2.7. Endocrine System Flashcards
What are the functions of the endocrine system?
- COORDINATES… the homeostatic balance
- REGULATES… physiological systems such as digestive and reproductive
- FACILITATES… differentiation of the sexes in the embryonic stage and the manifestation of secondary sexual characteristics at puberty
- MODIFIES AND INDUCES… behavioural changes
List the 10 endocrine glands:
- Hypothalamus
- Pituitary
- Pineal body
- Parathyroids
- Thyroid
- Thymus
- Adrenals
- Pancreas
- Ovaries
- Testes
What are hormones?
Chemical substances secreted by cells into extracellular fluids that regulate the metabolic function of other cells in the body
What 2 groups can hormones be classified into?
- Amino acid-based molecules
2. Steroid hormones
What is positive feedback? Give an example
A cycle of positive effects, greatly amplifying the original signal, involving one or more hormones.
eg. an infant suckling stimulates prolactin secretion which maintains lactation. If suckling decreases, the amount of prolactin released is decreased.
What is negative feedback? Give an example
A cycle of negative influence involving one or more hormones.
eg. The anterior lobe of pituitary gland produces TSH, which stimulates the thyroid gland to produce thyroid hormone. TSH production is inhibited by the presence of thyroid hormone.
Function of Hypothalamus
- Regulates homeostasis
- Controls pituitary function
- Integrates nervous and endocrine systems
Function of Pituitary
- ‘Master’ gland- stimulates other endocrine glands
Function of Pineal body
- Produces melanonin during nocturnal period
- Involved in biological rhythms and body clock
Function of Thyroid
Affects metabolism and growth
Functions of Parathyroid glands
Maintenance of calcium homeostasis
Functions of Thymus
Development of immune system
Functions of Adrenal glands
Medulla: Secretion of catecholamines (adrenaline/noradrenaline)
Cortex: secretion of corticosteroids
Sex steroids
Functions of Pancreas
- Insulin and glucagon control cellular uptake of glucose and regulate cellular metabolism affecting blood glucose
- Somatostatin- growth hormone-inhibiting hormone
Functions of Gonads (ovaries/testes)
- Produce sex steroids that affect reproductive cycles and gamete formation
Functions of Kidney
Erythrocyte production stimulated by erythropoietin
Functions of Heart
Atrial natriuretic peptide lowers blood pressure
Functions of Adipose tissue
- Appetite suppressed by leptin
- Affects steroid hormone metabolism
What 2 hormones does the POSTERIOR pituitary gland produce?
- Antidiuretic hormone
2. Oxytocin
What 6 hormones does the ANTERIOR pituitary gland produce?
- Prolactin
- Growth hormone
- Thyroid stimulating hormone
- Adrenocorticotropic hormone (ACTH)
- Melanocyte-stimulating hormone
- FSH/LH
Where are the adrenal glands situated?
On top of the kidneys
What 3 things does the adrenal cortex produce?
- Mineralocorticoids- eg. aldosterone (regulate amount of electrolytes and water in extracellular fluid)
- Glucocorticoids- eg. cortisol (effect on the metabolism of most body cells)
- Gonadocorticoids- eg. androgens, estrogens, progestogens (sex steroids)
What does the medulla produce?
Adrenaline and Noradrenaline (catecholamines) which produce short term responses
Where are insulin and glucagon released from?
Islets of Langerhans in pancreas
Describe the hormonal regulation of blood sugar levels in the body
- When blood sugar levels are HIGH, pancreas releases INSULIN. Insulin stimulates sugar uptake by the cells and glucagon formation in the liver, which lowers blood sugar levels; insulin exerts hypoglycaemic effects.
- When blood sugar levels are LOW, GLUCAGON is released. Glucagon stimulates glycogen breakdown and thereby raises blood sugar. It is a hyperglycemic hormone.
Define gestational diabetes
Diabetes that develops during pregnancy which occurs because the body can’t produce enough insulin to meet the extra needs during pregnancy.
