Homeostasis

Question 1

definition of homeostasis

Answer 1

maintainence of constant internal environment in the body

Question 2

what happens with low concentration of glucose

Answer 2

slow respiration

Question 3

what happens with high concentration of glucose

Answer 3

water moves out by osmosis

Question 4

definition of negative feedback

Answer 4

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

Question 5

thermoregulation when it is too hot

Answer 5

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

Question 6

thermoregulation when it is too cold

Answer 6

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

Question 7

definition of positive feedback

Answer 7

amplify changes

Question 8

definition of excretion

Answer 8

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

Question 9

definition of deamination

Answer 9

removal of amino groups to produce urea

Question 10

describe process and location of deamination

Answer 10

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

Question 11

why is ammonia converted to urea

Answer 11

less toxic and less soluble

Question 12

where does urea diffuse into

Answer 12

blood plasma

Question 13

what are the three nitrogenous excretory products

Answer 13

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

Question 14

what is the overall route of ultrafiltration and reabsorption

Answer 14

glomerulus
proximal convoluted tubule
loop of henle
distal convoluted tubule

Question 15

describe structure of kidney

Answer 15

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

Question 16

describe structure of bowman’s capsule

Answer 16

surrounded by tight network of capillaries (glomerulus)

Question 17

describe three layers of bowman’s capsule

Answer 17

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

Question 18

factors affecting glomerulus filtration rate

Answer 18

blood pressure
water potential
kidney disease
cancer

Question 19

what needs to removed from PCT into capillaries

Answer 19

glucose
amino acids
ions

Question 20

describe adaptations of cuboidal epithelial cells in PCT (6)

Answer 20

many microvilli
tight junctions
many mitochondria
many cotransporter proteins
folded basal membrane
aquaporins

Question 21

describe how glucose diffuses from PCT into capillaries

Answer 21

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

Question 22

what occurs in loop of henle

Answer 22

water reabsorption

Question 23

describe descending limb of loop of henle

Answer 23

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

Question 24

describe ascending limb of loop of henle

Answer 24

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

Question 25

describe counter current multiplies in loop of henle

Answer 25

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

Question 26

describe reabsorption in distal convoluted tubule and collecting duct

Answer 26

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

Question 27

where does glucose reabsorption occur

Answer 27

PCT

Question 28

what should not be present in urine

Answer 28

glucose and proteins

Question 29

cause of protein in urine

Answer 29

kidney infection/heart disease

Question 30

describe how glucose dip stick works

Answer 30

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

Question 31

advantage/disadvantage of dipsticks

Answer 31

painless/don't give current measure of glucose

Question 32

describe how biosensors work

Answer 32

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

Question 33

advantage of biosensors

Answer 33

rapid/quantitative/re-usable data

Question 34

how is water content controlled

Answer 34

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

Question 35

which cells secrete glucagon

Answer 35

a

Question 36

which cells secrete insulin

Answer 36

b

Question 37

describe process when glucose concentration is high

Answer 37

``` 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. ```

Question 38

describe process when glucose concentration is low

Answer 38

``` 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. ```

Question 39

describe closure of stomata

Answer 39

``` 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 ```

Question 40

describe opening of stomata

Answer 40

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