Anatomy Exam 3 - Study guide for exam 3 PDF

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Anatomy Exam 3 Muscles 1. Functions a. Movement b. Maintaining posture and body position c. Stabilizing joints d. Heat generation – especially in skeletal muscles i. ~40% is usefully as work and the rest is given off as heat ii. Dangerous heat levels are prevented by radiation of heat from the skin and sweating 2. 3 Types of Muscle tissues a. Skeletal muscle tissue: i. Attached to bones and skin ii. Striated iii. Voluntary (under conscious control) b. Cardiac muscle tissue i. Only in the heart ii. Striated c. Smooth muscle tissue i. In the walls of hollow organs: stomach, urinary bladder, and airways ii. Not striated iii. Involuntary d. All are: i. Vascularized and innervated- one artery, one nerve, and one or more veins ii. Excitability – by nervous system iii. Contractibility – pulls iv. Extensibility – stretches v. Elasticity – can do both and return to normal shape 3. Skeletal muscle organization a. Myofibrils are made of myofilaments. Actin and myosin are arranged to make sarcomeres. These are bundled together along with mitochondrion and nuclei and covered by a sarcolemma to make a myofibril. i. Z disc – No change ii. I band – shortens iii. A band – No change iv. H zone – disappears v. M line – No change b. Myofibrils are bundled together and covered by endomysium = fascicle c. Fascicles are covered by perimysium d. Fascicles bundled together and covered by epimysium = muscle

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Anatomy Exam 3 4. Skeletal muscle contraction a. Myosin has globular heads at an angle i. Head have ATP binding sites b. Actin partially overlaps with myosin c. Actin forms a double twisted strand i. Two regulatory protein tropomyosin and troponin bind to cover binding sides on Actin when not contracting d. Sliding filament theory i. When Ca++ comes in it interacts with the regulatory proteins and exposes the binding sites on actin ii. Myosin heads bind to actin to form a cross bridge 1. ATP  ADP iii. Myosin heads undergo conformational change and change angle iv. Myosin heads detach (cross bridge detachment) return to normal state and then bind again to undergo conformational change v. Repeat to pull sarcomere tight = contraction e. Sources of ATP to support skeletal muscle contraction i. Stored ATP - used first ii. Creatine Phosphate (CP) - ATP produced from direct phosphorylation of ADP by CP using the enzyme Creatine Kinase: 1. CP + ADP  ATP + creatine iii. Aerobic catabolism of glucose - produces the most ATP iv. Anaerobic catabolism of glucose – pyruvic acid is converted into Lactic Acid + ATP v. ATP use in skeletal muscle contraction 1. To activate myosin heads (enables crossbridge attachment) 2. For crossbridge detachment 3. Sequestration of calcium ions back into the Sarcoplasmic Reticulum for storage (active transport) f. Strength of contraction is affected by i. Sarcomere length prior to contraction 1. Very short – 1.2µm a. 0 force 2. Short – 1.2 – 2.1 µm a. Force – varies ~60% 3. Be able to read chart ii. The number of muscle fibers stimulated iii. The size of fibers through hypertrophy iv. The frequency of stimulation 5. Rigor Mortis a. Body stiffens about an hour after death because there’s no ATP to continue or end contraction. Body uses all ATP and then stops 6. The Triad a. Surrounds bundles of myofibrils all housed in the sarcolemma. 2

