B3 2 Flashcards
How does negative feedback work?
Corrective mechanisms off- conditions in body change from set point- change detected by receptor- corrective mechanisms switched off- conditions returned to set point- corrective mechanisms switched off
How are thyroxine levels controlled?
Hypothalamus detects cells need for energy- pituitary releases TSH - thyroid produces thyroxine- hypothalamus detects cells have enough energy- pituitary stops TSH production- thyroid stops producing thyroxine
What does adrenaline cause?
1) increased respiration to increase ATP
2) increased breathing rate
3) increased heart rate
4) diverting blood away from less urgent places (like ds) to muscles
Where is adrenaline produced?
Adrenal gland
What is tropism?
When plants detect stimuli in their environment and respond by growth in a particular direction
What hormone enables tropism?
Auxin
Where is Auxin found?
In cells near tips if plant shoots or roots. There is an uneven distribution of auxin
How do plants respond to light?
When light hits one side of the shoot tip auxin moves to the other side. This causes concentration of auxin to build up in that side. This increases length of that side which causes shoot to bend towards the light
What happens to root cells in terms of light?
The shaded side has more auxin but these cells elongate less so root bends away from light
How do plants respond to gravity in the roots?
More auxin gathers on the lower side. Roots grows more on the side with the least auxin so root bends and grows down
How do plants respond to gravity in the shoot?
The shoot grows more in the side with most auxin making it bend and grow up.
What is Auxin used for commercially?
- stimulates growth
- regulate fruit development
- killing weeds
- rooting powder
- delay ripening
- seedless fruit
- controlling dormancy
What is ethene used for?
- fruit ripening
What are gibberellins used for?
- promote growth
- end dormancy periods
What happens when you get too hot?
- body hairs lie flat
- sweat glands are active
- blood vessels widen (VASODILATION)
What happens when you get too cold?
- body hairs rise
- sweat glands stop
- blood vessels narrow (VASOCONSTRICTION)
- shivering
What happens when blood glucose levels are too high?
Pancreas detects it and insulin is released. Insulin travels to the lives and stimulates it to turn glucose into glycogen.
What happens if there is too little glucose in the blood?
Pancreas releases glucagon, which travels to the liver. It stimulates it to convert glycogen into glucose.
What is type 1 diabetes?
- cannot produce insulin
- genetic
- controlled by regular insulin injections
What is type 2 diabetes?
- cannot effectively use insults b
- linked to obesity
- controlled by regulating carbohydrate intake and losing weight
- sometimes insulin injections or insulin stimulating injections given
What are the parts of the kidney?
1) Capsule - outer membrane of the kidney. Helps to maintain kidney shape and protect it
2) Cortex - outer part of kidney
3) medulla- inner part of kidney
4) Nephrons- tubules that produce urine
How does kidney stuff work?
1) blood enters the kidney at high pressure through renal artery
2) this contains many branches, each of which leads to a glomerulus
3) each glomerulus contains a knot of capillaries
4) the blood vessels narrow at the exit to the glomerulus, increasing the blood pressure here
5) the increased blood pressure forces small molecules out through the capillary wall into the Bowman’s capsule
6) Large molecules (e.g. Protein) remain in bloodstream
7) next, selective reabsorption takes place. As the filtrate moves through the nephron tubule all glucose is reabsorbed as well as some water and salts
8) filtrate passes through the loop of Henle and collecting ducts.
9) excretion occurs
What is ADH and what does it do?
- Anti-diuretic hormone
- makes the walls of collecting ducts more permeable to water so increases water absorbed into the blood
