DTCC Anatomy Unit 4 Test

cardiac muscle

-branched and uni-nucleated cells

-striated

-makes up walls of the heart

-involuntary

smooth muscle

-spindle-shaped, uni-nucleated cells

-non-striated

-makes up walls of hollow organs (NOT heart)

-involuntary

skeletal muscle

-long, cylindrical, multi-nucleated cells

-striated

-attached to bones by tendons

-voluntary

4 functions of muscles

produce movement, maintain posture, stabilize joints, generate heat

4 functional characteristics of muscle

contractility, excitability, extensibility, elasticity

epimysium

layer of connective tissue around entire muscle

perimysium

holds fascicles together

endomysium

surround individual muscle cells/fibers

fascicles

bundles of muscle fibers

muscle fibers

individual muscle cells

insertion attachment

the movable bone attached to a muscle

orgin attachment

the immovable or less moveable bone attached to a muscle

myoglobin function

a red pigment that stores oxygen in muscle cells

glycosomes function

stores glycogen and then release glucose during muscle cell activity for ATP production

sarcolemma

muscle cell membrane

T-tubules

-channels of the sarcolemma that surround the myofibrils

-let glucose, oxygen, and calcium into the cell

-conduct action potentials to allow all myofibrils within a muscle fiber so they contract at the same time

sarcoplasmic reticulum

-a system of tubes surrounding each myofibril

-stores calcium and releases it when an action potential runs down the T-tubule

myofibrils

-thin threads that extend the length of a muscle fiber and makeup muscle fibers

-contain myofilaments (thin and thick filaments)

sarcomere

-segments of a myofibril, contractile element

-each contract individually

-align end to end

I band

space between thick filaments of 2 adjacent sarcomeres; where thin filaments are

A band

dark band within striation pattern; length of thick filament and overlapping thin filament

H zone

space in between thin filaments within A Band (contain M line)

Z discs

boundaries of the sarcomere (have a zig-zag shape)

thick filaments

contain MYOSIN that attaches to the thin filament and performs the power stroke

thin filaments

contain ACTIN; contain myosin-binding sites

Ca++ in Muscle Contraction

Ca2+ binds to troponin, which activates troponin to expose myosin-binding sites on the actin located on tropomyosin

troponin

on thin filaments; regulatory protein that holds tropomyosin in place and assists with turning contractions on and off by exposing myosin-binding site on actin; Calcium activates troponin to expose binding sites

tropomyosin

on thin filaments; covers myosin binding sites on the actin; troponin moves tropmyosin to expose sites

crossbridge

forms when the myosin head attached to the actin of the thin filament

power stroke

forms when myosin head pulls thin filament/actin towards the M-line; going from high energy position to low energy position

What is the role of ATP in muscle contraction?

-ATP causes myosin head to detach from actin (breaks cross bridge)

-ATP is used to move the myosin head to its high energy position, and ATP is broken into ADP and P

-prepares the myosin head for next power stroke, which causes the muscle to contract

Acetylcholine

causes muscle to contract by triggering an action potential which stimulates the opening of Ca++ channels

Acetylcholinesterase

breaks down acetylcholine, stopping the action potential which closes the Ca++ channels

What happens to Ca++ when action potentials stop in the muscle cell?

the Ca++ gets pumped out by Ca++ active transport pumps, back into the sarcoplasmic reticulum

Muscle fatigue

physiological inability to contract

muscle fatigue causes

1. ionic imbalances

-too much K lost from cells during APs

-Na/K pump can't keep up

-K Accumulates in T-tubules and interferes with Ca++

2. When there is no ATP available contractures occur, a state of continuous contraction

-no ATP to detach the myosin head from actin, so myosin head cannot return to high energy position; myosin head remains up, forming cross bridge

motor unit

consists of one motor neuron and all the muscle fibers it innervates or supplies; the smaller the motor unit the more precise the control

wave summation

this occurs when a second stimulus is received before the muscle fiber has relaxed, creating a second contraction that is stronger than the first; Leads to a build-up of tension

fused tetanus

when stimulus frequency is so high that no muscle relaxation takes place between stimuli

unfused tetanus

type of wave summation with partial relaxation observed between twitches

isotonic contraction

when muscle length changes during a contraction

concentric contraction (isotonic)

muscle shortens during the contraction

eccentric contraction (isotonic)

muscle lengthens during contraction

isometric contraction

used for posture; muscle contracts but there is no movement, muscle stays the same length; ex. when you are pushing against a wall

order energy pathways kick in during muscle contraction

creatine phosphate, anaerobic glycolysis, aerobic respiration

creatine phosphate

lasts 10-12 seconds, no oxygen is needed, 1 ATP produced

anaerobic glycolysis

lasts 45-60 seconds, no oxygen is needed, 2 ATP produced

aerobic respiration

lasts hours (as long as it is low intensity), oxygen is needed, 32 ATP produced

slow oxidative muscle fibers

-uses aerobic respiration

-high amounts of myoglobin

-slow to fatigue

-many capillaries

-small diameter

-red

-for endurance type activities; running a marathon; maintaining posture

fast oxidative muscle fibers

-uses aerobic respiration (sometimes anaerobic glycolysis)

