The Endocrine System

Question 1

The endocrine system controls what regulatory systems?

Answer 1

Regulation of cellular metabolism,
Maintenance of homeostasis,
Sexual development and reproduction,
Growth and development from childhood to adult,
Modulates long term behaviour

Question 2

What are the three classes of hormones?

Answer 2

Proteins,
Steroids,
Amino acid derivatives

Question 3

What type of cells do exocrine glands develop from?

Answer 3

Epithelial cells

Question 4

Where do endocrine glands secrete hormones?

Answer 4

Directly into the blood supply via fenestration on capillaries or into the extra cellular space. They are ductless

Question 5

Where do hormones act on?

Answer 5

They act on specific target tissues or on neighbouring cells.

Question 6

Describe some of the features of paracrine secretions

Answer 6

These are polypeptide hormones that diffuse over short distances, they allows for cell to cell communications as the hormone secreted by one cell can act on another.

Question 7

Where are paracrine secretions important?

Answer 7

In embryogenesis where gradients of polypeptides influence development change.

Question 8

Where do exocrine glands secrete

Answer 8

They are epithelial cells that secrete hormones into ducts. These ducts carry secretions to the surface of the epithelium.

Question 9

Describe the importance of specific carrier/binding proteins

Answer 9

Steroid or thyroid hormones are transported in blood by these molecules and they improve solubility, increase the half life and provide a reserve of the hormones in the blood.

Question 10

What horomes have cell surface membrane receptors

Answer 10

Peptides, glycoproteins and catecholamines

Question 11

What hormones have intracellular receptors in the nucleus

Answer 11

Steroids and Thyroids

Question 12

Describe the location of the following glands; pituitary, thyroid, parathyroid, adrenal (suprarenal), and pancreatic islets (islets of Langerhans)

Answer 12

Pituitary: below the hypothalamus in the brain
Thyroid: In the neck, anterior to the trachea
Parathyroid: Develop from the wall of the pharynx and are embedded in the posterior aspect of the thyroid
Adrenal: Sit on the top of the kidneys
Pancreatic Islet: located within the pancreas.

Question 13

What is the endocrine axes/cascade?

Answer 13

This is where the target tissue of one hormone is another endocrine gland. Allows for amplification.

Question 14

The hypothalamus secretes hormones that control?

Answer 14

The secretion and release of pituitary hormones

Question 15

The pituitary gland hormones control/stimulate what?

Answer 15

Many other endocrine glands (thyroid and gonads ect)

Question 16

Describe some of the functions of the hypothalamus

Answer 16

Controls the release of anterior pituitary hormones.

It also secretes hormones that are stored and released by the posterior pituitary gland.

Question 17

What 6 hormones does the anterior pituitary lobe secrete?

Answer 17

Growth Hormone (GH) - stimulates tissue growth
Thyroid stimulating hormone (TSH) - acts on the thyroid
Adrenocorticotropic hormone (ACTH) - ats on the adrenal glands
Follicle stimulation hormone (FSH) - acts on gonads
Luteinising hormone (LH) - acts on gonads
Prolactin - acts on mammary glands

Question 18

Describe some of the features of the posterior pituitary gland

Answer 18

Stores hormones which are secreted by neurosecretory cells in the hypothalamus. The hormones are transported via neuronal axons in the stalk of the posterior lobe of the pituitary.
The two hormones released are the antidiuretic hormone and oxytocin

Question 19

Describe the concept negative feedback in the endocrine axes

Answer 19

The final product of the cascade acts to inhibit a hormone higher up in the cascade. The hypothalamus is an important site of negative feedback in many hormone systems.

Question 20

What is a Pituitary Adenoma

Answer 20

Non-benign tumours in the pituitary gland that cause an over secretion of hormones.

Question 21

What is the thyroid developed from?

Answer 21

Epithelium of the tongue

Question 22

Follicular cells of the thyroid gland secrete what? Where are these secretions stored?

Answer 22

Tri-iodothyronine and thyroxine. These are stored in colloid (thyroglobulin)

Question 23

What does thyroxine regulate?

Answer 23

Rate of metabolism (energy use), growth and development (protein production) and regulates sensitivity of cells to other hormones

Question 24

What cells produce calcitonin? and what does it do

Answer 24

Parafollicular cells ( C cells). This hormone regulates calcium homeostasis and stimulates osteoblasts

Question 25

What hormone does the parathyroid glands produce and what is its function?

Answer 25

Produces the parathyroid hormone. It regulates calcium homeostasis. It stimulates osteoclasts to breakdown bone matrix and thus increasing the calcium levels in blood.

Question 26

Describe the structure of adrenal glands

Answer 26

Cortex - made of three layers of epithelia,

Medulla - neural crest

Question 27

Describe the three layers of the adrenal gland cortex

Answer 27

Zona glomerulosa - releases mineralocorticoids
Zona fasciculata - releases Glucocorticoids
Zona reticularis - releases sex steroids

Question 28

Describe the adrenal medulla

Answer 28

Forms from neural crest cells called neuroectoderm.
It also contains Chromaffin cells which produce catecholamines:
Epinephrine
Norepinephrine
Dopamine
All of which are in direct connection with the sympathetic nervous system.

Question 29

Describe some of the features of the pancreas

Answer 29

It has both exocrine and endocrine functions.
Exocrine - pancreatic acini which produce pancreatic amylase

Endocrine - Islets of langerhans which produce hormones; glycagon (made by alpha cells) and insulin (made by beta cells)

Question 30

What are the different gland shapes? Give an example of where they are found

Answer 30

Simple tubular glands - intestines
Simple coiled tubular gland - sweat glands
Simple tubular branched gland - Stomach and uterus
Simple acinar - Sebaceous glands