Exam 3 Study Guide PDF

Exam 3 Review Chapter 11 Types of Muscle Tissue: Skeletal —> bones to skin —> obvious striations —> controlled Cardiac —> walls of the Heart —> striations —> cannot be controlled Smooth —> visceral organs —> no striations —>...

Exam 3 Review Chapter 11 Types of Muscle Tissue: Skeletal —> bones to skin —> obvious striations —> controlled Cardiac —> walls of the Heart —> striations —> cannot be controlled Smooth —> visceral organs —> no striations —> cannot be controlled Connective Tissue Sheaths: *each skeletal muscle, as well as each muscle ber, is covered in connective tissue *support cells and reinforce whole muscle Epimysium —> dense irregular connective tissue —> surrounding entire muscle —> on top Perimysium —> brous connective tissue —> surrounding fascicles —> around Endomysium —> ne areolar connective tissue —> surrounding each muscle ber —> inside Microscopic Anatomy of Skeletal Muscle Fiber: Sarcolemma —> Plasma Membrane Sarcoplasm —> Cytoplasm Sarcoplasm contains many glycosides for glycogen storage, as well as myoglobin for O2 storage Modi ed Organelles: - Myo brils - Sarcoplasmic Reticulum - T Tubules Myo brils: are densely packed, rod-like elements - account for 80% of muscle cell volume - single muscle ber can contain 1000’s myo brils Myo bril features: - Striations - Sarcomeres - Myo laments - Molecular Comp. Of Myo laments Striations: stripes formed from repeating series of dark and light bands along the length of each myo bril * A band: dark regions * H zone: lighter region in middle of dark A band * M line: line of protein (myomesin) that bisects H zone vertically * I bands: lighter regions * Z disc line: coin-shaped sheet of proteins on midline of light I band fi fi fi fi fi fi fi fi fi fi fi fi fi  Sarcomere: smallest contractile unit of a muscle ber - Contains an A band with half an I band at each end and consist of areas between Z discs Sarcomere contains: - Thin (actin) laments - Thick (myosin) laments - Z disc - H zone - I band - A band - M line Composition of Thick and Thin Filaments Actin Myo laments: thin laments - Extend across the I band and partway in A band - Anchored to Z discs Myosin Myo laments: thick laments - Extend along the length of A band - Connected at M line *Sarcomeres shows hexagonal arrangement of one thick lament surrounded by six thin laments - I band: thin lament - H zone: thick laments - M line: thick laments linked by accessory proteins - Outer edge of A band: thick and thin laments overlap Thick Filaments: composed of protein myosin that contains two heavy and four light polypeptide chains - Heavy chains intertwine to form a myosin tail - Light chains form myosin globular head - During contraction, heads link thick and thin laments together, forming cross bridges Thin Filaments: composed of brous actin - Actin is the main protein that makes up the thin lament - Actin is like a beaded necklace - Each bead is a tiny molecule called G-actin - When connected together, they form a long twisted necklace we call F-actin - Tropomyosin and Troponin: Regulatory proteins bound to actin fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi fi  Sarcoplasmic Reticulum and T Tubules Sarcoplasmic Reticulum: network of smooth endoplasmic reticulum tubules surrounding each myo bril - Stores and releases calcium (Ca2+) - Regulates the calcium levels - Terminal cisterns form perpendicular cross channels at the A-I band junction T tubules: Tube formed by protrusion of sarcolemma deep into cell interior - Increase muscle ber’s surface area - Lumen continuous with extracellular space - Allow electrical nerve transmissions to reach deep into interior of each muscle ber * Tubules penetrate cell’s interior at each A-I band junction between terminal cisterns* - Triad: area formed from terminal cistern of one sarcomere, T tubule, and terminal cistern of neighboring sarcomere - When an electrical impulse passes by, T tubule proteins change shape causing SR proteins to change shape, causing release of calcium into cytoplasm fi fi fi  Sliding Filament Model of Contraction 1. At a relaxed state, thin and thick