The Circulatory System Flashcards
What are the two circuits in the double circulatory system?
One circuit takes blood from the heart to the lungs, then back to the heart and the other loop takes blood around the rest of the body
What do the left and right coronary arteries do?
Give the heart its own blood supply
Characteristics of arteries
- Elastic tissue in wall
- Thick muscle layer
- Small lumen
- Folded endothelium
Characteristics of veins
Large lumen
- Thin muscle wall
- not folded endothelium
What do the thick muscular walls with elastic tissue of arteries help?
Allows them to stretch and recoil as the heartbeat which helps maintain the high-pressure
What does the lining endothelium being folded? Allow the artery to do
Allows the artery to stretch, which also helps maintain high pressure
What kind of blood do arteries carry?
Oxygenated blood except for the pulmonary arteries
What do the pulmonary arteries carry?
Deoxygenated blood to the lungs
The arteries carry blood to the heart or away from the heart
From the heart to the rest of the body
What are arterioles and what are their functions
Arteries divide into smaller vessels called arterioles
- These former network around the body
- Blood is directed to different areas of demand in the body by muscles inside the arterioles, which contract to restrict the blood flow or relax to allow full blood flow
Veins have high or low pressure
Low
Where do veins take the blood?
Back to the heart
What do valves and veins do?
The blood flowing backwards
What kind of blood veins carry?
Deoxygenated blood except from the pulmonary veins
What do the pulmonary veins carry?
Oxygenated blood to the heart from the lungs
Characteristics of capillaries
- Always found near sales in exchange tissues so there’s a short diffusion pathway
- Their rules are only one cell thick which shorten the diffusion pathway
- Large number of capillaries to increase surface area for exchange
What are networks of capillaries called?
Capillary beds
In a capillary bed substances move out of the capillaries into the tissue fluid by pressure filtration. Explain this process.
- Nearest the arteries the hydrostatic ( liquid) pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid
- This force is fluid out of the capillaries into the spaces around the cells forming tissue fluid
- This reduces hydrostatic pressure in the capillaries so the pressure is much lower at the venule end near the veins
- due to fluid loss and an increasing concentration of plasma proteins which don’t leave the capillaries the water potential at the venule end of capillary bed is lower than the water potential in the tissue fluid
- This means water re-enters the capillaries from the tissue fluid at the venule end by osmosis
What happens to any excess fluid in pressure filtration in the capillaries?
Any excess fluid is drained to the lymphatic system which transports this excess fluid from the tissues and dump it back into the circulatory system
