26 The Heart Flashcards
Two types of blood systems
Open (crabs lobsters spiders snails)
Closed (humans)
Open blood system
The heart pumps blood into open ended vessels so then the blood leaves the blood vessel and moves around the cells in the animals body, then back into the blood vessels
Closed blood system
The blood remains in a continuous system of blood vessels
Materials are exchanged through thin walls of the smallest vessels
Why is a closed blood system more efficient than an open blood system
Blood can be pumped around the body faster- this moves nutirents, oxygen around faster which allows animal to be more active
Flow of blood to diff organisms can be increased/decreased
Eg. More blood can be supplied to legs when animal is running
Composition of human closed blood system
Blood
Heart
Blood vessels
3 main types of blood vessle
Arteries- carry blood away from heart
Veins- carry blood to heart
Capillaries- tiny vessels that link arteries and veins
Arteries
Carry blood away drom heart
Blood under high pressure
Thick strong wAlls
Small lumen
No valves
Veins
Carry blood to heart
Blood under low pressure
Thin weaker walls
Large lumen
Have valves
Structure of arteries and veins
Outer layer of protein called collagen prevents vessel from expanding too much
Middle layer of muscle and elastic fibre alters size of vessle
Endothelium is a thin layer of cells that surrounds the lumen
What is blood pressure
Force the blood exerts against the wall of a blood vessel
What do valves do
They control the direction of blood flow by not letting blood go backwards
Capillaries
Tiny much branched blood vessels.
Very thin walls made of a single layer of endothelium cells
Capillaries allow exchange of materials as they are porous
The heart is located
Between the two lungs pointing slightly to the left hand side of the chest and just above the diaphragm
Whats the heart made of
Cardiac muscle ans is surrounded by a double membrane called the pericardium
What do atria do
Theyre the upper chambers of the heart and they pump blood to the lower chambers (ventricles)
They have thin walls because they pump blood a short distance
What do ventricles do
They pump blood out of the heart
Where does the right ventricle pump blood to
The lungs
Where does the left ventricle pump blood to
Head and body
This is a longer distance than other ventricle so it has a thicker wall
How are the valves in the heart held in place
Theyre held in place by tough cords called tendons
The tendons are attached to the walls of the heart by small projecting muscles
Valve on the left hand side of the heart is called
Biscupid valve
(Two flaps)
What are the valves on the right side of the heart called
Triscupid
(Theee flaps)
Where are semilunar valves located
Top of the heart exit of pulmonary artery and vein
LORD
Left oxygenated
Right deoxygenated
Where does deoxygenated blood enter the heart
Enters the right atrium through the vena cava
