Transport in animals

Describe the single circulation of a fish

blood flows through heart once per circuit;

one atrium and one ventricle;

no septum;

only deoxygenated blood in heart;

blood under less pressure

Describe the double circulation of a mammal

blood flows twice through heart per circuit;

two atria and two ventricles;

heart has septum;

oxygenated and deoxygenated blood separated;

higher blood pressure

Explain the advantages of a double circulation

prevents mixing of oxygenated and deoxygenated blood;

blood flows at high pressure to body for efficient oxygen/nutrient supply;

lower pressure in pulmonary circuit prevents lung capillary damage

Describe the functioning of the heart

blood flows from vena cava to right atrium;

right atrium contracts pumping blood to right ventricle;

right ventricle pumps blood through pulmonary artery to lungs;

returns via pulmonary vein to left atrium;

left atrium pumps to left ventricle;

left ventricle pumps blood into aorta;

valves prevent backflow

Explain the effect of physical activity on the heart rate

increases blood flow to muscles to supply more oxygen and glucose for aerobic respiration;

removes excess carbon dioxide

Describe the structure of arteries veins

arteries have thick elastic/muscular walls and narrow lumen to withstand and maintain high pressure;

veins have valves to prevent backflow

Explain how the structure of capillaries is related to their function

thin walls (one cell thick) for efficient gas exchange;

small lumen and extensive network provides large surface area and direct access to cells;

pores allow easy passage of substances

State the function of red blood cells

transports oxygen via hemoglobin;

biconcave shape gives large surface area to volume ratio for diffusion;

lacks nucleus to maximize space

Describe the function of phagocytes

engulfs pathogens to form a phagosome;

uses enzymes to digest and destroy the pathogen

Describe the process of clotting

platelets collect at break in blood vessel;

converts soluble fibrinogen to insoluble fibrin;

forms mesh that traps red blood cells