Hormone Regulation

Question 1

What are endocrine glands?

Answer 1

Endocrine glands are ductless glands that secrete hormones into the blood.

Question 2

What regulates the secretion of hormones?

Answer 2

Secretion of hormones occurs in response to:

• hormonal (activated by other hormones)
• humoral (by changing blood levels of ions/nutrients (PTH activated by changing Ca levels)
• neural (fight/flight where the sympathetic nervous system activates the release of norepinephrine epinephrine (adrenaline).

Question 3

What are hormones?

Answer 3

Hormones are chemical substances secreted by endocrine cells, into the blood to regulate the activity of cells.

Question 4

What are the classifications of hormones? What is the difference?

Answer 4

Amino acids (peptides, proteins, amines) or steroids.

Steroid hormones cross the cell membrane where they enter cell nucleus, exerting their action inside the cell. Non steroid hormones bind with receptors on the cell membrane. Resulting in the activation of enzymes which act as a second messenger type of communication inside the cell.

Question 5

The hypothalamus is linked with the pituitary gland true or false?

Answer 5

True. The relationship between the pituitary and the hypothalamus is important because the release of each of the pituitary’s hormones is controlled by the hypothalamus.

Question 6

What are the two parts of the pituitary gland?

Answer 6

Anterior and posterior.

Question 7

Does the posterior pituitary gland produce the hormones it releases?

Answer 7

No, they are made in the hypothalamus. The posterior pituitary gland works as a “storage area” until they are released.

Question 8

What are the two hormones released by the posterior pituitary gland? When are they released and why?

Answer 8

Oxytocin and ADH.

Oxytocin is responsible for childbirth and the “let down” reflex in breast feeding. This is a positive feedback mechanism.
ADH reduces and inhibits the production of urine to reduce urine output.

Question 9

What 6 hormones are produced by the anterior pituitary gland?

Answer 9

All classified as ‘tropic’ hormones because they target other endocrine glands. Not including GH and PRL which act on non endocrine targets.

1. Adrenocorticotrophic hormone (ACTH) - regulate the cortex of the adrenal glands.
2. Thyroid-stimulating hormone (TSH) - regulates the thyroid.
3. Luteinising hormone (LH) and 4. Follicle-stimulating hormone (FSH) - These two are gonadotrophins. They regulate the production of sperm and/or ova, testosterone, oestrogen, progesterone.
4. Prolactin (PRL) - regulates the mammary glands to produce milk.
5. Growth hormone (GH)

Question 10

Where is the adrenals glands located? What are the two parts called?

Answer 10

Located over the kidneys.

Outer gland is the adrenal cortex. Inner gland is the adrenal medulla.

Question 11

What hormones does the adrenal cortex secrete?

Answer 11

Adrenal cortex secrete a group of hormones collectively called adrenocortical hormones. These hormones include mineralocorticoids, glucocorticoids and androgens.

Question 12

Where are epinephrine and norepinephrine secreted from?

Answer 12

The adrenal medulla. Adrenal medulla is an array of nerves extending from the autonomic nervous system / sympathetic nervous system.

Question 13

What role does epinephrine and norepinephrine have on the body?

Answer 13

Epinephrine and norepinephrine are effective in the fight/flight response, they aid the body to cope with stressful situations by increasing

• heart rate
• blood pressure
• blood glucose level
• respirations.

They are usually the short term response to stress.

Question 14

What do mineralocorticoids do?

Answer 14

Their target cells are in the kidney tubules, This group of hormones are important for the regulation of particular electrolytes (Na / K) in the blood..
Aldosterone is a mineralocorticoids.

Question 15

What do androgens do?

Answer 15

Group of hormones that affect sexual drive, sexual characteristics Secreted in response to ACTH and produced throughout life.

Question 16

What do glucocorticoids do?

Answer 16

• Maintain normal metabolism
• Regulate glucose levels therefore influence BGL
• Metabolise proteins for glucose
• Have a role in anti inflammatory & immune responses
• Ensure skeletal muscles receive adequate glucose during times of stress /during the fight/flight response therefore impacting on BP / vasoconstriction of vessels
• Cortisol is an example of this.

Question 17

When is cortisol secreted?

Answer 17

Sometimes called the stress hormone, cortisol is secreted during times of starvation, injury, or trauma

In response to stress the hypothalamus secretes corticotrophin releasing hormone (CRH) which stimulates the pituitary glands to produce ACTH which causes cortisol release from the adrenal glands.

Question 18

What can happens if cortisol levels do not return to normal after a stressful situation?

Answer 18

Health concerns can occur from too much or too little cortisol.

Question 19

What can happen when there are excessive amounts of cortisol?

Answer 19

• Compromises the immune response and inflammatory pathways making the body susceptible to disease
• Prolonged healing times
• Reduction in the ability to deal with vaccinations
• Vulnerability to viruses
• Chronic stress impairs cognition, decreases thyroid functioning, causing an accumulation of abdominal fat

Question 20

What is stress? What are the types of stress?

Answer 20

“Nonspecific response of the body to any demand or change”

• Occurs in response to a stressor / something that causes stress
• Can be physical as when lifting something heavy or running over a long distance
• Deprivation – nutrient deprivation during times of fasting or O2 deprivation during changes in atmospheric conditions
• Emotion as when watching a scary movie or reading a scary book or sitting an exam

Question 21

What are the phases of stress?

