The Heart Flashcards
Open circulatory system
Heart pumps blood into vessels that are opened
Blood flows around all the cells of the body
Insects
Advantages of closed circulatory system
Blood pumped around the body faster
Blood pumped in different restes in different parts as required
Arteries
Away from heart High pressure Thick, strong walls Small lumen No valves Divided into arterioles Blood in pulses Oxygenated
Veins
To heart Low pressure Thin, weaker walls Large lumen Valves Divided into veniole No pulse Deoxygenated Prevents back-flow and stores blood
Function of capillaries
One cell thick for Exchange of materials
E.g. gases, foods
Blood Pressure
The force the blood exerts on the wall of the blood vessels
Advantages of double circulation
Keeps oxygen rich and oxygen poor blood separate
Blood pressure is high enough to reach all parts of the body
Diastole
Heart muscle relaxes
Systole
Heart is contracted
Cardiac Cycle
Blood enters atria by different vessels
The bicuspid and tricuspid valve remain closed
The chambers are relaxed in diastole
Increased volume of blood cause increased pressure in atria
Atria contrast in systole
Valves open and blood flows in ventricles
Atria relaxes and ventricles filled with blood contract
Bicuspid and tricuspid valve close and semi-lunar valves open
Blood is pumped out to the lungs and body
Ventricles relax and semi-lunar valves close
Cycle starts again
Pacemaker
- Sino-atrial node
- Wall of the right atrium near the entrance of the vena cava
- Control the rate of heartbeat
- Sends out electrical impulses to cause atria to contract
Closed circulatory system
Blood remains in a continuous system of the vessels and exchange materials through the cell of blood vessels
Human
Transports blood out of the muscles of the heart
Cardiac vein
Carries very little CO2
Pulmonary vein
Doctor
Brings blood into the right atrium
Vena cava