Mass Transport- Circulatory System Flashcards
What do multicellular organisms need?
A specialised transport system to carry raw materials from specialised exchange organs to their body cells
What is the circulatory system made up of?
The heart and blood vessels
What does the heart do?
Pumps blood through blood vessels to reach different parts of the body
What does blood transport?
Respiratory gases, products of digestion, metabolic wastes and hormones
What blood vessel goes to the lungs carrying deoxygenated blood?
Pulmonary artery
What blood vessel carries deoxygenated blood to the heart?
Vena cava
What blood vessel carries deoxygenated blood to the liver?
Hepatic vein
What blood vessel carries deoxygenated blood to the kidneys?
Renal vein
What blood vessel carries oxygenated blood to the kidneys?
Renal artery
What blood vessel carries oxygenated blood to the liver?
Hepatic artery
What blood vessel carries oxygenated blood away from the heart?
Aorta
What blood vessel carries oxygenated blood to the heart from the lungs?
Pulmonary vein
What is the double circulatory system?
One circuit takes blood from the heart to the lungs then back to the heart, the other loop takes blood around the rest of the body
What are coronary arteries?
The hearts own blood supply
What is the role of arteries?
Carry blood from the heart to the rest of the body
What are the walls of the arteries like?
Thick and muscular
What is the role of the elastic tissue in arteries?
Stretch and recoil as the heart beats to help maintain the high pressure
Why is the endothelium of arteries folded?
To allow the artery to stretch and helps maintain high pressure
Do arteries carry oxygenated or deoxygenated blood?
All carry oxygenated blood except for the pulmonary arteries which take deoxygenated blood to the lungs
What are arterioles?
Smaller vessels that arteries divide into and then form a network around the body
How is blood directed to different areas of demand in the body?
By muscles inside the arterioles
What is the role of the arterioles?
Contract or restrict the blood flow or relax to allow full blood flow
What is the role of veins?
Take blood back to the heart under low pressure
How is the structure of veins different to arteries?
Have a wider lumen with very little elastic or muscle tissue and they have valves
What is the purpose of valves in the veins?
Stop blood flowing backwards
How is blood flow through the veins helped?
By contraction of body muscles surrounding them
Do veins carry oxygenated or deoxygenated blood?
All carry deoxygenated blood because oxygen has been used up by body cells, except for the pulmonary veins which carry oxygenated blood to the heart from the lungs
Which is the smallest blood vessel?
Capillaries
How are capillaries adapted for efficient diffusion?
- Always found very near cells inn exchange tissues so there’s a short diffusion pathway
- Walls are only one cell thick
- Large number of capillaries to increase surface area
What is tissue fluid?
The fluid that surrounds cells in tissues
What is tissue fluid made from?
Small molecules that leave the blood plasma (eg. oxygen, water, nutrients)
Why doesn’t tissue fluid contain red blood cells or big proteins?
They’re too large to be pushed out through the capillary walls
What happens in the capillary bed?
Substances move out of capillaries into tissue fluid by pressure filtration
What do cells take in and release from tissue fluid?
Take in oxygen and nutrients, release metabolic waste
What is the hydrostatic pressure at either end of the capillary bed?
Greater at the arteriole end
What does greater hydrostatic pressure in the capillary bed than in the tissue fluid mean?
An overall outward pressure forces fluid out of capillaries and into spaces around the cells, so tissue fluid is formed
What happens to hydrostatic pressure as the fluid leaves?
Reduces in the capillaries so pressure is much lower at venule end
Why is water potential at the venule end of the capillary lower than the water potential of the tissue fluid and what does this mean?
Due to the fluid loss and the remaining plasma proteins, so water moves by osmosis from tissue fluid to capillary
What happens to any excess tissue fluid?
It is drained into the lymphatic system which transports it back to the circulatory system
