The Heart Flashcards
(12 cards)
What is an open circulatory system
Blood is not always held within the blood vessels and can circulate through the body cavity so cells ar immersed directly in the blood
Disadvantages of open circulatory systems
Little control over direction of blood circulation
Relies of movement of muscles which assist the movement of blood back to the head of an insect
- no respiratory pigment insect blood does not carry oxygen
Blood is pumped at a low pressure into the haemocoel
How do insects pump blood
The heart pumps blood towards the head by peristalsis
The blood re enters the heart through pores called ostia
What is a closed circulatory system
Blood is enclosed within blood vessels
Tissues are not in direct contact with the blood
Tissue fluid exits the capillaries and bathes to cells
Benefits of a closed circulatory system
Heat pumps blood at a higher pressure
Blood flow is more rapid and efficient
Blood flow can be directed to where it is ended by vasoconstriction and vasodilation
More efficient delivery of oxygen and nutrients and removal o waste products like carbon dioxide
What i a single closed circulatory system - fish
The blood stays in blood vessels on a SINGLE pathway round the body cavity
Blood only passes through the heart once before returning to the gills
Heat gills body heart
What is a double circulatory system
The heart pumps blood and the blood goes twice through the heart
Why do mammals need a double circulatory system
Mammals are endothermic
So have a high metabolic rate and high energy requirement
So their cells need lots of glucose and oxygen and the removal of carbon dioxide
What are the advantages of a double circulatory system
The heart increases the pressure after the blood passes through the lungs sp blood flows more quickly to body tissues
= more efficient delivery of oxygen and glucose to body tissues
= the oxygen supply to the heart muscles is better
Systemic circulation carries blood at a higher pressure than pulmonary circulation
What is pulmonary circulation
Heart - lungs - heart
What is systemic circulation
Heart body heart
Describe the mammalian heart
4 chambered pump for both systemic and pulmonary circulatory systems
The double pump works synchronously keeping oxygenated and deoxygenated blood separate
The cardiac muscle is myogenic - beats from the muscle within itself never gets tired
