BY 32 – SPRING 2002
Study Outline
18.1. Control of Blood Flow:
a. In general, blood pressure is maintained within relatively narrow limits so that regulation of blood flow involves changes in __________________________ attributable to changes in the tone of ________________________________.
b. Factors which affect vascular smooth muscle fall into two broad categories called __________________________________________________ and ________________________________________________.
c. Extrinsic mechanisms involve _________________________________ and _____________________________. These mechanisms usually involve _________________________________ and are concerned mainly with the maintenance of _________________________________.
d. Activation of sympathetic nerves to vascular smooth muscle cells usually results in ____________________________.
e. Intrinsic mechanisms involve __________________________ in which blood flow is altered to better meet the needs of a tissue without changing ___________________________________.
18.2. Intrinsic Mechanisms:
a. Intrinsic mechanisms include two basic types called ____________________ and _______________________________________, and a third called ______________________________.
b. In the myogenic response, __________________________________ is kept constant despite changes in blood pressure. Thus this intrinsic mechanism is often referred to as pressure __________________________________.
c. The myogenic response is based on an inherent property of vascular smooth muscle cells in which in response to stretch they ______________________ whereas they relax when there is ______________________________ stretch.
d. As a result of the myogenic response, increases in perfusion pressure are accompanied by increases in __________________________________ due to vasoconstriction whereas decreases in perfusion pressure involve ________________________________________ in vascular resistance.
e. In metabolic hyperemia, blood flow changes in response to changes in the ____________________________ of a tissue. For example, increases in the metabolic activity of a tissue are accompanied by ______________________ of the blood vessels resulting in increased ____________________________.
f. Metabolic hyperemia is based on the release of ________________________ substances while tissues are metabolically active.
g. ___________________________ refers to the phenomena in which following the interruption of a blood supply to a particular region, the blood flow following the interruption exceeds the flow before the interruption.
18.3. Feedback Regulation of the Cardiovascular System:
a. Blood pressure is maintained within reasonably narrow limits by a number of control systems that include _______________________________________, _____________________________, and _____________________________.
b. Much of this control involves reflexes that begin with ___________________ input that travels to an area of the brainstem called the _____________________________________________.
c. Output from the cardiovascular center is mainly in the form of ___________________________________________.
d. The cardiovascular center is located in the ___________________________ and receives input from higher sources such as the ____________________ and ________________________.
e. Other sensory input includes sensory receptors in muscle which monitor __________________________ movements and movements associated with _________________________________. Sensory receptors in blood vessels include _______________________________ which monitor pressure and ______________________________________ which monitor the chemical composition of blood.
f. Activation of sympathetic nerves to veins results in increases in ________________________ which affect __________________________ whereas activation of sympathetic nerves to arteries results in an increase in _______________________________________.
g. Activation of sympathetic nerves to the heart results in an increase in _________________________ and ______________________________.
h. Activation of parasympathetic nerves results in a decrease in ________________________________.
18.4. The Baroreceptor and Chemoreceptor Reflexes:
a. Baroreceptors are located in the _________________________________ and __________________________.
b. When blood pressure increases, the frequency of action potentials generated by these baroreceptors _________________________________. Conversely, decreases in blood pressure are indicated by a _________________________ in the frequency of action potentials.
c. Following increases in action potential frequency in baroreceptors nerves, the cardiovascular center activates the ____________________________ system, whereas the _________________________ system is activated in response to a decrease in baroreceptors action potential frequency.
d. Chemoreceptors are located in two regions within arteries called the ____________________________ and ______________________________.
e. In general conditions of _________________________________________, ______________________________, and ___________________________ will result in stimulation of the __________________________ system in an attempt to _________________________ blood pressure.
18.5. Hormonal Control of Blood Pressure:
a. Juxtaglomerular cells in the kidney release ___________________________ in response to a decrease in __________________________________ and/or ___________________________________.
b. Renin cleaves angiotensinogen to form ______________________________ which then circulates to the lung where it is converted to _________________________________________ by an enzyme called _____________________________________.
c. Angiotensin II will cause ________________________________ in blood vessels and stimulates production of ____________________________ by the adrenal cortex. ________________________ promotes Na+ reabsorption in the kidney which in turn promotes _________________________ retention which tends to increase __________________________.
d. Decreases in blood pressure and/or volume stimulate certain neurons in the __________________________________ to release ADH which acts on the kidney to promote _____________________________ and on blood vessels resulting in ________________________________.
e. In response to sympathetic stimulation, the adrenal medulla will release _______________________________ which has the same basic effects as __________________________________, the main neurotransmitter of the sympathetic system.
f. In response to increased stretch of the atria of the heart, atrial cells release ___________________________ which acts on the kidney resulting in _________________________ and water _______________________ which tends to lower blood pressure.
g. Among the many local substances which can affect blood pressure is _________________________________ which is release by endothelial cells and is a potent ____________________________.
18.6. Response to Hemorrhage:
a. ______________________ is defined as failure of the cardiovascular system to deliver enough O2 and nutrients to tissues to meet the metabolic needs of cells.
b. The four basic types of shock are called ____________________________, ____________________________, _______________________________, and _______________________________.
c. The type of shock that results from hemorrhage or the excessive loss of body fluids through sweating, diarrhea, or vomiting is called ___________________________ shock.
d. A person in hypovolemic shock will have an __________________________ rate of breathing, primarily due to chemoreceptors being activated by the ___________________________ pH of blood due to an accumulation of ________________________ acid.
e. A person in hypovolemic shock will have a(n) _____________________ heart rate, primarily because of baroreceptors being activated by the ___________________________ in blood pressure. The pulse will be weak however because of reduced ______________________________.
f. In response to hypovolemic shock, sympathetic nerves to arteries become activated which results in an overall increase in ________________________, but also a redistribution in blood flow so that only the heart and brain retain a reasonably normal blood flow. As a result, a person in hypovolemic shock will have skin that is ______________________, _____________________, and will appear ___________________________.
g. Within the kidneys, the reduced blood flow during a hypovolemic shock will result in an increase in __________________________ release. The ultimate effects on the kidney involve increased salt and water retention as a result of the actions of ___________________________ and increased water retention as a result of _____________________________. Both will cause a decrease in ________________________________ output, which will tend to increase _______________________________ which will in turn tend to restore blood pressure.
h. Within the brain, the response to hypovolemic shock involves an increased sensation of ____________________________ due to the hypothalamus and increased _______________________________ due to the cerebrum. A late sign of shock involves ______________________.