2 - Endocrine Glands

Question 1

Give three examples of endocrine glands

Answer 1

1. the thyroid/parathyroid glands
2. gonads
3. pancreas

Question 2

What does the pancreas secrete?

Answer 2

Insulin

Question 3

What do the gonads secrete?

Answer 3

Males - testosterone / Females - oestrogen and progesterone

Question 4

What des the thyroid & parathyroid produce?

Answer 4

The thyroid produces thyroid hormones & the parathyroid produces parathyroid hormones

Question 5

What are the principle endocrine glands in both females and males?

Answer 5

• the principle endocrine glands in males and females are the same
• we have the endocrine glands associated with the brain
• for example, the pineal gland, the hypothalamus, and pituitary glands at the base of the brain
• in the throat we have a thyroid gland and four associated parathyroid glands

Question 6

What happens in the pancreas?

Answer 6

The pancreas secretes insulin, but also the hormone glucagon, which counteracts insulin actions on blood glucose

Question 7

How are the kidneys involved?

Answer 7

Attached to the kidney are adrenal glands, which produce a range of steroid hormones that can regulate salt and water balance

Question 8

Role of the gonads?

Answer 8

• the gonads are different between males and females
• in the female, there are ovaries which secrete oestrogen throughout the menstrual cycle and progesterone during pregnancy
• in males are the testes which produce testosterone

Question 9

What hormones are produced by the thyroid?

Answer 9

1. thyroxine
2. calcitonin

Question 10

What is the function of thyroxine and calcitonin?

Answer 10

Thyroxine - regulates metabolism
Calcitonin - Inhibit release of calcium from the bones

Question 11

What is the function of the parathyroid hormone?

Answer 11

Stimulates the release of calcium from the bones

Question 12

What hormones do islet cells (in the pancreas) produce?

Answer 12

1. insulin
2. glucagon

Question 13

What is the function of insulin and glucagon?

Answer 13

Insulin - decreases blood sugar by promoting uptake of glucose by cells
Glucagon - increases blood sugar by stimulating breakdown of glycogen in the liver

Question 14

What is the function of testosterone?

Answer 14

Regulates sperm cell production and secondary sex characteristics

Question 15

What Is the function of oestrogen and progesterone?

Answer 15

Oestrogen - stimulates egg maturation, controls secondary sex characteristics
Progesterone - prepares the uterus to receive a fertilised egg

Question 16

What hormone does the adrenal cortex produce?

Answer 16

Epinephrine

Question 17

What is the function of epinephrine?

Answer 17

“fight or flight”

Question 18

What hormones does the adrenal medulla produce?

Answer 18

1. glucocorticoids
2. aldosterone
3. testosterone (in both sexes)

Question 19

What are the functions of glucocorticoids (1), aldosterone (2), and testosterone (3)?

Answer 19

1. part of stress response, increase blood glucose levels and decrease immune response
2. regulates sodium content in the blood
3. adult body form (greater muscle mass), libido

Question 20

What hormone does the pineal gland produce?

Answer 20

Melatonin

Question 21

What is the function of melatonin?

Answer 21

Sleep cycles, reproductive cycles in many mammals

Question 22

What does the hypothalamus do?

Answer 22

The hypothalamus receives information from the nervous system and initiates responses through the endocrine system

Question 23

What does the hypothalamus serve as?

Answer 23

• the hypothalamus serves as an interface between higher brain function and the production of hormones secretes into the blood
  -therefore acts s a bridge between the nervous system and the endocrine system
• basically there’s a collection of nerves which can receive synoptic input but can also secrete locally acting hormones

Question 24

What is attached to the hypothalamus?

Answer 24

The pituitary gland

Question 25

What is the pituitary gland composed of?

Answer 25

The posterior pituitary and anterior pituitary

Question 26

What is the role of the posterior pituitary?

Answer 26

- stores and secretes hormones that are made in the hypothalamus - these are neuroendocrine hormones

Question 27

What is the role of the anterior pituitary?

Answer 27

- makes and releases hormones under regulation of the hypothalamus - the hypothalamus secretes peptide hormones to regulate the activity of the anterior pituitary

Question 28

Give examples of pituitary hormones

Answer 28

1. follicle-stimulating hormone 2. luteinising hormone 3. thyroid-stimulating hormone 4. adrenocorticotropic hormone 5. melanocyte-stimulating hormone 6. growth hormone 7. antidiuretic hormone 8. oxytocin

Question 29

What is the function of follicle-stimulating hormone (1) and luteinising hormone (2)?

Answer 29

1. stimulates egg maturation in the ovary and release of sex hormones 2. stimulates maturation of egg and of the corpus lute surrounding the egg, which affects female sex hormones and the menstrual cycle

Question 30

What is the function of thyroid stimulation hormone?

Answer 30

Stimulates the thyroid to release thyroxine

Question 31

What are the functions of adrenocorticotropic hormone (1) and melanocyte-stimulating hormone (2)?

Answer 31

1. causes the adrenal gland to release cortisol 2. stimulates synthesis of skin pigments

Question 32

What are the functions of growth hormone (1), antidiuretic hormone (2) and oxytocin (3)?