laments overlap only a little at ends of A band 2. During contraction, thin laments slide past thick laments, causing act and myosin to overlap more (neither thick nor thin laments change length, just overlap more) 3. When nervous system stimulates muscle ber, myosin heads are allowed to bind to actin forming cross bridges, which cause sliding contraction process to begin 4. Cross bridge attachments form and break several times, each time pulling thin laments a little closer toward center of sarcoma in a ratcheting action ( causes shortening of muscle ber) Z discs are pulled toward the M line I bands shorter Z discs become closer H zone disappears A bands move closer to each other Mechanical potential: The strength your muscles use to move things. Chemical potential: The stored fuel inside your cells (energy from food or ions). Voltage potential: The battery charge inside your cells, waiting to re. Action potential: The electric signal that makes things happen, like muscle movement or nerve signals. fi fi fi fi fi fi fi fi  Chapter 13 Organization of the Nervous System Central Nervous System vs Peripheral Nervous System: - Two main divisions of the nervous system CNS - Structure: Brain and Spinal Cord Function: Process information and controls body activities PNS - Structure: Nerves (Cranial and Spinal) Function: - Spinal nerves to and from spinal cord - Cranial nerves to and from brain - Communication lines between the CNS and the rest of the body Sensory (a erent) vs Motor (e erent) Sensory (A erent) Division: “coming to" Structure: somatic and visceral sensory nerve bers Function: conducts impulse from receipts to CNS Motor (E erent) Division: “exiting/sending orders” Structure: Motor nerve bers Function: transmits impulses from CNS to e ector organs (muscles and glands) - Two divisions: Somatic Nervous System and Autonomic Nervous System Somatic Nervous System vs Autonomic Nervous System Somatic Nervous System: Voluntary control of muscles and sensory info (moving your arm) Structure: Somatic motor nerve bers (voluntary) Function: Conducts impulses from the CNS to skeletal muscles Autonomic Nervous System: Involuntary control of internal organs (like breathing and heartbeat) Structure: Visceral (involuntary) motor nerve bers) Function: Conducts impulses from the CNS to cardiac muscle, smooth muscle, and glands - Two functional subdivisions: Sympathetic and Parasympathetic (which work in opposition to each other) Sympathetic Division vs Parasympathetic Division Sympathetic Division: hypes body up ( ght or ight) Function: Mobilizes body systems during activity Parasympathetic Division: calms body down ( rest and digest) Function: Conserves energy and promotes housekeeping functions during rest ff ff ff ff fi fi fi fl ff fi fi  Neuroglia (types, locations, and functions) Neuroglia (glial cells): small cells that surround and wrap delicate neurons Main types in CNS neurons: 1. Astrocytes Location: Found throughout the brain and spinal cord Function: - Most abundant CNS - Provide structural support to neurons - Regulate blood ow in the brain - Involved in the repair of nervous tissue 2. Microglial cells Location: scattered throughout the CNS Function: Act as immune cells of the CNS (defensive cells) 3. Ependymal cells Location: Lining the ventricles of the brain and the central canal of the spinal cord Function: produce cerebrospinal uid (CSF) 4. Oligodendrocytes Location: Found in the CNS brain and spinal cord Function: - Have processes that form myelin sheaths around CNS nerve bers Main types in PNS: 1. Satellite cells: Function: surround neuron cell bodies in PNS; functions similar to astrocytes of CNS Location: Found in the ganglia 2. Schwann cells: Function: surround all peripheral nerve bers from myelin sheaths in thicker nerve bers; similar function as oligodendrocytes Location: Found in the PNS Neuron Structure (cell body, processes) Neurons (nerve cells) are structural units of nervous system Large, highly specialized cells that conduct impulses Special Characteristics: - Extreme longevity (last a person’s lifetime) - Amitotic, with a few exceptions - High