A&P II Exam 2

With a decrease in blood volume there is a reduced delivery of dissolved oxygen to tissue. The body responds to restore homeostasis through...

• Releasing aldosterone from the kidney to stimulate thirst and increase fluid consumption

• Chemoreceptor activation that leads to inhibition of the cardioinhibitory center in the medulla oblongata to induce vasodilation

• Autoregulatory mechanisms that maintain blood flow to individual tissues, and neural mechanisms that help restore BP via vasoconstriction and increased heart rate

• Baroreceptor activation that leads to stimulation of the cardio-acceleratory center in the medulla oblongata, which induces vasoconstriction

During blood loss homeostatic adjustments compensate for reduced BP. What is an example of a neural mechanism that works to achieve homeostasis?

• Cardioacceleratory centers stimulate cardiac output and vasoconstriction to maintain sufficient blood flow

• Renin is released at the kidney, which converts angiotensinogen to angiotensin, causing vasoconstriction

• Vasomotor centers stimulate vasodilation via release of norepinephrine and nitric oxide

• ADH is released by the anterior pituitary gland to stimulate water reabsorption by the kidneys

How would applying a slight pressure to the common carotid affect heart rate? Hint: consider what pressure on the common carotid will do to the coronary sinus, where do baroreceptors reside.

• Heart rate will increase because pressure receptors in the carotid sinus will sense a decrease in pressure, reduce activity, and stimulate the cardioaccelaratory center to increase sympathetic activity to the heart

• The baroreceptors at the carotid sinus will sense the increased pressure and increase their activity, and stimulate the cardioaccelaratory center to increase sympathetic activity to the heart

• The pressure will transmit all the way to the heart, effectively increasing after load, and the heart responds by increasing contractility to maintain homeostasis

• Holy moly. I think that I’ll just choose the longest answer and call it a day

How would applying a slight pressure to the common carotid artery between the carotid sinus and the heart affect your heart rate?

• It will not change

• It will increase because baroreceptors in the carotid sinus are stimulated

• It will increase because baroreceptor activity in the carotid sinus is reduced

• It will decrease because baroreceptors in the carotid sinus are stimulated

What is a short term response to a hemorrhage?

• Neural responses in the short term, including a generalized stimulation of motor output resulting in increased venous return via the skeletal muscle pump

• Inhibition of baroreceptors or chemoreceptors results in vasomotor center stimulation and cardioaccelaratory center stimulation to help restore BP

• ADH is released by the posterior pituitary gland to stimulate the kidney to increase water reabsorption and thus blood volume

Shock is a broad term that refers to severe circulatory failure, meaning BP drops so low that tissues aren't perfused with blood. One example is anaphylaxis, which might occur during an allergic reaction to bee stings or eating shellfish. In this case massive histamine release causes vasodilation. What may work to treat shock?

• Application of a tourniquet, or a constriction around the legs. This will cut off the circulation so that cardiac output is directed toward the brain and heart

• Acetylcholine injection, the parasympathetic hormone, which will cause vasodilation

• Epinephrine injection, which will stimulate cardiac contraction, vasodilation, and heart rate

• Heparin injection will prevent blood clotting

Blood flow is...

• Proportional to pressure, meaning it decreases when pressure decreases

• Inversely proportional to pressure and resistance

• Inversely proportional to length

• Proportional to pressure, meaning it increases when pressure increases

The pressure gradient for circulatory blood flow...

• Is the pressure gradient from the left ventricle to the right, on a complete circuit through the cardiovascular system

• Is systolic pressure minus diastolic pressure, and is about 40 mmHg

• Is 140 mmHg

• Is the pressure gradient from the left ventricle to the right atrium, and is approximately 100 mmHg

When BP increases...

• Capillary reabsorption increases

• Capillary reabsorption decreases

• Capillary filtration increases

• Capillary filtration decreases

Capillary filtration...

• Is less than capillary reabsorption by about a 3.4 L/day

• Exactly matches capillary reabsorption

• Only occurs at a metabolic active tissues

• Is greater than capillary reabsorption about a 3 L/day