Human Physiology Ch 14

The mean arterial pressure of a patient with a pulse pressure of 20 mmHg, and a blood pressure of 100/60 mmHg would be approximately:

67

25. What is a coronary angioplasty? Stent?

Angioplasty is a procedure to open narrowed or blocked blood vessels(coronary arteries) that supply blood to the heart. A coronary artery stent is a small, metal mesh tube that expands inside a coronary artery and is placed during or immediately after angioplasty

What changes in blood flow and metabolism occur in the heart during exercise and from exercise training

Decreased heart rate at same workload Increased mitochondrial and myocardial capillary density

Arteriosclerosis is a stiffening of the arteries, making them less able to distend. Which of the following lifestyle recommendations would help a patient with this diagnosis prevent high blood pressure, and why?

Decreasing sodium intake, to decrease blood viscosity and resistance to flow

1. What is the equation for cardiac output?

The cardiac output is the volume of blood pumped per minute by each ventricle. The average resting cardiac rate in an adult=70 beats per minute The average stroke volume (volume of blood pumped per beat by each ventricle)=70 to 80 ml per beat. The product of these two variables gives an average cardiac output of 5.5 L per minute, which is also the total blood volume average. This means that each ventricle pumps the equivalent of the total blood volume each minute under resting conditions. CO=SVxHR

9. What is the Frank-Starling law?

Frank-Starling law of the heart=The relationship between EDV, contraction strength, and stroke volume is a built-in/intrinsic property of heart muscle. A greater amount of blood in a ventricle prior to contraction results in greater stretch of the myocardium which produces a stronger contraction from increased interactions between actin and myosin and an increase in the sensitivity of Ca2+-release. As the end-diastolic volume is increased, the stroke volume is increased.

16. At the arterial end of a capillary how do hydrostatic pressure and colloid osmotic pressure compare?

Hydrostatic pressure increases filtration by pushing fluid and solute OUT of the capillaries, while capillary oncotic pressure/colloid osmotic pressure pulls fluid into the capillaries.

30. What causes hypertension? Shock? Congestive heart failure?

Hypertension is blood pressure in excess of the normal and elevated ranges If other factors remain constant, blood flow increases as arterial blood pressure increases. The organs of people with hypertension are thus adequately perfused with blood until the excessively high pressure causes vascular damage. Because most patients are asymptomatic (without symptoms) until substantial vascular damage has occurred, hypertension is often referred to as a silent killer. The term hypovolemic shock refers to circulatory shock that is due to low blood volume from a hemorrhage (bleeding), dehydration, or burns which causes a rapid fall in blood pressure Septic shock=a dangerously low blood pressure (hypotension) that may result from sepsis, which is a serious infection.

Vasodilation and a subsequent increase in coronary blood flow is caused by

Norepinephrine, which stimulates alpha-adrenergic receptors nitrous oxide production during exercise

Which of the following events can cause edema?

Obstruction of lymphatic vessels, blocking lymphatic drainage Decreased plasma protein concentration, causing a decrease in osmosis of interstitial fluid into capillaries Increased tissue protein concentration, causing a decrease in osmosis of interstitial fluid into capillaries Hypertension, causing an increase in capillary filtration pressure so that more tissue fluid is formed at the arteriolar ends of capillaries

10. Stoke volume is directly proportional to? Inversely proportional to ?

Stroke volume is directly proportional to end diastolic volume and indirectly proportional to Total peripheral resistance. The end-diastolic volume—and thus the stroke volume and cardiac output—is controlled by factors that affect the venous return( return of blood to the heart via veins). The rate at which the atria and ventricles are filled with venous blood depends on the total blood volume and the venous pressure that is responsible for the return of blood to the heart.

4. What keeps HCN gates open?

Cyclic AMP acts on the HCN and Ca2+ channels of pacemaker cells that produce pacemaker potential to increase diastolic depolarization rate.

13. What does capacitance and compliance refer to?

compliance: 1. A measure of the ease a structure (lung) expands under pressure. 2. A measure of the volume change as a function of pressure changes.

