Endocrine System Flashcards
What are some types of cell communication?
Endocrine, paracrine, autocrine, neurocrine
What is endocrine communication?
Release of hormones into the bloodstream
What are glands in the endocrine system?
Any structure that makes and secretes a hormone
What is the ‘master gland’ of the body?
Pituitary Gland
What is cell target binding influenced by?
Levels of hormone in blood, number of receptors on target cell, strength of the binding
Which hormone does the thyroid secrete?
Thyroxine
What does thyroxine stimulate?
Metabolism
What hormones do the pituitary produce?
Many hormones including FSH
What does FSH do?
Regulates growth and triggers sexual maturity
What are some of the main endocrine glands?
Pineal gland, pituitary gland, hypothalamus, thyroid gland, parathyroid gland, adrenal glands
What are some of the main endocrine organs?
Gonads, pancreas, thymus
Where is the thymus located?
Superior mediastinum
By late teens, what is the thymus mainly?
Mostly fat
What is the role of the thymus?
Maturation of bone marrow derived stem cells into T cells (thymic cell education)
What does the thymus produce?
Thymosin - a hormone that promotes T cell maturation
What do your hormones control and regulate?
Reproduction, metabolism, growth and development, body defences, homeostasis
What does the hypothalamus regulate?
Thermoregulation, plasma osmolality, heart rate, feeding, wakefulness, emotion, lactation
What does the hypothalamus produce?
ADH and oxytocin
6 hormones that travel via the hypothalamo-hypophyseal portal system to the anterior pituitary (4 stimulatory, 2 inhibitory)
Where do ADH and oxytocin produced by the hypothalamus travel to?
Posterior pituitary
What is the pituitary gland also known as?
Hypophysis
What are the two lobes that the pituitary gland is divided into?
Anterior and posterior
What is stress defined as?
A state of real or perceived threat to homeostasis
What are some behavioural effects of the stress response?
Increased awareness, improved cognition, euphoria, enhanced analgesia
What are some physiological effects of the stress response?
Increased heart rate, increased respiratory rate, inhibition of feeding, digestion, growth, reproduction and immunity
Where are the principal effectors of the stress response?
Hypothalamus, anterior pituitary and adrenal gland
What is the adrenal cortex?
Outer part of the gland
What does the adrenal cortex produce?
Glucocorticoids (cortisol) and mineralcorticoids (aldosterone)
What is the central portion of the adrenal gland?
The medulla
What is the medulla of the adrenal gland composed of?
Large, pale staining epithelioid cells called chromaffin cells which are, in effect, modified nuerons
Why are chromaffin cells considered the equivalent of postsynaptic neurons?
When nerve impulses carried by the sympathetic fibres reach catecholamine-secreting chromaffin cells, they release adrenaline and noradrenaline
What is an example of neurocrine secretion?
Chromaffin cells as they are considered the equivalent of postsynaptic neurones and they secrete into the blood stream
What are some effects of adrenaline and noradrenaline?
Glycogen breaks down into glucose - increased blood glucose
Increased blood pressure
Increased breathing rate
Increased metabolic rate
Change in blood flow patterns leading to increased alertness and decreased digestive activity
What does the pineal gland produce?
Melatonin
What is melatonin involved in?
Control of circadian rhythm
What inhibits melatonin release?
Light exposure - neuronal pathway is from retina to hypothalamus to pineal gland
What does melatonin inhibit the release of?
Gonadotrophins (LH and FSH)
Why is the pineal gland visible on skull x-rays?
It calcifies in early adulthood
Where are examples of neurocrine communication?
Hypothalamus, posterior pituitary and adrenal medulla
What are hormones usually made from?
Amino acids or derived from lipids
What determines whether hormones are water soluble or lipid soluble?
Whether they are made from amino acids or derived from lipids so target cells for water soluble hormones have receptors on the membrane and target cells for lipid soluble hormones have intracellular receptors
