Transport in animals Flashcards
Definition of double circulatory system
A system in which the blood flows through the heart twice for each circuit of the body
Describe the fishes circulatory system
Fish have a Single circulatory system. The blood takes the route: heart- gills- body- heart.
Define open circulatory system
One in which the blood is not held in vessels
Define closed circulatory system
One in which the blood is held in vessels
Described and insects circulatory system
Insects have an open circulatory system. This means that the blood fluid circulates through the body cavity so that the tissues and cells are directly based in blood
What are the advantages of double circulatory systems in mammals.
Higher blood pressure therefore blood can flow quicker. Faster delivery of oxygen and nutrients. Faster removal of carbon dioxide and other wastes.
External features of the heart
Two main pumping chambers- ventricles and atria (thinner). Coronary arteries.
Where are the AV valves found and what is there role?
There are two atrioventricular valve is the left and the right. In atrial systole blood in the atria pushes the atrioventricular valves open. The valves remain open while the atria contract but close when the atria begin to relax.
Definition of single circulatory system?
A system in which the blood flows through the heart once for each circuit of the body.
Where are the semi lunar valves found and what is there role?
Found at the base of the major arteries. Ventricular systole raises the blood pressure in the ventricles, once this pressure is above the pressure in the arteries the semilunar valves are forced open. Then during diastole as the ventricle begins to relax the pressure decreases and the semilunar valves are pushed closed.
Structure of an artery
Inner layer- elastic tissue allows wall to stretch and recoil
Middle layer- smooth muscle
Outer layer- collage.
Features of arteries?
Thick wall to withstand high pressure
Small lumen to maintain high pressure
Features and structure of vein?
Large lumen to ease flow of blood
Thinner walls- does not need to stretch and recoil
Contains valves to prevent backflow in opposite direction
Describe arterioles structure and function?
Small blood vessels that distribute the blood from an artery to capillaries.
Can constrict to reduce rate of blood flow and divert it.
Describe function of venules?
Collects blood from capillary bed and leads into veins.
Structure and function of capillaries?
Very thin wall- single layer of flattened endothelial cells. Narrow lumen- 7 micro meters.
Walls are leaky.
What cells does the blood contain?
Red blood cells
White blood cells
Platelets
What does tissue fluid not contain?
Plasma protein and most of the cells found in the blood. As they are to large
How is tissue fluid formed ?
By plasma leaking from the capillaries
What is the function of tissue fluid ?
Surrounds the cells in tissues and supplies them with oxygen. By diffusion, facilitated diffusion and active uptake.
What movement is the blood plasma leaking?
Mass flow
How does tissue fluid form?
Due to the high hydrostatic pressure in the arterial end of the capillary, blood fluid can be pushed out through the gaps in the capillary wall.
Why does tissue fluid only consist of dissolved nutrients and oxygen?
Blood cells, platelets and plasma proteins are too large to pass through the gaps in the capillary wall.
How does the tissue fluid exchange gasses and nutrients to body cells?
Across the cells plasma membranes, by diffusion, facilitated diffusion and active uptake.
Does tissue fluid return to the capillary?
Some as the blood pressure at venous end is much lower.
Does all tissue fluid re- enter the blood?
Some tissue fluid is diverted into the lymph system.
What is the job of the tendinous cords?
To prevent valves from turning inside out when ventricle walls contract
Why is the left ventricle thick?
Walls of left ventricle can be 2/3 times thicker than right ventricle. The left ventricle needs sufficient pressure to overcome the resistance of systemic circulation
What are the cross- bridges function in the cardiac muscle?
To ensure the muscle produces a squeezing action.
What is the cardiac cycle?
The sequence of events in a heart beat.
Where does heart contraction start?
At the apex