Transport in humans Flashcards
What is blood made up of?
- plasma
- red blood cells
- white blood cells
- blood platelets
What does plasma contain?
- soluble proteins such as fibrinogen, prothrombin and antibodies
- dissolved mineral salts
- food substances (glucose, amino acids, fatty acids, glycerol and vitamins)
- excretory products (urea, uric acid
- hormones (e.g. insulin)
What are the functions of the different proteins present in plasma?
- fibrinogen and prothrombin play an important role in the clotting of blood
- antibodies help fight diseases
What do red blood cells contain?
- haemoglobin (iron containing protein)
What do red blood cells transport?
- oxygen as oxyhaemoglobin
- a small amount of carbon dioxide bound to haemoglobin
How does haemoglobin enable red blood cells to transport oxygen?
- combines reversibly with oxygen
Where do red blood cells transport oxygen to?
- from lungs to rest of the body
How do red blood cells transport oxygen?
- as air enters the lungs, oxygen dissolves in the fluid covering the moist epithelium of the alveoli
- oxygen diffuses into the capillaries of the lungs where they bind reversibly with haemoglobin in red blood cells forming oxyhaemoglobin
- when blood is transported to oxygen-poor tissues, oxyhaemoglobin releases its oxygen which then diffuses into tissue cells
How is the red blood cells adapted to absorb/release oxygen at a faster rate?
- circular, flattened biconcave disc
- centre of cell thinner than edge
- absent nucleus
What is the result of the adaptation of the red blood cell that enables it to absord/release oxygen at a faster rate?
- increased surface area to volume ratio
- absent nucleus causes it to be able to carry more haemoglobin (makes it able to carry more oxygen)
What are some features of the white blood cell?
- colourless and does not contain haemoglobin
- irregular in shape and does not contain a nucleus
- it can move, change shape and squeeze trhrough trhe walls of the thinnest blood capillaries into the space among tissue cells
What are the two main types of white blood cells?
- lymphocytes
- phagocytes
What do lymphocytes produce?
- antibodies
How do lymphocytes know when to produce antibodies?
- the entry of pathogens into the body
- stimulates the lymphocytes to produce antibodies
Why do lymphocytes produce antibodies?
- to protect the body from diseases-causing microorganisms/pathogens
How does one gain immunity to a particular infection that has infected them in the past?
- antibodies may be present in the blood
- long after the infection has been cured
- conferring immunity to that particular infection
What do phagocytes do to protect the body from bacterial infections?
- they carry out phagocytosis
What is the process of phagocytosis?
- phagocytes engulf and digest foreign particles such as bacteria, killing it
What happens to white blood cells after phagocytosis?
- cells die
- form pus
What are the physical differences between phagocytes and lymphocytes?
- phagocytes have lobed (bi,tri or multi-lobed) nuclei while lymphocytes have a large, rounded nucleus
- phagocytes have granular cytoplasm while lymphocytes have a small amount of cytoplasm
What happens to carbon dioxide in the blood?
- carbon dioxide in the form of bicarbonate ions
- carbon dioxide enters the blood from body tissues by diffusion into red blood cells
- since red blood cells contain carbonic anhydrase, bicarbonate ions get converted into hydrogen carbonate
- the hydrogen carbonate then diffuses out of the red blood cells to be carried in plasma
- the reverse occurs in the lungs
What are some waste products of metabolism from tissues?
- carbon dioxide in the form of bicarbonate ions
- nitrogenous waste such as urea, uric acid and creatinine
When does tissue rejection occur?
- when transplanted tissue is not accepted by the body of the transplant recipient
What happens during tissue rejection?
- the tissues of the transplanted organ are treated as foreign bodies by the recipient’s immune system
- thus, they are attacked by phagocytes
- this causes transplanted tissue to fail (basically die but use fail instead)
How can tissue rejection be prevented?
