14.1 Hormonal Communication Flashcards
Defintion of a endocrine gland
group of cells which are specialised to secrete hormones directly into the blood stream
What is the endocrine system made up of
endocrine glands
What are the major endocrine glands
-pituitary gland
-pineal gland
-thymus
-pancreas
-ovary
-testis
-adrenal gland
-thyroid gland
What is the function of the pineal gland
produces melatonin which affects reproductive development and daily cycles
What is the function of the thymus
produces thymosin which promotes production and maturation of white blood cells
What is the function of the pancreas
produces insulin which converts excess glucose into glycogen in the liver, and glucagon which converts glycogen back to glucose
What is the function of the ovary
produces oestrogen and progesterone which controls ovulation and secondary sex characteristics, progesterone also prepares the uterus lining for receiving a embryo
What is the function of the testis
produce testosterone which controls sperm production and secondary sex characteristics
What is the function of the adrenal gland
produces adrenaline which increases HR, breathing rate and raises blood sugar level
What is the function of the thyroid gland
produces thyroxine which controls the rate of metabolism and rate that glucose is used up in respiration, promotes growth
What is the function of the pituitary gland
-makes several hormones
-close proximity to the hypothalamus ensures hormonal and nervous responses are closely linked and coordinated
-produces growth hormone which control growth of muscles and bones
-produces anti-diuretic hormone which increases reabsorption of water in the kidneys
-gonadotrophins which control development of ovaries and testis
What are hormones
chemical messsengers which are secreted and transported directly in the blood for a widespread and long lasting effect
What are steroid hormones and their effect on target cells
-lipid-soluble
-diffuse through the cell surface membrane of target cells and bind to receptors which are present in the cytoplasm or nucleus to form a hormone-receptor complex
-hormone-receptor complex acts as a transcription factor which in turn facilitates or inhibits the transcription of a specific gene
What is an example of a steroid hormone
oestrogen
What are non-steroid hormones and their effect on target cells
-insoluble hormones so hydrophilic
-cannot directly pass through cell surface membrane of target cells
-bind to specific receptors on the cell surface membrane which triggers a cascade of responses within the cell mediated by chemicals called secondary receptors
What is an example of a non-steroid hormone
adrenaline
What is the difference between hormonal system (H) and nevour system (N) communication
-H transmission by blood system, N transmission by neurones
-H transmission is slow, N transmission is very rapid
-H travels to all parts of the body but only target cells respond, nerve implies travel to specific parts of the body
-H response is slow, widespread and long-lasting. N is localised, rapid and short-lived
-H effect may be permanent and irreversible, N is temporary and reversible
-H communication is by hormones, N communication is by nervous system
What is the contrast between endocrine and exocrine glands
-exocrine glands secrete chemicals through ducts in organs or to the surface of the body
-endocrine glands secrete chemicals directly into the bloodstream
What is the structure of the adrenal glands
-2 small glands located on the top of each kidney
-3cm in height and 5cm in length
-made up of adrenal cortex and adrenal medulla surrounded by a capsule
What is the productions of hormones by the adrenal cortex controlled by?
hormones released by pituitary gland
What are the hormones produced by the adrenal cortex
-glucocorticoids
-mineralocorticoids
-androgens
What is the function of glucocorticoids
-help regulate metabolism
-regulate blood pressure and cardiovascular function in response to stress
-regulate immune system, suppress inflammatory response
-release is controlled by the hypothalamus
What is the function of mineralocorticoids
-aldosterone mainly produced which helps control blood pressure by maintaining balance between salt and water concentrations in the blood and body fluids
-its release is mediated by signals triggered by the kidneys
What is the function of androgens
-small amounts of male and female sex hormones are released
-released by the ovaries or testes after puberty
-impact is relatively small
When are hormones secreted by the adrenal medulla released
when the sympathetic nervous system is stimulation when the body is stressed
What are the hormones secreted by the adrenal medulla
adrenaline
noradrenaline
What is the function of adrenaline
increases HR sending blood quickly to the muscles and brain. Rapidly raises glucose conc. levels by converting glycogen to glucose in the liver
What is the function of noradrenaline
-works with adrenaline in response to stress
-increases HR, widens pupils, widens air passages of lungs, narrows blood vessels in non-essential organs
What does noradrenaline and adrenaline control?
The SA node
Where is adrenaline and noradrenaline produced?
adrenal medulla
What are the difference in the effect of adrenaline and noradrenaline?
Adrenaline specifically increases heart rate, noradrenaline increases blood pressure
Define exocrine gland?
Secrete chemicals through ducts into organs or to the surface of body
Label the major endocrine glands on this diagram
What is the function of the adrenal cortex?
-Secretes steroid hormones which are vital to life eg. cortisol, aldosterone
What is the function of the adrenal medulla?
-Secretes catecholamine hormones
eg. adrenaline, noradrenaline
