Anatomy and Physiology Quiz 3

What are the two subdivisions of Efferent neurons?

somatic and aautonomic

somatic

controls skeletal muscles, voluntary

autonomic

smooth muscle, cardiac muscle, glands, and adipose tissue; involuntary

what are the two subdivisions of the autonomic division?

sympathetic branch and parasympathetic branch; homeostasis is the balance between the two

sympathtic

fight or flight

parasympathetic

rest and digest

autonomic pathways

CNS, preganglionic neuron, autonomic ganglion, postganglionic neuron, target tissue; can be modulated

the neuroeffector junction

synapse between postganglionic autonomic neuron and target cell

Somatic motor pathway

1 neuron, myelinated, very long, always excitatory

Neuromuscular Junction

synapse between somatic motor neuron and skeletal muscle fiber; acetylcholinesterase in synaptic cleft

What are the three types of muscles?

skeletal, cardiac, and smooth

skeletal muscle

large fibers(cells), multinucleate cells that are striated/striped

attatched to bones by tendons and surrounded by connective tissue

cardiac muscle

fibers are striated but smaller, branched, uninucleate. Joined together by junctions called intercalated disks

smooth muscle

fibers are small and lack striations

satellite cells

stem cells, differentiate into muscle for growth or repair

muscle fibers

or cells, bundles into fascicles surrounded by connective tissue sheath

structure of the skeletal muscle

muscle, fascicle, fiber, myofibril

Sarcolemma

muscle cell membrane

sarcoplasm

muscle cell cytoplasm

sarcoplasmic reticulum

modified endoplasmic reticulum

thin filament

actin with regulatory proteins

thick filament

myosin, heavy chains, motor domain, myosin head movement

regulatory proteins

on Actin, tropomyosin and troponin

accessoy proteins

titin (stabilizes myosin and returns to length after contraction) and nebulin (inelastic, aligns actin)

T-tubules

extensions of sarcolemma that associate with the ends of the sarcoplasmic reticulum

Sarcomere

junction of actin and myosin, stuck to other sarcomeres

what are the 4 sections of a sarcomere?

I band, H zone, M line, A band

I band

actin only, contains the z disk (where the sarcomeres are linked)

H zone

myosin only, contains the M line

M line

myosin linked with accessory proteins

A band

edges of the sarcomere, actin and myosin overlap

Muscle tension

force created by muscle

Load

weight or force opposing contraction

what steps lead up to a skeletal muscle contraction?

1. events at neuromuscular junction

2. excitation-contraction coupling

3. Contraction-relaxation cycle

Steps of the Contraction Cycle

ATP binds, myosin releases actin, myosin hydrolyzes ATP, Power stroke, Myosin releases ADP, Myosin stuck bound until given ATP

Acetylcholine (ACh)

released from somatic motor neuron and initiates action potential in muscle fiber,

How does ACh initiate contraction?

ACh is released from somatic motor neuron, ACh binds to sarcolemma, Na+ enter and K+ exits cell, depolarization, end-plate potential (EPP), muscle action potential, releases sarcoplasmic reticulum, calcium combines with troponin to initiate contraction

Summation

stronger contraction when the muscle does not relax completely between action potentials

Tetanus

maximal contraction

What causes decreased tension in resting muscles?

too much overlap between thick and thin filaments

Isotonic contractions

concentric action (shortening action) and eccentric action (lengthening action)

Isometric contractions

series elastic elements

sarcomeres shorten while elastic elements stretch

smooth muscle

in an organ, they contract and relax slowly, use less energy to generate and maintain a given amount of force. Vascular, gastrointestinal, urinary, respiratory, reproductive, ocular

Caridiac muscle

striated, sarcomere structure, short fibers, single nucleus, gap junctions, sympathetic and parasympathetic control

Compare fibers of skeletal, smooth, and cardiac

skeletal: sarcomeres

smooth: no sarcomeres

cardiac: sarcomeres

Compare location of skeletal, smooth, and cardiac

skeletal: attatched to bones, a few sphincters

smooth: forms the walls of hollow organs and tubes, some sphincters

cardiac: heart muscle

Compare tissue morphology of skeletal, smooth, and cardiac

skeletal: multinucleate, large, cylindrical fibers

smooth: uninucleate, small spindle-shaped fibers

cardiac: uninucleate, shorter branching fibers

Compare what each muscle controls with the skeletal, smooth, and cardiac

skeletal: Ca2+ and tropinin, fibers independent from one another, Ca2+ from SR

smooth: Ca2+ and calmodulin, some fibers electrically linked via gap junctions, Ca2+ from ECF and SR

cardiac: Ca2+ and troponin, fivers electrically linked via gap junctions, Ca2+ from ECF and SR

Autonomic reflexes

visceral reflexes, some are spinal reflexes with brain modulation, some are integrated in the brain.

polysynaptic, with at least one synapse in the CNS

Skeletal muscle reflexes

proprioceptors send input to CNS and then somatic motor neurons carry output signal (alpha motor neurons), and effectors called extrafusal muscle fibers contract muscle fibers

