Physio exam 5 part 2

functionality + heart

Who/what is secreted during the formation of platelet plug

intact endothelium secrets prostacyclin, nitric oxide, and CD39

Functions of prostacyclin and nitric oxide

Vasodilation
Inhibits platelet aggregation

CD39 function

breaks down ADP into AMP and Pi to inhibit platelet aggregation

How do platelets help form a clot

bind to collagen

What holds platelets to collagen

Von Willebrand factor

What do platelets secrete (and function)

ADP (sticky platelets)
Serotonin (vasoconstriction)
Thromboxane A (sticky platelets and vasoconstriction)

Hemostasis

cessation of bleeding wen a blood vessel is damaged

What are the processes involved in hemostasis

vasoconstriction
formation of platelet plug
formation of fibrin protein web

What do clottiing factorsr form

Fibrinn

What is fibrini madde from

fibrinogen

What are the two pathways of fibrinogen to fibrin protein web

intrinsic
extrinsic

Intrinsic pathway deffinition

activated by exposure to collagen
Factor VIII activates a cascade of other blood factorsE

Extrinsic pathway

Initiated by tissue thromboplastin (factor III)
more direct pathway

What do the intrinsic and extrinsic pathways funnel into

The common pathway

Extrinsic pathway steps

1. activation of Tissue factor
2. VII activated
3 VII, tissue factor, calcium, and phospholipids form VII complex
4. Funnel into common pathway

Intrinsic pathway steps

1. Collagen, glass, and other activatorsr activate XII
2. XII activates XI
3. XI activates IX
4. VIIII complex formed with VIII, activated IX, calcium, and phospholipids
5. Funnels into common pathway

Common pathway steps

1. X activated from VIII complexes
2. V complex formed with activated X, calcium, and phospholipids
3. Prothrombin converted to thrombin
4. thrombin + Fibrinogen --> fibrin
5. Fibrin --> Fibrin polymer

When is the intrinsic pathway used

Always happens

When is the extrinsic pathway used

Only when blood leaks into other tissues

What activates the intrinsic pathway

Platelets binding to exposed collagen

What activates the extrinsic pathway

When blood hits tissues, which releases tissue factor

Vitamin K role in blood clotting

Needed by the liver to make several of the needed clotting factors

How are clots dissoluted

plasmin digests fibrin

What is the precursor for plasminogen

plasmin

Right atrium

receives deoxygenated blood from the body

Left atrium

receives oxygenated blood from the lung

Right ventricle

pumps deoxygenated blood to the lungsL

Left ventricle

pumps oxygenated blood to the body

Fibrous skeleton

separates atria from ventricles

The atria work as ___ unit while the ventricles work as a ___ unit

one
separate

Pulmonary circulation beginning and end

right ventricle --> left atria

Systemic circulation beginning and end

left ventricle --> right atria

Blood pumps to lungs via...

pulmonary arteries

Blood returns to heart via...

pulmonary veins

blood pumps to body tissues via...

aortab

blood returns to heart via...

superior and inferior vena cava

Blood flow through the heart order (start with vein entering heart)

1. Superior and inferior vena cava (coronary sinus)
2. Right atrium
3. Tricuspid valve
4. Right ventricle
5. Pulmonary valve
6. Pulmonary Trunk
7. Right and Left Pulmonary arteries
8. Pulmonary capillaries (oxygenated)
9. Pulmonary veins
10. Left atrium
11. Bicuspid (mitral valve)
12. Left ventricle
13. Aortic valve
14. Aorta
15. Arteries
16. capillaries (deoxygenated)
17. Veins
18. repeat

Coronary sinus

major vein that brings blood back into heart

What are the atrioventricular (AV) valves

Tricuspid
Bicuspid/mitral

Papillary muscles and chordae tendinae function

prevent the valves from everting

What are the semilunar valves

Pulmonary
aortic

Where is the tricuspid valve

Between right atrium and ventricle

Where is the bicuspid/mitral valve

between left atrium and ventricle

Pulmonary valve locations

Between right ventricle and pulmonary trunk

Aortic valve location

Between left ventricle and aorta

What causes the "Lub" sound

AV valves closing
Blood pushed out of the ventricles

What causes the "dub" sound

closing of the semilunar valves
blood entering ventricles

Systole mechanism

contraction of heart muscles

Diastole mechanism

Relaxation of heart muscles

What is the cardiac cycle

repeating pattern of contracting and relaxation of the heart

Order of cardiac cycle

1. Atria contract (diastole)
2. Atria relax and ventricles contract (Systole)
3. Ventricles relax and fill (Diastole)

How long is systole

0.3 seconds

How long is diastole

0.5 seconds

isovolumetric contraction

ventricles begin contraction, pressure rises, ad AV valves close.
No blood entering or leaving the heart
Cause lub sound

isovolumetric relaxation

pressure in ventricles falls and all valves close
dub sound

Dicrotic notch

slight inflection in pressure during isovolumetric relaxation

As pressure rises in ventricles...

more blood is ejected

As pressure falls in the ventricles...

