PPY Exam 4 Slides Part 1

What does blood transport?

O2, CO2, nutrients, wastes products, and hormones

What is homeostasis?

regulation of body temperature and pH

What are the functions of blood?

-transportation
-homeostasis
-protecting against infections
-blood clotting prevent blood loss

What is hematocrit?

percentage of blood volume that is occupied by red blood cells

What is plasma?

strw-colored liquid consisting of H2O and dissolved solutes

What does plasma include?

Von Willebrand factor (VWF), fibrinogen, clotting factors, and prothrombin

What is blood serum?

blood plasma without fibrinogen and clotting factors prepared by taking blood allowing it to clot then removing the clot

_____ is the word for when the bleeding stops.

Hemostasis

At the site of the wound, platelets bind to collagen via VWF and are stimulated. The platelets:

-undergo major shape change
-bind to each other via fibrinogen
-release vasoconstrictors, platelet activators
-act as a surface to carry out clooting reactions

What is the function of platelets?

aggregate (clump together), form a plug (thrombus) to stop bleeding when a blood vessel is damaged

Platelets _____ to intact endothelium.

don't bind

What does the endothelium release?

small amounts of inhibitors of platelet aggregation (clumping together) prostacyclin (PGI2) and Nitric Oxide (NO)

What does PGI2 stimulate?

increase of cAMP which blocks platelet activation

What are the three steps involved in hemostasis?

-damage to blood vessel exposes collagen
-platelet plug formation
-vascular constriction and formation of a blood clot. Tissue Factor (Tromboplastin) released from damaged endothelium plus calcium and platelet phospholipids mediate Clot formation

What is platelet plug formation?

-binding to collagen (platelets bind to each other via fibrinogen)
-release of ADP, TXA2, and serotonin
-activation of more platelets

_____ binds to the exposed collagen and undergoes a conformational change.

Von Willebrand Factor

Conformational change of VWF exposes...

site on vWF for platelet GPIb

Platelets (GPIb on platelets) bind to collagen via _____.

Von Willebrand Factor

Platelet shape change results in:

-exposure of IIbIIIa involved in binding of platelets to platelets
-release ADP TXA2. (ADP stored in granules. PLA2 is activated and TXA2 synthesized)
-exposure of the internal membrane of the platelets. Exposure of platelet membrane exposes negative charged phospholipids that promote the assembly of vitamin-K dependent clotting factors on the platelet membrane surface-clotting cascade

GPIIb/GPIIIa binds to _____.

fibrinogen and platelets begin to aggregate

Loss of TXA2 by aspirin results in decrease in _____.

vasoconstrictor

_____ blocks cyclooxygenase and inhibits TXA2 synthesis.

aspirin

What is the formation of platelet plug (thrombus)?

-damage to blood vessels. Platelets come in contact with exposed collagen
-platelets interact with collagen via von Willebrand Factor. Binding activates the platelets. Platelets synthesize Thromboxane A2 (TXA2) and change shape, secrete ADP serotonin and TXA2. Platelets change shape exposing inner platelet membrane (negative charge).
-TXA2 and serotonin stimulate vasoconstriction.
-TXA2 and ADP also cause platelets to become stickier. When platelets stick to themselves via fibrinogen, release moreADP, Serotonin and TXA2. Sticking of platelets at the site of the wound is called platelet plug formation (Thrombus)

Fast moving blood carries away activated...

platelets not stuck to the plug

Adjacent endothelial cells increase synthesis of PGI2 and NO that inhibit...

platelet activation and aggregation

Why is the platelet thrombus with fibrinogen a temporary fix to stop bleeding?

it is too unstable and easily dislodged

How do you make the platelet plug stronger?

a meshwork of fibrin is formed. Fibrin formation stabilizes the plug

What is thrombin?

an enzyme that converts fibrinogen to fibrin

What is clott cascade?

-Xa synthesis
-prothrombin to thrombin (requires Xa)
-fibrinogen to Fibrin (requires thrombin)
-crosslinked Fibrin (requires XIII)

_____ is circulating in blood and made in liver.

Xa

Xa is required to make _____.

thrombin

Prothrombin + Xa = _____.

thrombin

What are the two ways to make Xa?

intrinsic and extrinsic

Both ways to make Xa must have a _____.

surface with a negative charge (provided by platelets after shapr change)

Clotting is localized by requiring a...

negatively charged surface

What is the intrinsic pathway?

-slower pathway
-all components are in the blood

What is the extrinsic pathway?

-much faster than intrinsic
-a component from injured tissure ("tissue factor" from endothelium0
-other components are in the blood

What are the factors required for the intrinsic pathway?

-negative charged surface (platelet lipids)
-clotting factors
-calcium
-vitamin K

What are the factors required for the extrinsic pathway?

-negative charged surface (platelet lipids)
-clotting factors
-calcium
-vitamin K
-tissue factor (thromboblastin)

What is vitamin K?

co-factor in reactions that modify clotting factor proteins so they can bind to negative platelet membrane via calcium

Fibrinogen + thrombin = _____

fibrin

Fibrin + XIII = _____

crosslinked fibrin (polymerized fibrin network)

Both pathways meet at Xa and finsh clot production in what is known as the _____.

common pathway

What is plasmin formed from?

plasminogen

Plasminogen + plasminogen activator (PA) = _____

plasmin

_____ produce plasminogen activator.

endothelial cells

What is plasmin involved in?

breaking down fibrin into soluble fragments (fibrinolysis)

Polimerized fibrin + plasmin = _____

soluble fragments

The heart consists of _____ pumps.

two

What do the pumps of the heart do?

