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Biology > Homeostasis > Flashcards

Homeostasis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

definition of homeostasis

A

maintainence of constant internal environment in the body

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2
Q

what happens with low concentration of glucose

A

slow respiration

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3
Q

what happens with high concentration of glucose

A

water moves out by osmosis

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4
Q

definition of negative feedback

A 
change in factor away from set point
detected by receptor
hormone is released/impulse sent
reaches target organ
performs corrective action
returns to set point
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5
Q

thermoregulation when it is too hot

A

central thermoreceptor detect increase in blood temperature
thermoreceptors in skin detect in surrounding temperature
vasodilation - arterioles in skin dilate
sweat glands secrete sweat
for heat loss

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6
Q

thermoregulation when it is too cold

A 
central thermoreceptors/thermorecpetors
vasoconstruction
shivering
hair erector muscles contract
decreasing production of sweat
increase in adrenaline = in respiration increase
heat generation
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7
Q

definition of positive feedback

A

amplify changes

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8
Q

definition of excretion

A

removal of unwanted producted of metabolic reactions such as urea and carbon dioxide

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9
Q

definition of deamination

A

removal of amino groups to produce urea

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10
Q

describe process and location of deamination

A 
(liver cells)
amino group + H
form ammonia + keto acid
keto acid used in krebs cycle/respired/convert to glucose
form urea by NH3 + CO2
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11
Q

why is ammonia converted to urea

A

less toxic and less soluble

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12
Q

where does urea diffuse into

A

blood plasma

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13
Q

what are the three nitrogenous excretory products

A

urea
creatinine - creatine made in liver and used in muscles and some converted to creatinine
uric acid - breakdown of purines and nucleotides

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14
Q

what is the overall route of ultrafiltration and reabsorption

A

glomerulus
proximal convoluted tubule
loop of henle
distal convoluted tubule

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15
Q

describe structure of kidney

A 
cortex
medulla
renal pelvis
renal vein (out)
renal artery (in) - afferent arteriole larger diameter than efferent arteriole
ureter
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16
Q

describe structure of bowman’s capsule

A

surrounded by tight network of capillaries (glomerulus)

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17
Q

describe three layers of bowman’s capsule

A 
endothelium (cell layer)
fenestration filters large cells
basement membrane 
molecular filter 68000 molecular mass
epithelial cells (bcapsule)
podocytes stable structure and provide less resistance to fluid
18
Q

factors affecting glomerulus filtration rate

A

blood pressure
water potential
kidney disease
cancer

19
Q

what needs to removed from PCT into capillaries

A

glucose
amino acids
ions

20
Q

describe adaptations of cuboidal epithelial cells in PCT (6)

A 
many microvilli
tight junctions
many mitochondria
many cotransporter proteins
folded basal membrane
aquaporins
21
Q

describe how glucose diffuses from PCT into capillaries

A

active transport of Na+ into blood
sodium pumps in basal membrane
Na+ conc decreases in cell
Na+ enter into cell
facilitated diffusion with glucose cotransporting into cell
secondary active transport
diffusion of glucose into blood by GLUT proteins

22
Q

what occurs in loop of henle

A

water reabsorption

23
Q

describe descending limb of loop of henle

A

permeable to water
aquaporins - osmosis
Na+ and Cl- diffuse in

24
Q

describe ascending limb of loop of henle

A

impermeable to water
active transport Na+/Cl-
decrease water potential in tissue fluid

25
Q

describe counter current multiplies in loop of henle

A

fluid in two different directions allow max conc. of solutes to be built inside and outside the bottom of loop

26
Q

describe reabsorption in distal convoluted tubule and collecting duct

A

Na+ actively pumped into tissue fluid
K+ pumped into tubule
regulate concentration of ions in blood

27
Q

where does glucose reabsorption occur

A

PCT

28
Q

what should not be present in urine

A

glucose and proteins

29
Q

cause of protein in urine

A

kidney infection/heart disease

30
Q

describe how glucose dip stick works

A

glucose oxidase
peroxidase

G.O + glucose makes hydrogen peroxide
Peroxidase + hydrogen peroxide → brown compound
darker brown = more conc. glucose

31
Q

advantage/disadvantage of dipsticks

A

painless/don’t give current measure of glucose

32
Q

describe how biosensors work

A 
pad impregnated with glucose oxidase
used sample of blood
glucose oxidase catalyse reaction
tiny electric current supplied
detected by electrode
produce reading
33
Q

advantage of biosensors

A

rapid/quantitative/re-usable data

34
Q

how is water content controlled

A

osmoreceptors detect decrease in water potential
in hypothalamus
ADH released
by posterior pituitary gland
increase in aquaporins in collecting duct
more water reabsorbed
water potential returns to set point

35
Q

which cells secrete glucagon

A

a

36
Q

which cells secrete insulin

A

b

37
Q

describe process when glucose concentration is high

A 
b cells
insulin bind to receptor on liver cells
increase permeability of cells to glucose
more GLUT4 proteins added by vesicles fusing with cell surface membrane
stimulates glycogenesis
increase in respiration
more diffusion of glucose into cells
decrease blood glucose conc.
38
Q

describe process when glucose concentration is low

A 
glucagon binds to receptor on cell surface membrane
receptor change shape
activate G proteins
adenlylyl cyclase activated
cyclic AMP
second messenger
activates kinase
enzyme cascade
glycogen broken to glucose
diffuse out of cells
increase in blood conc.
39
Q

describe closure of stomata

A 
At low water potential (water stress)
Abscisic acid binds to receptors
On cell membrane of guard cells
Proton pumps inhibited from pumping potassium ions
Stimulates Ca2+ to diffuse into cytoplasm
Acts as secondary messenger
High concentration of H+ in cell 
Volume of guard cell decreases
Cell is flaccid
Fast response
40
Q

describe opening of stomata

A

H+ pumped out of guard cells by active transport
Negative potential triggers voltage gated potassium ion channels to open
Potassium ions diffuse into lower water potential inside
Water moves in cell by osmosis
Turgor increases and stomatal pore opens as guard cells change shape

Biology (19 decks)

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