The Endocrine System

Question 1

Endocrine Gland

Answer 1

secretes hormones into the extracellular fluid (bloodstream) that surrounds the cells that make up the gland

Question 2

Exocrine Gland

Answer 2

secrete substances into a duct that carries the secretion to the body’s surface or to one of the body’s cavities.

Question 3

Hormones

Answer 3

A hormone is a secretion from an endocrine gland, they are transported by blood and affect target cells and organs.
Hormones are specific which means they can only affect cells with the correct receptors (lock and key)

Question 4

What are Paracrines?

Answer 4

chemicals that are secreted by all cells, and used to communicate locally with adjacent cells.

Question 5

Protein and Amine Hormones

Answer 5

these attach to receptors on the cell membrane of the target cell
this causes secondary messengers within the cell to activate cellular enzymes. e.g. insulin
receptor proteins are specific (bind to one molecule)
E.g. insulin attaches to protein = increase in glucose absorption.

Question 6

Steroid Hormones

Answer 6

move into the cell and attach to internal receptors that exist on organelles. E.g. mitochondria and nucleus
The hormone and internal receptor (hormone-receptor complex) activates the genes that control the production of proteins.

Question 7

Hormone Action

Answer 7

Change the functioning of cells by changing the type, activities or quantities of proteins produced.

Question 8

Hormones may:

Answer 8

1. activate genes to produce enzymes or proteins
2. alter the shape of enzymes so they no longer function
3. change the rate of enzyme or protein production

Question 9

Enzyme Amplification

Answer 9

One hormone molecule activates thousands of enzyme molecules.
Hormones trigger a cascading effect, thus very small quantities of hormones are required to produce a large effect.

Question 10

Hormones can be released from the body by:

Answer 10

The hormones are broken down in:
1. Target cells
2. Liver
3. Kidneys
Then excreted by bile or in the urine

Question 11

Hormone Facts

Answer 11

Some hormones rely on nervous system to produce releasing factors or inhibiting factors.
These factors (often from hypothalamus) result in hormone production by endocrine glands.

Question 12

Hypothalamus

Answer 12

Regulates many of the basic functions of the body (temperature, water balance, heart rate).
Many functions of hypothalamus are carried out through the pituitary gland.

Question 13

Pituitary Gland

Answer 13

Joined to hypothalamus by the infundibulum.

Secrete hormones that regulate the activity of endocrine glands

Question 14

Anterior Pituitary

Answer 14

• blood vessels connecting to hypothalamus
• releases hormones that regulate a range of bodily activities.
• secretions are controlled by releasing and inhibiting factors secreted by the hypothalamus

Question 15

Hormones by Anterior Pituitary

Answer 15

1. Gonadotropins (FSH- stimulates production and maturation of sperm and follicles, LH- cause ovulation to form corpus luteum and stimulates interstitial cells in testes to secrete male sex hormones)
2. Growth Hormone- stimulates body growth, increases rate at which amino acids are taken up by cells
3. Adrenocorticotropic Hormone (ACTH)- controls production and release of hormones from cortex of adrenal glands.

Question 16

Posterior Pituitary

Answer 16

• nerve fibres connecting to hypothalamus

Question 17

Hormones by Posterior Pituitary

Answer 17

1. Oxytocin (contractions of muscles in uterus and release of milk during breastfeeding) and Antidiuretic hormone ( causes kidneys to remove water from urine)
   produced by special nerve cells in hypothalamus
   - Both hormones travel down the infundibulum through nerve cells to the hypothalamus

Question 18

Thyroid Gland

Answer 18

• produces thyroxine
• regulates metabolic rate by regulating energy production from cell respiration
• produces calcitonin, more calcium storage in bones

Question 19

The Pancreas

Answer 19

exocrine and endocrine
pancreatic duct secretes digestive enzymes into small intestine
secretes insulin (decrease BG ), glucagon (increase BG)

Question 20

The Gonads

Answer 20

testes produce testosterone- develop and maintain sex characteristics
Ovaries produce oestrogen and progesterone

Question 21

Adrenal Medulla

Answer 21

adrenaline (fight or flight) and noradrenaline (increases rate and force of heartbeat)

Question 22

Adrenal Cortex

Answer 22

Produces corticosteroids (aldosterone- reduces sodium, increase potassium in urine and cortisol- promotes normal metabolism)

Question 23

Glucocorticoids

Answer 23

1. increase in ATP production
2. increase in blood pressure
3. decreased immune response
4. depressed inflammatory response (less swelling, pain, redness)
5. slower healing

Question 24

Parathyroid

Answer 24

produce parathormone which increases blood calcium and phosphate levels

Question 25

Thymus

Answer 25

decreases in size as child matures

secretes thymosins which help in maturation of WBC