Test 4

Determine if the following are vasodilators or vasoconstrictors. Enter D for vasodilator and C for vasocontsrictor.

look at HW 8

List the factors that affect venous return. Make predictions about venous return and cardiac output if these factors are changed.

look at chegg question chart

TTQ In which of the following conditions would you expect a decreased resistance to venous return?

low hematocrit

Explain how the renin angiotensin system and aldosterone act to regulate blood pressure - make predictions

-The RAAS is a complex multi-organ endocrine (hormone) system involved in the regulation of blood pressure by balancing fluid and electrolyte levels, as well as regulating vascular resistance & tone. RAAS regulates sodium and water absorption in the kidney thus directly having an impact on systemic blood pressure. -The renin-angiotensin system or RAS regulates blood pressure and fluid balance in the body. When blood volume or sodium levels in the body are low, or blood potassium is high, cells in the kidney release the enzyme, renin. ... Angiotensin II causes blood vessels to constrict and blood pressure to increase.

Explain the significance of the lymphatic system and describe how lymph flow occurs

-The lymphatic system collects excess fluid that drains from cells and tissue throughout the body and returns it to the bloodstream, which is then recirculated through the body. ... The spleen filters and stores blood and produces white blood cells that fight infection or disease. -The lymph flows into lymph nodes through afferent collecting lymphatic vessels and exits through efferent collecting lymphatic vessels. The lymph not only flows through the lymph node, but some of it is reabsorbed into the blood circulation at the lymph nodes

Explain how baroreceptors and chemoreceptors maintain blood pressure. Describe where they are located.

-When blood pressure rises too high, baroreceptors fire at a higher rate and trigger parasympathetic stimulation of the heart. As a result, cardiac output falls. ... The baroreceptors in the venae cavae and right atrium monitor blood pressure as the blood returns to the heart from the systemic circulation. -The arterial chemoreceptors are located in areas very close to the baroreceptors: The carotid bodies are situated at the carotid bifurcation, and the aortic bodies are located near the aortic arch.

List some ways that heart function can be decreased.

-inhibition of sympathetic stimulation (inhibit vasomotor center in brain) to reduce heart rate and contractility parasympathetic stimulation, which will decrease heart rate or any of the others listed in the book: valve disease, myocarditis, abnormal heart rhythm, hypertension

Explain how nitric oxide and endothelin affect blood flow

-nitric oxide Is a vasodilator, meaning it relaxes the inner muscles of your blood vessels, causing the vessels to widen. In this way, nitric oxide increases blood flow and lowers blood pressure -endothelin-1 (ET-1), a powerful endothelium-derived vasoconstrictor peptide that may stimulate NO production.

List the neurotransmitter released by each type of neuron below.

look at HW 8

Review Test Submission: Regulation of CO and venous return III

look at test

Stress increases the levels of norepinephrine in the blood, which has a sympathetic effect on blood vessels.

true

What is the effect of sympathetic stimulation on arterioles?

vasoconstriction

Describe the vasodilator and oxygen demand theories for local blood flow control

vasodilator theory (greater metabolism or decreased availability of oxygen increases vasodilation), oxygen demand theory (absence of oxygen due to it being used causes vasodilation as vessels relax)

What would happen to venous return if the resistance was increased?

venous return will decrease

What would happen to venous return if the right atrial pressure was increased to 2 mmHg?

venous return would decrease because the pressure gradient driving blood back to the heart would decrease

In your own words, define venous return.

volume of blood flowing into the right atrium per minute

TTQ Which of the following tends to decrease blood flow?

increase in tissue oxygen concentration

Which of the following tends to decrease blood flow?

increase in tissue oxygen concentration

List two ways that mean systemic filling pressure could be decreased.

increase vessel diameter increase vessel compliance decrease blood volume

How might total peripheral resistance affect cardiac output?

increased TPR would reduce cardiac output because the resistance to flow would be increased

TTQ Which of the following conditions is normally associated with an increased mean systemic filling pressure?

increased blood volume

TTQ Which of the following normally causes vasodilation of skeletal muscle arterioles during exercise?