Golgi tendon organs

free nerve endings wound inbetween collagen fibers in junction of tendons and muscle fibers, send info to CNS

Muscle spindles

stretch receptors encode signals about muscle length and changes in muscle length

myotatic unit

collection of neural pathways controlling a single joint

reciprocal inhibition

antagonistic muscles must relax as the prime mover muscles contract. sensory fibers branch upon arriving at the spinal cord

flexion reflexes

reflex to pull away from painful stimuli

3 classifications of movement

reflex, voluntary, or rhythmic

Integrated, coordinated responses require?

input from multiple regions of the brain

Where are reflex movement integrated?

least complex, integrated in spinal cord or brain

voluntary reflexes

most complex, integrated in cerebral cortex

rhythmic movements

intermediate complexity, integrated in spinal cord with higher center input required, Central pattern generators (CPGs)

3 levels of movement through CNS integration

spinal cord: reflexes and central pattern generators

Brain stem and cerebellum: posture and eye/hand movement

Cerebral cortex and basal ganglia: voluntary movements

the corticospinal tract

interneurons run from motor cortex to synapses with somatic motor neurons

Pakinson’s disease and basal ganglia function

abnormal movements, speech, cognitive changes, dopamine release reduction

Visceral Muscle Movement

smooth and cardiac, spontaneous depolarizing fibers called pacemakers

Cardiovascular system includes

heart, blood, vessels and capillaries

What is transported through the body in cardiovascular system?

nutrients, water, gases, hormones, immune cells, antibodies

What is eliminated by cardiovascular system?

CO2, heat, metabolic waste

Types of blood vessels

arteries, veins, capillaries, portal system (joins two capillary beds in series)

Parts of the heart

septum divides halves (left, right), atrium (in), ventricle (out)

Pulmonary circulation

short circuit, heart and lungs

arteries (O2 poor) and veins (O2 rich)

Systemic Circulation

heart and rest of the body,

aorta (O2 rich)

superior and inferior vena cava (O2 poor)

Blood flow motion components

dynamic (kinetic energy) and later (hydrostatic pressure)

Factors of blood flow

pressure, distance/length, radius, resistance, viscosity

Poiseuille’s law

resistance proportional to length and viscosity

resistance is inversely proportional to radius^4

velocity of flow

v, velocity = q, flow rate / a, cross-sectional area of tube

Mean arterial pressure (MAP)

pressure reserved in arteries during heart relaxation

MAP =~ cardiac output (CO) * peripheral resistance (PR)

What are the four chambers of the heart?

right and left atrium, right and left ventricle

What is the heart mostly made of?

myocardium, encased in pericardium

path of deoxygenated blood

vena cava → right atrium →right ventricle → pulmonary trunk

path of oxygenated blood

pulmonary veins → left atrium → left ventricle → aorta

atrioventricular valves

between atria and ventricles (tricuspid and bicuspid valve)

semilunar valves

between ventricles and arteries (aortic and pulmonary valve)

coronary circulation

supplies blood to the heart

autorhythmic cells

pacemakers, signal contraction, few contractile fibers

Contractile cells

striated fibers organized into sarcomeres

cardiac muscle compared to skeletal muscle

single nucleus per fiber

branch and join cells through intercalated disks

gap junctions

sarcoplasmic reticulum is smaller

myocardial contractile cells action potentials

depolarization (Na channels open) → initial repolarization (Na channels close) → plateau (Ca channels open, K channels close) → rapid repolarization (Ca channels close, K channels open)→ resting membrane potential (-90mv)

Myocardial autorhythmic cells action potentials

pacemaker potential (-60mV, Na+ in) → action potential (Ca2+ in and then K+ out) → back to resting (-60mV, K+ close If open)

What happens to the action potential of a myocardial autorhythmic cell if tetrodoxin, which blocks voltage-gated Na channels, is applied to the cell?

nothing because myocardial autorhythmic cells don’t use Na channels

What are the waves of the Electeocardiogram (ECG)?

P wave: depolarization of the atria

QRS complex: wave of ventricular depolarization and atrial repolarization

T wave: repolarization of the ventricle

What are the two segments of ECG waves?

P-R segment: AV nodal delay

T-P segment: ventricular atrial relaxation

What is the heart rate?

the time between two P waves or two Q waves

tachycardia

faster than normal heart rate

bradycardia

slower than normal heart rate

Diastole

cardiac muscle relaxes

Systole

cardiac muscle contracts

What are the five phases of the cardia cycle?

1. Heart at rest: Atrial and ventricular diastole

2. Ventricular filling: atrial systole

3. Early ventricular contraction (first sound)

4. Heart pumps: ventricular ejection

5. Ventricular relaxation (second sound)

Stroke Volume (SV)

End diastolic volume (EDV) - end systolic volume (ESV)

volume of blood before contraction minus after contraction

Cardiac output

volume of blood pumped by one ventricle in a given period of time

CO = HR * SV

average = 5 L/min

What are the three autonomic division controls?

parasympathetic control, sympathetic control, and tonic control