E109 Module Quiz 2

skeletal muscles,

Skeletal muscle

attached to skeleton, striated cells, organized into sarcomeres, multinucleated (large cells), fastest speeds of contraction, somatic nervous system

Cardiac muscle

heart, striated cells, organixed into sarcomeres, unicleated, intermediate contraction speed, autonomic nervous system

Smooth muscle

internal organs, vessels, smooth, organized into oblique bundles, uninuleated, slowest speeds of contraction, autonomic nervous system

Mechanical Energy

force and displacement

Flexion

moving bones closer together (ex: Biceps brachii)

Extension

moving bones away from each other (ex: Triceps)

Tendon

attacment of muscle to bone

Muscle fascicle

bundle of fibers

Muscle fiber

Muscle cells aka myofiber; components: thin and thick filaments

T tubules

invaginations of the plasma membrane into the cell (sarcoplasmic reticulum)

Sarcomere

functional unit of skeletal and cardiac muscle; section of myofibril that extends from one Z line to the next Z line or Z disk; Dense proteins that help to hold myofibrils in series; end of it is anchored to the Z disk on either end of the it

Sarcoplasmic reticulum

specialized for calcium storage

Thick filament

M-line; contains myosin molecules (tail and head) which is able to hydrolyze ATP

Thin filament

made by 5 different proteins (G-actin, tropomyosin, troponin, nebulin, titin)

M line

protein that connects the 2 myosin molecule tails together, such that the heads are sticking off in opposite directions

Nebulin

helps align actin

Titin

provides elasticity and stabilizes myosin

Muscle proper

consists of bundles of muscle fascicles along with connective tissue, blood vessels, nerve fibers, tendons, and this is what makes up the skeletal muscles in regards to shortening and exercising

Excitation-contraction coupling

excitation of muscle cell accomplished by way of the nervous system that is coupled or linked to contraction of the muscle cell; Muscle cells will not contract without being excited by the nervous system

Neuromuscular junction

consists of axon terminals, motor end plates on the muscle membrane, and Schwann cell sheaths; connection point between nervous system (somatic neuron) and muscle cell; each muscle cell has one one of this

Acetylcholine

neurotransmitter for all skeletal muscles; permeable to monotonic cations (+1) ex: Na, K

Ryanodine receptor

a calcium channel located in the sarcoplasmic reticulum membrane of skeletal muscle cells

Sliding filament theory

when myosin attaches the actin and pulls actin towards the center of the sarcomere, the whole sarcomere shortens because the actin filaments are sliding (the thin filaments are sliding past the thick filaments); when a muscle relaxes, the filaments slide back to resting state ready for another contraction when the myosin will bind to actin and pull the thin filament across the thick filament; Actin and myosin are not shortening themselves to make a muscle contraction

Length tension relationship

there is an optimal length for a sarcomere that will allow that sarcomere to shorten to produce the greatest or maximal force; too much or too little overlap of thick and thin filaments in resting muscle results in decreased tension

Isometric contractions

muscle generates force but does not produce movement; muscle contracts but does not shorten

Isotonic contractions

muscle generates force to produce movement; muscle contracts and shortens

Load-velocity relationship in skeletal muscle

there is an inverse relationship with the speed of contraction and the force that is generated by the muscle

Single Twitches

muscle relaxes completely before stimuli

Summation

stimuli closer together do not allow muscle to relax fully

Summation Leading to Unfused Tetanus

stimuli are far enough apart to allow muscle to relax slightly between stimuli

Summation leading to Complete Tetanus

muscle reaches steady tension; if muscle fatigues, tension decreases rapidly; no longer see individual twitches in muscle contraction

Motor unit

consists of one motor neuron and all of the muscle fibers it innervates; how we can alter muscle force

Myoglobin

oxygen-carrying pigment molecule that is found in the muscle; oxidative fibers have a lot of this

