Blood Vessels Heart and Circulation System

The heart is:

• a pump
• situated in the thorax (chest cavity) - slightly to left
• the size of a clenched fist
• always drawn as though it is in the animal- lying on its back

Deoxygenated blood - blood going to the heart / lungs not carrying oxygen

Oxygenated blood - blood going to the rest of the body containing oxygen

pulmonary artery - goingto the lungs

pulmonery vein - going to the heart - from lungs

aorta - main artery of the body - leaving heart

vena cava - main vein of body - going to heart

veins:

• carry deoxgenated blood to the heart
• don't have a pulse - have valves to prevent back-flow of blood
• have thin walls - large lumen (hole inside)

arteries:

• carry oxygenated blood away from the heart
• stretch as blood is forced through them - go back into shape afterwards - feels like pulse where they go close to the surface
• have thick walls + small lumen + thick layer of muscle+elastic fibres

Capillary :

• narrow walls a single cell thick so oxygen+glucose can pass from blood into cells easily - diffusion + carbon dioxide can pass from cells into blood
• tiny vessel with narrow lumen
• take blood from arteries to body cells to veins
• walls

Blood passes through the heart twice for every 1 circulation around the body

2 separate systems supply the lungs + the rest of the body

Blood travels in aCONTINUOUScircuit round the body

Gut -> blood vessel -> Liver -> Vena Cava->Heart -> Pulmonary Artery -> Lungs -> Pulmonary Vein -> Heart -> Aorta

Red Blood cells:

• contains haemoglobin -> when lots of oxygen-> OXYHAEMOGLOBIN
• shape - biconcave disk - increases surface area - allows for more absorption of oxygen
• have no nucleus

Whit blood cells:

• have a nucleus
• 2 types lymphocytes + phagocytes

Pulse Rate - measure of how quickly the heart beats -depressing an artery - makes you able to feel it

Muscle cells contract during exercise -> using energy -> released from respiration ->reaction between oxygen + glucose

heart beats faster using oxygen -> transports more oxygen + glucose to cells + removes waste carbon dioxide

exercise makes- heart rate increase + rate+depth of breathing increase +arteries supplying muscles dilate

All of these increase flow of blood to muscles - INCREASES supply of glucose + oxygen + INCREASES removal of carbon dioxide

Rate of breathing increaes/decreases after change in pulse rate - body needs to detect changes due to increased muscle activity

Glucose is stored as glycogen = glycogen stores in muscles + used during exercise