Exam 3

Question 1

What is Cholecystokinin (cck) and what does it do?

Answer 1

It’s a peptide hormone that induces gallbladder contraction and releases pancreatic enzymes. It also inhibits the release of gastrin and can affect the brain.

Question 2

What is triiodothyronine (T3)?

Answer 2

Are amino acid hormones produced in the thyroid to promote growth in kids and helps adults deal with metabolism.

Question 3

What is prolactin and what is its function?

Answer 3

It is a peptide hormone released from the anterior pituitary to cause milk production and an increase in maternal behavior.

-needs to inhibit dopamine in order to be released.

Question 4

What is ADH and what is its function?

Answer 4

peptide produced in the hypothalamus and released from the posterior pituitary.
Increase H2O permeability of the distal convoluted tubule and collecting ducts.
— doesn’t work in the loop of Henle due to no ADH receptors present.

Question 5

What is the RQ index

Answer 5

Respiration quotient which measures rate of CO2 production divided by rate of O2 consumed.
Proportional to metabolic rate and what type of food was ate.
—– carbs near 1 and lipids near .7

Question 6

What is Cortisol

Answer 6

Stress hormone that can block CRH and ACTH when present in high levels in the blood.

• — acts as a negative feedback system on the hypothalamus
• — enables you to remember stressful situations

Question 7

What is Gastrin?

Answer 7

Small peptide hormone that mimics the nervous system (no fatigue).
Stimulates cells in the stomach to produce HCL, pepsin and mucus to allow protein digestion.
Activated by the presence of food in the stomach.

Question 8

What is Ecdysone?

Answer 8

Steroid that is a molting hormone.
Activates the molting process in insects.
Is produced by prothoracic gland.

Question 9

How is the hypothalamus involved in the control of feeding?

Answer 9

The feeding center (I’m hungry) is controlled by the PVN and LH.

• — ablating the PVN & LH results in no eating
• — stimulating the PVN & LH leads over eating

The satiety center (I’m full) is controlled by the VMH.

• — ablating the VMH results in over eating
• — stimulating the VMH results in no eating

Question 10

How is serotonin involved in regulating hypothalamic function?

Answer 10

It is a neurotransmitter activator of carbohydrate appetite.
When large amounts of carbs. are present the brain will release more serotonin.
—– you stop eating carbohydrate and will eat some other non carb food

Question 11

How does hypothalamic releasing hormones cause a release of a specific anterior pituitary hormone?

Answer 11

Releasing hormones are released from the hypothalamus into a capillary bed.
They travel through the portal vein into another capillary bed where they bind to and energize the specific cells to make the hormone via signal transduction.

Question 12

What is ACTH and how does it release an anterior pituitary hormone into the blood?

Answer 12

Is a hormone released from the anterior pituitary.
Becomes activated when CRH is released from the hypothalamus into the anterior pituitary in response to stress.
ACTH goes to the adrenal gland to stimulate the release of cortisol (stress hormone).
Cortisol in high levels in the blood can block CRH and ACTH release.

Question 13

What is optimal foraging and how do animals use it?

Answer 13

It maximizes net energy gain per unit of time.
—- animals will select those prey items that offer the most energy compared to amount of time to catch and eat it.

Ex) humming birds will travel farther to nectar if it offers greater energy than those that are closer.

Question 14

Why do smaller animals produce more heat than larger ones?

Answer 14

Due to the surface to volume ratio being greater in smaller animals.

• — results in them losing heat much faster due to them having dire thermoregulation problem.
• — have a higher metabolic rate.

Question 15

How does negative feedback regulate hormone release?

Answer 15

Product of a hormone blocks future production
—- stops overproduction.
When a hypothalamus RH stimulates the production of a hormone to produce and release a product into the blood.
When there is high amount in the blood, the product will travel back to the anterior pituitary and hypothalamus to block future production.

Question 16

What does positive feedback do?

Answer 16

Presence of product promotes more to be made.
Ex) stretch receptors in uterus stimulate the hypothalamus to release oxytocin.
Oxytocin binds to receptors in uterus to cause smooth muscle contraction.
Mother goes into labor and more oxytocin is released to enhance labor contractions.
Oxytocin stops being released when baby is out.

Question 17

How does (+) and (-) feedback regulate the human menstrual cycle?

Answer 17

GnRH increases LH and FSH levels
LH & FSH stimulate follicle cells to produce estrogen.
High levels of estrogen pre-ovulation increase LH & FSH production.
After ovulation estrogen has a (-) feedback effect on LH, FSH & GnRH production by shutting them down.

