Animal transport Flashcards
why do animals need circulatory systems?
- hormones and enzymes often produced in one part of the body and required in another part
- circulatory systems transport these substances
- eg. digested food, absorbed in intestines is required by all cells in body
- waste products of metabolism produced by al cells, need to be disposed of in particular part of body
components of a circulatory system
- heart
- fluid substances are transported in
- vessels fluids can flow in
open circulatory system
- heart that pumps haemopymph through short vessels into large cavity called haemocoel
- in the haemocoel, haemolyph directly bathes organs enabling diffusion of substances
- when heart relaxes, haemolymph sucked back via pores called ostia
closed circulatory system
- blood is fully enclosed within vessels
- from heart, blood pumped through progressively smaller vessels, in capillaries, substances diffuse in and out of blood and into cells
- blood returns to heart
single circulatory system
- blood passes through two- chambered heart just once per complete circuit of the body
double circulatory system
- blood passes through four-chambered heart twice per complete circuit of the body
pulmonary circulation
- consists of all vessels involved in transporting blood between heart and lungs
systemic circulation
- consists of all vessels involved in transporting blood between heart and body, not lungs
advantage of single circulatory system
- less complex, does not require complex organs
disadvantages of single circulatory system
- low blood pressure - slow movement of blood
- activity level of animals tends to be low
advantages of double circulatory system
- heart can pump blood further around body
- high pressure
- fast blood flow `
characteristics of arteries and arterioles
- carry blood under high pressure
- narrow lumen - maintains pressure
- thick elastic and muscle layers allow vessel to expand with heart beat then recoil
how are arterioles different from arteries?
- arterioles have more muscle and less elastic fibres, little pulse surge, constrict and dilate to move blood
capillaries characteristics
- lumen only one blood cell thick - ensures red blood cells travel single file
- substances exchanged from blood cells to surrounding tissue through gaps in endothelium
- large surface area
adaptations of capillaries
- large surface area - allow diffusion of substances in and out of capillaries
- small cross-sectional area - reduces rate of blood flow from artery supplying them
- endothelium is one cell thick - short diffusion pathway
veins characteristics
- no pulses as blood pressure is low - pressure is lost as blood moves around body
- walls conatin lots of collagen and few elastic fibres and muscle - greater proportion of vessel is lumen
venules charcateristics
- no elastin fibres or smooth muscles
- several venules split from one vein
how do breathing movement help blood flow?
- chest movements help movement of blood
how does blood flow through veins?
- series of valves and contraction of skeletal muscle
- skeletal muscle contracts and blood is forced towards heart forcing valves open
- as skeletal muscles relax, blood pushes back against valves causing them to close
functions of blood
- transport
- defence
- thermoregulation
- maintaining pH of bodily fluids
specialised features of erythrocytes
- flattened biconcave disc shape - large surface area to volume ratio for gas exchange
- large amount of harmoglobin - oxygen transport
- no nucleus or organelles - maximises space for haemoglobin and oxygen
- larger diameter than capillary - slows blood flow to enable diffusion
why does blood have a low water potential?
- large proteins eg. albunium - dissolved in blood plasma
- water tends to move into blood from surrounding tissues by osmosis
what does high hydrostatic pressure in arteriole end of a capillary cause?
water is forced out of capillary
what does high oncotic pressure at the venule end of a capillary cause?
low water potential in blood caused by water being forced out - water moves back into capillary
what happens when not all tissue fluid returns to the capillaries?
- excess drains to the lymphatic system through valves and nodes where it forms lymph
- lymph is a pale yellow fluid similar to tissue fluid but contains more lipids
- lymphatic system drains into the circulatory system via the thoracic duct
what would happen without the lymph system?
- rate of water loss in blood would be too large
- there would be a build up of tissue fluid in tissues called oedema
what does the lymphatic system consist of?
- lymphatic capillaries and lymph vessels with valves
- lymph nodes - sac-like organs that trap pathogens and foreign substances and contain large numbers of white blood cells
- lymphatic tissue - in spleen, thymus, tonsils - contain large amounts of white blood cells