-high amounts of myoglobin

-intermediate to fatigue

-many capillaries

-intermediate diameter

-red/pink

-for sprinting or walking

fast glycolytic muscle fibers

-uses anaerobic glycolysis

-low amounts of myoglobin

-fast to fatigue

-few capillaries

-large diameter

-white (pale)

-for short term intense or powerful movements; hitting a baseball

changes in muscle cells caused by aerobic exercise (swimming, jogging, walking, biking)

-changes result in an increase in strength and resistance to fatigue

-the number of mitochondria and capillaries increase

-increase amount of myoglobin

-increase fat stored in cells and ability to break it down for energy

-changes most dramatic in slow oxidative

-may also convert fast glycolytic to fast oxidative fibers with in the muscle

rigor mortis

-when no ATP available contractures occur a state of continuous contraction

-when someone has died, they are no longer getting oxygen, they can't make ATP, constant contraction, all their muscles stiffen and harden

agonist muscle

the muscle primarily responsible for the movement of a bone

antagonist muscle

the muscle opposing the movement

synergist muscle

Muscle that assists a prime mover; helping to accomplish the movement

fixator muscle

muscle stabilizing the orgin

parallel fascicle arrangement

run parallel to the long axis of the muscle; slender

fusiform fascicle arrangement

spindle-shaped muscles with parallel fibers

circular fascicle arrangement

fascicles arranged in concentric rings (sphincter)

convergent fascicle arrangement

muscle origin is broad and fascicles converge toward a tendon of insertion

unipennate fascicle arrangement

fascicles insert into only one side of the tendon

bipennate fascicle arrangement

fascicles insert into the tendon from both sides; muscle looks like a feather

multipennate fascicle arrangement

Fascicles attach obliquely from many directions to several tendons; looks like many feathers side by side, with all their quills (tendons) inserted into one large tendon

deltoid (shape of muscle)

triangular

trapezius (shape of muscle)

trapezoidal

serratus (shape of muscle)

saw-toothed

orbicularis (shape of muscle)

round

gracilis (shape of muscle)

slender

maximus (size of muscle)

largest

minimus (size of muscle)

smallest

longus (size of muscle)

long

brevis (size of muscle)

short

rectus (direction of fibers)

parallel to midline; straight

transverse (direction of fibers)

perpendicular to midline

oblique (direction of fibers)

diagonal

flexor (type of movement)

reduces joint angle

extensor (type of movement)

increases joint angle

adductor (type of movement)

moves bone closer to midline

abductor (type of movement)

moves bone away from midline

2 components of the CNS

brain and spinal cord

sensory division of PNS

carries information from receptor organs to the CNS

subdivisions: somatic sensory and visceral sensory

somatic sensory division

Carries information from skin, muscles, and joints to CNS

visceral sensory division

Carries information from internal organs to CNS

Motor Division of PNS

carries information from CNS to effector organs (muscles and glands)

subdivisions: autonomic motor division and somatic motor division

autonomic motor division

carries information to smooth muscle, cardiac muscle and glands; involuntary

subdivisions: sympathetic division and parasympathetic division

parasympathetic division

rest and rejuvenate/digest; digestive activities increased after eating

examples: constrict pupils, slows heart rate, constricts bronchi, salivary glands stimulated, stimulates pancreas and gallbladder

sympathetic division

fight or flight; digestive activities inhibited

examples: pupils dilate, heart rate increases, relaxes bronchi in lungs (more O2), more glucose released from liver, activates adrenal medulla

somatic motor division

carries information to skeletal mucles; voluntary

neuroglia in CNS

astrocytes, oligodendrocytes, microglia, ependymal cells

astrocytes

-support and brace neurons; anchor them to a blood supply

-help form synapses between neurons

-mop up extracellular space

microglia

-monitor the health of neurons

-phagocytose microbes and dead neurons

ependymal cells

-Epithelial layer lining cavities in brain and spinal cord

-ciliated

-circulate cerebrospinal fluid through cavities

Oligodendrocytes

insulates axons within CNS with myelin sheath

neuroglia of PNS

satellite cells and schwann cells

satellite cells

-surround cell body

-nutrient exchange

schwann cells

insulate axons with myelin sheath

dendrites location and function

-100s of short branched projections (increase SA)

-receive info from sensory receptors or other neurons

-convey info to cell body as signals called graded potentials or postsynaptic potentials

soma location and function

where most of metabolism occurs in cell, location of nucleus, DNA and most organelles

trigger zone location and function

within axon hillock, location where the electrical impulses are produced