Anatomy Exam 3 b. Part of the Sarcoplasmic reticulum (SR) which stores Calcium for muscles contractions c. Terminal cisternae – T (transverse) tubules – Terminal cisternae i. Happens at the A band/ I band junction 7. The neuromuscular Junction a. Where the nerve meets the muscles b. Each muscles fiber has only one neuromuscular junction c. Axon terminal does not directly touch the muscle. There’s a synaptic cleft which is a space between the axon and the fibers. d. An impulse is sent down the axon of a motor neuron. The Axon releases acetylcholine (Ach), a neurotransmitter, which defuses across the cleft and binds to receptors on the surface of the sarcolemma. When enough has been stimulated, the sarcolemma exhibits electrical changes (negative to neutral charge). The electrical changes spreads until it reached the SR where it stimulates the voltage-gated channels that regulate the Ca++ release from the SR cisternae. When it’s released it binds to the regulatory protein so the myosin heads can bind to the actin and boom sliding filament theory 8. Motor unit a. The motor neuron and all the skeletal muscles fibers it innervates. b. One motor neuron innervates many muscle fibers but a muscle fiber is only innervated by one motor neuron i. Can’t have it listening to more than one thing at once c. Smaller motor units are for fine movement like fingers while the big ones are for large weight-bearing muscles and gross movements like thighs 9. Tension vs Load a. Tension = force exerted by contracting muscles b. Load = opposing force exerted on the muscles by weight of the object moved c. Tension > load = able to move object d. Tension does not equal shortening fibers. It can be static like holding a book or rigor mortis. Shortening happens then the tension exceeds the opposing force. Isotonic Contractions o Eccentric is when the muscle - Muscle changes in length and moves contracts as it lengthens the load - Are eight concentric or eccentric Isometric contractions o Concentric is when the - The load is greater than the tension the muscle can develop muscles shorten and does - Tension increases to the muscles work capacity, but the muscle neither shortens nor lengthens

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Anatomy Exam 3 10. Skeletal muscle fiber types a. Classified by the speed and ATP pathways b. Speed of contraction – how fast Myosin ATPase hydrolyzes ATP i. Slow or Fast c. Major pathway for ATP production i. Aerobic respiration  oxidative fiber ii. Anaerobic respiration using glycogen  glycolytic fibers d. Slow oxidative fibers (marathon runners – endurance) e. Fast oxidative fibers (sprinters) f. Fast glycolytic fibers (Baseball and hokey) 11. Exercise a. Aerobic endurance exercise i. Leads to an increase in 1. Muscle capillaries 2. Number of mitochondria 3. Myoglobin synthesis 4. Can convers fast glycolytic fibers into fast oxidative fibers 5. INCEASE STAMINA b. Resistance exercises (typically anaerobic) i. Leads to an increase in 1. Muscles hypertrophy – increase in size a. Myofibril 2. Glycogen stores 3. INCREASE MUSCLE STRENGTH 12. Smooth Muscles a. Found in the walls of most hollow organs – not the heart b. Usually has two layers i. Longitudinal and circular c. Has slower contractions i. Myosin ATPase 10-100X slower than skeletal 13. Differences between Smooth and Skeletal a. Smooth are i. Spindle-shaped and uninucleate ii. No striations – thick and thin filaments are arranged diagonally instead of alternating iii. Lacks a sarcomere and myofibrils iv. Thick filaments have heads along their entire length v. Doesn’t have a Z line 1. Dense bodies anchor the thin filament with intermediate filaments attached to resists tension vi. There’s no troponin complex instead a protein calmodulin binds Ca vii. Tropomyosin is present in think filaments but does not block binding sites viii. Sarcolemma of smooth muscles lacks a T-tubules 4

Anatomy Exam 3 1. Shallow cavities called caveoli that contain extracellular fluid rich in calcium ix. Only has an endomysium 14. Excitation – Contraction coupling in smooth muscle a. Calcium ions enter the cytosol via calcium channels in plasma membrane and SR b. Ca binds to and activated calmodulin c. Activated the myosin light chain kinase (MLCK) enzymes d. The activated kinase enzyme convers ATP to ADP + pi which phosphorylates myosin and activates it e. Activated myosin forms cross bridges with actin of the thin filaments and shortening begins. f. Repeats 15. Contractions a. Smooth and synchronized thanks to gap junctions that electrically couple cells b. Some cells are self-excitatory i. Pacemakers that change electrical potential without external stimuli c. Rate and intensity of contraction may be modified by neutral and chemical stimuli d. Also, the sliding filament mechanism 16. Peristalsis a. Longitudinal layer contracts – the organ dilates and shortens b. Circular layer contracts – the organ constricts and elongates c. Moves substances along via sequential alternating waves of contractions 17. Cardiac Muscle a. Intercalated Disks i. Gap junctions ii. Desmosomes b. Aerobic muscles – coronary circulation c. Minimal cell division after infancy – gets bigger via hypertrophy and Autorhythmic cells d. 1% Autorhythmic cells e. 99% contractile cells 18. Cardiac Vs Skeletal similarities a. Striated with sarcomeres b. Troponin and tropomyosin c. T-tubules and SR d. Like slow oxidative fibers i. Myoglobin, mitochondria, and slow to fatigue 19. Cardiac Vs smooth similarities a. Gap junctions 5