increased plasma adenosine concentration

TTQ Which of the following is expected in the vascular system during exercise (1 pt.)?

increased sympathetic activity

TTQ Which of the following is correct regarding sympathetic stimulation of the heart?

increases cardiac contractility

Explain the function of humoral agents in the control of blood flow

, -Humoral control of the circulation means control by substances secreted or absorbed into the body fluids— such as hormones and ions. Some of these substances are formed by special glands and transported in the blood throughout the entire body. Others are formed in local tissue areas and cause only local cir-culatory effects. Among the most important of the humoral factors that affect circulatory function are the following. -Vasoconstrictor Agents, Norepinephrine and Epinephrine.

Define hydrostatic pressure (of capillaries and interstitium) and colloid osmotic pressure (of capillaries and interstitium) and explain how they contribute to capillary exchange (make predictions).

-hydrostatic pressure: A pressure generated by fluid on the walls of the capillary, usually forcing water out of the circulatory system. -oncotic pressure: A form of osmotic pressure exerted by proteins in a fluid that usually tends to pull water into the circulatory system.

Describe the metabolic and myogenic mechanisms of blood flow autoregulation

-Autoregulation is a manifestation of local blood flow regulation. ... When blood flow falls, arterial resistance (R) falls as the resistance vessels (small arteries and arterioles) dilate. -

Describe what happens to the brain during ischemia and the reflex that occurs.

-Brain ischemia is a condition in which there is insufficient blood flow to the brain to meet metabolic demand. This leads to poor oxygen supply or cerebral hypoxia and thus leads to the death of brain tissue or cerebral infarction / ischemic stroke. -The medullary ischemic reflex is a big response to a drop in blood pressure in the brain particularly in the medulla, where the lack of oxygen due to decreased perfusion triggers an autonomic response from the cardiac and vasomotor centers.

Explain what happens to arterial pressure and cardiac output during exercise and the mechanisms for these effects.

-During exercise, the cardiac output increases more than the total resistance decreases, so the mean arterial pressure usually increases by a small amount. Pulse pressure, in contrast, markedly increases because of an increase in both stroke volume and the speed at which the stroke volume is ejected. -

Explain why there is net filtration at the arterial end of a capillary and net reabsorption at the venous end (make predictions).

-Net filtration occurs near the arterial end of the capillary since capillary hydrostatic pressure (CHP) is greater than blood colloidal osmotic pressure (BCOP). There is no net movement of fluid near the midpoint since CHP = BCOP. Net reabsorption occurs near the venous end since BCOP is greater than CHP. -

Explain how the structure of capillaries allows for fluid and nutrient/waste exchange

-Only two layers of cells thick, the purpose of capillaries is to play the central role in the circulation, delivering oxygen in the blood to the tissues, and picking up carbon dioxide to be eliminated. -Their single-layer endothelium composition, which varies among the different types of capillaries, and surrounding basement membrane makes capillaries a bit "leakier" than other types of blood vessels. This allows oxygen and other molecules to reach your body's cells with greater ease.

Describe the long term mechanisms of blood flow regulation

-Renin-Angiotensin-Aldosterone System (RAAS) -Anti-Diuretic Hormone (ADH) -Further Control of Blood Pressure

How do each of the following increase arterial pressure? constriction of arterioles constriction of veins stimulation of the heart

1. Smaller diameter means the same volume of blood exerts more pressure on the vessel 2. Squeezes blood from the vein blood reservoirs and increases venous return to the heart. This additional venous return will be pumped to the arteries. More volume in the arteries = more arterial pressure. 3. Increased cardiac contractility will increase the pressure by which blood is ejected from the heart, therefore increasing arterial pressure. See page 218 for more explanation

Explain how blood flow to the muscles, brain, heart, and internal organs changes during exercise

As cardiac output rises with exercise, brain blood flow remains constant (or increases slightly) while blood flow to the heart increases to meet the increased demands for myocardial blood flow that are primarily associated with exercise-induced increases in heart rate.

In a few sentences, summarize the Frank-Starling law of the heart.

