Anatomy (BIOL 2220) Exam 3 - Cummings

skeletal muscle

striated, voluntary, multinucleated

cardiac muscle

striated, involuntary, uninucleated

smooth muscle

nonstriated, involuntary, uninucleated

properties of muscle

excitability, contractibility, extensibility, elasticity

functions of muscle

motion, maintenance of posture, stabilizing joints, heat protection

skeletal muscle composition

skeletal muscle fibers, blood vessels, nerve fibers, connective tissue

direct attachment

muscle has contact with bone

indirect attachment

extension between muscle and bone holds them together

epimysium

dense irregular connective tissue covering muscle

tendon

rope-like attachment from muscle to bone made of connective tissue

aponeurosis

sheet-like attachment from muscle to bone made of connective tissue

origin

point of muscle contact with unmovable bone, almost always superior/proximal to insertion

insertion

point of muscle contact with moveable bone, almost always inferior/distal to origin

fascicle

chunk of muscle with connective tissue covering

perimysium

connective tissue covering a fascicle

muscle fiber

muscle cell

endomysium

reticular connective tissue covering individual cells

myofibers

muscle cells aka muscle fibers

sarcolema

plasma membrane of muscle cell

sarcoplasm

cytoplasm of muscle cell

nuclei of skeletal muscle

multiple per cell, really long cells

sarcoplasmic reticulum

modified endoplasmic reticulum, primarily runs parallel to fibers but some run perpendicular (terminal cisternae)

T tubule

runs between two terminal cisternae

terminal cisternae

sarcoplasmic reticulum tubes that run perpendicular to fibers

myofibrils

configuration gives striation, made up of sarcomeres

sarcomeres

made up of myofilaments

myofilaments

made up of actin or myosin (proteins)

sarcomere Z line

aka Z disk, ends of sarcomere

sarcomere A band

entire length of thick myofilament

sarcomere I band

only the thin myofilament

sarcomere H zone

only the thick myofilament

sarcomere M line

middle of the H zone

thick myofilaments

myosin, consist of tail and 2 heads, one head is actin-binding site, one head is ATP-binding site

thin myofilaments

actin, consist of myosin-binding site, tropomyosin (long strands), and troponin I, T, and C

troponin I

allows binding to actin

troponin T

binds to tropomyosin

troponin C

binds to calcium

titin

attaches thick myofilaments to Z disc

sliding filament theory

thick myofilament grabs the thin myofilament and pulls toward the center

excitation-contraction coupling

get nervous impulse to muscle

neuromuscular junction

only one nerve per fiber, no direct connection, synaptic vesicles, neurotransmitters, motor end plate

synaptic cleft

space between nerve and fiber

motore end plate

ACh receptors and acetylcholinesterase

twitch

single contraction in response to a single stimulus

tetanus

multiple stimuli that cause multiple contractions without full relaxation between them

incomplete tetanus

relaxes between contractions but not fully

complete tetanus

no relaxation between contraction

wave summation

second stimulus applied before complete relaxation

treppe

muscle completely relaxes but is then immediately stimulated again

isotonic

muscle moves

isometric

muscle does not move

direct phosphorylation

creatine phosphate couples with ADP to make ATP which can power a muscle contraction for 15 seconds, CP is replenished during inactivity

anaerobic respiration

glycolysis breaks down glucose, pyruvic acid is converted to lactic acid, lactic acid diffuses into the bloodstream

aerobic respiration

glycolysis breaks down glucose, pyruvic acid enters mitochondria for complete breakdown

muscle fatigue

ATP use exceeds ATP production, excessive accumulation of lactic acid, ionic imbalances (especially potassium)

requirements for resting state

oxygen reserves must be replenished, lactic acid must be converted into pyruvic acid, glucose, or glycogen, glycogen stores must be replaced, and ATP reserves must be resynthesized

strength of contraction increases with

number of fibers stimulated, size of fibers, frequency of stimulation

degree of muscle stretch

too much doesn't allow contraction

slow oxidative fibers

split ATP slowly and resist fatigue

fast oxidative fibers

split ATP quickly and resist fatigue

fast glycolytic fibers

split ATP fast, anaerobic

anaerobic exercise

slow oxidative fibers are used, increase in stamina, increase in myoglobin and number of capillaries that lead to muscle, endurance

resistance exercise

strength training, anaerobic, muscle becomes larger

disuse atrophy

muscle loses gain and gets smaller, "use it or lose it"

smooth muscle characteristics

small fibers, no connective tissue sheaths, organized into sheets, unstructured neuromuscular junction, less developed sarcoplasmic reticulum

smooth muscle sarcoplasmic reticulum

no sarcomeres, no pattern to myofilaments, no T tubules, has caveoli instead

visceral smooth muscle

contracts as a unit (wavelike)

multiunit smooth muscle

stimulating one stimulates another

smooth muscle contraction

neurotransmitter stimulates production of action potential, calcium is released by caveoli which binds to calmodulin, activated calmodulin activates myosin light chain kinase, activates kinase charges myosin cross bridges, actin and myosin interact to shorten fibers

regulators of contraction

autonomic nerves release different neurotransmitters, chemical factors

origin of muscle tissue

mesoderm

agrin

growth factor

fulcrum

joint in human body, lever moves about it

resistance

weight of load that has to be overcome

effort

performance by muscle

mechanical advantage

small muscles do big work because effort is far from fulcrum in comparison to load

first class lever

fulcrum between resistance and effort

second class lever

resistance is between fulcrum and effort, effort can be more or less than load, ex: tippy toes

third class lever

effort is between resistance and fulcrum, effort needs to be more than load

agonists

prime mover, performs desired action

antagonists

opposes desired action

synergists

helps agonists, steady the movement

fixators

type of synergists, fixes origin of agonist

criteria for naming muscles

location, shape, relative size, direction of muscle fibers, number of origins, location of attachment, action

parallel fasciculi

run length of muscle

convergent fasciculi

start at different ends but go to the same place

pennate fasciculi

short fasciculi that run toward tendon that runs length of muscle, unipennate or bipennate

circular fasciculi

run in a circle around opening

functions of nervous system

sense change, interpret change, and respond

central nervous system

brain and spinal cord, receives all sensations and initiates all actions

peripheral nervous system

everything that extends from CNS, carries sensory info to CNS and motor info away from CNS

afferent division

subdivision of PNS, sensory, A for arrive at CNS

efferent division

subdivision of PNS, motor, E for exit CNS

somatic nervous system

voluntary motor

autonomic nervous system

involuntary motor

sympathetic division

subdivision of ANS, fight or flight

parasympathetic division

subdivision of ANS, calms down body after fight or flight response, housekeeping

neurons

make up more than 50% of nervous system

neuroglia

support and protect neurons

characteristics of neurons

can conduct an impulse, longevity, lose ability to divide, high metabolic rate