UBC BIOL 155 FINAL 1 EXAM
QUESTIONS AND ANSWERS 2026
- 2027
What 2 hormones are involved in nursing? - ANSWERS-PRL and
oxytocin
Steps in the production of milk - ANSWERS-1. Receptors in nipples
are stimulated
2. impulses propagated to spinal cord
3. stimulation of hypothalamic nuclei (posterior pituitary gland)
4. Pituitary gland releases oxytocin
5. milk is ejected from the nipples
Function of PRL - ANSWERS-stimulates milk production -
constricition of myofibril cells, squeeze and push the milk out of the
mammary duct
function of oxytocin - ANSWERS-uterine contraction and expression
of milk from the breast
Where is milk stored? - ANSWERS-- Alveoli and in small ducts
adjacent to the cells that secrete it compressing and flattening the cells
- lactiferous sinuses
,How do actin and myosin interact by the thin filament? - ANSWERS-
1. calcium binds TnC which changes the shape of the whole triponin
molecule
2. tripomyosin is pulled off and the binding sites are fully exposed
3. myosin heads come in and bind simultaneously
4. once you get cross bridge formation, you get cross bridge cycling
and leads to the force of contractions
two hormones that control calcium plasma levels - ANSWERS-1.
parathyroid hormone - when calcium levels get too low
2. calcitonin - when calcium levels get too high
what are the three target tissues of parathryoid - ANSWERS-bone -
calcium storage organ
kidneys - distilled convulated tubule
digestive tract - food digestion
How does parathyroid hormone work? - ANSWERS-- Stimulates
osteoclasts to chew up more bone —> more calcium is released from
bones to the blood
and inhibits osteoblasts, so that new bone can not be put down
- controlled re-uptake of calcium from the filtrate back into the blood
(recover more calcium from urine when it goes through the nephron)
- stimulates the production of calcitrol in the kidneys enhancing the
amount of calcium and PO4 absorbed from the food digested
,Ca PO 4 - ANSWERS-calcium phosphate crystals that get turned into
calcium ions
How does calcitonin work? - ANSWERS-- increased reabsorption of
calcium, which will increase blood calcium levels and calcium will be
retained in the kidneys and used to make new bone
- inhibits osteoclasts decreasing the amount of bone chewed up,
stimulation of osteoblasts to use up more calcium
what are the target tissues of calcitonin? - ANSWERS-bone and
kidney
steps of thyroid hormone synthesis - ANSWERS-1. thyroglobulin
synthesis
2. uptake of iodide from blood - the iodide that gets taken up is picked
up by the thyroid peroxidase and transported into the secretory
vesicles before it gets released into the follicular cavity - it also strips
off an electron (I- becomes I)
3. iodine is attached to tryosin amino acids by iodination of enzymes
single iodination - Monoiodotryosin (MIT)
double iodination - diiodotryosine (DIT)
4. coupling enzymes attach to DIT, but have to have at least a MIT
preferably a DIT beside it. they reach over and grab the benzene ring
from adjacent tryosine that has been iodinated, cut it off and attach it
to the benzene ring of the first tryosine and you get pro T3 or t4 (still
not active)
, 5. endocytosis of a droplet of colloid - internalized by a phagosome
which fuses with lysosomes (enzymes that break down peptide bonds)
- cut up thyroglubin into amino acids
6. T3 and T4 which are liberated, so they diffuse out of the cell and
diffuse into the blood where they are picked up proteins increasing
solubility in the blood
uptake of iodide in blood - ANSWERS-sodium iodide co transporter
increases the rate in which iodine comes in
thyroglublin - ANSWERS-secretory vesicles that have thyrglobulin
also have iodinating ezymes that also have couppling enzymes that
also have thyroid peroxidase (thyroid peroxidase in the membrane,
other two are in the vesicle)
dynamic range - ANSWERS-from threshold to receptor saturation
(min to max saturation)
Large dynamic range - ANSWERS-- covers more environmental
range
- large change in stimulus causes a small change in AP frequency
- poor sensory discrimination
- small change in stimulus intesity results in small change in
magnitude
- hard to tell the intensity of two stimuli that are close together
QUESTIONS AND ANSWERS 2026
- 2027
What 2 hormones are involved in nursing? - ANSWERS-PRL and
oxytocin
Steps in the production of milk - ANSWERS-1. Receptors in nipples
are stimulated
2. impulses propagated to spinal cord
3. stimulation of hypothalamic nuclei (posterior pituitary gland)
4. Pituitary gland releases oxytocin
5. milk is ejected from the nipples
Function of PRL - ANSWERS-stimulates milk production -
constricition of myofibril cells, squeeze and push the milk out of the
mammary duct
function of oxytocin - ANSWERS-uterine contraction and expression
of milk from the breast
Where is milk stored? - ANSWERS-- Alveoli and in small ducts
adjacent to the cells that secrete it compressing and flattening the cells
- lactiferous sinuses
,How do actin and myosin interact by the thin filament? - ANSWERS-
1. calcium binds TnC which changes the shape of the whole triponin
molecule
2. tripomyosin is pulled off and the binding sites are fully exposed
3. myosin heads come in and bind simultaneously
4. once you get cross bridge formation, you get cross bridge cycling
and leads to the force of contractions
two hormones that control calcium plasma levels - ANSWERS-1.