As end diastolic volume increases, cardiac output and stroke volume increase. This is because the volume of blood returning to the heart dictates the length of the cardiac muscle sarcomeres. Stretching, due to increased venous return, puts sarcomeres in optimal position to generate more force. This occurs until the sarcomeres become too stretched to generate force.

What would happen to venous return if the right atrial pressure was increased to 7 mmHg? Why?

Blood flow to the heart from the veins would stop because the pressure gradient would be zero.

Based on your answer to question 2, does cardiac output depend on venous return? If so, what is the relationship? Draw a graph depicting the relationship between the two variables in your notes.

Cardiac output depends on venous return. As venous return increases, cardiac output should increase, up to a point.

Explain the mechanism by which increased body fluid volume leads to increased arterial pressure

Changes in blood volume affect arterial pressure by changing cardiac output. An increase in blood volume increases central venous pressure. This increases right atrial pressure, right ventricular end-diastolic pressure and volume.

Explain how and why coronary blood flow changes during the cardiac cycle

Coronary circulation is the circulation of blood to the heart through coronary arteries(right ana left). When the heart contracts(systole) blood flow decreases as the vessels also compressed along with Cardiac contractions When the hearth relax gets adequate blood flow by increased blood flow Continuously there will be heart contractions and relaxes so, the blood flow in the coronary arteries cant be constant.

Why is it important for the sympathetic nervous system to increase arterial pressure during times of stress?

Increased pressure will help maintain blood flow to muscles, which are needed to escape danger

Indicate the effects of parasympathetic stimulation on both the heart and vasculature.

heart: reduces heart rate at SA node vasculature: little effect

Relate cardiac output to total peripheral resistance and intrapleural pressure

Mean artirial pressure= (CO) x TPR

List the local vasodilator substances.

Nitric oxide -histamine -Carbon dioxide -acetycholine -prostaglandins

Which of the following are vasodilators?

histamine hydrogen ions adenosine carbon dioxide

Describe the conditions that lead to primary hypertension

Primary hypertension can result from multiple factors, including: blood plasma volume. hormone activity in people who manage blood volume and pressure using medication. environmental factors, such as stress and lack of exercise.

Define resistance to venous return.

Resistance to flow of blood through veins and back to the heart.

Categorize mechanisms of blood pressure control as rapid acting, intermediate, and long term

Short term adjustments of blood pressure are made by changes in cardiac output and total peripheral resistance, by the effect of autonomic nervous system on heart, veins and arterioles. While short term changes in blood pressure are regulated by sympathetic nervous system and renin-angiotensin-aldosterone system (RAAS), long term control is controlled by the kidney. Long term regulation involves adjusting total blood volume by maintaining salt and water balance via mechanisms that regulate urine output and thirst. The regulation of blood volume has profound effect on cardiac output and mean arterial pressure.

Pure water is _________ compared to the intracellular fluid.

hypo-osmotic

Describe how the cardiac output and venous return curve shift during exercise and explain the mechanisms for this

The changes include large increases in heart rate and cardiac contractility to increase cardiac output, increased rate and depth of respiration which requires enhanced blood flow to respiratory muscles, vasodilation and increased blood flow in the contracting skeletal muscles, and vasoconstriction in the rena

Describe the arrangement of the coronary vasculature

The coronary arteries wrap around the outside of the heart. Small branches dive into the heart muscle to bring it blood.

What would happen to the pressure gradient if the right atrial pressure was increased to 2 mmHg?

The gradient would decrease from 7 mmHg (7 mmHg fillng pressure - 0 mmHg right atrial pressure) to 5 mmHg (7 mmHg fillng pressure - 2 mmHg right atrial pressure).

Explain what is meant by mean systemic filling pressure.

The pressure of the fluid in the vascular system if the heart was stopped.

Baroreceptors work well for controlling blood pressure after slight fluctuations due to postural changes.

True

Relate cardiac output to venous return

Venous return (VR) is the flow of blood back to the heart. Under steady-state conditions, venous return must equal cardiac output (CO) when averaged over time because the cardiovascular system is essentially a closed loop (see figure). Otherwise, blood would accumulate in either the systemic or pulmonary circulations.