ventricles fill

What is the primary pace maker

SA node

SA node location

right atrium

What are the secondary pacemakers of the heart

AV node
Purkinje fibers

Pressure changes/contraction order

1. Blood comes in to right and left atria, passively fill in ventricles
2. Atria contract, eject blood into ventricles
3. Ventricles start to contract by the papillary muscles pulling on chordae tendonae, isometric volumetric contraction, "Lub"
4. Pressure in ventricles is higher than aorta and trunk, semilunar valves open and blood is ejected into atria and pulmonary trunk
5. Semilunar valves close, isometric volume relaxation, dub sound

What takes over when SA node goes out

AV node

Where does the AV node "go"

goes into ventricles and splits in interventricular septum, spreads action potential to ventricles

Steps of Pacemaker potential

1. Hyperpolarization activates HCN channels, causing small uptick
2. Voltage-gated Ca2+ open at -40mV, causes depolarization and large increase
3. K+ channels open, causes depolarization + hyperpolarization and large decrease

Pacemaker cells depolarize...

spontaneously

How is pacemaker potential/heart rate sped up (molecularly)

Na+ inflow

How does the sympathetic system affect pacemaker potential

epinephrine and norepinephrine increase production of cAMP, which keeps cardiac pacemaker channels open (HCN)

How does the parasympathetic nervous system affect pacemaker potential

secrete acetylcholine which opens K+ channels and lead to a slower heart rate

What is pacemaker potential

slow, spontaneous depolarization of SA nodes during diastole produced in clocklike manner

Myocardial action potential order

1. Resting membrane potential = -85
2. Action potential causes Na+ channels to open
3. Na+ influx cases depolarization, huge spike
4. Plateau at -15mV for 200-300 milliseconds due to Ca2+ slow influx
5. K+ efflux causes repolarization, slow decline

What are the reason and explanation for excitation-contraction coupling of the heart muscle

prevents a long action potential leading to longer refractory period in order to prevent fatigue and allow the heart to rest

Myocardial action potentials location and cause

Happens in contractile muscle cells
Depolarized to threshold by action potentials from SA node

How does the SA node pace the heart

Sends out action potentials

How does the myocardium relax

Ca2+ in cytoplasm is actively transported into the SR, allows myocardium to relax

Why is the AV node slower than the SA node

SA node action potentials spread more rapidly (0.8-1.0 m/sec) compared to AV node (0.03-0.05 m/sec)

When conducting an impulse, where is the fastest action potentials?

Purkinje fibers (5 m/sec)

Mechanism of excitation-contraction coupling

1. action potentials conducted along sarcolemma and T tubules open voltage-gated Ca2+ channels
2. Ca2+ diffuses into cells and stimulates opening of calcium release channels of SR
3. Ca2+ from SR bind to troponin to stimulate contractions
4. since atria and ventricles contract as single units, they cannot sustain contraction
5. Long refractory period causes "break"

What does the P wave indicate

atrial depolarization

Where is the P wave located

First smallest bump up

What does the QRS wave indicate (and what is not seen)

Ventricular depolarization (atrial repolarization)

Where is the QRS wave located

Large spike

What does the T wave indicate

Ventricular repolarizationWh

Where is the T wave located

Small bump after major wave

When is "lub" heard on an EKG

Occurs after QRSS wave as AV valves closeW

When is the "Dub" heard on an EKG

Occurs at the beginning of the T wave as semilunar valves close

Order of electrical activity of the heart

1. Action potentials spread via intercalated discs (gap junctions)
2. SA node to AV node to stimulate atrial contraction
3. AV node at base of right atrium and bundle of His conduct stimiulation to ventricles
4. In interventricular septum, bundle of His divides into right and left bundle branches
5. Branch bundles become purkinje fibers and stimulate ventricular contraction

What are the types of blood vessels

Arteries
Arterioles
Capillaries
Venules
Veins

What are the three Tunics (layers) of blood vessels (inner to outermost)

Tunica interna
Tunica media
Tunica externa

Tunica interna location and composition

innermost layer
Simple squamous endothelium on a basement membrane and elastic fibers

Tunica media location and composition

Middle layer
smooth muscle tissue

Tunica externa location and composition

Outer layer
Connective tissue

What are the types of arteries

Elastic arteries
Muscular arteriies
Arterioles

Elastic arteries location and function

Closer to the heart
Allow stretch as blood is pumped into them and recoil when ventricles relax

Arteries composition (compared to other vessels)

Slightly thicker tunica interna
Much thicker tunica media

What is in veins that differs them from arterials

feature valves and larger lumen

Muscular arteries location and function (and structural difference)

Farther from heart
Have more smooth muscle in proportion to diameter
have more resistance due to smaller lumina

Arterioles location and function (and structural difference)

20-30 micrometers in diameter
Provide greatest resistance
Control blood flow through capillaries

What is capillary blood flow regulated by

vasoconstriction and vasodilation of arterioles
Precapillary sphincters

What are the smallest blood vessels (provide diameter)

capillaries (7-10 micrometers)