B13 Transport in Humans T17 Flashcards
Why do large multicellular organisms need a transport system?
Why do single celled organisms not need it?
low SA:V, diffusion is too slow to supply all their needs
single celled organisms have a large SA:V, so diffusion is fast enough
roles of the blood
- defend againt pathogens
- control body temperature (homeostasis)
- helps maintain cell pH
(4 points)
What is the blood made up of
- plasma
- red blood cells
- white blood cells
- platelets
Description of plasma
Explain its function
liquid part of blood, mainly water
carries:
- blood cells around body
- dissolved nutrients (glucose, amino acids, fatty acids and glycerol)
- hormones carbon dioxide
- urea
- heat
Description of red blood cells
Explain its function
biconcave disk-like cells, no nucleus, filled with haemoglobin, flexible to fit in narrow blood vessels
haemoglobin transports oxygen to lungs, and unloads it in respiring tissues
How are red blood cells specialised to carry oxygen?
biconcave - large SA:V to pass oxygen through
cytoplasm - large amounts of haemglobin to transport oxygen
no nucleus - fits more haemoglobin
(flexible to fit in narrow blood vessels)
Where are products of digestion transported from and to?
(glucose, amino acids, fatty acids and glycerol)
from small intestine to respiring tissue
Where is oxygen transported from and to?
from alveoli to respiring tissue
Where is carbon dioxide transported from and to?
respiring tissue to lungs
Where is urea transported from and to?
liver to nephron
What are the 2 types of white blood cells
- lymphocytes - makes antibodies
- phagocytes - englufs bacteria
What do phagocytes look like?
multi-lobed nucleus
granular cytoplasm
How do phagocytes work?
Phagocytes carry out phagocytosis by engulfing and digesting pathogens
Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it
This is a non-specific immune response
What do lymphocytes look like?
arge round nucleus which takes up nearly the whole cell
clear, non-granular cytoplasm
How do lymphocytes work
(What do they also produce)
Antibodies are Y-shaped proteins with a shape that is specific (complementary) to the antigens on the surface of the pathogen
This is a specific type of immune response as the antibodies produced will only fit one type of antigen on a pathogen
also produce antitoxins to neutralise toxins released by pathogens
(TA)
Description of platelets
Function of platelets
smallest cells, no nucleus, made in bone marrow
release chemicals to make blood clots
(TA)
How do platelets work
1) When the skin is broken (i.e. there is a wound) platelets arrive to stop the bleeding
2) A series of reactions (the clotting cascade) occur within the blood plasma
3) Platelets release chemicals that cause fibrinogen proteins to form a mesh of insoluble
fibrin across the wound, trapping red blood cells and therefore forming a clot.
4) The clot eventually develops into a scab to protect the wound from bacteria entering
(TA)
How do vaccinations work
Vaccinations involve making an individual immune to a certain disease. By immunising a large
proportion of the population, the spread of the pathogen is reduced as there are less people to
catch the disease from (called herd immunity).
Vaccines contain either a dead or inactivated form of the pathogen. When injected, they
stimulate the immune system to the white blood cells to produce the correct complementary
antibody to combat it, but since it is dead or inactivated it does not cause any symptoms
What are memory cells
Some of these white blood cells remain in the body as memory cells. If this person is then
exposed to the actual pathogen, these memory cells will produce antibodies much faster in a
greater quantity, so the pathogen can be destroyed before symptoms are felt.
Advantages of vaccines
- They have eradicated many diseases so far
(e.g smallpox) and reduced the occurrence of
many (e.g rubella). - Epidemics (lots of cases in an area) can be
prevented through herd immunity.
Disadvantages of vaccines
- They are not always effective in providing
immunity. - Bad reactions (such as fevers) can occur in
response to vaccines (although very rare).
Why do mammals need a double circulatory system?
the metabolic rate is higher and so need a
faster system
How heart works
Process:
1. Blood flows into the right atrium through the vena cava, and left atrium through the pulmonary
vein.
2. The atria contract forcing the blood into the ventricles.
3. The ventricles then contract, pushing the blood in the right ventricle into the pulmonary artery
to be taken to the lungs, and blood in the left ventricle to the aorta to be taken around the body.
4. As this happens, valves close to make sure the blood does not flow backwards.
Order of circulatory system
deoxygenated blood -> oxygenated blood from lungs
Adaptations of the heart
- muscular wall of left ventricle is thicker - blood needs to be pumped all around the body - whereas right ventricle only going to lungs and back
- 4 chambers that separate the oxygenated blood from the deoxygenated blood: 2 atria above
and 2 ventricles below - Valves to make sure blood does not flow backwards
- Coronary arteries cover the heart to provide its own oxygenated blood supply
how the heart rate changes during exercise and under the influence of adrenaline
how factors may increase the risk of developing coronary heart disease
how the structure of an artery is adapted to transport blood
away from heart
high pressure to pump blood around body
how the structure of a capillary is adapted to transport blood
as arteries get further from heart, get narrow and branch into capillaries
lots of thin capillaries - large SA:V for quick diffusion
1 cell thick cell wall - short diffusion distance
exchange of oxygen and glucose diffuse out of capillaries into cells - respiration
carbon dioxide diffuses into capillaries from cells as waste product of aerobic respiration
how the structure of a vein is adapted to transport blood
capillaries join together to form veins going INTO heart
lowest pressure - blood moving slowly -> veins need largest lumen (space for blood to flow)
valves to stop blood flowing wrong way
lowest pressure is consistent - so thinner than artery walls and little elastic or muscle