metabolic rate: require continue supply of oxygen and glucose All have cell body and one or more processes Processes: Dendrite: receives signal Axon: send signal fi fl fl fi fi  Nuclei vs Ganglia Nuclei: clusters of neuron cell bodies in CNS Function: controlling speci c functions like movement and breathing Ganglia: clusters of neuron cell bodies in PNS Function: processing information for things like re exes Tracts vs Nerves Tracts: Bundles of neuron processes in CNS Nerves: Bundles of neuron processes in PNS Processes: Dendrite and Axon White Matter vs Gray Matter White Matter: Regions of brain and Spinal cord with dense collections of myelinated bers Gray matter: mostly neuron cell bodies and non-myelinated bers Dendrites —> Gray Matter Receives input/signals Axons —> White Matter Sends signals Myelination in the PNS & CNS system Myelin Sheath: - Composed of myelin, a whitish protein lipid substance Functions: - Protect and electrically insulate axon - Increase speed of nerve impulse transmission Myelinated bers: segmented sheet surrounds most long or large-diameter axons Non-myelinated bers: do not contain sheath and conduct impulses more slowly Myelination in the PNS: Made: by Schwann cells in the PNS How does it work: Schwann cells wrap around axons in layers, creating myelin to insulate and speed up signals Myelin Sheet Gaps: Nodes of Ranvier - gaps between the myelin sheaths and sites where axon collaterals can emerge Non-Myelinated Fibers: These bers transmit signals much slower because there’s no insulation to speed up the process. fi fi fi fi fl fi fi  Myelin Sheaths in the CNS - Formed by processes of oligodendrocytes - Each cell can wrap up to 60 axons at once - Myelin sheath gap is present - No outer collar of perinuclear cytoplasm - Thinnest bers are un-myelinated, but covered by long extensions of adjacent neuroglia Structural Classi cation of Neurons Three types grouped by number of processes: 1. Multipolar: three or more processes (1 axon, other dendrites) - Most common and major neuron type in CNS 2. Bipolar: two processes (one axon, and one dendrite) - Rare (ex: retina and olfactory mucosa) 3. Unipolar: one T-like process - Also called pseudo unipolar - Found mainly in PNS. Common only in dorsal root ganglia - Peripheral process: associated with sensory receptors - Central process: enters CNS Functional Classi cation of Neurons Three types of neurons grouped by direction in which nerve impulse travels relative to CNS: 1. Sensory: Bipolars and Unipolar - Transmit impulses from sensory receptors toward CNS - Almost all are unipolar; cell bodies are located in ganglia in PNS 2. Motor: Multipolar - Carry impulses from CNS to e ectors - Multipolar; most cell bodies are located in CNS 3. Interneurons: Multipolar - Also called association neurons - Multipolar; lie between motor and sensory neurons - Shuttle signals through CNS pathways - 99% of body’s neurons and interneurons fi fi fi ff Chapter 14 Brain Regions and Organization: Four Regions: 1. Cerebral hemispheres (cerebrum) 2. Diencephalon 3. Brain Stem, consisting of Midbrain Pon Medulla 4. Cerebellum Gray Matter: short, non-myelinated neurons and cell bodies White Matter: myelinated and non-myelinated axons Cerebral Hemispheres: Form superior part of brain and accounts for 83% of brain mass Surface Markings: - Gyri: ridges - Sulci: shallow grooves - Fissures: deep grooves Longitudinal Tissue: - separates the two cerebral hemispheres Transverse Cerebral Fissure: - separates cerebrum and cerebellum Several sulky divide each hemisphere into ve lobes: Frontal Parietal Temporal Occipital Insula Insular lobe is buried under portions of temporal, parietal, and frontal lobes Major Sulci that divide lobes: - Central Sulcus: separates pre central gyrus of frontal lobe - Parieto-occipital sulcus: separates occipital and parietal lobes - Lateral sulcus: outlines temporal lobes Each hemisphere has three basic regions: - Cerebral cortex: gray matter - super cially (cortex = shell) - White matter: internally - Basal nuclei: gray matter deep within white matter Cerebral hemispheres are connected by a