Question 18

What is aldosterone?

Answer 18

A steroid hormone that binds to cytoplasmic receptors to increase transcription and protein synthesis.
Increases sodium reabsorption of tubular epithelium cells.

Question 19

What is the function of the loop of Henle?

Answer 19

Descending loop is there to remove water through aqua porins, can’t remove sodium.
Ascending loop removes sodium through sodium channels and has tight junctions to prevent water moving between cells.

Question 20

How are solutes resorb?

Answer 20

Proximal convoluted tubule re-filters all the things brought in at bowmans capsule.
—- has lots of channels and pumps to move materials from urine back into the blood.

Question 21

How does filtration occur?

Answer 21

Is controlled by bowmans capsule which filters blood through slits as a result of blood pressure.
—- 200L per day

Question 22

How does sodium reabsorption occur in the kidney?

Answer 22

• Renin is released by secretory cells due to decreased pressure and low sodium concentration in the distal tubule.
• circulating renin increases angiotensin II and aldosterone.
• aldosterone stimulates sodium reabsorption from the filtrate in the renal tubule.

Question 23

How is water reabsorption controlled?

Answer 23

• low blood pressure and/or high plasma osmolarity triggers positive feedback regulation.
• hypothalamic neurosecretory cells become activated and stimulate neurosecretory terminals in pituitary.
• ADH is released and increases water permeability of the ducts (+ feedback)
  
  • — enhances the rate of osmotic removal of water from the urine
• increased recovery of water absorption counteracts low blood pressure & high plasma osmolarity (- feedback).

Question 24

What is the function of the insect juvenile hormone (JH).

Answer 24

It’s a lipid hormone that when present in the development of the insect, will determine which stage it will molt in.
—- JH will keep the animal in the same stage

Question 25

What is the Q10 ratio?

Answer 25

Looks at O2 consumption at two different temps but it must be ever 10 degrees.

• — below 2.5 tells you the animal is not metabolizing O2 at the right level.
  
  • — not optimal temp for it to live in.

Question 26

What is countercurrent heat exchange?

Answer 26

Exchange of heat between arteries and veins.
— vein acquires heat from artery
Uses blood from the core to warm cooler blood returning from the limbs.
—– conserves body heat.

Question 27

What is supercooling?

Answer 27

Use of antifreeze to avoid freezing in order to survive.

• — reduce water, protein concentrations
• — increase salt in the blood

Question 28

What is the function of chief cells?

Answer 28

Found in the stomach to release pepsinogen

Question 29

What is the function of parietal cells?

Answer 29

Release HCL to make the stomach more acidic and to convert pepsinogen to pepsin.

Question 30

What do goblet cells do?

Answer 30

Release mucus to protect the inner lining of the stomach from acids

Question 31

What do gastrin secreting cells do?

Answer 31

Release gastrin into capillary bed surrounding the stomach.

Question 32

What is the difference between the cellular actions of steroid and peptide/protein hormones?

Answer 32

Cells respond to steroid hormones by producing cytoplasmic receptors.
Whereas cells responding to peptide/protein hormones produce membrane receptors.

Question 33

What is the function of oxytocin?

Answer 33

It is a small peptide hormone produced by the posterior pituitary.

• — in pregnant women it will bind to smooth muscle receptors in the uterus to start contractions during labor
• — in non pregnant women stretch receptors on nipples trigger hypothalamus to release oxytocin. This enables smooth muscles to contract and produce milk from the nipple.

Question 34

How do aplysia produce hormones

Answer 34

They use bag cells to secrete egg laying hormone.
Function:
1) alters digestion by using proteins from digestive system for reproduction.
2) changes behavior as they now look for a mate.
3) lay eggs and die

Question 35

What is neurohypophysis?

Answer 35

The posterior pituitary which directly contacts the brain.

• hormones produced in soma and travel the axon
• then stored in vesicles at the axon terminal where A.P. and Ca2+ are needed
• released into capillary bed ( no synapse)
• one nerve releasing one hormone

Question 36

What is adenohypophysis

Answer 36

The anterior pituitary
Hormones are released by endocrine cells into the blood.
All hormones influenced by hypothalamic releasing hormones.

Question 37

What is HGH?

Answer 37

Steroid that stimulates growth in child and increases metabolism in adults.

• affects muscle activity
• has a GH inhibiting hormone called somatostatin.
  
  • — inhibits insulin and glucagon
  • — produced in hypothalamus and pancreas
  • — slows metabolism down