Anatomy Exam 3 b. Pacemakers and Autorhythmic cells c. Innervated by autonomic nervous system – involuntary d. Influenced by hormones Nervous System 1. Functions a. Sensory input b. Integration c. Output 2. Afferent vs efferent a. Afferent nerve fibers – conduct signal TO CNS i. Sensory b. Efferent nerve fibers – conduct signals AWAY from CNS i. Motor neurons and effector neurons 3. Central Nervous System (CNS) a. Consists of the brain and the spinal cord. The dorsal body cavity surrounded by meninges 4. Peripheral Nervous System (PNS) a. All neutral structures outside of the CNS like cranial nerves, spinal nerves, and sensory receptors b. Many subdivisions i. Sensory 1. Somatic afferent fibers 2. Visceral afferent fibers ii. Motor 1. Somatic nervous system (voluntary) 2. Autonomic (involuntary) a. Sympathetic b. Parasympathetic 5. Histology a. Neurons – excitable cells that transmit electrical signals i. Special characteristics 1. Generally amitotic cells (no cell division after birth) 2. High metabolic rate a. Continuous supply of oxygen and glucose ii. Made of 1. Cell body – soma 2. Dendrites: reception of incoming info 3. Axon: transmits electrical impulses called action potentials 4. Axon hillock 5. Axon terminal 6

Anatomy Exam 3 b. Neuroglia (glia cells) are the supporting cells – vary based on location i. In CNS 1. Astrocyte a. Numerous extensions  wrap around neurons i. Involved in forming the blood brain barrier and regulate brain function 2. Microglia a. Macrophages to engulf/destroy phages and cell debris 3. Ependymal cells a. Ciliated columnar cells that line the ventricles and circulate cerebrospinal fluid 4. Oligodendrocytes a. Their extensions myelinate axons of neurons in the CNS ii. In PNS 1. Satellite cells – surround neuron cell bodies in the PNS 2. Schwann cells (neurolemmocytes) – myelinate axons of neurons in the PNS 6. Myelin sheath a. Segmented protein – lipid sheath around some axons to electrically insulate the axon and increase speed of nerve impulse transmission. 7. White Matter vs. Grey Matter a. White – dense collection of myelinated fibers b. Grey – mostly neuron cell bodies 8. CNS vs. PNS terms a. Tract – a bundle of axons in the CNS b. Nerve – a bundle of axons in the PNS c. Nucleus – a cluster of neuron cell bodies in the CNS d. Ganglion – a cluster of neuron cell bodies in the PNS 9. Arrangement a. Myelinated axons covered in endoneurium b. Bundled together is a fascicle and is covered in perinurium c. Bundled together to make a nerve covered in epineurium 10. How signal is sent a. From the cell body down the axon to a chemical signal to the next neuron b. Axolemme (one of the balls on the string of the axon) i. Normally less Na inside than out ii. More K inside than out iii. Depolarization: Na floods in and becomes positive (flush a toilet) iv. Repolarization K floods out and becomes negative v. Hypopolarization is the lag time for the potential to reset. (toilet refills)