An increase in tissue metabolism results in a decrease in which of the following?

arteriole resistance

TTQ An increase in tissue metabolism results in a decrease in which of the following?

arteriole resistance

State the relationship between cardiac output and venous return.

as venous return increases cardiac output increases

Decreased pH in the extracellular fluid at the carotid bodies would cause an ________ in activity in the vasomotor center.

increase

Increased pressure in the carotid arteries _______ impulses generated by the baroreceptors.

increase

Draw a graph to relate cardiac output to right atrial pressure in your notes (don't need to submit a drawing). Shift the curve on your graph to the right. Does this increase or decrease cardiac output at any given right atrial pressure?

decrease

List two ways that mean systemic filling pressure could be increased.

decrease vessel diameter by sympathetic stimulation decrease vessel compliance increase blood volume

Which of the following would result from applying acetylcholine to the heart?

decreased heart rate

What effect does adenosine have on the microcirculation?

dilates arterioles

An increase in shear stress in a blood vessel would result in an increase which of the following?

endothelin production

TTQ A healthy 25-year-old male medical student has an exercise stress test at a local health club. Which of the following set of physiological changes is most likely to occur in this man's skeletal muscles during exercise?

everything inc, look at HW 8

Sympathetic stimulation causes contraction of abdominal muscles, which decreases blood pressure.

false

The CNS ischemic response is a response to high carbon dioxide in the interstitial fluid of the brain and is a mechanism for long term, steady-state control of blood pressure.

fasle

Capillary exchange 1 ques

go look

capillary exhchange 2 ques

go look

List all the ways you can think of that the resistance to venous return could be increased.

gravity

There is resistance to blood returning to the heart from the veins (resistance to venous return). Where does this resistance come from?

gravity

Indicate the effects of sympathetic stimulation on both the heart and vasculature.

heart: increased heart rate and force of contraction vasculature: constricts arteriole and veins

Based on what you've learned from each part of this activity, list the factors that affect venous return. Determine if there is a direct or inverse relationship between these factors and venous return.

mean circulatory/systemic filling pressure - direct intrapleural pressure - inverse right atrial pressure - inverse resistance to venous return - inverse

The protein concentration of the plasma is about 7.3 g/dL and the concentration of protein in the interstitial fluid is on average 2.9 g/dL. Given that all other solutes tend to be the same between the two fluids, which has the greatest colloid osmotic pressure?

plasma

TTQ Which of the following normally causes the cardiac output curve to shift to the right for a given right atrial pressure (1 pt.)?

surgically opening the chest, resulting in a intrapleural pressure of 0 mmHg

Describe the effects of sympathetic stimulation on the nervous system.

sympathetic nervous system can accelerate heart rate, widen bronchial passages, decrease motility of the large intestine, constrict blood vessels, increase peristalsis in the esophagus, cause pupillary dilation, piloerection (goose bumps) and perspiration (sweating), and raise blood pressure.

Cardiac output depends on the function of the heart, independent of venous return. List some ways that heart function can be increased.

sympathetic stimulation that increases heart rate or cardiac muscle contractility

How could this resistance be increased?

sympathetic stimulation will increases resistance to venous return because the vessels constrict

What is the relationship between right atrial pressure and venous return?

the greater the pressure gradient from the veins to the right atrium, the greater the venous return

In your own words, define cardiac output.

the volume of blood pumped by the left ventricle per minute

What will happen to the volume of cell bathed in pure water? Why?

the volume will increase because osmosis will cause water to enter the cell, where the intracellular fluid has a greater solute concentration

In a capillary bed, where does adenosine come from? What would cause it to accumulate?

tissue metabolism - it is produced when ATP is broken down accumulates if blood flow doesn't increase when tissue metabolism increases

The normal right atrial pressure of the heart is 0 mmHg. The normal mean circulatory filling pressure is 7 mmHg. In what direction is the pressure gradient for blood flow under normal conditions?

towards the right atrium

Normally, there is alway some slight sympathetic stimulation of arterioles to help maintain blood pressure.

true