugly: Female abuse of testosterone: they become masculinized; breast tissue diminishes, the voice becomes deeper (irreversible); hair loss; acne; increase in the size of the external genitals (irreversible) Slow twitch: provide endurance; slow to fatigue; darker in color (myoglobin); greater blood supply; aerobic (consume large amounts of oxygen); females generally have more slow twitch muscle fibers than males Fast twitch muscle: provide explosive strength, quick to fatigue, light in color (have a reduced amount of myoglobin), less blood supply, anaerobic; males tend to have more fast twitch muscle fibers than females Basic terminology: o Prime mover: the muscle that provides the most amount of force in a contraction Chapter 8: Nervous System Spinal cord terminates in somewhere around the lumbar vertebrae. Central Nervous System: Brain and spinal cord Peripheral Nervous System: anything other than the brain and spinal cord; it is the nerves that connect to the spinal cord Working Unit of the Nervous System: o Neurons: It is a cell that can generate or transmit an electrical impulse Parts of a neuron (1)cell body: contains the nucleus and organelles; (2)Dendrites: may receive electrical impulses from adjacent neurons; (3)Axons:Transmits electrical impulses away from the cell body; they are normally connected to the dendrites of adjacent neurons; may be connected to the cell body of adjacent neurons; each neuron connects to multiple other neurons Connect: a loose indirect attachment not a direct connection Terminal Button Direction of an electrical flow in a neuron: dendrites to cell body to axons; this is a unidirectional flow (one way). Can’t force it to go the other way. Neuroglia cells: Support the neurons; they can provide protection; physical support for nutrients; Schwann Cells: surround the axons of some neurons; they produce a protein called myelin which speeds up electrical impulses; Oligodendrocytes: produce myelin on the axons of some neurons Schwann cells are derived from the neural crest; oligodendrocytes are derived from the neural tube. Motor neurons have long axons and short dendrites. Sensory neurons have long dendrites and short axons. 3 classes of neurons: o Sensory Neuron: associated with the sense organs o Motor Neuron: associated with the muscles o Interneurons: Found predominately in the brain; they receive info from the sensory neurons; they perform integration on that information; and they export info to the motor neurons. Nerve Impulses: electrical impulses will NOT cross a gap; there is a gap between the axons and dendrites of adjacent neurons; in order for an impulse to be transmitted across this gap, the gap needs to be filled. (The gap is called the Synaptic Gap (Cleft)); when an impulse reaches the gap, neuro transmitters are released from the axon; they briefly fill the synaptic gap. The impulse crosses the cap, the neuron transmitters are absorbed by the dendrites, which reestablishes the gap. Synaptic gap controls whether or not an impulse reaches its target area. Neuro transmitters can be recycled. Produced in the cell body; If you have an syndrome labeled as a chemical imbalance, then you are not producing enough of neuron transmitters. Brain Stem: Controls basic body functions; including heart rate, breathing rates, vomiting, coughing, hiccups, and blood pressure; also controls some reflexes of the head and neck that are stimulated by auditory inputs (loud noises) and by visual inputs (incoming projectiles to dodge) o Consists of 3 parts: Medulla: connects directly to the spinal cord. Midbrain Pons Division of the brain o Diencephalon: most of the diencephalons is hallow and filled with fluid; the region is divided into 2 parts: Thalamus region: basically a relay center. it receives all inputs from the sense organs and relays those inputs to other areas in the brain Hypothalamus: it functions with the brain stem (it does almost everything the brain stem can do) but in addition it controls appetite, body temperature, water balance of the blood, blood pressure, sexual activity, (really important) serves as a link between the nervous system and the endocrine system, it controls the pituitary glands. Pituitary glands controls most other endocrine glands. o Cerebellum: 2nd largest region of the brain, divided into left and right hemispheres, main function control of skeletal muscle, it controls antagonistic pairs of skeletal muscles, it ensures that one member of the antagonistic pair relaxes while the other one contracts; it controls muscle tone (tone is the stiffness under muscles at rest) (some muscle fibers with all muscles are contracted at any given time, not always the same) it also controls posture (posture is controlled by contracting specific muscle fibers) o Cerebrum: largest portion of the human brain, divided into right and left hemispheres that are interconnected, controls conscious thought, dreams, memory. Sulci and gyri are the convolutions (raised areas and valleys) of the brain Intelligence correlates with the number of sulci and gyri. The more bumps and ridges, the potentially more intelligent you are. Spinal Cord: Terminates around the lumbar, runs on the outside of the vertebral column, protected by neural spines; it is hallow; made up of gray matter and white matter; white matter is made up mainly of axons and dendrites; gray matter is made up mainly of cell bodies; the spinal cord mainly controls skeletal muscle; serves as a connecting point for peripheral nerves Meninges: are several layers of connective tissue that surround and protect the brain and spinal cord; retains fluid against the brain and the spinal cord; acts as a shock absorber o Meningitis: infection of the meninges Ventricles: are hallow regions of the brain and spinal cord; there are 4 ventricles within the brain; all 4 ventricles produce cerebrospinal fluid; this fluid fills the ventricles and support the brain; 2 lateral ventricles (left & right)(are the largest) found in the cerebrum; 3rd ventricle (name) found in the diencephalon, 2nd largest; the 4th ventricle (name) found in the brain stem: connects to the hallow region of the spinal cord **** All ventricles are interconnected**** The ventricles are drained by the hallow space in the spinal cord, the fluid accumulates in the meninges. Peripheral Nervous System: o Somatic Nervous System: a division of the Peripheral nervous system; consists of Cranial nerves Cranial nerves: are found mainly in the head; they are associated mainly with the sense organs; occur in pairs; they connect directly to the brain, not to the spinal cord; Examples: optic nerves (connects eyes to brain) vegus nerve: occurs in pairs, not connected to spinal cord; branches and connects to the internal organs Spinal Nervers: occur in pairs, connect directly to the spinal cord, control skeletal muscle o Autonomic Nervous System: a division of the peripheral nervous system; can be divided into the 2 parts Parasympathetic Division: controls the body under normal conditions; mainly influences smooth muscle and endocrine gland Sympathetic Division: fight or flight; controls the body during times of stress; it shuts down smooth muscle contraction; it causes skeletal muscle to contract more forcefully; causes the release of adrenaline; increases heart rate, increases breathing rate
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