Chapter 7 The Endocrine System

Key Concepts

• catecholamine• cyclic Amp (cAMP)• endocrine• epinephrine• estrogen• exocrine• glucagon• growth hormone• hormone

• insulin• nonepinephrine• parathyroid hormone

(PTH)• phenolic amine

hormones• progesterone• protein hormones• steroid hormones• testosterone

Review Questions

In the following diagram of the major glands, what do A through F refer to?

A.B.C.D.E.F.

Pituitary

Thyroid

ParathyroidAdrenal

Testis

Ovary

A

B

C

D

E

F

What are the three categories of hormones?

1. Steroid hormones2. Protein hormones3. Phenolic amine hormones

What are the steps illustrated in the following diagram?

A.

B.

C.

D.

E.

F.

A steroid hormone passes through a cell membraneIt combines with a protein receptor in the cytoplasmThe hormone-receptor complex enter the nucleus andActivates the synthesis of messenger RNAThe messenger RNA leaves the nucleus andFunctions in the manufacture of protein molecules

What effect does testosterone have on muscle cells (fibers)?

It binds with a receptor, travels to the nucleus,initiates mRNA production, and the productionof contractile proteins, leading to larger,stronger muscles

What steps are illustrated in the following diagram? A.

B.

C.

D.

E.

The protein hormone reaches its target cell via the blood and

Combines with a receptor located on the cell membraneAs a result, molecules of an enzyme such as adenyl cyclase are activated andCause the activation of a second messenger such as cyclic AMP, whichBrings about various cellular changes

What three stimuli initiate hormone secretion?

• Neural• Hormonal• Concentration of a substance in

the blood

A single bout of moderate exercise results in long-term changes in glucose tolerance and insulin sensitivity. True or False?

False. Changes in glucose tolerance andinsulin sensitivity persist for less than 72hours. To maintain therapeutic benefits,aerobic exercise should be done for 30minutes at least every other day.

Insulin and glucagon are produced by what gland?

The pancreas

What role does the adrenal medulla play in exercise?

• Secretes catecholamines, epinephrine, and norepinephrine, which increase the availability of fuel to the active muscles.

• During exercise, blood levels of both epinephrine and nonepinephrine rise, resulting in increases in glycogenolysis, lipolysis, heart rate, stroke volume, and the redistribution of blood flow to the working muscles and the skin.

Gonadal hormones drop after intense exercise. True or False?

False. Gonadal hormones in both men

and women tend to rise followingvigorous exercise.

What are some effects of intense exercise on the female reproductive system?

• Delayed menarche• Amenorrhea• Anovulation

How does exercise affect glucagon and insulin levels?

Exercise increases glucagon levels anddecreases insulin secretion. There is alsoan increase in insulin receptor sensitivity,so that less insulin is needed.

Useful Websites

Endocrine System (Hormones) Topicswww.nlm.nih.gov/medlineplus/

endocrinesystemhormoneshtml

The Pituitary Foundationhttp://www.pituitary.org.uk/endocrine/index.shtml/

Selected Images

Figure 7.1 Locations of the major endocrine glands.

Figure 7.2 The three basic hormone structures.

Figure 7.3 (A) A steroid hormone passes through a cell membrane and (B) combines with a protein receptor in the cytoplasm. (C) The hormone-receptor complex enters the nucleus and (D) activates the synthesis of messenger RNA. (E) The messenger RNA leaves the nucleus and (F) functions in the manufacture of protein molecules.

Figure 7.4 (A) The protein hormone reaches its target cell via the blood and (B) combines with a receptor located on the cell membrane. (C) As a result, molecules of an enzyme such as adenyl cyclase are activated and (D) cause the activation of a second messenger such as cyclic AMP, which (E) brings about various cellular changes.