Chapter 8: transport in mammals Flashcards
Describe the mammalian circulatory system
- closed double circulation
- consisting of a heart, blood vessels and blood
what are arteries?
vessels carrying blood away from the heart
what are veins?
vessels carrying blood to the heart
what are arteries made of?
- inner endotelium called the tunica intima
- tunica media
- tunica externa
what is the tunica media?
middle layer of arteries which contains smooth muscle, collagen and elastic fibres
what is the tunica externa
outer coating of arteries containing elastic fibres and collagen fibres
what is the tunica intima?
inner layer made of squamous epilthelium cells
what are the distinctive characteristics of the arteries?
strength and elasticity
why do artery walls need to be extremely strong?
-to withstand the blood pressure leaving the heart
why do artery walls need to be elasticy
to reduce the likelihood that they will burst because of the high blood pressure
what are arterioles?
smaller vessels than the arteries
what is the main difference between the arteries and the arterioles?
the arterioles have a greater proportion of smooth muscle so that the muscle can contract and reduce/ increase blood flow
what are capillaries?
the smallest of all blood vessels
what is the function of capillaries?
to take blood as close as possible to all cells, allowing rapid transfer of substances between cells and blood
what are capillary beds?
networks of capillaries
what are semi-lunar valves?
half-moon valves that allow blood to move towards the heart, but not away from it
how is blood in the veins moved?
-muscles contract and the blood in the veins is pushed up through the valves
give another name for red blood cells
erythrocytes
what causes the red colour in red blood cells?
haemoglobin
what is the main function of haemoglobin?
to transport oxygen from lungs to respiring tissues
give 4 adaptations of red blood cells
- bioncave disc shape
- very small diameter
- very flexible (can deform so they can pass through vessels)
- have no nucleus, mitochondria or endoplasmic reticulum
what are lymphatics?
tiny, blind-ending vessels that are found in almost all body tissue
describe the role of the valves in the lymph vessel walls
- wide enough to allow large protein molecules to pass through
- important because they are too big for capillaries
what are lymph nodes?
- involved in the protection against disease
- bacteria is removed by white blood cells as the lymph passes through a node
- some white blood cells in the nodes secrete antibodies
describe the structure of a white blood cell
- nucleus
- larger than red blood cells
- spherical or irregular in shape
what is the purpose of a phagocyte?
cells that destroy invading microorganisms by phagocytosis
give another example of a phagocyte
monocytes
how do lymphocytes destroy microorganisms?
-secrete chemicals called antibodies, which attatch to and destroy the invading cells
describe the structure of haemoglobin
- four polypeptides
- each polypeptide contains one haem group
- each haem group can combine with one oxygen molecule
- one haemoglobin can carry 8 oxygen molecules
what does saturated mean?
a sample of haemoglobin that has combined with the maximum amount of oxygen
describe the saturation of oxygen in an actively respiring muscle?
the partial pressure will be about 20-25% saturated
the haemoglobin from the lungs carries lots of oxygen and releases around 75% at the muscles
give the first reaction with carbonic anhydrase
C02 + H20 ==> H2CO3
give the first reaction in the cytoplasm of red blood cells
H2C03 ==> H+ + HCO3-
