Vasomotor Center and Autonomic Nervous System

The function of the circulation is to transport ______ to the body tissues

The function of the circulation is to transport waste products ______

The function of the circulation is to conduct hormones from one part of the body to ______

The function of the circulation is to maintain an appropriate environment in all the tissue fluids of the body for optimal survival and function of the ______

Arteries : under high pressure, blood flows at a high ______

Arterioles: last branches of the arterial system, strong muscular wall, capable to close completely or to dilate several fold in response to tissue ______

The mean pressure in the aorta is about ______ mm Hg

The arterial pressure alternates between a systolic pressure level of ______ mm Hg and a diastolic pressure level of ______ mm Hg

The mean pressure falls progressively to about ______ mm Hg at the venae cavae where they empty into the right atrium

The pressure in the systemic capillaries varies from as high as ______ mm Hg near the arteriolar ends to as low as ______ mm Hg near the venous ends

The average “functional” capillary pressure is about ______ mm Hg

Pulmonary artery systolic pressure averages about ______ mm Hg and diastolic pressure ______ mm Hg

The mean pulmonary arterial pressure is ______ mm Hg

The mean pulmonary capillary pressure averages only ______ mm Hg

The normal right atrial pressure is about ______ mm Hg

The venous pump is efficient enough that during walking the venous pressure in the feet remains less than ______ mm Hg

The peripheral circulation of the whole body has about 10 billion ______ with a total surface area estimated to be 500 to 700 square meters

The capillary wall is composed of a unicellular layer of ______ and is surrounded by a very thin basement membrane on the outside of the capillary

Features of primary hypertension: Cardiac output is increased to match the blood flow to the extra ______ tissue

Sympathetic nerve activity, especially in the kidneys, is increased in ______ patients

Angiotensin II and aldosterone levels are increased twoto threefold in many ______ patients

The renal-pressure natriuresis mechanism is impaired, and the kidneys will not excrete adequate amounts of salt and water unless the arterial pressure is high or unless kidney function is ______

The arterial pressure is regulated not by a single pressure controlling system but instead by several interrelated systems, each of which performs a specific ______

Rapidly acting pressure control mechanisms, acting within seconds or minutes: (1) the ______ feedback mechanism

Pressure control mechanisms that act after many minutes: the ______-angiotensin vasoconstrictor mechanism

About one third of all deaths in the Western society results from ______ artery disease

Venous blood from the left ventricular muscle returns to the right atrium of the heart by way of the ______ sinus

The resting coronary blood flow in the human being averages about 225 ml/min, which is about 4 to 5 per cent of the total ______ output

The coronary capillary blood flow in the left ventricle muscle falls to a low value during ______

The main vasodilator substance released in response to low oxygen is ______

It transmits parasympathetic impulses through the vagus nerves to the ______ and sympathetic impulses through the spinal cord and peripheral sympathetic nerves to virtually all arteries, arterioles, and veins of the body.

Vasomotor tone: Is the state of partial constriction of the blood vessels caused by continuous slow firing of the sympathetic nerves from the vasoconstrictor area of the vasomotor center. 42 43 The rate of excitatory and inhibitory effects of the vasomotor center itself is regulated by the higher brain ______.

The sympathetic nerves to skeletal muscles carry sympathetic vasodilator fibers as well as ______ fibers.

Emotional Fainting—Vasovagal SyncopeFainting Attack. This is a vasodilatory reaction occurs in people who experience intense emotional disturbances that cause fainting. The muscle vasodilator system becomes activated, and at the same time, the vagal (parasympathetic) cardioinhibitory center decreases the ______ rate markedly.

Reflex mechanisms for controlling normal arterial pressure A. Baroreceptor reflexes This reflex is initiated by stretch receptors, called baroreceptors, located in the walls of several large systemic arteries( specially carotid artery and arch of aorta). A rise in arterial pressure stretches the baroreceptors and causes them to transmit signals into VMC. “Feedback” signals are then sent back through the autonomic nervous system to the circulation to reduce arterial pressure downward toward the normal ______.

The chemoreceptors (carotid and aortic bodies) are chemosensitive cells sensitive to oxygen lack. They lie in the bifurcation of each common carotid artery and aorta respectively). Chemoreceptors are supplied with an abundant blood flow. Whenever the arterial pressure falls below a critical level (80 mm Hg), they become stimulated due to diminished oxygen and buildup of CO2 and ______ ions.

VMC ischemic response when blood flow to the vasomotor center in the lower brain stem becomes decreased severely enough to cause nutritional deficiency—that is, to cause cerebral ischemia—the vasomotor center become strongly ______.

In the walls of both the atria and the pulmonary arteries located low-pressure receptors that detect increases in pressure in the low pressure areas of the circulation caused by increase in blood volume, and they elicit reflexes parallel to the baroreceptor ______.

The kidneys have a powerful mechanism for controlling pressure called the reninangiotensin system. Renin is a protein enzyme released by the kidneys when the arterial pressure falls too ______.