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Anatomy Exam 3 vi. Another action potential cannot be generated unless it’s an exceptionally strong stimulus that can cause depolarization leading to another action potential c. Speed i. 4X the diameter = 2X the velocity ii. 1/4X capacitance = 4X the velocity iii. decrease capacitance with myelinate 1. allows with salutatory conduction to the signal and “jump” the sheaths instead of moving through the entire axon 11. Multiple Sclerosis a. Autoimmune disease i. Body attacks myelin causing demyelination of axons in the CNS. This causes the impulse transmission to slowdown and interferes with communication/control between the brain and body 12. Nerve Fibers a. Group A – that the larges diameter and heavily myelinated. Transmits impulse at the rate of 150m/s  Motor neurons b. Group B – intermediate diameter and lightly myelinated. Transmits impulse at a rate of 15 m/s  Preganglionic autonomic fibers c. Group C – smallest diameter and unmyelinated. Transmits impulse at 1m/s  Postganglionic autonomic fibers 13. Classification of Nerves a. Classified by direction transmit impulse b. Sensory afferent nerves – impulse toward CNS c. Motor efferent nerves – impulse away from CNS d. Mixed nerves – bother sensory and motor fibers that impulse to and from CNS

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Anatomy Exam 3 14. Regeneration a. Severed axons in the PNS can regenerate (if cell body is intact) but severed axons in the CNS cannot. CNS PNS - Immune system debridement - Microglia debridement is poorly done and not complete - Neurilemmal forms a regeneration - No neurilemmal, tube, or tube  guides regeneration of the regeneration guide severed axon - Growth-inhibiting proteins in oligodendrocytes

15. In the PNS a. The axon becomes fragmented at the injury and damage continues distally portion b. Macrophages clean out the dead axon distal to the injury c. Axon sprouts or filaments grow through a regeneration tube formed by Schwann cells d. The axon regenerated and a new myelin sheath forms e. **The greater the distance between severed ends, the less likely it is to regenerate. i. 1.5mm a day 16. Regions and organization of the CNS a. Brain i. Cranial nerves 1. 12 pairs of nerves associated with the brain a. I – olfactory b. II – optic c. III – oculomotor d. IV – trochlear e. V – Trigeminal f. VI – abducens g. VII – facial h. VIII – vestibulocochlear i. IX – glossopharyngeal j. X – vagus k. XI – accessory l. XII – hypoglossal Order: oh, once one take the anatomy final, very good vacations are here Modality: some say marry money but my brother says big brains matter more ii. Protection 1. Cranium – 8 cranial bones 2. Meninges

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Anatomy Exam 3 a. Dura mater – strongest, two layers of fibrous connective tissue b. Arachnoid mater – middle layer with web-like extensions. subarachnoid space contains cerebrospinal fluid (CSF) c. Pia mater – layer of delicate vascularized connective tissue that clings tightly to the brain 3. Cerebrospinal fluid a. Filtered from blood b. Inside and outside of the brain: ventricles and subarachnoid space c. A liquid cushion that provides nutrients and removes wastes. 4. Blood Brain Barrier – a selective barrier a. Astrocytic feet b. Nutrients  facilitated c. Fat-soluble  alcohol, nicotine, anesthetics. b. Spinal Cord i. 30 pairs of mixed nerves 1. 8 cervical (C1-C8) 2. 12 thoracic (T1-T12) 3. 5 Lumbar (L1-L5) 4. 5 Sacral (S1-S5) 5. 1 coccygeal (C0) ii. Cauda Equine 1. The collection of nerve roots at the inferior to the spinal cord iii. Cervical and lumbar enlargements 1. The nerves serving the upper and lower limbs emerge here 2. Cut at or below cervical enlargement = flaccid paralysis and paresthesia of all four limbs 3. Cut above lumbar = paraplegia – just the lower limbs iv. Protections 1. Vertebral column – bony protective structure of the spinal cord 2. Menings a. Dura mater b. Arachnoid mater – subarachnoid space contains cerebrospinal fluid (CSF) c. Pia mater 3. Cerebrospinal fluid a. In the central canal in the core of the spinal cord and inside the subarachnoid space b. Acts as a liquid cushion, provides nutrients, removes metabolic wastes 17. Concussion a. A violent jarring or shaking that results in disturbance of brain function 10

