Week 9 - Hormones And Chromosomes

Question 1

What are hormones and what are the three types?

Answer 1

Hormones are signalling molecules They can be) 1) peptides 2) amino acid derivatives 3) lipid derivatives

Question 2

How do lipid derived hormones act when they arrive at a cell?

Answer 2

As they are lipid soluble, they diffuse through the plasma membrane and bind to their intracellular receptors

Question 3

What are the two types of lipid derived hormones?

Answer 3

D - steroid hormones (cholesterol derivatives, small molecules bound to plasma proteins in the blood) - eicosinoids (arachidonic acid derivatives)

Question 4

What are the two hormones secreted by the posterior pituitary gland?

Answer 4

Anti-diuretic hormone (ADH) and Oxytocin

Question 5

What is the effect of ADH?

Answer 5

At the kidneys; Increases permeability to water at distal and collecting tubules At the arterioles; Causes vasoconstriction

Question 6

What are the effects of oxytocin?

Answer 6

At the uterus; 1) stimulates uterine contractions At the breasts; 2) stimulates milk ejection

Question 7

What are the features of the posterior pituitary gland

Answer 7

1) Pars nervosa - nerve fibres originate at hypothalamus, transport hormones to posterior pituitary 2) DIRECTLY connected to hypothalamus 3) neural lobe or neurohypophysis 4) DOESN’T synthesise hormones, hormones are synthesised by HYPOTHALAMUS neurones.. And secreted by the posterior pituitary

Question 8

You are on holiday in South Africa and the sun is scorching. You start to get dehydrated. Outline the mechanism that regulates blood osmolarity in terms of hormonal control.

Answer 8

An increase in osmolarity is detected by osmoreceptors in hypothalamus Hypothalamus produces ADH, which is transported to the posterior pituitary gland by nerve fibres ADH secreted from posterior pituitary gland increases H2O permeability thus water is reabsorbed at distal and collecting tubules Osmolarity decreases

Question 9

What re the features of the anterior pituitary gland?

Answer 9

1) porta distalis - portal blood vessels that connect pituitary and hypothalamic capillary beds together 2) synthesises its own hormones, 7 hormones released from 5 cell regions

Question 10

What is the distribution of Somatotrophs in the anterior pituitary gland? What does this cell region secrete?

Answer 10

50% of pituicytes in anterior pituitary gland Somatotrophs secrete growth hormone

Question 11

What are the the 7 hormones of the anterior pituitary gland and where do they target?

Answer 11

See week 9 Hormones

Question 12

What controls hormone secretion from the anterior pituitary?

Answer 12

Hormones from the hypothalamus; They can be stimulatory or inhibitory hormones STIMULATORY (their functions are pretty obvious from the name!) - growth hormone releasing hormone - gonadotropin releasing hormone - corticotropin releasing hormone - thyrotopin releasing hormone INHIBITORY - dopamine (prolactin inhibiting hormone) - somatostatin (inhibit growth hormone secretion)

Question 13

What factors effect growth as well as growth hormone?

Answer 13

• nutrition - presence of sex hormones (secondary characteristics - if have chronic illness - genetic determination

Question 14

What are the most abundant types of hormones? Give an example of this type?

Answer 14

Polypeptide hormones. E.g. CCK

Question 15

What areas if the body does growth hormone affect?

Answer 15

MUSCLES - * decrease in glucose intake * increase in amino acid intake - increased muscle mass Protects against hyperglycaemia ADIPOSE TISSUE - * decrease in glucose uptake * increase in lypolysis * Decrease in fatty deposits LIVER - * increase in gluconeogenesis * decrease in glucose intake * increase in protein synthesis * …. Leads to synthesis if IGF1 and IGF2

Question 16

What does the synthesis of IGF1 and IG2 lead to?

Answer 16

Soft tissue growth - increase in protein synthesis - increase in chondrocyte proliferation Skeletal growth - increases cartilage formation - increases bone depOsition

Question 17

How is growth hormone regulated?

Answer 17

Growth hormone releasing hormone and growth hormone inhibiting hormone (somatostatin)

Question 18

What stimuli to the hypothalamus influence the secretion of growth hormone?

Answer 18

Metabolic - Hypoglycaemia Low fatty acids Neural - Stress, exercise, sleep Hormonal- Sex steroids Conditions such as starvation and anorexia

Question 19

What are the clinical features if growth hormone excess in patients who had excess pre teen?

Answer 19

Growth hormone excess before epiphyseal plate fusion; GIGANTISM - increased skeletal and soft tissue growth -

Question 20

What are the clinical features of growth hormone excess in adults? What is the cause of this excess?

Answer 20

Epiphyseal plate has closed. ACROMEGALY - cardiomegaly - course facial features - large teeth, nose, hands - diabetic - protruding jaw

Question 21

A 17 year old patient comes to see you in your GP practice with her parents. Their parents are worried because their daughter’s features have changed, which they describe as “enlarged and more prominent”. they show you a picture of when she was younger. You notice her hands Re more enlarged and she has a prominent jaw. The patient mentions she’s started to urinate more frequently. What do you think should be investigated and what treatments are you considering if any?