Sequential events by which increased salt intake increases the arterial pressure, but feedback decrease in activity of the renin angiotensin system returns the arterial pressure almost to the normal ______.

For long-term survival, fluid intake and output must be precisely balanced, a task that is performed by multiple nervous and hormonal controls, and the kidneys that regulate excretion of salt and water. An increase in arterial pressure in the human of only a few millimeters of mercury can double renal output of water, which is called pressure diuresis, as well as double the output of salt, which is called pressure ______.

About 90 to 95 per cent of all people who have hypertension are said to have “primary hypertension,” also widely known as “essential hypertension” by many clinicians. These terms mean simply that the hypertension is of unknown origin, in contrast to those forms of hypertension that are secondary to known causes, such as renal artery ______.

The interstitial fluid pressure (Pif), which tends to force fluid inward through the capillary membrane when Pif is positive but outward when Pif is ______.

The capillary plasma colloid osmotic pressure (π p), which tends to cause osmosis of fluid ______ through the capillary membrane.

The interstitial fluid colloid osmotic pressure (π if), which tends to cause osmosis of fluid ______ through the capillary membrane.

The slight imbalance of forces, 0.3 mm Hg, causes slightly more filtration of fluid into the interstitial spaces than ______.

This slight excess of filtration is called net filtration, and it is the fluid that must be returned to the ______ through the lymphatics.

If the sum of these forces, the net filtration pressure, is ______, there will be a net fluid filtration (outward movement) across the capillaries.

If the sum of the Starling forces is ______, there will be a net fluid absorption from the interstitial spaces into the capillaries.

Under normal conditions the NFP is slightly ______ (0.3 mmHg), resulting in a net filtration of fluid across the capillaries into the interstitial space in most organs.

Acute control is achieved by rapid changes in local vasodilation or ______ of the arterioles, metarterioles, and precapillary sphincters, occurring within seconds to minutes to provide very rapid maintenance of appropriate local tissue blood flow.

Long-term control means slow, controlled changes in flow over a period of days, weeks, or even months. It occurs when the long-term metabolic demands of a tissue change. The arterioles and capillaries usually increase both in number and size within a few weeks to match the needs of the tissue. Oxygen also plays a main role in long term control of blood ______.

Norepinephrine is a very powerful ______ while epinephrine is less. They are released by the sympathetic system stimulation either directly from the sympathetic nerve endings or indirectly from the adrenal medulla into the entire circulation.

Vasopressin (antidiuretic hormone) is formed in the hypothalamus and transported downward to the posterior pituitary gland to be released into the circulation. It is even a more powerful ______ hormone than the angiotensin.

Ischemia causes the muscle to release acidic substances, such as lactic acid, or other pain-promoting products, such as ______, that are not removed rapidly enough by the slowly moving coronary blood flow.

The pain is usually felt beneath the upper sternum over the heart, and often referred to distant surface areas of the body, most commonly to the left arm and left shoulder but also frequently to the neck and even to the side of the face. The pain is frequently described as hot, pressing, and ______ in quality.

Immediately after an acute coronary occlusion, blood flow ceases in the coronary vessels beyond the occlusion except for small amounts of ______ flow from surrounding vessels.

The area of muscle that has either zero flow or so little flow that it cannot sustain cardiac muscle function is said to be ______.

The most common causes of death after acute myocardial infarction are: Decreased cardiac output. Damming of blood in the pulmonary blood vessels and then death resulting from ______.

Circulatory shock means generalized inadequate blood flow through the body, to the extent that the body tissues are damaged because of too little flow, especially because of too little ______ and other nutrients delivered to the tissue cells.

Shock caused by decreased cardiac output. factors that severely reduce cardiac output (cardiogenic shock): Cardiac abnormalities that decrease the ability of the heart to pump blood as in myocardial infarction, severe heart valve dysfunction, ______.

Hypovolemic (hemorrhagic) shock. Hypovolemia means diminished blood volume. Hemorrhage is the most common cause of ______ shock.

Shock occasionally results without any loss of blood volume. Instead, the vascular capacity increases so much that even the normal amount of blood becomes incapable of filling the circulatory system adequately. One of the major causes of this is sudden loss of vasomotor tone throughout the body, resulting especially in massive dilation of the veins as occurs in Deep general anesthesia and ______ damage.

Anaphylactic shock. Anaphylaxis is an allergic condition in which the cardiac output and arterial pressure often decrease drastically. It results primarily from an antigen-antibody reaction that takes place immediately after an antigen to which the person is sensitive enters the circulation. One of the principal effects is to cause the basophils in the blood and mast cells in the pericapillary tissues to release ______ or a histamine-like substance.

This refers to a bacterial infection widely disseminated to many areas of the body, with the infection being borne through the blood from one tissue to another and causing extensive ______.

Peritonitis caused by spread of infection from the uterus, fallopian tubes, instrumental abortion performed under unsterile conditions, rupture of the gastrointestinal system (perforation). Generalized bodily infection resulting from spread of a ______ infect.