Section 5 - Blood and Organs P2

Question 1

What are platelets?

Answer 1

They are small fragments of cells that help blood clot

• when you damage a blood vessel, platelets clump together to plug the damaged area
• blood clots stop you from losing to much blood and prevent microorganisms from entering the wound
• platelets are held together by a mesh of protein called fibrin

Question 2

How do vaccinations work?

Answer 2

• vaccination involves injecting dead or inactive pathogen into the body. These carry antigens, so even though ,they’re harmless they still trigger an immune response - your lymphocytes produce antibodies to attack them.
• some lymphocytes remain in the blood as memory cells so if live pathogens of the same type ever appear the antibodies to kill them will be produced fast and in great numbers.

Question 3

What does a vaccination result in?

Answer 3

It results in the manufacture of memory cells, which enables future antibody production to the pathogen to occur sooner, faster and in greater quality.

Question 4

Why are vaccinations needed?

Answer 4

when you’re infected with a new pathogen your lymphocytes can take a while to produce the right antibodies, in that time you get ill, or die
-to avoid this you can be vaccinated

Question 5

What are nephrons?

Answer 5

The filtration unita in the kidneys

Question 6

What are the three main processes that happen in the nephrons?

Answer 6

ultrafiltration
reabsorption
release of wastes

Question 7

What is the process of ultrafiltration?

Answer 7

• blood from the renal artery flows through the glomerulus
• a high pressure is built up, squeezing water, urea, ions and glucose out into the Bowman’s capsule
• the filtered liquid is known as the glomerular filtrate, only contains small molecules (amino acids etc.)

Question 8

What is the glomerulus?

Answer 8

a bundle of capillaries at the start of the nephron

Question 9

What is the process of reabsorption?

Answer 9

as the filtrate flows along the nephron, useful substances are selectively reabsorbed back into the blood

• all glucose is reabsorbed from the proximal convoluted tubule by active transport
• sufficient ions are reabsorbed
• sufficient water is reabsorbed from the collecting duct by osmosis

Question 10

What is the process of the release of wastes?

Answer 10

• the remaining substances after ultrafiltration and reabsorption forms urine
• this continues out the nephron, through the ureter, down to the bladder where it is stores before being released by the urethra

Question 11

How is water taken into the body?

Answer 11

food and drink

Question 12

What are the main ways water is lost from the body?

Answer 12

breathing
sweating
urinating

Question 13

Define osmoregulation:

Answer 13

osmoregulation is how the body has to constantly balance the water coming in against the water going out

Question 14

How can the kidneys help with osmoregulation?

Answer 14

-adjusting the amount of water that is excreted by kidneys in the urine

Question 15

What controls the amount of water reabsorbed in the kidneys?

Answer 15

ADH (anti-diuretic hormone)

Question 16

What does ADH do to the kidneys?

Answer 16

it makes the collecting ducts of the nephrons more permeable so more water is reabsorbed back into the blood

Question 17

Where is ADH released from?

Answer 17

the pituitary gland

Question 18

What mechanism controls the process of osmoregulation?

Answer 18

NEGATIVE FEEDBACK

-if the water content gets too high or too low a mechanism will be triggered that brings it back to normal