Chapter 15

If you checked the pulse in a persons carotid artery and left wrist at the same time would the pressure waves occur simultaneously?

The carotid wave would arrive slightly ahead of the wrist wave because the distance from heart to carotid artery is shorter.

How much blood do veins hold? Why?

They hold more than half of the blood in the circulatory system. Because they have thinner walls with less elastic tissue than arteries, they can expand easily when they fill with blood.

What control are most systemic arterioles under? What is involved in vasoconstriction? what causes vasodialation?

Tonic sympathetic control causes vasoconstriction. Norepinephrine causes vasoconstriction. Decreased sympathetic stimulation causes vasodilation.

When can venous blood volume be shifted into the arteries.

Venous blood volume can be shifted to the arteries if arterial blood pressure falls.

Hypertension

a significant risk factor for development of cardiovascular disease

Parasympathetic output part of pathway for baroreceptors

an increase in parasympathetic output releases more Ach onto muscarinic receptors, to the SA node, decrease in heart rate, causing decrease in cardiac output, causing decrease in blood pressure

Reactive hyperemia

an increase in tissue blood flow following a period of low perfusion

Atherosclerosis

an inflammatory condition in which fatty deposits called plaques develop in arteries. If plaques are unstable they may block the arteries by triggering blood clots.

Arterioles

are the main site of variable resistance in the systemic circulation. A small change in the radius of an arteriole creates a large change in resistance.

Myogenic autoregulation

arterioles regulate their own blood pressure through myogenic autoregulation. Vasoconstriction increases the resistance offered by an arteriole and decreases the blood flow through the arteriole.

total blood flow at any level of circulation is equal to what?

cardiac output

Cardiovascular function can be modulated by what?

cardiovascular function can be modulated by input from higher brain centers and from the respiratory control center of the medulla.

Continuous capillaries

continuous capillaries have leaky junctions between cells but also transport material using transcytosis. Continuous capillaries with tight junctions form the blood brain barrier.

Sympathetic output part of pathway for baroreceptor reflex

decrease in sympathetic output cuases less NE released onto a receptor and b1 receptors, the - receptor effects the arteriolar smooth muscle causing vasodilation causing decrease in peripheral resistance and decrease in blood pressure. The b-1 receptor effects ventricular myocardium, decreasing force of contraction, causing decrease in cardiac output and decrease in b/p

What transport mechanisms are used by capillary exchange of material between the plasma and interstisial fluid compartments?

diffusion transcytosis and bulk flow

When does the baroreceptor reflex function?

each time a person stands up.

Fenestrated capillaries

fenestrated capillaries have pores that allow large volume of fluid to pass rapidly.

Filtration and absorbtion

fluid movement is called filtration if the direction of flow is out of the capillary and absorption if the flow is directed into the capillary

cardiac contraction creates what?

high pressure in the ventricles which drives blood though the vessels of the systemic and pulmonary circuits speeding up cell to cell communication.

Baroreceptors

in the carotid artery and the aorta monitor arterial blood pressure and trigger the baroreceptor reflex

Mean arterial pressure

is defined as diastolic pressure plus one third systolic pressure minus diastolic pressure

What are blood vessels composed of?

layers of smooth muscle, elastic, and fibrous connective tissue and endothelium.

Resistance to flow is regulated by what?

local and reflex control mechanisms that act on arteriolar smooth muscle and help match tissue perfusion to tissue needs

Lymph flow

lymph capillaries accumulate fluid, interstitial proteins and particulate matter by bulk flow. Lymph flow depends on smooth muscle in vessel walls, one way valves and the skeletal muscle pump.

Homeostatic regulation of the cardiovascular system is aimed at what?

maintaining adequate blood flow to the brain and heart

Vascular smooth muscles function?

maintains a state of muscle tone

What does the homeostatic baroreceptor reflex do?

monitors arterial pressure to ensure adequate perfusion of the brain and heart

Active hyperemia

process in which increased blood flow accompanies increased metabolic activity.

Pulse pressure

pulse pressure equals systolic pressure minus diastolic pressure

Precapillary sphincters

regulate blood flow into individual capillaries

Metarterioles

regulate blood flow through capillaries and allow white blood cells to go directly from aterioles to the venous circulation.

Norepinephrine (role, source, type)

role- baroreceptor reflex, Source- sympathetic neurons, Type- neurotransmitter.

Vasopressin (role, source, type)

role- increase b/p in hemorrhage, source- posterior pituitary, Type- neurohormone

Angiotensin (role, source, type)

role- increase b/p, source- plasma hormone, type- hormone

Adenosine (role, source, type)

role- increase blood flow to match metabolism, source- hypoxic cells, type- paracrine

Epinephrine (b2 receptors) (role, source, type)

role- increase blood flow to skeletal muscle, heart, liver, source- adrenal medulla, type- neurohormone

Hisatmine (role, source, type)

role- increases blood flow, source- mast cells, type- paracrine

Nitric oxide (role, source, type)

role- local control of blood flow, source- endothelium, type- paracrine

Natriuretic peptides (role, source, type)

role- reduce b/p, source- atrial myocardium brain, type- hormone and neurotransmitter.

Korotkoff sounds

sound that Blood squeezing through a compressed brachial artery makes

What is edema? What causes it?

the condition in which excess fluid accumulates in the intertitial space. Factors that disrupt the normal balance between capillary filtration and absorption cause edema.

