Circulatory System Flashcards
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**
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
When taking your pulse are you feeling arteries or veins?
Arteries
Arteries have a pulse
What are arterioles?
Small arteries just visible to the naked eye?
What do veins do?
Carry blood towards the heart
Usually carry deoxygenated blood (except the pulmonary vein)
blood usually is of low pressure
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
What are venules?
small veins which drain blood away from the capillaries
What is vaso-constriction?
constricts blood vessels in certain areas of the body to make sure blood is available where it is needed most.
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
What is vaso-dilation?
it is when the blood vessels open up
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
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.
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)
The circulation system is divided into which 2 systems?
pulmonary system and systemic system
What is the pulmonary system?
the blood that circulates through the lungs
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?
- High blood pressure (hypertension) - Extra water is forced out of the arterial side of the capillaries
- 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?
- Lymph capillaries and lymph veins drain fluids from tissues to help prevent edema - swelling
- Lymph nodes - hold white blood cells, therefore, filter bacteria and viruses from lymph also, cleanse the blood by removing debris
- 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.