Smooth Muscle Layers in Stomach

oblique layer, circular layer, longitudinal layer

Dense bodies

actin attaches to these in smooth muscle and allows actin to stay in place (because the structure anchors it)

Varicosities

Neurons that innervate the smooth muscle (post-ganglionic cells) surround the smooth muscle by extended terminals

Single-unit smooth muscle cells

connected by gap junctions, and the cells contract as a single unit

Multi-unit smooth muscle cells

not electrically linked, and each cell must be stimulated independently

Slow wave potentials

fire action potentials when they reach threshold

Pacemaker potentials

always depolarize to threshold; Have special ion channels that allows cells to depolarize automatically and when it reaches threshold voltage, it will generate an action potential;Like clockwork, they depolarize action potential (do on their own and do not require nervous system input);  in smooth muscle that regulates motility of the gut in repeated basis

IP3 receptor

analogous to ryanodine receptor in skeletal muscle; when there is an increase in IP3 (second messenger) due to the binding of epinephrine/acetylcholine on membrane receptor, it can bind to its receptor and cause calcium from sarcoplasmic reticulum to be released

Calmodulin

calcium binds to this in smooth mucle cells for contraction

MLCK (myosin light chain kinase)

calcium-calmodulin complex activates it which further phosphorylates light chains in myosin heads and increases myosin ATPase activity

Myosin phosphatase

removes phosphate from myosin light chains, which decreases myosin ATPase activity —> decreased muscle tension

Systemic circulation

Regulated by the left side of the heart; Pumps oxygenated blood to every other cell in your body

Pulmonary circulation

Regulated by the right side of the heart; Sends deoxygenated blood to the lungs to be reoxygenated

Artery

blood moving away from the heart

Vein

blood moving towards the heart

Atrioventricular valve

barrier separating atrium from the ventricle

Mitral valve/bicuspid valve

 left AV valve; Has 2 cusps: 2 flaps of tissue that close that make up the valve; left atrium → left ventricle

Tricuspid valve

right AV valve; Has 3 flaps of tissue that make up the valve to open and close it; Only pumps blood right to the lungs next to the heart; right atrium → right ventricle

Pvetricle < Patrium

AV valve open

Pventricle < Paorta

Semilunar valve vlosed

Pventricle > Paorta

AV valve closed

Pventricle > Paorta

Semilunar valve open

Pulmonary semilunar valve

 right ventricle → lungs

Aortic semilunar valve

left ventricle to the aorta

Systole

contraction

Diastole

relaxation

Late diastole

both sets of chambers are relaxes and ventricles fill passively

Atrial systole

atrial contraction forces a small amount of additional blood into ventricles

Isovolumic ventricular contraction/systole

first phase of ventricular contraction pushes AV valve closed but does not create enough pressure to open semilunar valves. Maximum blood in ventricles = end-diastolic volume (EDV); blood volume does not change

Ventricular ejection

as ventricular pressure rises and exceeds pressure in the arteries, the semilunar valves open and blood is ejected

Isovolumic ventricular relaxation/diastole

as ventricles relax, pressure in ventricles falls, Blood flows into cusps of semilunar valves and snaps them closed. Minimum blood volume in ventricles = end-systolic volume (ESV); blood volume does not change

End systolic volume

volume of blood contained in the ventricles at the end ventricular systole

End Diastolic volume

volume that is contained in the vesicles at the end of ventricular diastole, maximum amount of blood that the ventricles could pump when they pump

Stroke volume

the difference between how much blood is contained in the ventricles and how much blood the ventricles does pump (EDV - ESV) = how much blood the ventricle is ejecting every time it contracts per stroke

Intercalated discs

specialized junctions between cardiac muscle cells (physically connected), and their job is to make the heart contract as a single, coordinated unit

Calcium sparks

brief, localized Ca²⁺ releases from the sarcoplasmic reticulum via ryanodine receptors that initiate cardiac muscle contraction; summate to produce the global Ca2+ transient which can bind to troponin