The flow through individual arterioles affects depends on what?

the flow through individual arterioles depends on their resistance. The higher the resistance in an arteriole, the lower the blood flow in that arteriole.

Cardiovascular disease

the leading cause of death in the united states. Risk factors predict the likelihood that a person will develop cardiovascular disease during her or his lifetime.

Bulk flow

the mass movement of fluid between the blood and the interstitial fluid

colloid osmostic pressure

the osmotic pressure difference between plasma and interstitial fluid due to the presence of plasma proteins

baroreceptor reflex

the primary reflex pathway for homeostatic control of blood pressure

Angiogenesis

the process by which new blood vessels grow and develop especially after birth

Reflex control of blood pressure is where?

the reflex control of blood pressure resides in the medulla oblongata

Explain the role of ventricles and aorta in relation to pressure

the ventricles create high pressure that is the driving force for blood flow. The aorta and arteries act as a pressure reservoir during ventricular relaxation.

would you expect to find valves in the veins leading from the brain to the heart?

veins from the brain do not require valves because the blood flow is aided by gravity.

How is blood pressure measured

with a sphygmomanometer

peripheral resistance

1. The total resistance against which blood must be pumped 2. also known as afterload 3. Major factor effecting perfusion.

At rest what is the desirable systolic pressure and diastolic pressure?

120 mm hg and 80mm hg

How much fluid is filtered out of the capillaries each day? What returns the fluid?

About three liters of fluid filter out of the capillaries each day. The lymphatic system returns this fluid to the circulatory system.

Arterial blood pressure

Arterial blood pressure is indicatve of the driving pressure for blood flow.

What is arteriolar resistance influenced by?

Arteriolar resistance is influenced by local control mechanisms that match tissue blood flow to the metabolic needs of the tissue.

How does blood flow against gravity in the veins?

Blood flow against gravity in the veins is assisted by one-way valves and by the respiratory and skeletal muscle pumps.

Properties of the walls of aorta and the function of these properties?

Both stiff and springy, this allows them to absorb energy and release it through elastic recoil.

What is the site of exchange between blood and interstitial fluid?

Capillaries and postcapillary venules

how does the resistance of arterioles affect blood blow?

Changing the resistance of the arterioles affects mean arterial pressure and alters blood flow through the arteriole.

Orthostatic hypotension

Decrease in blood pressure upon standing

Process of reactive hyperemia (pathway)

Decrease in tissue blood flow due to occlusion, metabolic vasodilators accumulate in ECF, arterioles dilate but occulsion prevents blood flow, remove occlusion, decrease resistance creates an increase in blood flow, as vasodilators wash away arterioles constrict and blood flow returns to normal.

efferent output from the what goes to the heart and arterioles?

Efferent output from the medullary cardiovascular control center

What is a powerful vasoconstrictor?

Endothelins are powerful vasoconstrictors

Chemicals that mediate Vasodilation?

Epinephrine (b2 receptors), nitric oxide, adenosine, histamine, natriuretic peptides

What is the role of epinephrine?

Epinephrine binds to arteriolar a-receptors and causes vasoconstriction. Epinephrine on B2-receptors, found in the arterioles of the heart liver and skeletal muscle causes vasodilation.

How does blood exchange occur?

Exchange of materials between the blood and the interstitial fluid occurs primarily by diffusion.

What is the relationship between blood volume and pressure

If blood volume increases, blood pressure increases. If blood volume decreases, blood pressure decreases.

The formula given for calculating MAP applies to a typical resting heart rate of 60-80 beats/min. If heart rate increases would the contribution of systolic pressure to mean arterial pressure decrease or increase and would MAP decrease or increase?

If heart rate increases, the relative time spent in diastole decreases. In that case, the contribution of systolic pressure to mean arterial pressure increases and MAP increases.

Baroreceptor reflex in response to increase in mean arterial pressure pathway

Increase in blood pressure causes increase in firing of baroreceptors in carotid arteries and aorta onto the sensory neurons.They send message to cardiovascular Control center in medulla oblongata, which activate sympathetic and parasympathetic output.

Process of active hyperemia (pathway)

Increase in tissue metabolism, increase in release of metabolic casodilators into ECF, Arterioles dilate, Decrease resistance creates increase in blood flow, Oxygen and nutrient supply to tissue increases as long as metabolism is increased.

What does increased sympathetic activity do? Increased parasympathetic?

Increased sympathetic activity increases heart rate and force of contraction, in the arterioles causes vasoconstriction. Increased parasympathetic activity slows the heart rate. Parasympathetic has no significant effect of arterioles.

what is arterial pressure a balance of?

It is a balance between cardiac output and the resistance to blood flow offered by the arterioles (peripheral resistance).

Clood pressure is highest where? How does it decrease?

It is highest in arteries and decreases as blood flows through the circulatory system.

Vasodilator paracrines for arterioles

Nitric oxide, Hydrogen ions, Potassium, carbon dioxide, prostaglandins, adenosine, histamine. Low oxygen causes vasodilation.

Chemicals that mediate vasoconstriction?

Norepinephrine (a-receptor), Vasopressin, and angiotensin

Describe Pulse

Pressure created by the ventricles can be felt as pulse in the arteries.