Anatomy Exam 3 i. Can be linear or rotational 1. A hard enough rotational hit can disconnect axons in the brain and spinal cord 18. Brain development and organization a. The adult brain weighs about 3.5lb b. Regions i. Cerebrum 1. 83% of brain mass 2. right and left hemispheres a. longitudinal fissue connected deep by corpus callosum. 3. Surface markings a. Gyri (hills) , sulci (valleys), and fissures (deep sulci) b. Lateral sulcus i. Temporal lobe from parietal and frontal c. Parieto-occipital sulcus i. Parietal from occipital lobe d. Central sulcus i. Frontal from parietal lobes ii. Gyrus immediately anterior 1. Precentral gyrus iii. Gyrus immediately posterior 1. Postcentral gyrus 4. Lobes a. Frontal b. Parietal c. Temporal d. Occipital e. Insula 5. Regions of each hemisphere a. Cerebral cortex i. Composed of grey matter = cell bodies, dendrites, is Highly convoluted, 2-4mm thick, makes up 40% of brain mass, and is the conscious mind ii. Areas 1. Motor – control of voluntary movements a. primarily motor cortex – precentral gysus, Skeletal muscles. Neurons called neurons called pyramidal cells axons bundle to form the pyramidal tracts  cross over in

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Anatomy Exam 3 medulla oblongata (Decussation of pyramids)  Contralateral control b. premotor cortex – muscle memory c. Broca’s area – motor speech area d. frontal eye field – muscles to position the eyes. iii. Broca’s vs Wernicke’s area  Speech production (broca’s) to language (Wernicke’s) 1. Sensory – for the conscious awareness of sensation a. Primary somatosensory cortex, primary visual cortex, primary auditory cortex, primary olfactory cortex, primary gustatory cortex 2. Association – integrate and interpret sensory inputs form the sensory areas a. Each primary sensory area has an associated area b. Cerebral white matter i. Deep to cortex. Is composed of tracts of myelinated axons ii. Tracts 1. Commissural – connect areas in the two cerebral hemispheres through the corpus callosum 2. Projection – connect the cerebrum to the lower brain areas and the spinal cord: the pyramidal tracts 3. Association – connect areas within the same cerebral hemisphere like Broca’s and Wernicke’s area c. Basal nuclei i. Islands of nuclei (clusters of neuron cell bodies) within the cerebral white matter ii. 3 major ones associated with nuclei in the brain stem and involved in initiating and stopping movements. ii. Diencephalon 1. Thalamus a. 80% of the diencephalon b. gateway to cerebral cortex c. sorts, edits, and relays ascending input 2. Hypothalamus a. Inferior to thalamus 12

Anatomy Exam 3 b. Controls autonomic nervous system c. Physical response to emotion, perception of emotions, body’s temp, satiety center, thirst center, sleep-wake cycles, and endocrine function of 9 hormones 3. Epitheliums a. Most dorsal portion of diencephalon b. Pineal gland i. Secretes melatonin to help regulate the sleep-wake cycle iii. Brain stem 1. Regions a. Midbrain i. Between the diencephalon and pons ii. corpora quadrigemina (house of 4 twins) – dorsal protrusions 1. superior colliculi – visual reflex centers 2. inferior colliculi – auditory relay centers iii. Substantia nigra – contains dopamine releasing neurons that project and modulate basal nuclei and in the cerebrum iv. Red nucleus – relay nuclei for some descending motor pathways b. Pons i. Between midbrain and medulla oblongata ii. Nuclei help maintain rhythm of breathing iii. Connect motor cortex (cerebrum) and cerebellum for skeletal muscle coordination c. Medulla oblongata i. Inferior region of the brain stem ii. Continuous with spinal cord iii. Decussation of the pyramids 1. Tracts from motor cortex cerebrum that cross left arm impulse moves impulse from right cerebrum for contralateral control iv. Functions: vomit, constrict/dilate blood vessels 2. Automatic responses necessary for survival a. Blood pressure, heart rate iv. Cerebellum 1. 11% of brain mass 2. dorsal to brainstem 3. allows smooth coordinated movements a. input from cortex, brain stem, and sensory receptors as well as muscle memory. b. Impairment – Alcohol 13

Anatomy Exam 3 c. Ventricles – cavities in the brain that contain CSF i. Lateral (2) lateral ventricles in cerebral hemisphere ii. Third – located in diencephalon iii. Fourth – in bra...