B14 - Hormonal Communication Flashcards
1
Q
What is the endocrine system?
A
- made up of endocrine glands
- uses hormones to send information about changes in the environment around the body to bring about a response
2
Q
What are endocrine glands?
A
- group of cells which are specialised to secrete chemicals known as hormones directly into the bloodstream
- e.g. pancreas secretes insulin and glucagon and adrenal glands secrete adrenaline
3
Q
What are the functions of the glands (pituitary, thyroid, adrenal, thymus, pancreas)?
A
- pituitary:
- produces growth hormone, controlling growth of bones and muscles,
- ADH hormone which increases reabsorption of water in the kidneys
- gonadotrophins which control development of ovaries and testes
- thyroid:
- produces thyroxine which controls rate of metabolism and rate that glucose is used up in respiration
- promotes growth
- adrenal:
- produces adrenaline which increases heart rate and breathing rate
- raises blood glucose level
- thymus:
- produces thymosin which promotes production and maturation of white blood cells
- pancreas:
- produces insulin which converts excess glucose into glycogen in the liver
- glucagon which converts glycogen to glucose in the liver
4
Q
What are the functions of the gender specific glands (pineal, ovary, testes)?
A
women:
- pineal: produces melatonin which affects reproductive development and daily cycles
- ovary : produces oestrogen, which controls ovulation and secondary sexual characteristics (during puberty)
- progesterone which prepares the uterus lining for the receiving an embryo
- men:
- testes (singular testis): produces testosterone which controls sperm production and secondary sexual characteristics
5
Q
What are exocrine glands?
A
- secrete chemicals through ducts into the organs or to the surface of the body
- e.g. digestive system
6
Q
What are hormones?
A
- chemical messengers that carry ifnormation from one part of the body to the other
- can be steroids (cortisol), proteins (insulin), glycoproteins (FSH), polypeptides (glucagon), amine (adrenaline) or tyrosine derivatives (thyroid)
- secreted in response to change in concentration of a substance e.g. blood glucose
- once secreted, travel via the plasma across the body, diffuse out of blood and bind to specific receptors, found in the membrane or in cytoplasm of cell in the target organs (target cells), once bound to receptors, hormones stimulate target cells to produce a response
7
Q
What are steroid hormones?
A
- lipid soluble so can pass through the lipid component of the cell membrane and bind to steroid hormone receptors to form a hormone-receptor complex, receptor may be found in the nucleus or cytoplasm depending on hormone
- The HRC formed acts as transcription factor which facilitates or inhibits the transcription of a specific gene e.g. oestrogen
8
Q
What are non-steroid hormones?
A
- are hydrophilic so cannot pass through the cell membrane, instead bind to specific receptors on the cell surface membrane of the target cell
= triggering cascade reaction mediated by chemicals called second messengers e.g. adrenaline
9
Q
Hormonal vs Neuronal communication
A
- hormones not directly released onto the target cells, resulting in slower and less specific communication than neuronal
- hormones not broken down as fast as neurotransmitters so have a longer lasting and widespread effect
10
Q
Hormonal system vs Nervous system
A
Hormonal
- communication is by chemicals (hormones)
- transmission by blood system
- relatively slow transmission
- hormones travel to all parts of body but only target organs respond
- widespread response
- long lasting response
- effect may be permanent and irreversible
Nervous
- communication via nerve impulses
- transmission by neurones
- very rapid transmission
- nerve impulses travel to specific parts of the body
- response is localised
- rapid response
- short lived response
- effect is temporary and reversible
11
Q
What does the adrenal gland consist of?
A
- adrenal cortex - think ‘outside the CORE(tex): outer region of the glands, produces cortisol (stress hormone) and aldosterone (water regulation)
- adrenal medulla: inner region of the glands, produces non-essential hormones like adrenaline
12
Q
What are the components of the adrenal cortex?
A
- controlled by hormones released by pituitary gland, releases 3 main types of hormones:
- Glucocorticoids: including cortisol, which helps regulates metabolism by controlling how the body converts fats, proteins and carbohydrates to energy; helps regulate blood pressure and heart function in response to stress. Another hormone released is corticosterone, which works with cortisol to regulate immune response and suppress inflammatory reactions; release of these hormones is through hypothalamus
- mineralcorticoids: aldosterone which controls blood pressure by maintaining balance between salt and water concentrations in blood and bodily fluids, release mediated by signals triggered by kidney
- androgens: small amount of male and female sec hormones released - impact is small compared to oestrogen and testosterone (released by ovaries and testes after puberty), important in women after menopause
13
Q
What are the components of the adrenal medulla?
A
- hormones released by the sympathetic nervous system when the body is stressed and releases the hormones:
- adrenaline - increases heart rate, sending blood quickly to the muscles and brain and rapidly raises blood glucose concentration levels by converting glycogen to glucose in the liver to use for energy
- noradrenaline: hormone works with adrenaline in response to stress, producing increased heart rate (more oxygen transported around body) , widening of pupils ( to allow more light and see more), vasoconstriction in non essential organs (increasing blood pressure), widening of air passages in lungs etc.
14
Q
What is the function of the pancreas?
A
- exocrine gland - to produce enzymes and release them via the duct into the duodenum
- endocrine gland - to produce hormones and release them into the blood
15
Q
What is the function of the pancreas as an exocrine gland?
A
- mostly made up of exocrine glandular tissue
- responsible for producing digestive enzymes and alkaline fluid - pancreatic juice
- enzymes and juices are secreted into ducts which lead to the pancreatic duct , then released into the duodenum (top of small intestine)
- produces 3 main hormones:
- amylase - breaks down starch into simple sugars e.g. pancreatic amylase
- proteases - break down proteins into amino acidse.g. trypsin
- lipases - breaks down lipids into fatty acids and glycerol e.g. pancreatic lipase
