Exam 4 Study Guide

know / memorize the material and terms

what makes skeletal muscle different from smooth and cardiac?

only voluntary muscle type

what makes smooth muscle different from skeletal and cardiac?

found in walls of hollow organs

what makes cardiac muscle different from skeletal and smooth?

only found in heart

what is a sarcomere?

functional unit of skeletal muscle

name the units of muscle from largest to smallest

whole muscle, muscle fascicles, myofibers, myofibrils, sarcomeres

where is epimysium found?

surrounding whole muscle

where is perimysium found?

around fascicles

where is endomysium found?

around muscle fibers

what do the T-tubules do?

carry electrical impulses into muscle fiber

what is the terminal cisternae?

storage space for calcium

what are Z discs?

form boundaries of sarcomere

where does actin attach to?

Z discs

what does myosin attach to?

M lines

How do Z discs change in respect to M line during sarcomere shortening?

Z discs move closer together while the M line remains fixed at the center of the sarcomere

what is a neuromuscular junction?

contact between nerves and muscle fibers

what does action potential in nerve release? (In NMJ)

acetylcholine across synaptic cleft

what does acetylcholine (ACh) cause?

depolarization of muscle fiber, Na+ release into fiber

what does Na+ do when released into fiber?

depolarizes SR to release calcium, cross-bridge formation can now occur

what occurs first during cross-bridge formation?

Ca2+ binds with troponin, causes tropomyosin to move off actin binding cite

what happens when bind site is exposed during cross-bridge formation?

myosin can bind onto actin

what is a power stroke?

movement of myosin head, pulling actin

what is ATP needed to break in myosin ATPase?

break bond between myosin and actin

what does it mean if a muscle contraction is isometric?

muscle does not shorten, tension is present

what does it mean if a muscle contraction is isotonic?

muscle shortens with tension

what is a motor unit?

consists of a single motor neuron and all the fibers it innervates

what are small motor units?

units that use precise movements; eye muscles

what are large motor units?

units used for forceful movements; thigh muscles

what is a muscle twitch?

muscle fiber response to a single AP

what is wave summation?

multiple Aps cause repeated muscle twitches

what is incomplete tetanus?

high amount of Ap’s cause muscle to not fully relax

what is tetanus?

muscle remains contracted from repeated stimulation

what are the two types of muscle fibers?

slow twitch and fast twitch

what are some functions of slow twitch muscle fibers?

fatigue resistant; contract slower

what do slow twitch muscle fibers contain?

more blood supply; mitochondria; contain myoglobin

what are slow twitch muscle fibers a primary source for?

aerobic respiration

what do fast twitch fibers contain?

more myosin ATPase for repeated contractions

what are fast twitch fibers a primary source for?

anaerobic respiration

what is hypertrophy?

increase in muscle size

what is atrophy?

decrease in muscle size

what is oxygen deficit?

temporary difference in amount of oxygen the body needs during exercise and amount it consumes

what is EPOC? (excess post-exercise oxygen consumption)

following exercise to restore cells back to normal

what doe EPOC increase?

increased respirations cause more oxygen to be consumed so cells can be replenished

why does DOMS (delayed onset muscle soreness) occur?

after vigorous or untrained exercising, highly repetitive eccentric contractions cause pain in muscles

when does DOMS (delayed onset muscle soreness) peak?

48-72 hours in active muscles following exercise

what does the energy source Adenylate kinase do?

2 ADP molecules into 1 ATP and 1 AMP

how fast is Adenylate kinase used?

5-10 seconds

what is the energy source Creatine kinase?

stored ATP in muscle cells

how fast is Creatine kinase used?

10-15 seconds

what process does anaerobic respiration use?

glycolysis

how long can anaerobic respiration be used for?

3 minutes before lactate accumulates

what is aerobic respiration used for?

in long duration activities

what is the resting membrane potential for smooth muscle?

-55 to -60 mV

what is the resting membrane potential for skeletal muscle?

-70 to -90 mV

what does calmodulin do?

replaces role of troponin in cross-bridge formation

what is used instead of calcium to initiate cross-bridge cycle?

phosphate

what are neurons?

electrically excitable cells

what are axons?

long extension that sends electrical signals to other cells

what are dendrites?

short extensions that receive electrical signals from other cells

what are glial cells?

most numerous nervous system cell type

what are ganglia?

clusters of neuron cell bodies outside of brain & spinal cord

what are plexus?

branching of nerves outside of brain & spinal cord

what is the CNS (central nervous system)?

receives info from body and sends information out to body, brain & spinal cord

what is the PNS (peripheral nervous system)?

detect stimuli in/around body, sends info to CNS; sensory & motor subdivisions

what does the sensory system do?

sends signals from special receptors in body towards CNS

what does the motor system do?

sends signals from CNS to effector organs

what subdivisions does the motor system contain?

somatic and autonomic

what does the somatic system do?

voluntary movement of skeletal muscle

what does the autonomic system do?

involuntary movement of smooth and cardiac muscle

what subdivisions does the autonomic system contain?

sympathetic and parasympathetic

what does the sympathetic system do?

readies the body for physical activity; fight or flight

what does the parasympathetic system do?

regulates resting function; digestion (rest & digest)

what are 2 main parts of the axon?

axon hillock and initial segment

what is the axon hillock?

cone-shaped area branching off neuron

what is the initial segment?

part after hillock that starts uniformity shape of axon

when combined, what do the axon hillock and initial segment form?

trigger zone

what is generated in the trigger zone?

action potentials

what do astrocytes do? (type of glial cells)

regulate extracellular brain fluid by promoting tight junction formation; create blood-brain barrier

what do astrocytes create in the brain?

blood-brain barrier

what do ependymal cells do? (type of glial cells)

line ventricles of brain and central canal of spinal cord

what do ependymal cells create?

choroid plexuses

what are microglia? (type of glial cell)

CNS-specific immune cells

what do microglia do? (type of glial cell)

respond to inflammation and phagocytize necrotic tissue, microbes, and other foreign substances

where are microglia most active?

immediately in areas of injury

what differs microglia from astrocytes when in contact with areas of injury?

microglia eventually will dissipate; astrocytes stay in location permanently

what do oligodendrocytes do? (type of glial cell)

form myelin sheath in CNS; insulation around axons

what do schwann cells form? (type of glial cell)

form myelin sheaths in PNS

what do satellite cells do? (type of glial cell)

surround cell bodies; provide support, nutrition, and protection to cell bodies (heavy metals)

what do myelinated axons form?

form white matter of CNS

why are myelin sheaths white in appearance?

due to high lipid concentration

are myelin sheaths continuous or non-continuous?

continuous

what do myelin sheaths do?

help axons conduct electrical signals more rapidly

what are the gaps in myelin sheaths called?

nodes of Ranvier

what do unmyelinated axons contain?

series of schwann cells; can contain more than one axon

what do unmyelinated axons form?

gray matter of CNS with cell bodies, dendrites, and glial cells

what are the 4 main ion channels?

Leak, Gated, Ligan-gated, voltage-gated

what are some characteristics of leak ion channels?

constantly open; ion flows down concentration gradient

what are some characteristics of gated ion channels?

closed until opened by specific signal

what are ligands in ligan-gated ion channels?

neurotransmitters or hormones

what are some characteristics of voltage-gated ion channels?

open/close in response to voltage changes

what is a graded potential?

relatively small change in membrane potential in one localized area