Increase in arterial blood pressure caused by

Vasoconstriction of arterioles Increase in heart rate and stroke volume

22. What is the difference between vasoconstriction/vasodilation? How does this relate to blood flow and resistance?

Vasodilation decreases resistance and increases flow. Vasoconstriction increases resistance and decreases flow. The cardiac output is about 5 to 6 L per minute. This total cardiac output is distributed unequally to the different organs because of unequal resistances to blood flow through the organs. Adrenergic sympathetic fibers that release norepinephrine activate alpha-adrenergic receptors to cause vasoconstriction throughout the body.

Comparisons of venous and arterial systems:

Veins have a greater ability to distend than arteries. The venous system serves as blood reservoir to meet changing circulatory demands. Less Volume in arterial system from lower compliance of the vessels.

12. What factors affect venous return?

Veins have thinner, less muscular walls than do arteries, and therefore have a higher compliance. So a given amount of pressure will cause more distension (expansion) in veins than in arteries, so veins can hold more blood. Lower venous pressure is due to a pressure drop between arteries and capillaries and the high venous compliance. Venous return is aided by (1) sympathetic nerve activity, which stimulates smooth muscle contraction in the venous walls and thereby reduces compliance (2) the skeletal muscle pump, which squeezes veins during muscle contraction (3) the pressure difference between the thoracic and abdominal cavities, which promotes venous blood flow back to the heart.

Baroreceptors are located in the

aorta and carotid arteries.

17. What main force causes fluid to enter venous ends of capillaries?

colloid osmotic pressure in the capillary (blood plasma)

The kidneys help regulate blood volume by increasing or decreasing the amount of urine produced. If a person is dehydrated, there is a(n) _____________ in plasma osmolality, which causes a(n) ____________ in ADH production, stimulating the kidneys to reabsorb water from the filtrate.

increase; increase

Which of the following will not increase the heart rate?

increased blood pressure

During exercise, the rate of venous return of the blood __________, causing a(n) __________ in stroke volume.

increases; increase

Action potentials are conducted from the baroreceptors to the brain via

the vagus and glossopharyngeal nerves.

The action potential from the brain to the heart travels along

the vagus and sympathetic efferents.

The sum of all the vascular resistance within the systemic circulation is called the

total peripheral resistance.

A temporary occlusion of a cerebral vessel could cause a __________, also called a mini-stroke.

transient ischemic attack (TIA)

21. Where is the most blood in the body at rest?

venous system

Blood flow is directly related to the ____ from one end of a vessel to the other, but inversely related to the____

pressure gradient, resistance

Cerebral blood flow is exclusively regulated by

intrinsic mechanisms (autoregulation).

The heart contains a large amount of __________ and __________; this indicates that it is highly specialized for __________.

mitochondria; myoglobin; aerobic respiration

According to the Starling Law, the __________ effects on heart rate and contractility include decreasing the rate of contraction and increasing the filling time, resulting in a stronger contraction.

parasympathetic

2. What are the effects of autonomic nerve activity on the heart?

parasympathetic stimulation of the heart slows the heart rate and reduces the strength of contraction; sympathetic stimulation accelerates the heart rate and increases the strength of contraction.

11. How is cardiac output affected by chronotropic effects?

positive chronotropic effect=increase cardiac rate negative chronotropic effect= decrease cardiac rate

29. What is the baroreceptor reflex?

helps maintain blood pressure at nearly constant levels.

A __________ stroke occurs when a cerebral vessel ruptures.

hemorrhagic

The causes and characteristics of hypertension:

A diet high in salt is associated with an increased risk of hypertension. Blood pressure over 120/80 is considered to put a person at risk for cardiovascular disease. Hypertension can cause atherosclerosis and stroke.

5. What kind of receptors does ACh bind to, and what channels are opened? What is the effect on heart rate?

Acetylcholine, released by vagus nerve endings, binds to ACh receptors and causes the opening of separate K+ channels. The outward diffusion of K+ partially counters the depolarizing mechanisms that produce pacemaker potential, which results in decrease in diastolic depolarization rate and action potential production, so theres a slower cardiac rate.

19. What are the functions of renin, angiotensin II, aldosterone, and ANP in relation to blood volume and pressure? 20. How do ACE inhibitors work?