Answer 21

Consider patient’s age, she is 17 and her epiphyseal plates have not fused. Patient most likely has acromegaly possibly caused by a pituitary tumour. MRI scan to see if there is a pituitary tumour. Treatment options: - surgical removal of tumour - if surg. Unsuccessful) somatostatin receptor agonist (to inhibit further somatostatin) - growth hormone receptor antagonist

Question 22

What are the clinical features of pituitary dwarfism and does this occur in children or adults?

Answer 22

In CHILDREN! No symptoms of Growth hormone insufficiency in adults Excess subcutaneous fat Normal body proportions Slow growth rate

Question 23

What hormones do the adrenal glands secrete?

Answer 23

Adrenal medulla secrete catecholamines Adrenal cortex secretes steroid hormones

Question 24

The adrenal glands each are basically 2 endocrine glands with hormones being secreted from the cortex and the medulla. What hormones are secreted from where, mention the zones of the adrenal cortex as well.

Answer 24

To remember the zones : GUIDE ALAN FOWARD CAUSE REEM IS ANGRY From top to bottom (Capsule) Zona Glomerulosa - Aldosterone (mineral balance) Zona fasiculata - Cortisol (glucose and lipid metabolism) Zona reticularis - Androgen (male sex hormones) (Adrenal medulla) - adrenaline (80%) and noradrenaline (20%)

Question 25

Name three androgens associated with male development?

Answer 25

1) Testosterone 2) Dihydrotestosterone - Embryo life: causes differentiation of penis in embryo life In later life: male balding, prostate growth, sebaceous gland activity 3) Androstenedione -

Question 26

Name some testosterone orecursors and where are they converted to tstosterone?

Answer 26

DHEA and DHEa-S which bind less efficiently to androgen receptors (weak steroids) Activated in peripheral tissues They are controlled by ACTH in the anterior pituitary

Question 27

What is the role of adrenal gland derived testosterone in men?

Answer 27

Is insignificant as role not understood; - secondary characteristics - aggression in boys No consequences in excess or in small amounts

Question 28

What are the roles of testosterone in women?

Answer 28

Unlike in men, adrenal glands are the primary source of testosterone Responsible for; - growth of pubic and auxiliary hair - sex drive - kick start puberty - maintain muscle and bone mass

Question 29

What is the cause of adrenal cortex hyperfunction and what are some clinical features?

Answer 29

Over production of ACTH in anterior pituitary gland Hirsutism - when females develop a male pattern of body hair Acne, Irregular periods Breast shrinkage ******* HAIB *******

Question 30

Hannah comes into your GP asking you for some treatment for her irregular periods and unusual man pattern like hair. What treatment would you give her and why?

Answer 30

Hannah seems to be having over stimulation of ACTH producing more androgens than usual. Treatment would be an anti- androgen such as cyproterone acetate, and ethinylestradiol

Question 31

What are the clinical features if Addison’s disease?

Answer 31

Destruction of the entire adrenal cortex Low sex hormone Loss of body and pubes hair Loss of libido Muscle wasting and thin limbs Low cortisol Hypoglycaemia Hypercalaemia Hypoaldosteronism

Question 32

Once LH and FSH enter interstitial space within testes, what are their functions at their targets?

Answer 32

LH - stimulate leydig cells to secrete testosterone

FSH-

stimulate sertoli cells

Question 33

What is the function of sertoli cells?

Answer 33

Sertoli cells

Can Nourish Cheeky Sperm

Create seminiferous tubules

Nourish germ cells to promote spermatogenesis (note. dont nourish sperm)

Convert testosterone to DHT or oestradiol

Secrete Inhibin which negatively feeds back on FSH

Question 34

Function of androgen-binding protein?

Answer 34

Binds to an androgen funnily enough! Binds to testosterone - stimulating spermatogenesis

Question 35

What are the functions of testosterone?

Answer 35

Question 36

What is Klinefelter syndrome and is it common?

Answer 36

1) COMMON genetic condition where males have an extra X chromosome
2) LOW PRODUCTION OF TESTOSTERONE, undiagnosed until adulthood usually
3) Little or no sperm production

Question 37

What enzyme converts testosterone to DHT?

Answer 37

5 alpha reductase

Question 38

What what is an associated disorder, what are the consequences?

Answer 38

5 alpha reductase deficiency

As no DHT is produced you get decreased development of male reporiductive system (see notes on DHT functions)

Question 39

What is androgen insensitivity syndrome and what are the signs?

Answer 39

1) Body is insentitive to testosterone and DHT.
2) Genetals develop in a female like pattern and testes remain inside the body
3) Persons are genetically male, but genitals are female