Answer 21

Alarm phase, adaption phase and exhaustion phase.

Question 22

What does the alarm phase of stress consist of?

Answer 22

When a threat is perceived; the sympathetic nervous system reacts and epinephrine (with smaller amounts of norepinephrine) are released from the adrenal medulla.
This is the fight/flight response (dilated pupils, increase in BP, HR, respirations etc.) This is an immediate response.

The endocrine system’s response is slower, the hypothalamus secretes CRH which stimulates ACTH production. ACTH goes to target the release of cortisol from the adrenal cortex which increases the BGL as it sends necessary glucose to the muscles to meet the need of the body in the perceived threat. This is a longer sustained response.

Question 23

What does the adaption phase of stress consist of?

Answer 23

Adaption is more likened to the ability of people to ‘adapt’ to the stressor, to find the stressor is not as threatening as first thought

Question 24

What does the exhaustion phase of stress consist of?

Answer 24

Exhaustion is more likened to the stressor being ongoing whereby cortisol secretion continues and levels remain raised in the body for a length of time.

Question 25

What is the role of the pancreas?

Answer 25

• Responsible for much of the digestive processes in the small intestine
• Within the pancreas is a small amount of tissue called pancreatic islets OR islets of langerhans
• Islets secrete these two hormones (alpha release glucagon, beta release insulin)
• Both glucagon and insulin are responsible for nutrient metabolism

Question 26

What is the role of insulin?

Answer 26

When a person eats, various hormones are released in the gut to begin the metabolism of food products and absorption occurs causing hyperglycaemia.
As a result, insulin is released from the beta cells.

• Insulin acts on all body cells and ensures the uptake of glucose for muscle and fat cells.
• Insulin actions the breakdown of glucose for ATP
• Insulin inhibits fat breakdown and promotes fat storage.
• Insulin promotes protein manufacture.
• Works to lower blood glucose level.

Question 27

What is the role of glucagon?

Answer 27

• Secretion is in response to a deficiency of nutrients
• Glucagon promotes the liver’s action of breaking down glycogen to glucose
• Glucagon promotes the liver to produce glucose from proteins
• During fasting, glucagon produces ketones from fatty acids
• Works to raise blood glucose level.

Question 28

What is dibetes mellitus?

Answer 28

Metabolic disorder characterised by a collection of symptoms/problems

Inadequate amount of insulin produced OR a diminished number of insulin receptors at target tissues/cell impairing the ability of glucose to enter the cell
Result = hyperglycaemia

Question 29

What is the role of the thyroid gland?

Answer 29

Located in front of the neck, below the larynx
The manufacture of thyroid hormones is controlled by the hypothalamus and anterior pituitary.
Cold / temperature and stress regulate thyroid gland activity
Two thyroid hormones - T3 and T4 with the assistance of protein and iodine.

Question 30

What is hyperthyroidism?

Answer 30

• Excess of thyroid from excess of TSH
• Often seen in people with pituitary tumor, autoimmune disease or overmedicated with thyroid meds
• Goiter is commonly seen
• Overactive body actions.

Question 31

What is hypothyroidism?

Answer 31

• Inadequate thyroid from inadequate TSH
• Often seen in people with an inflammation of gland or those with a lack of dietary iodine
• Goiter is commonly seen
• Underactive body actions eg, weight gain, fatigue, slow reflexes, less tolerance to cold.

Question 32

What is the role of the growth hormone (GH)?

Answer 32

• Over a 24 hr period, GH is secreted in larger quantities when sleeping & times of stress
• Gland is most active during puberty and decreases during aging
• Responsible for growth and repair of tissues, increased Ca levels leading to increase in mineralisation of bone, increases muscle and cartilage, stimulates fat breakdown and gluconeogenesis.

Question 33

What is the role of calcitrol? (Vitamin D)

Answer 33

Ca plays a role in many body functions and there needs to be strict regulation of blood Ca levels
Calcitriol (Vitamin D) is a Ca regulating hormone
It comes from sunlight, very little is present in foods found in our diet
Ensures the absorption of Ca from the small intestine which increases blood Ca levels

Question 34

What are the parathyroid glands and what is their role?

Answer 34

4 parathyroid glands located on the posterior of the thyroid gland

• Parathyroid glands secrete parathyroid hormone (PTH)
• PTH regulates Ca metabolism
• When Ca levels are low, PTH stimulates bone breakdown releasing Ca; stimulates Vit D action in the small intestine, ensures the kidneys retain Ca

Question 35

What can go wrong in the endocrine system?

Answer 35

• A high hormone secretion level results in hypersecretion of that hormone
• A low hormone secretion level results in hyposecretion of that hormone
• Hormone dysfunction may be linked to the failure of the feedback mechanism that overrides / controls secretion

Question 36

How does age impact the endocrine system?

Answer 36

Birth - body processes are already influenced and controlled completely by hormones

Puberty to late adulthood adulthood - reproductive hormones are produced / secreted

Late adulthood - oestrogen production decreases resulting in menopause for women

As a person ages the general functioning of the endocrine system slows.