-one propels the blood through the lungs so it can get oxygenated
-other pumps it to all the other tissues in the body

What is the flow of deoxygenated blood through the heart?

-enters the right atrium via the superior/inferior vena cava
-goes through tricuspid value and into right ventricle
-leaves right ventricle via the semilunar pulmonary valve to go through the pulmonary artery to get to the lungs (to get oxygenated)

What is the flow of oxygenated blood through the heart?

-leaves the lungs and enters the left atrium via the pulmonary vein
-passes through the bicuspid/mitral valve into the left ventricle
-pumped out of left ventricle through semilunar aortic valve and into the aorta where it gets sent to rest of the body

What is the flow of blood through the body?

-aorta
-arteries
-arterioles
-capillaries
-venules
-veins
-superior/inferior vena cava

What is the pulmonary circuit is supplied by?

right heart

What is the systemic circuit is supplied by?

left heart

In the pulmonary circuit, pressures are _____.

low (thinner muscle)

In the systemic circuit, pressures are _____.

higher (thicker muscle)

What does parrallel flow allow for?

independent regulation of blood flow to organs at the arterioles (can shut off just one capillary bed)

What is coronary circulation?

heart has its own set of capillaries

What do coronary arteries do?

supply oxygenated blood to heart

What does coronary venules do?

take deoxygenated blood away from heart

What are the layers of the heart wall?

-pericardium
-endocardium
-myocardium
-epicardium

What is the pericardium?

outer liner of the heart

What is the endocardium?

inner layer of endothelial cells of the heart

What is the myocardium?

-cardiac muscle
-constitutes the bulk of cells in the atria and ventricles

What do myocardial conducting cells (SA, AV, purkinje fibers) do?

-conduct action potentials (function similar to neurons)
-initiate and propagate the AP that travels through the heart to signal atrial and ventricle contraction

What is the epicardium?

outer layer of heart

What are gap junctions?

electrically connect each muscle cell

What are desmosomes?

mechanically connect each muscle cell

What is the sequence of cardiac action potentials?

-action potential starts at the SA node (automatic/beats on own)
-sent to left and right atrium (contract at the same time)
-goes to AV node (having a second node allows for a delay. This is important because atriums must fully relax before ventricles contract)
-goes to bundle of His then purkinje fibers (right and left ventricle contract at the same time)

What is the membrane potential of autorhtmic cells (for transmission of action potential)?

-depolarization caused by opening of voltage gated Ca2+ channels
-Ca2+ channels close and K+ channels open (Repolarization)
-funny Na+ channel close (repolarization)
--Opens at -60mv to start depolarization over again (not normal; very low)
--No ball and chain

What is the membrane potential of cardiac muscle (for muscle contraction)?

-VG Na+ channels opens quickly (not funny sodium channel) (0)
--Depolarization and then inactivates
-K+ channel opens (1) (transient V-gated K+)
--Start of repolarization
--Closes almost instantly
-L type Ca2+ channel opened up for a prolonged period (2)
--Closes
-Different K+ channel opens (3)
--Repolarization continues until membrane potential is hit (4)

Tension overlaps action potential so there is no _____.

summation

What do the atrioventricular valves (AV) do?

prevent blood from flowing into atria

What is the right AV valve?

tricuspid valve (lower pressure)

What is the left AV valve?

bicuspid/mitral valve (higher pressure)

What do papillary muscles keep AV valves from doing?

pushing inward

When contracted, the AV valves are _____.

closed (contract during ventricle contractions)

When relaxed, the AV valves are _____.

open (relax during atrial contraction)

What do semilunar valves do?

prevent blood from flowing back into the heart after contraction

What are the two semilunar valves?

pulmonary and aortic

Why are all valves are at the same level in the heart?

to avoid pressure differences

_____ opens and closes valves.

pressure

Contraction of heart chamber leads to an increase in _____.

pressure

How do valves open?

-from atria to ventricles and from venticles to pulmonary artery/aorta
-open in direction of blood flow

Why do AV vales open towards ventricles?

due to increased pressure caused by atrial contraction

Why do semilunar valves open towards aorta/pulmonary artery?

due to increased pressure caused by ventricle contraction

What is systole?

ventricle contraction

What is diastole?

ventricles are filling and not contracting

What are the 4 phases in the cardiac cycle?

-ventricular filling
-isovolumetric contraction
-ejection from ventricles
-isovolumetric relaxation

What is passive filling of ventricles?

blood flowing free from atrium to ventricles

Why is atrial contraction done to fill ventricles?

to empty out atriums

What is ventricular filling?

-AV valve are open and semilunar valves are closed
-pressure is higher in atriums/aorta/pulmonary artery than ventricles

What is isovolumetric contraction?

-ventricles contract but blood volume is kept constant to open semilunar valves
-all valves are closed bc blood volume is constant
-ventricle pressure is higher than atrium, but aorta/pulmonary artery is higher than ventricle (allows every valve to be closed)

What is ejection from ventricles?

-blood leaves ventricles and goes to aorta/pulmonary artery
-semilunar valves are open
-pressure in ventricles is higher than aorta/pulmonary artery
-papillary muscles keep AV valves shut

What is isovolumetric relaxation?

-ventricles relax to lower pressure, but blood doesn't move
-every valve closed
-ventricle pressure is higher than atrium, but aorta/pulmonary artery is higher than ventricle (allows every valve to be closed)

What is the lub sound?

soft sound of the shutting of AV valves (simultaneously)

What is the dub sound?

louder sound of the shutting of semilunar valves (simultaneously)

What are the different waves of ECG/EKG?

p, q, r, s, and t

What is the Qt interval?

time from depolarization to end of repolarization