Endocrine, Paracrine, Autocrine & Intracrine

Question 1

What are the 10 endocrine structures?

Answer 1

Hypothalamus 
Pituitary 
Thyroid 
Parathyroid
Pancreas
Thymus 
Adnrenal 
Ovaries 
Metabolism 
Pineal

Question 2

Describe cortisol

Answer 2

Secreted and synthesised by the adrenal cortex

Steroid

Question 3

Describe regulation of hormone secretion

Answer 3

Maintain homeostasis, hormone secretion must be regulated as needed - accomplished by neural and feedback mechanisms

Question 4

What are 4 hormones released by the hypothalamus?

Answer 4

Corticotropin releasing hormone (CRH)
Thyrotropin releasing hormone (TRH)
Growth hormone releasing hormone (GHRH)
Gonadotropin releasing hormone (GnRH)

Question 5

Describe the posterior pituitary and the two main hormones released

Answer 5

Pars nervosa - negative feedback loop stimulated by the anterior pituitary
ADH + Oxytocin

Question 6

Describe the anterior pituitary and the 6 main hormones released

Answer 6

Pars tuberalis, pars distalis and pars intermedia 
Hormones and secreted by: 
TSH - Thyrotrophs 
FSH - delta / gonadotropic
LH - delta / gonadotropic
ACTH - corticotrophs
GH - somatotrophs 
Prolactin - lactotrophs

Question 7

What does ACTH act on?

Answer 7

Adrenal gland

Question 8

What does TSH act on?

Answer 8

Thyroid gland

Question 9

What does GH act on?

Answer 9

Liver - somatomedins

Question 10

What does Prolactin (PRL) act on?

Answer 10

Mammary glands

Question 11

What does FSH act on?

Answer 11

Testes and ovaries

Question 12

What does LH act on?

Answer 12

Testes and Ovaries

Question 13

What does MSH (Melanocyte stimulating hormone) act on?

Answer 13

Melanocytes

Question 14

What does Oxytocin act on?

Answer 14

Prostate + ductus deferens

Uterine smooth muscle

Question 15

Describe the pineal gland

Answer 15

Pinealocytes - produce melatonin

Glial cells - bipolar elongated cells that run between nests of pinealocytes - indistinct unless stained

Question 16

Describe melatonin

Answer 16

Regulates seasonal changes in the body and sleep

Question 17

Describe the parathyroid gland

Answer 17

• Embedded in the posterior surface of the thyroid
• separated by the dense capsular fibres of thyroid
• Parathyroid hormone PTH calcium homeostasis
  Chief cells and Oxyphils

Question 18

Describe hyperthyroidism

Answer 18

• Increase thyroid stimulating immunoglobulins
• Antibodies to TSH receptors on thyroid follicular cells
• Increase secretion of thyroid hormone and hypertrophy of gland
  Causes rapid heart rate , weightloss and goiter
  Treatment - Drugs to inhibit thyroid hormone synthesis or surgical removal of the gland

Question 19

Describe hypothyroidism

Answer 19

• Autoimmune destruction is the most common cause
• antibodies destroy the gland or blockthyroid hormone synthesis
  Symptoms - Weight gain, decreased heart rate, periorbital, menstrual dysfunction
  Treatment - thyroid hormone replacement

Question 20

Describe the adrenal gland

Answer 20

Cortex - secretes steroid hormones

medulla - neuroendocrine component - polyhedral

Question 21

Describe cushings syndrome

Answer 21

• Result of chronic excess glucocorticoids
• Over production of cortisol by adrenal cortex
• Treatment - use meds to block steroid hormone biosynthesis

Question 22

Describe cholera

Answer 22

Caused by vibrrocholerae
Severe diarrhoea 
Shock and death if fluid not replaced 
Cholera toxin produced by bacteria that enters the gut binds to G protein that controls adenylate cyclase 
- Increase adenylcyclase activity 
- Increase cAMP
- Increase active transport by ions by interstitial cells 
- Increase Na and H2O into the gut

Question 23

Describe paracrine communication

Answer 23

• Occurs when a cell releases a signalling molecule into its immediate environment
• molecule is bound by and effects neighbouring cells

Question 24

Describe autocrine communication

Answer 24

• Cell releases a regulatory molecules bound by its own receptors
• Acts on cell which releases it - positive feedback to cell

Question 25

Describe intracrine communication

Answer 25

• Not example of intracellular communication

- Intracellular signalling between different parts of the same cell - molecules do not leave the cell