Answer 32

1. stimulates growth during infancy and puberty 2. signals the kidney to conserve more water 3. affects childbirth, lactation, and some behaviours

Question 33

How are hormones regulated?

Answer 33

Hormones are regulated by feedback loops

Question 34

What is a negative feedback loop?

Answer 34

A negative feedback loops inhibits a response by reducing the initial stimulus, thus preventing excessive pathway activity

Question 35

What is a positive feedback loop?

Answer 35

A positive feedback loop reinforces a stimulus to produce an even greater response

Question 36

Give an example of a positive feedback loop

Answer 36

- a prime example of a positive feedback loop involved in pregnancy is oxytocin - as the babies head moves down the birth canal, the production of oxytocin is stimulated, and the more the baby moves, the more oxytocin is produced and the more rhythmic contraction of the uterine muscles occur - therefore there is a positive feedback enabling the baby to be born

Question 37

What is the posterior pituitary involved in?

Answer 37

It is involved in secreting hypothalamic hormone

Question 38

What is the role of neutrons in the posterior pituitary?

Answer 38

- neurone are sent down from the hypothalamus into the posterior pituitary - these neurone or neuroendocrine cells secrete small peptides directly into the bloodstream across a synapse

Question 39

What are the posterior pituitary neurohormones? (include the function)

Answer 39

- neuroendocrine has signalling, so these neurohormones include oxytocin and ADH (anti-diuretic hormone), and these are small peptides - oxytocin interacts with receptors in the mammary glands (also involved in the contraction of uterine muscles and is involved in birth)

Question 40

What are the pituitary hormone effects?

Answer 40

LH and FSH stimulate spermatogenesis and testosterone secretion by the testes

Question 41

What are the testes hormone effects?

Answer 41

Testosterone and inhibin inhibit the secretion of GnRH by the hypothalamus and LH and FSH by the pituitary

Question 42

What does the hypothalamus produce in the male reproductive system?

Answer 42

-normally the hypothalamus produces a hormone called Gonadotropin Releasing Hormone (GnRH) which is a small peptide/neuropeptide

Question 43

What does the production of GnRH result in?

Answer 43

- GnRH interacts with receptors on gonadotroph in the anterior pituitary - this leads to the production of LH and FSH which travel through the bloodstream (being soluble peptide hormones) & interact with receptors in the testes

Question 44

What hormones are needed to sperm production?

Answer 44

FSH from the anterior pituitary & testosterone from the leydig cells

Question 45

What are the two different types of receptors and what do they do?

Answer 45

1. FSH receptors - found in the Sertoli cells and when they interact with these receptors, the process of spermatogenesis is promoted 2. LH receptors - interact with leading cells in the tested causing increasing in intracellular activating that leads to the production of testosterone (positive feedback)

Question 46

What is the negative feedback in the male reproductive system?

Answer 46

- there is a negative feedback effect so that too much FSH and LH is produced - testosterone produced by the leydig cells travel through the bloodstream interacting with he nuclear receptors in the anterior pituitary nd the hypothalamus to prevent further production of GnRH and further production of FSH

Question 47

How do we ensure the negative feedback in the male reproductive system is strong enough?

Answer 47

There is the production of another hormone from the Sertoli cells called inhibin (protein hormone)

Question 48

How is the anterior pituitary and peptide hormones linked?

Answer 48

In the anterior pituitary there is direct synthesis and secretion of peptide hormones from the anterior pituitary cells

Question 49

What is the role of the hypothalamus and peptide hormones (anterior pituitary)?

Answer 49

- the production of the peptide hormones is under the control of the hypothalamus - the hypothalamus decreases neurosecretory peptides, but these enter the portal vessels, which are blood vessels that feed into the anterior pituitary

Question 50

What does the anterior pituitary regulate?

Answer 50

- regulation of production of follicle stimulating hormone and luteinising hormone - these are peptide hormones which regulate the action of the testes or the ovaries

Question 51

What happens during menstruation?

Answer 51

There is a loss of the lining of the uterus

Question 52

What happens day 5 of the menstrual cycle?

Answer 52

Another egg develops in the ovary after menses and this is stimulated by increases in oestrogen production by the ovary until we get to the midpoint of the menstrual cycle

Question 53

What happens to the progesterone and oestrogen levels during the menstrual cycle?

Answer 53

- progesterone level is low as oestrogen is being produced - this suppressed FSH and LH production by negative feedback -but about day 12 to 14, about the midpoint of the menstrual cycle, we have a surge in LH and FSH production causing positive feedback on the hypothalamus and the anterior pituitary

Question 54

What does early stage FSH production cause?

Answer 54

- this early stage FSH production surge causes ovulation (release of an egg) - this coincides with the transformation of the follicle into the corpus luteum, and it produces progesterone instead of oestrogen

Question 55

What happens when progesterone levels rise after the release of an egg?

Answer 55

There is a negative feedback effect on FSH and LH

Question 56

What causes more progesterone production?

Answer 56

- the development of the corpus luteum - as the egg is fertilised, the corpus luteum is maintained and progesterone levels level off and there is an extension of the luteal phase were the lining of the uterus is beneficial to implantation of the egg

Question 57

What happens if there is no ovulation?

Answer 57

There is a fall in progesterone levels