Heart-3

Joe's ESV is 40mL, and his EDV is 125mL. What is Joe's stroke volume?

(SV=EDV-ESV) 125-40 = 85sv

What effect would stimulating the acetylcholine receptors of the heart have on cardiac output?

stimulating the acetycholine receptors of the heart would slow the heart rate, since cardiac output is the product of stroke volume and HR, a reduction in heart rate will lower the cardiac output (that is if the SV remains the same).

Describe the effects of NE, E, glucagon, and thyroid hormones on the contract ability of the heart.

Factors that increase contractility = positive inotropic action >Open C++ channels >Sympathetic stimulation (NE, E) >Hormones (E, NE, TH, Glucagon) >Drugs: dopamine and digitalis- increase Ca++ entry

List 5 general classes of blood vessels

1. Arteries- carry blood away from heart, high pressure blood. 2.Arterioles- smaller arterial structures sometimes called resistance vessels 3. Capillaries- exchange vessels have simple squamous ET 4. Venules- small venous structures lead away from capillaries 5. Veins-return blood toward the heart.

What are the 3 types of capillaries and what is different about each type?

>Continuous capillaries- Endothelium is a complete lining, located in all tissues except epithelia and cartilage, FOUND IN BRAIN(blood brain barrier) and in thymus(restricted permeability), permit water, small solutes and lipids to diffuse into IF. >Fenestrated Capillaries- contain windows and pores that penetrate endothelial lining, pores allow rapid exchange of water and solutes between plasma and IF, found in choroid plexus of brain (hypothalamus, pituitary, pineal, and thyroid), found in intestinal tract and kidneys. >Sinusoids Capillaries- resemble fenestrated capillaries but are flattened and irregularly shaped, Blood moves slowly through them, have large gaps between adjacent cells allowing free exchange of water and solutes between blood and IF, PHAGOCYTIC cells line these capillaries and remove debris, pathogens, and dead RBC, Found in liver, spleen and bone marrow

How long does a drug that increases the length of time required for the repolarization of pacemaker cells affect the heart rate?

A drug that increases the length of time required for the repolarization of pacemaker cells would decrease the heart rate, b/c the pacemaker cells would generate fewer action potentials per minute.

Why can't cardiac output increase indefinitely?

Available filling time becomes shorter as the heart rate increases.

Define vasomotion.

Cycling between contraction and relaxation of smooth muscles (the opening and closing of the sphincters)

IF the cardioinhibitory center of the medulla oblongata were damaged which part of the autonomic nervious system would be affected, and how would the heart be influenced?

Damage to the cardioinhibitory center of the medulla oblongata which is part of the parasymthatic division of the autonomic nervous system, would reduce parasympathetic action potentials to the heart. The resulting sympathetic dominance would increase the heart rate.

How does the body respond to a decreased in B/P?

Decrease in B/P stimulates vasomotor centers located in the medulla oblongata.

Why are valves located in veins but not in arteries?

In contrast to veins, arteries carry blood away from the heart. Veins are less muscular and are often closer to the skin. There are valves in veins to prevent backflow of blood.

What effect would an increase in venous return have on the stroke volume?

Increase venous return results in increased filling of ventricles of the heart and this increased filling is going to require a more forceful contraction so stroke volume is going to increase b/c SV is the amount of blood pumped by L ventricle during each heart beat.

Harvey has a heart murmur in his left ventricle that produces a loud gurgling sound at the beginning of systole. Which valve is probably faulty?

It would appear that Harvey has a regurgitating mitral valve. When an AV valve closes properly, the blood flowing back into the atrium produces the abnormal heart sound murmur. If the sounds is heard at the beginning of the systole, this would indicate the AV valve because this is the period when the valve is just closed and the blood in the ventricle is under increasing pressure thus; the likelihood of backflow is the greatest. If the sound is heard at the end of systole or beginning of diastole, it would indicate a regurgitating semilunar valve in this case, the aortic semilunar valve.

WHich layer of blood vessel responds to nervous stimulation?

The Tunica Media responds to nervous stimulation, >Vasoconstriction- contraction of arterial smooth muscle causing the lumen to constrict with a corresponding elevation in B/P. >Vasodilatation- Relaxation of arterial smooth muscle causing the lumen to dilate w/ a corresponding decrease in B/P. It is affected by overload (tention the ventricle must produce to open the semilunar valves and eject blood) peripheral B/P and capillary blood flow.

WHy is it a potential problem if the heart beats too rapidly?

The heart pumps in proportion to the amount of blood that enters, a heart that beats too rapidly does not have sufficient time to fill completely between beats, when the heart beats too fast very little blood leaves the ventricles and enters circulation so tissues suffer damage from inadequate blood supply.

How would an increase is sympathetic stimulation of the heart affect the end-systolic volume (ESV)?

Well an increase in Sympathetic stimulation would increase heart rate (HR). It also increases contractility with a positive inotropic action leaving more blood in ventricles at the end of systole.

Caffeine has effects on conducting cells and contractile cells that are similar to hose of NE. What effect would drinking large amounts of caffeine have on the heart?

caffeine acts directly on the conducting system and contractile system of the heart, increasing the rate at which they depolarize, drinking large amounts of it would increase heart rate.

what is cardiodynamics?

dynamics of the hearts action in pumping blood. >End-systolic volume(EDV)- amount of blood in the ventricles at the end of ventricular diastole (130mL) >End-systolic volume(ESV)-amount of blood left in each ventricle after ventricular systole(50mL) >Stroke volume(SV)-amount of blood ejected from each ventricle with each cardiac contraction(70-80 mL) >Ejection fraction(EF)- the % of the EDV that is ejected from the ventricle with each ventricular contraction (60%EDV is a normal EF) >Cardiac Output(CO)-amount of blood pumped by the left ventricle in one minute, used in looking at cardiac function over time.