- tissue can be transplanted from a genetically-similar donor
- tissue can be transplanted from one part of the body to another as it will be recognised as the recipient’s own tissue (skin grafting)
- immunosuppressive drugs can be taken to suppress the immune system of the recipient. However, there are problems associated with this
What are the associated problems with immunosuppressive drugs to suppress the recipient’s immune system?
- lowered resistance to infection
- needing to continue taking that drug for life
What proteins are used in blood clotting?
- platelets
- thrombokinase
- thrombin
- fibrin
What is needed for thrombokinase to convert prothrombin into thrombin?
- calcium
- vitamin k
How is fibrin formed?
- thrombin converts fibrinogen (soluble plasma protein) into fibrin (insoluble protein that forms long threads)
What is the complete process of blood clotting?
- clotting process begins at the site of the injury when blood vessels are damaged
- platelets are activated
- activated platelets and damaged tissue release thrombokinase
- thrombokinase converts plasma protein, prothrombin into thrombin in the presence of calcium and vitamin k
- thrombin converts fibrinogen, a soluble plasma protein into fibrin, an insoluble protein that forms long threads
- fibrin forms a mesh across the damaged surface and traps red blood cells, forming a clot
What does the clot do?
- prevents further blood loss
- restricts the entry of pathogens into blood
What is the classification of the 4 blood groups based on?
- the antigens present on the surfaces of the red blood cells
What are the different antigens present on the red blood cells of each group?
- blood group A: antigen A
- blood group B: antigen B
- blood group AB: antigens A and B
- blood group O: no antigens present
What are the different antibodies present in the difference blood groups?
- blood group A: antibody b
- blood group B: antibody a
- blood group AB: no antibodies
- blood group O: antibodies a and b
What happens when an antigen is recognised as foreign by antibodies?
- agglutination
- red blood cells clump together and are marked for phagocytosis
What would be the results of the different blood groups tranfusions into a recipient with the blood type A?
- A: accepted
- B: rejected
- AB: rejected
- O: accepted
What would be the results of the different blood groups tranfusions into a recipient with the blood type B?
- A: rejected
- B: accepted
- AB: rejected
- O: accepted
What would be the results of the different blood groups tranfusions into a recipient with the blood type AB?
- A: accepted
- B: accepted
- AB: accepted
- O: accepted
What would be the results of the different blood groups tranfusions into a recipient with the blood type O?
- A: rejected
- B: rejected
- AB: rejected
- O: accepted
What are the different blood vessels present?
- arteries
- arterioles (structurally similar but smaller in diameter)
- capillaries
- venules
- veins
What is the function of arteries?
- they carry oxygenated blood (except the pulmonary artery)
- they carry blood away from the heart (A in artery for away)
What is the physical structure of an artery?
- thick, muscular, elastic walls
- smallest lumen in relation to the size of the blood vessel
Why does an artery have to be elastic?
- permits stretching and recoiling strength
- resists pressure largely from elastic fibres to push blood along
Why does an artery have to be thick?
- helps maintain high blood pressure in artery
Why does an artery have to be muscular?
- allows for constriction and dilation of artery
What is an arteriole?
- split up arteries
- structurally similar but smaller in diameter
What are the 3 layers of arterial wall?
- outer layer is a protective layer
- consists of connective tissue and elastic fibre
- middle layer consists of smooth muscle and more elastic fibres
- innermost layer next to lumen consists of endothelium (single layer of flattened cells)
What happens during constriction of arteries (and arterioles)?
- contraction of muscles in arterial wall
- lumen narrower
- less blood flow per unit time
- causes paleness (idk ask mrs cheong)
What happens during dilation of arteries (and arterioles)?
- relaxation of muscles in arterial wall
- lumen wider
- more blood flow per unit time
- causes flush (again idk)
How do arterioles control blood flow into capillary beds?
- contracting the smooth muscle layer in the arteriole wall
- using sphincters, which are bands of smooth muscle located where arterioles branch into capillaries
- contraction prevents blood flow into capillary beds
