A&P Quiz 3

ch. 12, 13, 14, 15?

Skeletal Muscle

Support voluntary movement. Fibers are large, multinucleate cells that appear striped or striated under microscope. Usually attached to bones by tendons

Cardiac Muscle

Fibers are striated but smaller, branched and uninucleate. Cells are joined in series by junctions called intercalated disks. Cells have one nucleus.

Smooth Muscle

Fibers are small and lack striations. Cells have one nucleus. Muscle in hollow organs and blood vessels

Flexor

Brings bones together

Extensor

Moves bones away

Antagonistic Muscles

Move bones in opposite directions. Flexor-extensor pairs

Muscles fibers/cells

Compose skeletal muscles. Long and cylindrical, fused cells with many nuclei

Satellite cells

Type of stem cells. Differentiate into muscle for growth or repair

Fascicles

Bundled muscle fibers. surrounded by connective tissue sheath.

Connective tissue (in muscles)

Continuous with connective tissue sheath. Holds muscle to bone with tendon

Muscle equivalent for muscle cell

Muscle fiber

Muscle equivalent for cell membrane

Sarcolemma

Muscle equivalent for cytoplasm

Sarcoplasm

Muscle equivalent for modified endoplasmic reticulum

Sarcoplasmic reticulum

Myofibrils

Bundles of contractile and elastic proteins responsible for muscle contraction. Contain actin and myosin

Myosin

forms thick filament of the myofibril that convert chemical bond energy of ATP into motion

Transverse Tubules (T-Tubules)

Extensions of the cell membrane (sarcolemma) that associate with the ends (terminal cisternae) of the sarcoplasmic reticulum

Sarcomere during contraction (image)

What initiates an action potential in muscle fiber?

Acetylcholine (ACh)

Steps of excitation-contraction coupling

1. Acetylcholine is released from the somatic motor neuron

2. Acetylcholine initiates an action potential in the muscle fiber

3. The muscle action potential triggers calcium release from the sarcoplasmic reticulum

4. Calcium combines with troponin to initiate contraction

Latent period

Short delay between the muscle action potential and beginning of muscle tension development

Anaerobic glycolysis

Produces lactate and acid. Quick, no oxygen required, small amount of energy released

Aerobic Respiration

Citric acid cycle and electron transport chain. Slow, oxygen required, large amount of energy released

Slow twitch fibers

Rely primarily on oxidative phosphorylation. Fatigue-resistant

Fast twitch fibers

Develop tension faster, easily fatigued

Summation

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

Tetanus

maximal contraction

Isotonic Contractions

contraction where the muscle changes its length while maintaining a constant level of tension or load (bicep curl)

Isometric Contractions

create force without movement

Autonomic Reflexes

Unconscious, involuntary motor response that regulates internal organs, smooth muscle and cardiac muscle

Proprioceptors

Sensory receptors located in skeletal muscle, joint capsules and ligaments. Input signals go to the CNS through sensory neurons

Myotatic Unit

Collection of pathways controlling a single joint

Reciprocal Inhibition

Antagonistic muscles must relax as the prime mover muscles contract

Flexion reflexes

Pulls limbs away from painful stimuli

Reflex movement

least complex, integrated at the spinal cord or brain

Postural reflexes

Help us maintain body position

Voluntary movements

Most complex, integrated in cerebral cortex

Rhythmic movements

intermediate complexity, integrated in spinal cord with higher center input required

Poiseuille’s Law

Resistance is proportional to length and viscosity. Inversely proportional to radius

Pathway of deoxygenated blood

vena cava → right atrium → right ventricle → pulmonary trunk

Pathway 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)

Contractile Cells

Striated fibers organized intro sarcomeres

Autorhythmic cells (Pacemaker cells)

Signal for contraction, smaller and fewer contractile fibers, don’t have organized sarcomeres

Electrocardiogram

Show the summed electrical activity generated by all cells of the heart

P wave

Depolarization of the atria

QRS complex

wave of ventricular depolarization, and atrial repolarization

T Wave

Repolarization of the ventricle

Tachycardia

Faster than normal heart rate

Bradycardia

Slower than normal heart rate

Diastole

Cardiac muscle relaxes

Systole

Cardiac muscle contracts

Efferent Neurons

Carry commands from CNS to the muscles and glands of the body

Somatic Motor Neurons

Control skeletal muscles, mostly voluntary

Autonomic Neurons

Controls smooth muscle, cardiac muscle, many glands and adipose tissue. Mostly involuntary. Divide into sympathetic (fight-or-flight) and parasympathetic (rest-and-digest)

Neuroeffector junction

Synapse between postganglionic autonomic neuron and target cell

Neuromuscular Junction

Synapse between somatic motor neuron and skeletal muscle fiber

Troponin

Complex of three regulatory proteins associated with tropomyosin that binds calcium ions to help initiate muscle contraction (skeletal and cardiac)

Tropomyosin

Regulatory protein that lies along actin filaments and blocks the myosin binding sites, helping control when muscle contraction can occur

Golgi Tendon Organs

Found in junction of tendons and muscle fibers. Composed of free nerve endings that wind between collagen fibers inside connective tissue capsule

P-R segment

Atrioventricular (AV) nodal delay - slows down electrical impulses as they travel from the atria to the ventricles

T-P segment

ventricular and atrial relaxation

How to find heart rate from ECG

Time between two P waves or two Q waves

Parasympathetic Control

Decreases heart rate, K+ permeability increases

Sympathetic Control

Increases heart rate, Na and Ca permeability increases

Arteries

Act as a pressure reservoir, thick layers of vascular smooth muscles, lots of elastic and fibrous connective tissue

Arterioles

Site of variable resistance, part of the microcirculation, less elastic and more muscular

Metarterioles

Branches of arterioles, partial smooth muscle layer, pre-capillary sphincter's open and close to direct blood flow to capillaries or venous circulation

Pericytes

Contractile cells associated with capillaries, contribute to capillary impermeability, secrete paracrine factors that promote vascular growth and differentiation

Venules

Receive blood from capillaries, thin exchange epithelium, little connective tissue, convergent pattern of flow

Veins

Take blood back to the heart, act as a volume reservoir, thin walls of vascular smooth muscles, contain one-way valves

What causes a striated appearance in muscles?

Organized myofibrils made of actin and myosin arranged into repeating sarcomeres

Contractility

The ability of muscle tissue to shorten fibers, generating movement

Extensibillity

The capacity of muscle tissue to be stretched without damage

Elasticity

The property of muscle tissue to return to its original shape after contraction or extension

I band

Region of skeletal muscle sarcomere that contains only thin filaments

Z line/disk

Set of sarcomere proteins located at the ends of a sarcomere, serving as attachment sites for actin filaments, help define boundaries of each sarcomere

H Zone

Region of a sarcomere that contains only thick filaments and no overlap with thin filaments

A band

Contains the entire length of the thick myosin filaments, plus the overlapping portions of the thin actin filaments

M line

Structural feature of skeletal muscle sarcomeres that divides the A band in half and serves as an attachment site for thick (myosin) filaments

Thick filaments are made of

Myosin

Thin filaments are made of

Actin

Phases of an ECG (depolarization vs. repolarization, diasytole vs. systole)