parathyroid hormone - when calcium levels get too low
2. calcitonin - when calcium levels get too high
what are the three target tissues of parathryoid - ANSWERS-bone -
calcium storage organ
kidneys - distilled convulated tubule
digestive tract - food digestion
How does parathyroid hormone work? - ANSWERS-- Stimulates
osteoclasts to chew up more bone —> more calcium is released from
bones to the blood
and inhibits osteoblasts, so that new bone can not be put down
- controlled re-uptake of calcium from the filtrate back into the blood
(recover more calcium from urine when it goes through the nephron)
- stimulates the production of calcitrol in the kidneys enhancing the
amount of calcium and PO4 absorbed from the food digested
,Ca PO 4 - ANSWERS-calcium phosphate crystals that get turned into
calcium ions
How does calcitonin work? - ANSWERS-- increased reabsorption of
calcium, which will increase blood calcium levels and calcium will be
retained in the kidneys and used to make new bone
- inhibits osteoclasts decreasing the amount of bone chewed up,
stimulation of osteoblasts to use up more calcium
what are the target tissues of calcitonin? - ANSWERS-bone and
kidney
steps of thyroid hormone synthesis - ANSWERS-1. thyroglobulin
synthesis
2. uptake of iodide from blood - the iodide that gets taken up is picked
up by the thyroid peroxidase and transported into the secretory
vesicles before it gets released into the follicular cavity - it also strips
off an electron (I- becomes I)
3. iodine is attached to tryosin amino acids by iodination of enzymes
single iodination - Monoiodotryosin (MIT)
double iodination - diiodotryosine (DIT)
4. coupling enzymes attach to DIT, but have to have at least a MIT
preferably a DIT beside it. they reach over and grab the benzene ring
from adjacent tryosine that has been iodinated, cut it off and attach it
to the benzene ring of the first tryosine and you get pro T3 or t4 (still
not active)
, 5. endocytosis of a droplet of colloid - internalized by a phagosome
which fuses with lysosomes (enzymes that break down peptide bonds)
- cut up thyroglubin into amino acids
6. T3 and T4 which are liberated, so they diffuse out of the cell and
diffuse into the blood where they are picked up proteins increasing
solubility in the blood
uptake of iodide in blood - ANSWERS-sodium iodide co transporter
increases the rate in which iodine comes in
thyroglublin - ANSWERS-secretory vesicles that have thyrglobulin
also have iodinating ezymes that also have couppling enzymes that
also have thyroid peroxidase (thyroid peroxidase in the membrane,
other two are in the vesicle)
dynamic range - ANSWERS-from threshold to receptor saturation
(min to max saturation)
Large dynamic range - ANSWERS-- covers more environmental
range
- large change in stimulus causes a small change in AP frequency
- poor sensory discrimination
- small change in stimulus intesity results in small change in
magnitude
- hard to tell the intensity of two stimuli that are close together
