Circulatory System

How do capillaries differ from arteries and veins?

Only 1 endothelial cell surrounds the lumen in the tunica intima

True or False. Arteries and veins have valves.

False. Only veins have valves to prevent backflow of blood. High pressures in arteries and going in flow of gravity allows for no need of valves for blood flow.

True or False? The three layers of blood vessels in veins are arteries are the same size.

False. Veins are pretty straight forward in that they have the three layers of normal/expected size. In contrast, arteries have a thick Tunica Media layer.

What factors affect resistance?

viscosity, length of tube, diameter of tube/radius

There are three main layers that make up a blood vessel. The innermost layer, the Tunica Intima are composed of which of the following items? I. Endothelial Cells II. Basement membrane III. Smooth Muscle (A) I and II only (B) I and III only (C) II and III only (D) III only

(A) I and II only Tunica Intima is made up of endothelial cells and the basement membrane

Why does the blood pressure drop from arteries to arterioles? Why is it beneficial?

-Arterioles have a high area to volume ratio = volume of blood that travels interacts with more surface area of the wall = higher resistance = decrease pressure and velocity -arterioles dump into capillaries which require low pressures

How do the layers of an artery differ from the layers of a vein?

-Tunica media thicker than that of vein -Elastin in tunica media of large/middle arteries

What are arteries and veins known to carry generally? What are the exceptions?

-arteries: oxygenated blood veins: deoxygenated blood -pulmonary vein: carries oxygenated blood pulmonary artery: carries deoxygenated blood umbilical vein: carries oxygenated umbilical artery: carries deoxygenated

What are the variables in finding blood flow? What are the units of blood flow and its variables?

-stroke volume(heart rate) -volume/min (blood flow); volume/beat (stroke volume), beat/min (heart rate)

Imagine an artery and vein getting severed. Match the analogies of what the blood flow will look like with either arteries or veins. 1) small pool of blood; quick clot 2) blood spewing out like a water from a hose

1) Vein 2) Artery Because arteries have such high pressures, their flow will be like that of a water hose. In contrast, veins have low pressures so their flow will be that of a small puddle.

How can nutrients be exchanged between the lumen and the layer around it?

1) through cell membrane of endothelial cells 2) via fenestrations 3) spore between cells (intercellular cleft) 4) pinocytosis (form vesicle inside)

What comprises the Tunica Intima? I. endothelial cells II. lumen III. basement membrane A) I and III B) I and II C) I, II, III D) III only

A) I and III The Tunica Intima includes the endothelial cells that surround the lumen and the basement membrane that surrounds the endothelial cells.

Why is the velocity the lowest in capillaries?

According to the continuity equation (Av = Av) and since capillaries have the highest cross sectional area, it is expected that the capillaries would have the lowest velocity.

Why do large/middle arteries need elastin?

Arteries will have high pressures and have to ensure they don't break when at these high pressures.

You are consuming a lot of salt in having popcorn, having pretzels and many more. How can this increase blood volume?

Because you are consuming more salt, a lot of water would leave the cells and add to the blood volume.

How do large/middle arteries and small arteries/arterioles differ?

Large/middle have elastin in tunica media while small/arterioles have large amount of muscle.

In bacterial sepsis (overwhelming bloodstream infection), a number of capillary beds throughout the body open simultaneously. What effect would this have on the blood pressure? Besides the risk of infection, why might sepsis be dangerous for the heart?

Opening up more capillary beds (which are in parallel) will decrease the overall resistance of the circuit. The cardiac output will therefore increase in an attempt to maintain constant blood pressure. This is a risk because the increased demand on the heart can eventually tire it, leading to a heart attack or precipitous drop in blood pressure.

What comprises the tunica externa?

The Vasa Vasorum (which are small vessels on large blood vessels), proteins different from basement membrane, collagen, nerve endings.

When our body is cooling, what happens to our capillary beds?

The capillaries are made to be as thin as possible causing less blood to flow through and release less heat.

When our body overheats, what happens to our capillary beds?

The capillaries vasodilate to release more heat to the environment with more blood passing through

If all autonomic input to the heart were cut, what would happen?

The heart would continue beating at the intrinsic rate of the pacemaker (SA node). The individual would be unable to change his or her heart rate via sympathetic or parasympathetic system.

