Circulatory System Flashcards
What are the properties of multi-cellular organisms e.g mammals that need a specialized transport system? - circulatory system
Low surface to volume ratio
Use to carry raw materials to their body cells
What is the circulatory system made out of?
- Heart
- Blood vessels
Where does the heart pump blood trough?
- Blood vessels (arteries, veins and capillaries) - to reach different parts of the body
What do blood transport?
Respiratory gases
products of digestion
metabolic wastes
hormones round the body
What are the two circuits of circulatory system?
- One takes blood from the heart to the lungs then back to heart
- Other loop takes blood around the rest of the body
How does the heart has its own blood suppy?
Left and right coronary arteries
What is this?
Aorta
oxygenated blood to body
What is this?
Pulmonary artery
deoxygenated blood to lungs
What is this?
Left coronary artery
What is this?
Right coronary artery
What is this?
Deoxygenated blood to heart
Diagram of artery
What is the function of arteries
Carry blood from the heart to the rest of the body
How are arteries’s walls adapted for function?
The walls are thick and muscular
they have elastic tissue to stretch and recoil as the heart beats
this helps to maintain high pressure
How is the inner lining (endothelium) folded is adapted for artery;’s function?
Allow the artery to stretch
this also maintains high pressure
What do all arteries carry?
Oxygenated blood expect pulmonary arteries
take deoxygenated blood to the lungs
What are arteries divide into smaller vessels called…?
Arterioles - form a network throughout the body
What is the function of arterioles?
Blood is directed to different areas of demand in the body by muscles in arterioles
which contract to restrict or relax to allow full blood flow
Diagram of vein
What is the function of veins?
Take blood back to the heart under lower pressure
Properties of lumen and muscle wall with veins
- Have a wider lumen than equivalent arteries
- Very little elastic or muscle tissue
Why do veins have valves?
To stop the blood flowing backwards
How is blood flow through veins is helped by?
Contraction of the body muscles surrounding them
What do all veins carry?
Deoxygenated blood (oxygen used up by body cells)
expect pulmonary veins carry oxygenated blood to the heart from the lungs
What do arterioles branch into?
Capillaries - smallest of blood vessels
(e.g glucose and oxygen are exchanged between cells and capillaries so adapted to efficient diffusion)
Diagram of capillaries
Properties of capillaries
- Always found near cells in exchange tissues (e.g alveoli in lungs) - short diffusion pathway
- Walls are also one cell thick - shortens diffusion pathway
- A large number of capillaries so increase SA for exchange
- The network of capillaries in tissues are called capillary beds
What is tissue fluid?
Fluid that surrounds cells in tissues
What is tissue fluid made up of?
Small molecules that leave the blood plasma
e.g O2 , water and nutrients
What does tissue fluid not contain?
Red blood cells or big proteins
-they are too large to be pushed out of the capillary walls
What do cells take in from tissue fluid?
Oxygen and nutrients
release metabolic waste into it
In capillary bed , the substances move in and out of the capillaries into tissue fluid by what?
Pressure filtration
Steps of formation of tissue fluid
- At the start of capillary bed (nearest arteries), the hydrostatic pressure inside capillaries is greater than in tissue fluid
- The difference means outward pressure forces fluid out of capillaries and into spaces around cells forming tissue fluid
- Water and smaller molecules forced out e.g 02, Na+ and glucose
- Large molecules stay inside capillary e.g proteins
Return of tissue fluid
- As fluid leaves , hydrostatic pressure reduces capillaries - so pressure lower at venule end of capillary bed (nearest to veins)
- Water potential is lower than in tissue fluid due to the increasing concentration of plasma proteins (don’t leave the capillary bed)
- Some water re-enters the capillaries from tissue fluid to venule end by osmosis
- Hydrostatic pressure drop in capillary so water moves down pressure gradient
What happens to the excess tissue fluid?
Drains into the lymphatic system (network of tubes -act as frain)
transport this excess tissue fluid and puts back into circulatory system
Name all blood vessels entering and leaving the heart
- Entering
- Vena Cava
- Pulmonary veins
- Exiting
- Aorta
- Pulmonary arteries
List four types of blood vessel
- Arteries
- artieroles
- Veins
- capillaries
Explain why water returns to capillary at the venule end of the capillary bed
Due to fluid loss
Increasing concentration of plasma proteins (don’t leave the capillaries)
water potential at the venule end of capillary bed is lower than water potential in tissue fluid
Some water re-enters the capillaries from tissue fluid at the venule end by osmosis
Describe two structural features of an artery and explain how each feature relates to function
- e.g elastic tissue in walls - stretch and recoil as heartbeats to maintain high pressure
- Inner lining (endothelium) is folded so that artery can expand when the heartbeat causes a surge of blood
At the arteriole end of a capillary bed the hydrostatic pressure is 5.1kPa in a capillary
and 0.13 kPa in the space around the cells
Explain the effect this has no movement of fluid between capillary and cell space
The hydrostatic pressure is greater than hydrostatic pressure around cells
So fluid moves out of capillary into spaces of the cells