major commissure called corpus callosum Cerebral cortex is the executive of the brain Site of conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, understanding Thin (2-4mm) super cial layer of gray matter Composed of neuron cell bodies, dendrites, glial cells, and blood vessels but no axons 40% of mass of brain Four general considerations of cerebral cortex: Contains three types of functional areas: Motor areas: control voluntary movement Sensory areas: conscious awareness of sensation Association areas: integrate diverse information fi fi fi  Ventricles of the brain; cerebrospinal uid Fluid- lled chambers that are continuous to one another and to central canal of spinal cord - Filled with cerebrospinal uid (CSF) - Lined by ependymal cells (neuroglia cells) Paired lateral ventricles are large, C-shaped chambers located deep in each hemisphere - Pair is separated by membranous septum pellucidum Each lateral ventricle is connected to the third ventricle via inter ventricular foramen - Third ventricle lies in diencephalon Third ventricle is connected to the fourth ventricle via cerebral aqueduct - Fourth ventricle lies in hindbrain - Continuous with central canal of spinal cord Cerebrospinal Fluid (CSF): Forms a liquid cushion of constant volume around brain Functions: Gives buoyancy to CNS structures - Reduces weight of brain by 97% by oating it so it is not crushed under its own weight Protects CNS from blows and other trauma Nourishes brain and carries chemical signals Choroid Plexus: cluster of capillaries that hangs from roof each ventricle, enclosed by Pia mater and surrounding layer of ependymal cells CSF is ltered from plexus at constant rate Ependymal cells use ion pumps to control composition of CSF and help cleanse CSF by removing wastes Cilia of ependymal cells help to keep CSF in motion fi fi fl fl fl Meninges: Function: - Cover and protect CNS - Protect blood vessels and enclose venous sinuses - Contain CSF - Form partitions in skull Consists of three layers: dura mater, arachnoid mater, and Pia mater Dura Mater: - Stronger meninx - Made up of two layers of brous connective tissue * Periosteal layer: attaches to inner surface of skull (found only in brain, not spinal cord) * Meningeal layer: true external covering of brain (extends into vertebral canal as spinal dura mater) Two layers are mostly fused, but separate in certain areas to form dural venous sinuses Sinuses collect venous blood from brain, empty into jugular veins of neck Dura mater extends inward in several areas to form at partitions that divide cranial cavity Partitions referred to as dural septa fi fl  Act to limit excessive movement of brain Three main septa: Falx cerebri: in longitudinal ssure; attached to crest Galli Falx cerebelli: along vermis of cerebellum Tentorium cerebelli: horizontal dural fold over cerebellum and in transverse ssure Arachnoid Mater: - Middle layer with spiderweb-like extensions - Separated from dura mater by subdural space - Subarachnoid space contains CSF and largest blood vessels of brain Pia Mater: - Delicate connective tissue that clings tightly to brain, following every convolution - Contains many tiny blood vessels that feed brain Diencephalon (structure & function): Consists of three paired gray-matter structures * 2 Thalamus * Hypothalamus * Epithalamus (All three enclose the third ventricle) Thalamus: Bilateral egg-shaped nuclei that form super-lateral walls of third ventricle Makes up 80% of diencephalon Bilateral nuclei connected by inter thalamic adhesion (intermediate mass) Contains several nuclei, named for location Nuclei project and receives bers from cerebral cortex Main Thalamic function is to act as relay station for information coming into cortex - Sorts, edits, and relays ascending input such as: Impulses from hypothalamus for regulating emotion and visceral function Impulses from cerebellum and basal nuclei to help regulate motor responses Impulses for memory or sensory integration Overall, it acts to mediate sensation, motor activity Hypothalamus: - Located below thalamus - Contains many important nuclei such as: - Mammillary bodies: