anat exam three

The hormone ___ stimulates the production of red blood cells in response to low oxygen levels in the blood.

erythropoietin

List and define the three most important factors that affect stroke volume.

1. preload: the degree to which heart muscle cells are stretched before the contract

2. contractility: contractile strength achieved at a given muscle length

3. afterload: pressure that must be overcome for the ventricles to eject blood

Define systole and diastole. Which heart chamber are usually referenced when these terms are used?

Systole: contraction

Diastole: relaxation

The contraction and relaxation of the ventricles are normally described with the terms systole and diastole.

Define the terms end diastolic volume (EDV) and end systolic volume (ESV) and relate them to the calculation of stroke volume.

EDV: the amount of blood that collects in a ventricle during diastole

ESV: the volume of blood remaining in a ventricle after it has contracted

Stroke volume equals EDV - ESV

The ___ layer of the serous pericardium covers the heart.

visceral

What two important functions does the cardiac conduction system preform?

The important functions of the cardiac conduction system are to initiate impulses (pacemaker) and to distribute impulses throughout the heart so that it depolarizes and contracts in an orderly manner.

EDV = 100 mL/contraction and ESV = 40 mL/contraction, what is the ejection fraction? Is this ejection fraction a sign of a healthy functioning heart?

((100-40)/100) * 100 = 60%, Yes this is normal

If Hr = 100 contraction/min, SV = 100 mL/contraction, and R = 100 mmHg/mL/min, what is the mean arterial pressure?

1,000,000 mmHg

Why could there be cause for concern if a young pregnant mother is Rh-, her husband is Rh+, and this is their second child? Can this be prevented? If yes, how?

Because dad is positive the baby will also be positive and carry the D protein. Mom does not carry the D protein. Mom's immune system did not produce antibodies against the D protein until she was first exposed during the delivery of the last child. The anti D antibodies can cross the placenta and kill the fetus due to erythroblastosis fetalis. Yes, RhoGAM can prevent Mom's immune system if given before the first exposure to the D protein and prevent the immune system from developing antibodies against the D protein.

If a patient was prescribed an ACE inhibitor, a drug that prevents the production of Ang II, how would this affect blood pressure. Justify.

A decrease in Ang II would decrease secretion of aldosterone and/or ADH and reduce blood volume. The reduced blood volume would also decrease venous return, contractility, stroke volume, Q, and blood pressure. Ang II also causes vasoconstriction directly and/or through increased SNS activity and increase resistance. Decreased Ang II would allow resistance to decrease and lower blood pressure.

Explain automaticity in cardiac tissue...

Cells with the property of automaticity do not maintain a stable resting membrane potential. Instead, they have an unstable resting potential that continuously depolarizes, drifting toward threshold for firing. These spontaneously changing membrane potentials, called pacemaker potentials, initiate the action potentials that trigger the heart's rhythmic contractions.

There are 2 sets of tubes. In one set you have a single tube with a diameter of 4 mm and a second set with two tubes but each tube is half the diameter of the first tube. Assuming blood pressure was the same, would the 2 set of vessels carry more, less or the same amount of fluid as the single 4 mm vessel. Justify.

The two 2 mm blood vessels will transport less blood that the single 4 mm tube. Doubling the number of tubes only doubles the flow, while doubling the radius of the tube increase the flow by a factor of 16.

When our bodies transition from rest to exercise, we experience parasympathetic withdraw and increase in sympathetic activity as evidence by the increase in heart rate. Sympathetic activity increases Q and also increases resistance in most parts of the body including the arms and legs. How then do we increase blood flow to the legs when we run without sending more blood flow to the arms?

Secretion of humoral factors such as nitric oxide, H+, CO2, and K+ by metabolically active tissues causes vasodilation of arterioles that supply blood to tissue. Where as non-metabolically active tissue does not secrete humoral factors and blood vessels remain constricted. Blood will flow to area of least resistance (hence to the legs).

Melissa was resting quietly on the sofa when the doorbell rang. She jumped up to run to the door, but suddenly she felt light headed and began to see stars. Explain the physiology that led to her light-headedness.

When Melissa stood up she caused a reduction in venous return and a decrease in ventricular filling (EDV). This causes a decrease in stroke volume and then Q. Since a decrease in Q causes a decrease in blood pressure she was unable to send blood to the brain and she felt light headed.

What component of blood is responsible for the initiation fo the blood clotting process?

platelets

What is the average normal pH range of blood?

7.35-7.45

Cardiac muscle cells are like skeletal muscle cells in that they...

have I and A bands

Compared to skeletal muscle, cardiac muscle...

has gap junctions that allow it to act as a function syncytium

An incompetent valve increases the stress on the heart because...

that valve leaks and a portion of the blood pumped must be pumped twice

During the period of ventricular filling...

blood flows mostly passively through the atria and the open AV valve into the ventricles

During what phase of the cardiac cycle does intraventricular pressure rise and the pulmonary valve is open?

ventricular ejection

The source of blood carried to the capillaries in the myocardium would be the...

coronary arteries

Factors that aid venous return include all except...

urinary output

If the vagal nerves to the heart were cut, the result would be that...

the heart rate would increase by about 25 beats per minute

A blood vessel that contains one-way valves is known as a...

a vein

Jenny was studying for EXSC 224 exam when a friend came up from behind and startled her causing her heart rate to increase due to an increase in sympathetic activity. The sympathetic nervous system increased Jenny's heart rate primarily by...

causing threshold to be reached more quickly

A lack of intrinsic factor, leading to a deficiency of vitamin B12 causing an appearance of large pale cells called macrocytes is characteristic of...

pernicious anemia

The tricuspid valve is closed...

when the ventricle is in systole

The cardiac (fibrous) skeleton is an important structure in the the heart because...

all of the above (LOOK UP)

Blood within the pulmonary veins returns to the...

left atrium

Fred's blood was determine to be AB positive. What does this mean?

there are no antibodies to A, to B, or to Rh antigens in the plasma

The atria and ventricles are in systole simultaneously during...

none of the above (LOOK UP)

If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid...

threshold is reached more quickly and heart rate would increase

What organ in the body regulates erythrocyte production?

kidney

Oscar was helping his dad cut down a tree. Unfortunately he did not follow his father's advice while operating the chain saw. While trimming limbs off the tree trunk Oscar slipped and cut his leg severing the femoral artery. What effect did this gash have on his blood pressure.

a lowering of blood pressure due to a decrease in venous return

The arteries that directly feed into the capillary beds are called...

aterioles

Norepinephrine acts on the heart by...

causing threshold to be reached more quickly

85% of Americans test positive for the ___ Rh factor while all others are considered Rh negative.

D

Which tunic of an artery is most responsible for maintaining blood pressure and continuous blood circulation?

tunica media

Isovolumetric contraction ...

refers to the shoer period during ventricular systole when the ventricles are completely closed chambers