Lecture 12 Endocrine System

Question 1

What are the general functions of the Endocrine System?

Answer 1

1. Regulating growth, development, metabolism
2. Maintaining homeostasis of blood composition and volume
3. Controlling digestive processes
4. Controlling reproductive activities

Question 2

What are endocrine glands? Explain them.

Answer 2

The Endocrine system is composed of endocrine glands that are spread throughout the body.

Endocrine glands produce and secrete hormones that communicate and control other body cells. They travel in the blood to reach target cells.

An endocrine gland (via hormones) can communicate with any body cell that has a receptor for that hormone so the functions can be quite diverse.

Question 3

What are Target cells?

Answer 3

Body cells display receptors for specific types of hormones.
* Cells that have specific receptors for a hormone are called target cells

Question 4

Briefly explain how the Endocrine system works.

Answer 4

Endocrine glands produce and secrete hormones that travel in the blood in order to reach target cells.

Endocrine glands lack ducts so hormone secretions from endocrine cells enter the interstitial fluid and then the blood.

Hormones are transported in the blood from the endocrine gland where they are produced to all body tissues.

Hormones then leave the blood and enter the interstitial fluid, which provides the hormone potential access to all body cells.

Hormones bind only to target cell receptors to initiate a particular response in the target cell

Question 5

What’s the difference between the nervous and endocrine systems?

Answer 5

The endocrine system uses chemical signaling (hormones, produced by glands) while the nervous system uses electrical signaling.

The signal transmission of the nervous system is fast, while in the endocrine system, it is slow because they have to travel some distance through the bloodstream.

Question 6

What is a reflex? Explain them.

Answer 6

A reflex is a pre-programmed involuntary response to a stimulus.
* Secretion of hormones from endocrine glands is controlled through a reflex.

Endocrine reflexes are stimulated by one of three types of stimulation.
* Hormonal, Humoral, Nervous

Question 7

Explain Hormonal Stimulation.

Answer 7

The release of a hormone in response to another hormone binding.

Question 8

Explain Humoral Stimulation.

Answer 8

The control of hormone release in response to changes in extracellular fluids such as blood or the ion concentration in the blood.

Question 9

Explain Nervous Stimulation.

Answer 9

Direct stimulation from the nervous system.

Question 10

What is the Infundibulum?

Answer 10

Thin/hollow stalk which connects the hypothalamus and pituitary gland.

Question 11

Where is the Pituitary gland located? Explain the different parts of the pituitary gland.

Answer 11

The pituitary gland is housed in the sphenoid bone of the skull and is composed of two portions.
* The posterior pituitary
* The anterior pituitary

Question 12

Explain the Posterior pituitary and the Anterior pituitary.

Answer 12

Posterior pituitary (neurohypophysis)
* Composed of neurons that extend from the hypothalamus to the posterior pituitary created the hypothalamo-hypophyseal tract.
(the posterior pituitary does not form any hormones, instead, it stores the hormones that were made in the hypothalamus.)

Anterior pituitary (adenohypophysis)
* Composed of hormone-producing cells
* Connections between the hypothalamus and the anterior pituitary gland involve 2 capillary plexuses that are interconnected. This is called the hypothalamo-hypophyseal portal system.

Question 13

What are Antidiuretic Hormones (ADH)?

Answer 13

Produced in the hypothalamus and stored and released in the posterior pituitary

Targets:
- Kidneys: reduces water loss in the urine & promotes water reabsorption
- Thirst Center: relays nerve signals to tell the body to drink more water
(when you are dehydrated)

Question 14

What are Oxytocin Hormones?

Answer 14

Produced in the hypothalamus and stored and released in the posterior pituitary

Targets:
- Smooth muscle of uterus: to help deliver a baby
- Smooth muscle of breasts in lactating females: help ejection of breast milk

Question 15

What are Regulatory hormones?

Answer 15

They are produced in the hypothalamus and are transported through the hypothalamo-hypophyseal portal system to the anterior pituitary.
* The anterior pituitary then releases its hormones into general circulation so they can reach their target cells.

These regulatory hormones act as either:
* Releasing hormones: causing an increase in secretion in a specific A.P. hormone.
* Inhibiting hormones: causing a decrease in secretion in a specific A.P. hormone.

Question 16

What are Thyroid stimulating hormones (TSH)?

Answer 16

Stimulates release of hormones from the thyroid gland

Question 17

What are Prolactin hormones?

Answer 17

Regulates production of breast milk in lactating females.

Question 18

What are Adrenocorticotropic hormones (ACTH)?

Answer 18

Stimulates the adrenal cortex to secrete glucocorticoids which increase blood levels of nutrients molecules.

Question 19

What are Follicle-stimulating hormones (FSH) and Luteinizing hormones (LH)?

Answer 19

• Act on the gonads in both males and females
• Development of egg and sperm cells, release of reproductive hormones

Question 20

What are Growth hormones?

Answer 20

Stimulates the liver to release insulin-like growth factors which stimulate cell growth and division

• When growth hormone is over produced it can cause Hypersecretion (pituitary giantism)
• When growth hormone is under produced it can cause Hyposecretion (pituitary dwarfism)

Question 21

What are Calcitonin hormones?

Answer 21

Produced by parafollicular cells and ultimately lowers blood calcium levels.

Targets:
- Bone: inhibits bone breakdown by osteoclasts and lengthens lifespan
- Kidney: increases loss of calcium in the urine
(triggered by high Ca2+ concentration in the blood)

Question 22

What are the two regions of adrenal glands?

Answer 22

Regions:
* Inner Adrenal Medulla
* Outer Adrenal Cortex
- Adrenal Cortex Zones:
* Zona glomerulosa
* Zona fasciculata
* Zona reticularis

Question 23

What are the two hormones produced by the Adrenal Medulla? Explain them.

Answer 23

Epinephrine and Norepinephrine via stimulation from the sympathetic division of the autonomic nervous system.

Targets:
- Heart, blood vessels, liver, adipose cells
(prepares body for fight of flight)

Question 24

What are Mineralocorticoids?

Answer 24

Hormones of the Adrenal Cortex- zona glomerulosa
- A group of hormones that help regulate the concentration of electrolytes in the body fluids

Question 25

What are Glucocorticoids?

Answer 25

Hormones of the Adrenal Cortex- zona fasciculata
- Cortisol is a major hormone. Is released in response to ACTH.
- Increases fat and protein breakdown, increases glucose synthesis, decreases inflammatory response

Question 26

What is Androgens?

Answer 26

Hormones of the Adrenal Cortex- zona reticularis
- Weak androgens are secreted and then converted to testosterone by peripheral tissues. Stimulate pubic and axillary hair growth and sexual drive in females.

Question 27

Explain what happens in the Pancreas.

Answer 27

Has Exocrine glands that produce pancreatic digestive juices; acini cells and Endocrine glands that consist of pancreatic islets.
- composed of: Alph and Beta cells that secrete glucagon and insulin
(maintain blood glucose levels)

Question 28

What are Glucagon Hormones?

Answer 28

Function is to lower blood glucose levels in response to low blood glucose levels.

Target:
* Liver, where it promotes:
- Glycogenolysis: break down of glycogen to glucose
- Gluconeogenesis: synthesis of glucose liver cells

Question 29

What are Insulin Hormones?

Answer 29

Function is to lower blood glucose levels after food intake

Target:
- Liver
- Skeletal Muscle
- Adipose Tissue

Question 30

Are you going to pass that exam?

Answer 30

Yes!