Module 7 Endocrine System

Question 1

What does the HPA axis stand for?

Answer 1

Hypothalamus-pituitary-adrenal
It’s an endocrine pathway

Question 2

How is cortisol released from the adrenal cortex?

Answer 2

1. Corticotropin releasing hormone (CRH) is released from the hypothalamus to stimulate the anterior pituitary.
2. Anterior pituitary releases adrenocorticotropic hormone (ACTH)
3. ACTH stimulates the adrenal cortex to release cortisol

Question 3

What type of hormone is cortisol?

Answer 3

Steroid hormone

Question 4

What type of hormone is CRH?

Answer 4

Corticotropin releasing hormone is a peptide hormone. Why does this make sense?

Question 5

What type of hormone is adrenocorticotropic hormone?

Answer 5

Peptide hormone. Why does this make sense?

Question 6

What does cortisol signaling do? Hint think about the type of hormone it is.

Answer 6

It’s a steroid hormone so the receptors are found inside target cells. Cortisol signaling changes the expression of proteins.

Question 7

What stimulates the release of CRH?

Answer 7

Long-term stress such as surgery, burns, illness, and strenuous exercise, emotional stress, and anxiety.

Question 8

What stimulates a short-term stress response?

Answer 8

The sympathetic nervous system (fight or flight mode)

Question 9

What does cortisol do?

Answer 9

1. Increases glucose in blood
2. Stimulates the breakdown of fat and protein for energy
3. Inhibits the anterior pituitary and hypothalamus via negative feedback loops.
4. Decreases inflammation

Question 11

Why is inflammation decreased with the release of cortisol?

Answer 11

The immune system can overreact when we’re stressed. We make medicines that are built similarly to cortisol to decrease inflammation.
To decrease swelling after an injury, prevent organ rejection after a transplant, treat autoimmune disorders like asthma, allergic reactions, etc.

Question 12

Hypersecretion

Answer 12

Too much secretion of a hormone that can be caused by tumors in endocrine cells.

Question 13

Hyposecretion

Answer 13

Not enough secretion of a hormone

Question 14

We have a patient who has some of the symptoms shown in the diagram below. Key symptoms to focus on are hyperglycemia (high blood sugar), thin extremities and weakness, and they bruise easily.

Answer 14

If the patient has hyperglycemia then they likely have too much cortisol that is being released. We suspect a tumor is causing hypersecretion.

Question 15

We measure levels of hormones in the patient and find that CRH levels are lower than normal, but ACTH and cortisol levels are higher than normal. Where is their tumor located?

Answer 15

In the anterior pituitary.

Question 16

A patient has a damaged pituitary gland which results in hyposecretion. The most likely result is that levels of cortisol will ______________ and CRH levels will ____________ compared to normal values.

Answer 16

1. decrease
2. increase
   CRH is released by the anterior pituitary. Since it’s damaged there’s little secretion of CRH. With little CRH there’s less ACTH and cortisol being released which means less negative feedback will be decreased so CRH levels will increase.

Question 17

Explain the relationship between the hypothalamus and the posterior pituitary gland

Answer 17

1. Neurosecretory cells release neurohormones (oxytocin/ADH)
2. Neurohormones travel down the neuron to the posterior pituitary gland.
3. At the axon terminals; exocytosis moves these neurohormones into the capillaries
4. Travel to target organs.

Question 18

Explain the relationship between the hypothalamus and the anterior pituitary gland.

Answer 18

1. Neurosecretory cells release tropic neurohormones into capillary bed #1
2. Neurohormones travel in the capillary bed #1 to the endocrine cell to the membrane receptor.
3. Endocrine cells receive the neurohormone and initiate the release of another hormone via exocytosis into capillary bed #2
4. Hormone 2 travels to the rest of the body