What would be the purpose of having only muscle in the small arteries and arterioles?

These vessels need to create resistance if need to change blood pressure

How does the body control the size of the capillary beds?

They have smooth muscle that react to autonomic control.

Why do we have endothelial cells surrounding vessels?

To absorb the nutrients that the blood vessel needs

True or False. Veins have a high compliance while arteries have a low compliance.

True. The veins have high compliance, meaning they're high-volume, low pressure vessels, and even a small increase in pressure expands the volume a lot and do not recoil. The arteries, on the other hand have low compliance, and are low-volume, high pressure vessels, meaning with same amount of pressure, their volume doesn't expand as much.

How does resistance apply to blood vessels?

When vessels relax, they have a larger radius so they have less resistance while vessels constrict they have a smaller radius so they have greater resistance

What is the difference between arteries and veins in terms of pressure and volume? a) arteries have high pressure and low volume while veins have low pressure and high volume b) veins have high pressure and low volume while arteries have low pressure and high pressure c) arteries have high pressure and high volume while veins have low pressure and low pressure d) arteries have high pressure and high volume while veins have low pressure and low pressure

a) arteries have high pressure and low volume while veins have low pressure and high volume

At any given time, there is more blood in the venous system than the arterial system. Which of the following features of the vein allows for this? a) relative lack of smooth muscle b) presence of valves c) proximity of veins to lymphatic vessels d) thin endothelial lining

a) relative lack of smooth muscle The relative lack of smooth muscle in venous walls allows stretching to store most of the blood in the body. Valves in the veins allow for one-way flow of blood toward the heart, not stretching. Both arteries and veins are close to lymphatic vessels, which has no bearing on their relative difference in volume. Both arteries and veins have a single-cell endothelial lining.

Which vascular structure creates the most resistance to blood flow? a) aorta b) arterioles c) capillaries d) veins

b) arterioles The greatest amount of resistance is provided by the arterioles, which also results in the greatest drop in blood pressure. Arterioles are highly muscular and have the ability to contract and dilate in order to affect blood pressure.

Which vessel has the highest cross sectional area? a) venule b) capillary c) arteriole d) small arteries

b) capillary The cross sectional area of capillaries is greater than that of arteries and veins.

A patient's chart reveals that he has a cardiac output of 7500 mL per minute and a stroke volume of 50 mL. What is his pulse, in beats per minute? a) 50 b) 100 c) 150 d) 400

c) 150

Which of the following is true regarding arteries and veins? a) Arteries are thin-walled, muscular, elastic whereas veins are thick-walled and inelastic. b) Arteries always conduct oxygenated blood, whereas veins always carry deoxygenated blood. c) The blood pressure in the aorta is always higher than the pressure in the superior vena cava. d) Arteries facilitate blood transport by using skeletal muscle contractions, whereas veins make use of the pumping of the heart to push blood.

c) The blood pressure in the aorta is always higher than the pressure in the superior vena cava.

What type of muscle is the tunica media composed of? a) cardiac muscle b) skeletal muscle c) smooth muscle d) skeletal muscle and smooth muscle

c) smooth muscle

In Mark, blood is flowing through a healthy artery with a radius of 2 cm. However, Jessica's arteries are occluded by 20%, reducing the radius of her artery to 1 cm. How much higher is the resistance of Jessica's blood as compared to Mark's? a) 2x greater b) 4x greater c) 8x greater d) 16x greater

d) 16x greater

What is the order of the different layers of a blood vessel from lumen and out? a) tunica media, tunica externa, tunica intima b) tunica externa, tunica intima, tunica media c) tunica externa, tunica media, tunica intima d) tunica intima, tunica media, tunica externa

d) tunica intima, tunica media, tunica externa

How is blood pressure determined?

delta P= Q (blood flow) * R (resistance)

If vessels constrict, what happens to the diameter, flow, resistance, blood pressure?

diameter decrease flow decrease (continuity equation assumes flow rate is constant but in vasoconstriction it is not constant) resistance increase blood pressure increase

If vessels dilate, what happens to the diameter, flow, resistance, blood pressure?

diameter increase flow increase resistance decrease blood pressure decrease

How is cardiac output determined?

stroke volume x heart rate

Which vessels carry most of the blood?

veins (65%)