Endocrine Hormones

Question 1

What are endocrine hormones?

Answer 1

Messenger molecules that are secreted by endocrine glands into the bloodstream.

Question 2

Define the target cell in the context of endocrine hormones.

Answer 2

A cell that an endocrine hormone can affect because it contains receptors for the hormone on either its plasma membrane or within its cytoplasm.

Question 3

Explain how steroid hormones influence target cells.

Answer 3

1. Steroid hormones pass through the plasma membrane of target cells
2. Steroid hormone binds with receptors in the cytoplasm.
3. The hormones and receptors form steroid complexes that move into the nucleus where they influence gene expression.

Question 4

How do non-steroid hormones affect target cells?

Answer 4

They bind with receptors on the plasma membrane of the cells, activating an enzyme in the cell membrane to trigger a second messenger, which affects cell processes.

Question 5

Compare and contrast negative and positive feedback loops.

Answer 5

Both:
- Involves a gland that produces substance

Negative feedback loop:
- Includes the hypothalamus, pituitary gland and thyroid gland
- Rising level of substance will cause production to stop
- Declining level of substance will cause production to begin

Positive Feedback loop:
- Only Pituitary gland
- Rising level of substance will cause production to continue

Question 6

Outline the way feedback controls the production of thyroid hormones

Answer 6

Decreased production of hormones will trigger a program to increase hormone levels

Increased production of hormones will trigger a halt to the production of hormones

Question 7

Describe the feedback mechanism that controls milk production by the mammary glands.

Answer 7

1. The infant suckles on the nipple.
2. Nerve impulses are sent to the hypothalamus
3. Hypothalamus stimulates the anterior pituitary gland to release the hormone prolactin into her bloodstream.
4. Prolactin travels to the breast mammary glands and stimulates milk production.
5. Motivates the infant to continue suckling

Question 8

Why do endocrine hormones only affect some of the cells in the body? Choose the best answer.

A. They only reach certain cells.
B. Many hormones cannot cross the plasma membrane of cells.
C. Some cells feedback negatively in response to a hormone.
D. Only some cells have receptor proteins that can bind to a given hormone.

Answer 8

D. Only some cells have receptor proteins that can bind to a given hormone.

Question 9

People with a condition called hyperthyroidism produce too much thyroid hormone. What do you think this does to the level of TSH? Explain your answer.

Answer 9

The level of TSH would be lowered.

Because of the increased amount of thyroid hormone, the negative feedback loop will cease production of TRH, which would not trigger TSH to be produced.

Question 10

Which is more likely to maintain homeostasis — negative feedback or positive feedback? Explain your answer.

Answer 10

The negative feedback loop.

It maintains homeostasis by ensuring a healthy level of substances in the body by beginning and ending procedures as needed.

Question 11

Does testosterone bind to receptors on the plasma membrane of target cells or in the cytoplasm of target cells? Explain your answer.

Answer 11

Receptors.

Testosterone is a steroid hormone, which is a lipid, so they cross the plasma membrane to bind to receptors.

Question 12

True or False. Endocrine hormones can affect the expression of genes.

Answer 12

True

Question 13

True or False. Non-steroid hormones cannot affect intracellular processes.

Answer 13

False

Question 14

True or False. Insulin binds to receptors on the plasma membrane of cells.

Answer 14

True

Question 15

Which hormone is secreted by the pituitary gland?

A. Prolactin
B. Insulin
C. Cortisol
D. Thyrotropin-releasing hormone

Answer 15

A. Prolactin