Circulatory System Flashcards by Vicki schenk

What do arteries do?

Carry blood away from the heart

**Usually oxygenated blood**

**Exception is the pulmonary artery - which is deoxygenated blood**

**Usually carry blood which is high in pressure**

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How are the arteries constructed?

They have thick elastic walls - 3 layers

Inner layer - smooth endothelial

Middle layer - thick elastic and muscular

Outer layer - connective tissue

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When taking your pulse are you feeling arteries or veins?

Arteries

Arteries have a pulse

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What are arterioles?

Small arteries just visible to the naked eye?

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What do veins do?

Carry blood towards the heart

Usually carry deoxygenated blood (except the pulmonary vein)

blood usually is of low pressure

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How are veins constructed?

3 layers

Inner layer - endothelial cells

Middle layer - thin and not as elastic as arteries

Outer layer - connective tissue

Have one way valve (pocket valves) to ensure return of blood to the heart

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What are venules?

small veins which drain blood away from the capillaries

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What is vaso-constriction?

constricts blood vessels in certain areas of the body to make sure blood is available where it is needed most.

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What are some examples of vaso-constriction?

**Helps prevent heat loss “white” finger and toes

**Reduces blood flow to the gut and kidneys so that blood flow to skeletal muscles can be increased during exercise

**helps ensure blood flow to brain and heart is not affected

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What is vaso-dilation?

it is when the blood vessels open up

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What is an example of vaso-dilation?

helps regulate body temperature - during exercise, the body heats up, the vessels in the skin dilate to help cool the body down - “redness” in the face

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What are capillaries?

small, thin-walled (one cell thick). Made of endothelial cells.

It’s where the exchange of nutrients, gases, and waste takes place.

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How do capillary beds control blood flow?

At the junction of the arterioles and the capillary beds are special sphincter muscles which can contract to shunt off the blood flowing into the capillary bed.

(Happens as a result of shock or trauma or exposure to cold temperatures)

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The circulation system is divided into which 2 systems?

pulmonary system and systemic system

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What is the pulmonary system?

the blood that circulates through the lungs

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What is the systemic system?

Blood that circulates around the body (except the lungs)

What are the major blood vessels to the head?

Carotid Artery

Jugular Vein

What are the major blood vessels to the arms

Subclavian Artery

Subclavian Vein

What are the major blood vessels to the lungs?

Pulmonary Arteries

Pulmonary Veins

What are the major blood vessels to the kidneys?

Renal artery

Renal vein

What are the major veins to the legs & trunk?

iliac artery

iliac vein

What are the major blood vessels to the digestive system?

From the aorta

to the mesenteric artery

to the Intestine

to the hepatic portal vein

to the liver

to the hepatic vein

to the posterior vena cava

What is the cross-sectional area of a circle?

It is the area you see if you slice a blood vessel and look at it end-on?

You only have a fixed volume of blood circulating in your body so if you increase the total cross-sectional area of the vessels what will happen to your blood pressure?

Your blood pressure will drop

This is helpful so you don’t burst thin-walled capillaries

You have a fixed volume of blood circulating in your body, if you increase the total cross-sectional areas of the vessels what happens to the blood velocity?

The blood velocity will drop This helps by providing more time for nutrient-waste exchange

What does blood pressure and velocity look like in the arteries?

Both the blood pressure and blood velocity is high in arteries \*\*The total cross-sectional area of arteries is low because there are not that many of them in total.\*\*

What does the blood pressure and velocity look like in the capillaries?

The blood pressure and velocity drops drastically in the capillaries because they have a very high total cross-sectional area - There are lots of roads to choose from.

What does the blood pressure and velocity look like in the veins?

The blood pressure is lowest in the veins because they are the furthest from your heart and because the diameter of each vein is quite large. The velocity increases a bit in veins because your skeletal muscles surrounding each vein contract and push on the vein and squeeze the blood along.

What is osmotic pressure?

The pressure of water "wanting" to move in a certain direction (HIGH to LOW Concentration) Because the blood contains high amounts of proteins (the tissues want to "push" water INTO the blood vessels.) \*\*BUT on the arterial side BLOOD PRESSURE is higher than OSMOTIC PRESSURE (nutrients and water is forced into the tissues)

What happens to blood pressure as blood passes through the capillaries

As the blood heads to the venous side, blood pressure drops (cross-sectional area increases) At this point, OSMOTIC PRESSURE is greater than BLLOD PRESSURE so water and wastes (CO2, Urea & Ammonia) flow back into the blood

What is the buildup of fluid in the tissues around the capillary bed called?

edema

What causes edema?

1. High blood pressure (hypertension) - Extra water is forced out of the arterial side of the capillaries 2. A lack of fluid removal from the venous side - Fluid is removed by the lymphatic system

What are the major functions of the lymphatic system?

1. Lymph capillaries and lymph veins drain fluids from tissues to help prevent edema - swelling 2. Lymph nodes - hold white blood cells, therefore, filter bacteria and viruses from lymph also, cleanse the blood by removing debris 3. Lacteals - Absorb fatty acids and glycerol into lacteals

Do lymphatic veins have valves?

yes. They ensure the one way flow of the lymph fluid

What are the pressures on the arterial side of a capillary bed?

Blood pressure is approximately 40mmHg Osmotic pressure is approximately 25mmHg

What happens to a patient if the fluid balance between blood and tissues is Net Blood Pressure in the Arterioles = 17mmHg Net Osmotic Pressure in the Venule = 15mmHg

The patient would have edema (swelling) Water would flow into the tissues

What happens to a patient if the fluid balance between blood and tissues is Net Blood Pressure in the Arterioles = 15mmHg Net Osmotic Pressure in the Venule = 17mmHg

The person's blood pressure would increase - Water would go into the blood.