Autorythmic cells

have unstable membrane potentials called pacemaker potentials; do not have a resting membrane potential proper

SA (sinoatrial) node

located at the superior margin of atria;  where the initial pacemaker potential start and they travel through the atria rapidly both left and right

AV (atrioventricular) node

ocated at inferior margin of the atria

bundle branches

modified nerve fibers that extend from the junction of atria and ventricles to apex of ventricles (tip of heart)

 Purkinje fibers

extension of bundle branches

EKG/ECG

measuring the electrical activity on skin as it is associated with electrical events in the heart; represents the summed electrical activity of all cells in the heart recorded from the surface of the body

positive/upward ECG tracing (positive deflection)

Electrical activity moving from negative to positive

negative/downward ECG tracing (negative deflection)

Electrical activity moving from positive to negative

P wave

atrial depolarization; Stimulus (pacemaker potential) starts in SA node and spreads throughout the atria → generate electrical pulse that leads on the skin can pick up (slight positive deflection)

QRS wave

positive deflection; when the signal (depolarization) travels from AV node and to bundle branches to the apex of heart; negative deflection; ventricular depolarization - as the action potential signal spreads out in Purkinje fibers and begins to form ventricular depolarization from apex of heart back towards the aorta and pulmonary artery

T wave

positive deflection; ventricular relaxation

Atrial fibrillation

No distinct P wave; Atria are not coordinated but the ventricles are doing thing of depolarization and repolarization and still pumping blood

Ventricular fibrillation

Zero conducting happening in a coordinated fashion; Ventricles are not undergoing regular repeating depolarization, repolarization to initiate ventricular contraction and a regular pumping of blood out of the heart

Descending aorta

Carries oxygenated blood from the left ventricle to the lower body

Cardiac Output

how many milliliters of blood does heart pump blood per minute (Heart rate (BPM) * Stroke Volume (mL)

Parasympathetic nervous system

favors rest and digest; uses acetylcholine at muscarinic receptors

Sympathetic nervous system

favors fight-flight response; uses epinephrine and norepinephrine at a, B1, B2 adrenergic receptors

Heart rate

how many beats per minute your heart is generating

Parasympathethic stimulation

this stimulation hyperpolarizes the membrane potential of the autorhythmic cell and slows depolarization, slowing down the heart rate (increase in K+ permeability causing hyperpolarization, decrease in Ca2+ permeability slows down rate of depolarization)

Sympathethic stimulation

and epinephrine depolarize the autorhythmic cell and speed up the pacemaker potential, increasing the heart rate (increase in Na+ permeability through If channels, increase in Ca2+ permeability increases rate of derpolarization)

Frank–Starling mechanism

Relationship between stretching of ventricle and stroke volume it can produce; states that increased ventricular filling (EDV) stretches cardiac muscle fibers, producing a stronger force/contraction and increased stroke volume, thereby increasing cardiac output

Hydrostatic pressure

pressure exerted by a fluid on the walls of its container when the fluid is not in motion. It is proportional to the height of the column; the further away you get from original source of the pressure, the lower the hydrostatic pressure

Flow rate (ml/min)

general flow of a volume of fluid through a tube; Generally set up by the heart

Flow velocity (cm/min)

how quickly does the fluid or blood flow through the tube; Set by the blood vessels

Capillaries

exchange occurs of nutrients and gases with blood supply; increase in capillaries is is increase in cross-sectional area which allows blood to flow well

Arteries, arterioles, veins

have a layer of smooth muscle associated with them; have the capacity to have different radius or diameters based on innervation from the nervous system, based on neurotransmitter input

Paracellular diffusion

Movement of substances between adjacent endothelial cells of the capillary wall

Transcytosis

Movement of substances through the endothelial cell itself

Arterial end of capillary

more hyrostatic pressure than colloid osmotic pressure

Venous end of capillary

More colloid osmotic pressure than hydrostatic pressure

Sphygmomanetry

listening for changes in blood flow as you constrict and relax a vessel