Aldosterone, a steroid hormone secreted by the adrenal cortex, stimulates the reabsorption of salt (NaCl) by the kidneys. Aldosterone is thus a "salt-retaining hormone." Retention of salt indirectly promotes retention of water (in part, by the action of ADH). The action of aldosterone produces an increase in blood volume, but, unlike ADH, it does not produce a change in plasma osmolality The juxtaglomerular apparatus in the kidneys senses these changes and, in response, secretes the enzyme renin into the blood. This enzyme cleaves a ten-amino-acid polypeptide called angiotensin I from a plasma protein called angiotensinogen. renin=An enzyme secreted into the blood by the juxtaglomerular apparatus of the kidneys. Renin catalyzes the conversion of angiotensinogen into angiotensin II. As angiotensin I passes through the capillaries of the lungs, an angiotensin-converting enzyme (ACE) removes two amino acids. This leaves an eight-amino-acid polypeptide called angiotensin II This natriuretic hormone would thus be antagonistic to aldosterone and would promote Na+ and water excretion in the urine in response to a rise in blood volume. A polypeptide hormone with these properties, identified as atrial natriuretic peptide (ANP), is produced by the atria of the heart. atrial natriuretic peptide=A chemical secreted by the atria that acts as a natriuretic hormone (a hormone that promotes the urinary excretion of sodium).

6. What part of the brain controls the autonomic innervation of the heart?

Autonomic innervation of the heart is controlled by the cardiac control center in the medulla oblongata of the brain stem.

28. How is blood pressure determined? Pulse pressure? Mean arterial pressure? Know laminar/turbulent flow, Korotkoff sounds?

Blood pressure is measured in units of millimeters of mercury (mmHg). The height of this blood column bounced between the systolic pressure at its highest and the diastolic pressure at its lowest, as the heart went through its cycle of systole and diastole. diastolic blood pressure=The minimum pressure in the arteries that is produced during the phase of diastole of the heart. It is indicated by the last sound of Korotkoff when taking a blood pressure measurement. When the cuff pressure is equal to the systolic pressure, the first Korotkoff sound is heard as blood passes in a turbulent flow through the constricted opening of the artery. The mean arterial pressure represents the average arterial pressure during the cardiac cycle. mean arterial pressure (MAP)=An adjusted average of the systolic and diastolic blood pressures. It averages about 100 mmHg in the systemic circulation and 10 mmHg in the pulmonary circulation.

27. How is blood flow regulated to the brain and skin?

Brain=beta receptors skin=alpha receptors

26. How does exercise affect the heart?

Cardiovascular changes during exercise are affected by sensory feedback from the contracting muscles and by the baroreceptor reflex, which increase the activity of the sympathoadrenal system and reduce parasympathetic nerve activity during exercise. As a result, there is an increase in cardiac rate, stroke volume, and cardiac output.

The condition caused by an interruption in the blood supply to a section of the brain?

Cerebral vascular accident (CVA)

To maintain a constant deep body temperature, what changes will occur in cutaneous blood flow?

Constriction of arteriovenous anastomoses in the fingertips and toes when body temperature decreases Dilation of the arteriovenous anastomoses in the fingertips and toes when body temperature increases

15. What causes edema? elephantiasis?

Edema= swelling caused by excessive interstitial fluid increase, which is prevented by a proper balance between capillary filtration and osmotic uptake of water and by proper lymphatic drainage. The total blood volume is only about 5.5 L, yet the kidneys produce about 180 L/day of blood filtrate

Increase in blood flow to skeletal muscles causes

Epinephrine stimulates beta-adrenergic fibers Intrinsic metabolic changes cause vasodilation

Polycythemia, a high red blood cell count, can be the result of disease or as an adaptation to life at high altitudes. What are the effects of an increased red blood cell count on blood viscosity, blood flow and resistance.

Increased blood viscosity Increased resistance to flow Increased blood pressure

Sympathetic innervation of the heart responses

Increased heart rate Increased strength of contraction Increased Stroke volume

Vessels that supply blood to the brain=

Internal carotid and vertebral arteries

14. What is net filtration pressure, colloid pressure and oncotic pressure? How do Starling forces relate?

Net filtration pressure=the interaction of the hydrostatic and osmotic pressures, driving fluid out of the capillary. Colloid osmotic pressure/oncotic pressure=Osmotic pressure exerted by plasma proteins that are present as a colloidal suspension and is greater than colloid osmotic pressure of interstitial fluid. Through the action of the Starling forces, blood plasma and interstitial fluid are continuously interchanged. The return of fluid to the vascular system at the venular ends of the capillaries, does not equal the amount filtered at the arteriolar ends. Approximately 85% to 90% of the filtrate is returned directly to the blood capillaries; the remaining 10% to 15% is returned to the blood by way of the lymphatic system.