paired anterior nuclei that act as olfactory relay stations - Infundibulum: stalk that connects to pituitary gland - Hypothalamus is the main visceral control and regulating center that is vital to homeostasis - Chief homeostasis - Controls autonomic nervous system: - Examples: blood pressure, rate and force of heartbeat, digestive tract motility pupil size - Initiates physical responses to emotions: - Part of limbic system: perceives pleasure, fear, rage, biological rhythms, and drive (sex drive) fi fi fi The hypothalamus also: - Regulates body temperature: sweating or shivering - Regulates hunger and satiety: in response to nutrient blood levels or hormones - Regulates water balance and thirst - Regulates sleep-wake cycles - Controls endocrine system functions such as: - Secretion of anterior pituitary gland - Production of posterior pituitary hormones Epithalamus: - Most dorsal portion of diencephalon - Forms roof of third ventricle - Contains pineal gland (body) - Extends from posterior border - Secretes melatonin that help regulate sleep-wake cycle  Brain Stem (structure, function) Brain Stem: - Consists of three regions: midbrain, pons, medulla oblongata - Similar in structure to spinal cord but contains nuclei embedded in white matter - Controls automatic behaviors necessary for survival - Contains ber tracts connecting higher and lower neural centers - Nuclei are associated with 10 of the 12 pairs of cranial nerves Midbrain: - Located between diencephalon and pons - Cerebral peduncles: two ventral bulges that contain pyramidal motor tracts - Form pillars that hold up cerebrum - Cerebral aqueduct: channel running through midbrain that connects third and fourth ventricles - Midbrain nuclei scattered throughout white matter include: - Corpora quadrigemina: paired dorsal protrusions - Superior colliculi: visual re ex centers - Inferior colliculi: auditory relay centers - Substance nigra: functionally linked to basal nuclei - Parkinson’s disease is degeneration of this area Pons: - Located between midbrain and medulla oblongata - Fourth ventricle separates pons from cerebellum - Composed of conduction tracts: - Longitudinal bers connect higher brain centers and spinal cord - Transversal/dorsal ber relay impulses between motor cortex and cerebellum - Some nuclei play role in reticular formation, and some help maintain normal rhythm of breathing Medulla Oblongata - Also known as medulla - Blends into spinal cord at foramen magnum - Structures of the medulla oblongata - Pyramids: two ventral longitudinal ridges formed by pyramidal tracts from motor cortex - Decussation of the pyramids: points where pyramidal tracts cross over to opposite side of body - Functions of the medulla oblongata - Medulla is an autonomic re ex center - Many functions overlap with hypothalamus - Hypothalamus relays instructions via medulla - Functional groups of medulla include: - Cardiovascular center - Cardiac center adjusts force and rate of heart contraction - Vasomotor center adjusts blood vessel diameter for blood pressure regulation - Respiratory center - Generate respiratory rhythm - Control rate and depth of breathing (with pontine center) - Various other centers regulate: vomiting, hiccuping, swallowing, coughing, sneezing fi fi fi fl fl  Cerebellum: - 11% of brain mass - Located dorsal to pons and medulla - Processes input from cortex, brain stem, and sensory receptor to provide precise, coordinated movements of skeletal muscles - Also plays a major role in balance - Cerebellar hemispheres connected by worm-like vermis - Contains thin cortex of gray matter with distinctive tree-like pattern of white matter called arbor vitae - Purkinje cells (Purkinje neurons) originate in the cerebellar cortex, and synapse with deep cerebellar nuclei Cerebellar Peduncles: - All bers in cerebellum are ipsilateral from and to the same side of body - Three paired ber tracts connect cerebellum to brain stem - Superior cerebellar peduncles connect cerebellum to midbrain - Middle cerebellar peduncles connect pons to cerebellum - Inferior cerebellar peduncles connect medulla to cerebellum fi fi