Hormonal Control of Growth, Development and Reproduction- 21

Question 1

What hormones are important during pre-natal and post-natal development.

Answer 1

Insulin and Insulin like growth hormone.

Question 2

What hormone is important for post natal development

Answer 2

Growth hormone

Question 3

What hormone is important for pre and post natal brain development.

Answer 3

Thyroid hormone (T3)

Question 4

What hormones are important for growth and development during puberty

Answer 4

Testosterone and estradiol

Question 5

Where is growth hormone secreted and what controls it.

Answer 5

A protein hormone that is released by somatotropic cells in the anterior pituitary controlled by hypothalamus.

An increase cAMP via GHRH receptor activation leads to enhanced secretion of griwth hormone.

Question 6

What are most effects of GH on growth mediated by

Answer 6

IGF-1 action by the liver.

Question 7

What is the release of growth hormone described to be.

Answer 7

Pulsatile in nature meaning secretion occurs in discrete but irregular phases (maximal at night during puberty)

Question 8

What is height determined by

Answer 8

Bone growth.

Question 9

What is the mechanism of bone growth.

Answer 9

New bone tissue is added at the region called the epiphyseal bone plate. Once it closes no more bone growth can occur.

Question 10

What do chrondrocytes do during bone growth

Answer 10

They add new cartlidge at the epiphyseal plate to push the bone up.

Question 11

What do osteoblasts do during bone growth?

Answer 11

Osteoblasts convert Cartlidge to bone in the epiphyseal plate.

Question 12

What does growth hormone stimulate in bone growth.

Answer 12

Differentiation of precursor cells in the epiphyseal plate into chondrocytes.

Which secrete IGF-1 and become respovsive to IGF-1.

IGF-1 acts in a paracrine manner to stimulate chondrocyte division.

Question 13

What are other importants effects of IGF-1

Answer 13

Stimulates protein synthesis in muscle and other cell types.
Increases levels of circulating energy sources
Powerful mitogen, promoting cell growth and division.

Question 14

What role does thyroid hormone play in growth and development

Answer 14

Stimulates synthesis of GH
Potentiates the effects of GH and IGF-1 on bone growth.
Promotes differentiation of chondrocytes.

Question 15

What are the highest sex hormones in males.

Answer 15

Testosterone
Dihydrotestosterone

Question 16

What sex hormones are highest in females

Answer 16

Estrogens(mainly estradiol)
Progesterone

Question 17

What type of hormone are sex hormones.

Answer 17

Steroid hormones (so can pass membrane)

Question 18

What is the release of sex hormones mediated by and what is the process.

Answer 18

Hypothalamus releases
Gonadotropin-releasing hormone which produces
gonadotrophs from the anterior pituitary. (FSH and LH)

Which act on ovaries/testes to produce sex hormones.

This can allow negative feedback of the process.

Question 19

What peptide is important for the onset of puberty

Answer 19

Kisspeptin as it triggers release of GnRH

Question 20

What effects does LH and FSH have in males.

Answer 20

LH acts on leydig cells to produce testosterone which promotes development of secondary sexual characteristics and accessory structure.

FSH works on sertoli cells to begin spermatogensis and inhibin (negative feedback on release)

Question 21

What are the receptors for (dihydroxy)testosterone

Answer 21

Intracellular receptors binding to these results to translocation from the cytoplasm to the nucleus and gene transcription changes.

Question 22

What are the effects of testosterone on growth

Answer 22

stimulate secretion of GH
Stimulate proteins synthesis in tissues such as muscles.

Question 23

What do LH and FSH regulate in females

Answer 23

The levels of oestrogen and progesterone.

Question 24

What happens during the ovarian cycle

Answer 24

Describes the changes occurring in follicles of the ovary ie maturation of follicle and release of egg.

Question 25

What happens during the uterine cycle.

Answer 25

Describes the changes that occur in the endometrial lining of the uterus.
If fertlisation does not occur the corpus luteum will degenerate.

Question 26

Why do hormone levels fluctuate in women.

Answer 26

FSH and LH stimulate oestrogen release from follicles.
One follicle becomes dominant and secretes high levels of oestrogen.
LH surge triggers ovulation.
The Corpus luteum forms and secretes a high amount of oestrogen and progesterone.
Negative feedback leads to low FSH and LH levels.
If pregnancy does not occur the corpus degrades meaning oestrogen and progesterone levels fall leading to a surge in LH and FSH again.

Question 27

What is the function of human chorionic gonadotrophin hormone and where is it secreted.

Answer 27

HCG is released from the conceptus ie everything both embryonic and extra-embryonic that develops from the zygote
HCG prevents degrading of the corpus luteum.

Question 28

When does menopause occur

Answer 28

around 50 years old

Question 29

What causes menopause

Answer 29

The failure of the ovaries to respond to gonadotropins
The concentration of plasma estrogen is too low to maintain tissues

Question 30

WHat can happen during menopause

Answer 30

Osteoporosis due to estrogen being a bone productive hormone
Loss of cardio protective tissue

Question 31

What is a treatment used for menopause

Answer 31

Hormonal Replacement Therapy