24. What is the action of NO, nitroglycerine on the heart?

Nitroglycerin corrects the imbalance between the flow of oxygen and blood to the heart. At low doses, nitroglycerin dilates veins more than arteries, thereby reducing preload (volume of blood in the heart after filling). Nitroglycerin helps angina (chest pain) by widening the blood vessels so more blood gets to your heart muscle.

3. What type of receptors do norephinephrine and epinephrine bind in the heart?

Norepinephrine from sympathetic axons and epinephrine from the adrenal medulla bind to β1-adrenergic receptors in the heart to stimulate cyclic AMP production

18. How does volume of blood in heart relate to ADH (vasopressin) secretion?

One of the major hormones that regulate the blood volume is antidiuretic hormone (ADH), also known as arginine vasopressin. This hormone is produced by neurons in the hypothalamus. The release of ADH occurs when osmoreceptors detect an increase in blood plasma osmolality Stimulation of osmoreceptors produces sensations of thirst, leading to increased water intake and an increase in the amount of ADH released from the posterior pituitary. Drinking excessive amounts of water without excessive amounts of salt does not result in a prolonged increase in blood volume and pressure. The water does enter the blood from the intestine and momentarily raises the blood volume; at the same time, however, it dilutes the blood. Dilution of the blood decreases the plasma osmolality and thus inhibits the release of ADH. With less ADH there is less reabsorption of water in the kidneys—a larger volume of more-dilute urine is excreted. Water is therefore a diuretic—a substance that promotes urine formation—because it inhibits the release of antidiuretic hormone.

Which of the following events would occur during moderate exercise? (check all that apply)

Oxyhemoglobin in arterial blood remains at 97%. Increased oxyhemoglobin saturation from the veins to the arteries. The oxygen percentage unloading at the tissues would increase.

7. What is EDV, total peripheral resistance, contractility, preload, afterload, and ejection fraction?

The end-diastolic volume=the volume of blood in the ventricles before they contract. This is a workload imposed on ventricles before contraction=preload. The total peripheral resistance presents an impedance to the ejection of blood from the ventricle. afterload= presents an impedance to the ejection of blood from the ventricles at systole or after systole has begun Contractility=the strength of contraction at any given fiber length. Norepinephrine from sympathetic nerve endings and epinephrine from the adrenal medulla increase contraction strength.

8. What is stroke volume affected by?

The stroke volume is regulated by three variables: 1. the end-diastolic volume (EDV), which is the volume of blood in the ventricles at the end of diastole. 2. the total peripheral resistance, which impedance(restriction) to blood flow in all of the arteries. 3. the contractility, or strength, of ventricular contraction.

What medication is given to break up clots and restore blood flow?

Tissue plasminogen activator

Peripheral resistance is __________ related to vessel length, and __________ related to vessel radius.

directly; inversely

What is the diagnostic level for blood pressure to be considered hypertension? How do ACE inhibitors help regulate blood pressure? Vasodilation of the blood vessels would have which of the following responses? Why can cocaine abuse cause chest pain? Why could the cocaine use cause fetal distress? What causes the edema to occur in women who suffer from preeclampsia? Which of the following will increase in production with preeclampsia? Which of the following symptoms are common with preeclampsia? Alisha and her patients all suffer from different situations that can affect their blood pressure. Which of the following can be directly related to increased blood pressure levels or hypertension? Which of the following medications are used to treat congestive heart failure and hypertension?

greater than 140 mm Hg systolic and/or greater than 90 mm Hg diastolic prevent vasoconstriction decreased total peripheral resistance The cocaine causes vasoconstriction of the coronary arteries. decreased blood flow to the placenta and baby loss of plasma proteins that regulate osmotic balance endothelin and thromboxane hypertension and decreased organ perfusion blood volume, total peripheral, resistance and cardiac output diuretics and ACE inhibitors