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biology ZAHRA NEW USE > Homeostasis > Flashcards

Homeostasis Flashcards

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1
Q

Homeostasis

A

Maintains stable internal envi within restricted limits by physiological control systems

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2
Q

Importance of maintaining stable core temp

A

Temp too high do hydrogen bonds in tertiary structure of enzymes break so enzymes denature and active site change shape and substrates can’t bind so fewer e-s complexes

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3
Q

Importance in maintaining stable blood ph

A

Above or optimum ph ionic and hydrogen bonds break In tertiary break
Enzyme denature active site change shape and substrates can’t bind
So fewer E-S complex

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4
Q

BGC conc too low

A

Hypoglycaemia
Not enough glucose for respiration so less atp produced and active transport can’t happen

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5
Q

BGC. Too high

A

Hyperglycaemia
Wp of blood decreased
Water lost from tissues to blood via osmosis
Kidneys can’t absorb all glucose so more water lost in urine causing dehydration

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6
Q

Negative feedback

A

Receptors detect change from optimum and effectors respond to counteract change returning levels back to optimum

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7
Q

Conditions controlled by sep mechanisms in negative feedback

A

Departures In different directions from original state can all be controlled
Giving greater degree of control

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8
Q

Positive feedback

A

Receptors detect change from normal
Effectors respond to amplify change
Producing greater deviation from normal

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9
Q

Glycogenesis

A

Glucose 2 glycogen

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10
Q

Glycogenolysis

A

Glycogen to glucose

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11
Q

Gluconeogenesis

A

AA or glycerol to glucose

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12
Q

Insulin’s role In decr BGC

A

Beta cells in IOL in pancreas detect BGC too high so secrete insulin
Attach to specific receptors on CSM of target cells like liver
Causing more glucose channel protiens to join CSM
increasing permeability to glucose so more glucose enter cell by FD
Also activates enzymes for glycogenesis
Lowering glucose conc in cells creating a conc gradient so glucose enters cells via FD

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13
Q

Glucagon in incr BGC

A

Alpha cells In IOL in pancreas detect BGC too low so they secrete glucagon
Attach to specific receptors on target cells eg liver activating enzymes for glycogenolysis and gluconegensis establishing a conc gradient so glucose enters blood via FD

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14
Q

Adrenaline role in increasing BGC

A

Adrenal glands secrete adrenaline
Attach to specific receptors on CSM of target cells eg liver
Activating exhumed for glycogenolysis
Establishing a conc gradient so glucose enters blood via FD

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15
Q

2nd messenger model of adrenaline and glucagon action

A

Adrenaline and glucagon attach to specific receptors on cell memb which
Activate enzyme adenyl Cyclade which changes shape
Which convert many ATP to many cyclic AMP
cAMP acts as 2nd msngr activating protein kinase enzymes
Protein kinases activate enzymes to break down glycogen to glucose

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16
Q

Adv of 2nd msngr model

A

Amplify signal from hormone
As each hormone can stimulate production of many molecules of cAMP which can in turn activate many enzymes for rapid increase in glucose

17
Q

Type 1 diabetes

A

B cells in IOL. In pancreas produce insufficient insulin
Normally develop in childhood due to auto immune response destroying B cells of IOL
controlled by injections of insulin
Bgc monitored with biosensors and dose of insulin matched to glucose intake
Eat regularly and control carbs

18
Q

Type 2 diabetes

A

Receptors lose responsiveness to insulin so fewer glucose transport protein less uptake of glucose and less conversion of glucose to glycogen
Reduce sugar and fat intake
More exercise and lose weight

19
Q

Why can’t insulin be taken as tablet

A

Insulin is a protein
Would be hydrolysed by endo and exopeptidases

20
Q

Formation of glomerular filtrate

A

High hydrostatic pressure in glomerulus as diameter of afferent arteriole > efferent arteriole
Small substances like water glucose forced into glomerular filtrate filtered by
Pores podocytes and capillary basement memb
Large protiens remain in blood

21
Q

Reabsorp of glucose by PCT

A

Na AT out epithelial cells to capillary

na moves by FD into epithelial cells down a conc gradient bringing glucose against its conc gradient
Glucose moves into capillary by FD down its conc gradient

22
Q

Reabsorp of water by PCT

A

Glucose in capillary lowers wp
Water moves by osmosis down a WPG

23
Q

Features of cells in PCT allowing rapid Reabsorp of glucose into blood

A

Microvilli provide LSA
many channel and carrier protiens for FD and co transport
Many Mitochondria produce ATP FOR AT
many ribosomes produce carrier and channel protiens

24
Q

Why is glucose found in urine of untreated diabetic

A

BGC is too high so not all glucose re absorbed at the PCT
As glucose carrier and co transporter protiens are saturated and working at max rate

25
Q

Importance of maintaining a gradient of sodium ions in the medulla

A

So WP decreases down the medulla and do a water potential gradient is maintained between the collecting duct and medulla
To max Reabsorp of water by osmosis

26
Q

Role of loop of henle in maintaining A gradient of sodium ions in medulla

A

Ascending limb
Na AT out so filtrate conc decreases and water remains as ascending limb Is impermeable to water
This increases conc of na in medulla Lwp
Descending limb
Water moves out by osmosis then Reabsorped by capillaries
Na recycled and diffused back in

27
Q

Ascending limb

A

Impermeable to water
Na moves out by AT

28
Q

Descending limb

A

Water leaves by osmosis
Na moves in recycled

29
Q

Why do animals needing to conserve water have longer loop of henle

A

More na moved out so na gradient maintained for longer in medulla
So wpg is maintained for longer
So more water can be reabsorbed from collecting duct by osmosis

30
Q

Reabsorption of water by DCT AND CD

A

water moves out dct and ct by osmosis form a WPG
controlled by ADH which increases their permeability

31
Q

Osmoregulation

A

Control of wp of the blood

32
Q

Role of hypothalamus in osmoregulation

A

Contain osmoreceptors which detect increase or decrease in blood WP
produced more adh when Wp is low or less adh when Wp is high

33
Q

Role of posterior pituitary gland in osmoregulation

A

Secrete more or less adh into blood due to signals from hypothalamus

34
Q

Adh role in osmoregulation

A

Attach to receptors on collecting duct and dct
Stimulating addition of channel protiens into cell surface membrane
So increases permeability of cells of CD and DCT to water
So increased water re absorption from collecting duct and DCT by osmosis
So decreases volume and increases conc of urine produced

35
Q

how does lack of insulin affect reabsorption of glucose in kidneys of person who doesn’t secrete insulin

A

high concentration of glucose in the blood
which is reabsorbed by facilitated diffusion however it requires carrier and channel protiens
but these are working at maximum rate so not all the glucose is reabsorbed

biology ZAHRA NEW USE (37 decks)

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