Endocrine System Flashcards
(20 cards)
Name glands within the endocrine system
Where are hormones secreted to and transported to ?
- Operate over a long range
- Secreted into the blood by endocrine glands in response to a specific signal
- Transported in the blood to their target cells
The endocrine system provides the means to:
• interpret the electrical signals from the brain as biochemical signals
• allow the various differentiated cells of the body to work in harmony
• maintain homeostasis
What is the hypothalamus connected to and what do its hormones do ?
- Connected to the pituitary via the pituitary stalk and regulates the two lobes by neural and hormonal pathways
- Hypothalamic hormones regulate the secretion of anterior pituitary hormones
What does the pituitary do, how long is it, where is it found and what are the two distinct parts
-The pituitary together with the hypothalamus form the primary interface between the electrical activity of the brain and the biochemical activity of other body organs.
-The pituitary is about 1 cm in diameter lying in a bone cavity at the base of the skull.
-Two distinct parts - the anterior lobe (derived from the ectoderm of the buccal cavity) and the posterior lobe (derived from neural tissue)
Anterior pituitary responds to signals from hypothalamus to secrete…
- Adrenocorticotrophic hormone (ACTH)
- Thyroid stimulating hormone (TSH)
- Growth hormone
- Follicle stimulating hormone (FSH) and luteinising hormone (LH),
- Prolactin
- Melanocyte stimulating hormone
what two hormones does the Posterior pituitary store amd secrete?
Stores and secretes two hormones:
-Anti-diuretic hormone (vasopressin) (ADH) which regulates re-absorption of water in the kidneys and hence fluid balance
-Oxytocin - allows secretion of milk in response to suckling
* Both these hormones are synthesised in the hypothalamus
Virtually all the biochemical processes involved in homeostasis are ultimately controlled by either the……………. or the…………..
Hypothalamus or pituitary
what hormones do Parathyroids secrete?
-Four glands associated with the thyroid.
-Secrete parathyroid hormone which increases serum calcium and
-calcitonin which decreases serum calcium.
what hormones does the Thyroid secrete and what do they do?
-thyroid gland secretes calcitonin and the thyroid hormones - Triiodothyronine (T3) and its precursor thyroxine (T4). Very little is free in blood - the majority is bound to thyroxine binding protein.
-Thyroid hormones increase the metabolic rate of all body tissues and the plasma level is controlled by a feedback loop.
The pancreas secretes…
-Islets of Langerhans secrete insulin, glucagon and somatostatin
-Glucagon - secreted from alpha2 or A cells.
-Insulin - from Beta or B cells
-Somatostatin from delta or D cells
Insulin and glucagon
Operate together to maintain blood sugar in both fasting and fed states.
Adrenal cortex produces…..
-Glucocorticoids such as cortisol which regulate fat, carbohydrate and protein metabolism and have anti-inflammatory activities
-Mineralocorticoids such as aldosterone which regulate water and electrolyte balance
-Adrenogenital corticoids (androgens and oestrogens) which affect sexual function
Adrenal medulla secretes…
-Secretes adrenaline and noradrenaline.
-Increased amounts are secreted at times of physical or emotional stress in response to sympathetic nerve stimulation
name 3 Catecholamines and what secretes them
-Dopamine
-Noradrenaline (norepinephrine)
-Adrenaline (epinephrine)
-Secreted by some neurones and the chromafin cells of the adrenal medulla
Effects of catecholamines
Growth hormone
-Growth Hormone Releasing Hormone (GHRH)
-Hypophyseal Portal System
-Anterior Pituitary - GH
-191 aa peptide
-Cell membrane receptor
-Pulsatile
-Majority produced during sleep - particularly one hour after proper sleep commences
What does the growth hormone do
• Increases protein production
• Increases calcium retention & mineralisation of bones
• Increases muscle mass (sarcomere hypertrophy)
• Promotes lipolysis - metabolism of fats
• Dec uptake of glucose by liver
• Promotes gluconeogenesis
• Stimulates the Immune System
• Increases deiodination of T4 to T3
