2.3 other endocrine glands

insulin - function

- secreted from beta cells -> reduces amt. of glucose in the blood (blood sugar level)

- promotes uptake of glucose from blood (cells of the body)

glucagon - function

- secreted by alpha cells

- increases blood sugar by conversion of glycogen (starch) to glucose in the liver

- stimulates breakdown of fat in the liver & fat storage tissue

gonads (testes and ovaries) - secretion

androgens: e.g., testosterone (responsible for the development & maintenance of male sex characteristics)

- males: produced by testes

- females: produced in ovaries, adrenal glands, and fat cells

progesterone + oestrogen

- produced by ovaries (stimulates development and maintenance of female sex characteristics)

= tg. w/ gonadtropic hormones --> regulates menstrual cycle and involved in changes during pregnancy

stomach and small intestine - secretion

secretes hormones that coordinate the exocrine glands of digestive system

kidneys - secretion

secretes erythropoietin -> stimulates production of RBC by bone marrow

heart - secretion

secretes hormones that reduce blood pressure

Placenta- secretion

secretes no. of hormones during pregnancy -> helps maintain pregnancy and stimulates development of the fetus &, mother's mammary glands

parathyroid gland - location, secretion

- located in rear surface of bones of thyroid gland

- usually 4, some ppl have more

- secretes parathyroid hormone (PTH/parathormone)

---> ↑ Ca2+ levels in the blood & phosphate excretion in urine

thymus - location, secretion

- located in the chest (above ❤️ , behind sternum)

- like pineal gland, the largest in infants & children, shrinks after puberty

- secretes group of hormones - thymosins ( influence maturation of T-lymphocytes)

1. adrenal medulla - secretions + function

- produces adrenaline & noradrenaline

- adrenaline (epinephrine) has similar effects to the sympathetic division of ANS → fight or flight response

- noradrenaline (norepinephrine) has similar effects to adrenaline BUT ↑ rate & force of heartbeat

2. adrenal cortex - secretion + function

- more than 20 diff. hormones produced; known as corticosteroids

- 2 main ones:

1. aldosterone: acts on kidneys to ↓ [Na] and ↑ [K] in urine

2. cortisol: promotes normal metablism, helps body withstand stress and repair damaged tissue

pancreas - glands + secretion

- both exocrine & endocrine gland

→ releases digestive enzymes to the small intestine thru pancreatic duct

→ made of islets of Langerhans** that secrete insulin and glucagon

pineal gland - location, secretion

found deep in brain

secretes melatonin, regulation of sleep patterns

thyroid gland - location, secretion, function

- located in the neck, below the larynx

- consists of 2 lobes (each side of trachea), joined by narrow piece of tissue that lies across front of trachea

- follicular cells secrete 2 hormones responding to TSH: thyroxine (T4) and triiodothyronine (T3)

- releases calcitonin: regulates levels of Ca and PO in blood

thyroxine (t4) - role

- 4 iodine atoms attached

- 80% of thyroid hormones

- converted into T3 by enzymes

- controls body metabolism by regulating anabolic reactions (complex molecules break down → release energy)

- overall: releases energy + maintain body temp.

trioodothyroxine (T3) - how many atoms attached

- 3 iodine atoms attached

- 20% of thyroid hormones

- T4 ----> T3

adrenal glands - location, structures

- 2 adrenal glands, 1 immediately above each kidney

- inner: adrenal medulla (1)

- outer: adrenal cortex (2)

insulin role

ROLE in...

- liver: converts glucose → glycogen + fat

- skeletal muscle: formation of glycogen from glucose

- fat storage tissue: causes glucose to be converted into fat

- level of secretion is determined by amt. of glucose in blood (controlled by neg. feedback loop)