5.1.4 Hormonal Communication Flashcards
Define Endocrine gland
group of cells which are specialised to secrete hormones into the blood
Define Exocrine gland
group of cells which are specialised to secrete enzymes into ducts
Define hormone
chemical messengers which travel in the bloodstream
Define target tissue
What are 8 endocrine glands?
- Pituitary gland
- Thyroid gland
- Adrenal gland
- Pineal gland
- Thymus
- Pancreas
- Ovary
- Testes
What is the general role of the pituitary gland and the hormones it releases?
- produces growth hormones which control growth of bones and muscle
- antidiurectic hormone (ADH) which increases reabsorption of water in kidneys
- gonadotrophins which control development of ovaries and testes
What is the general role of the thyroid gland and the hormones it releases?
- produces thyroxine which controls rate of metabolism
and
-the rate of glucose that is used up in respiration, promotes growth
What is the general role of the adrenal gland and the hormones it releases?
- produces adrenaline which increases heart and breathing rate and raises blood sugar level
(flight/fight response)
What is the general role of the testis and the hormones it releases?
- produces testosterone which controls sperm production and secondary sexual characteristics
What is the general role of the pineal gland and the hormones it releases?
- produces melatonin which affects reproductive development and daily cycles
What is the general role of the thymus and the hormones it releases?
- produces thymosin which promots production and maturation of white blood cells
What is the general role of the pancreas and the hormones it releases?
- produces insulin which converts excess glucose into glycogen in the liver
- produces glucagon which converts glycogen back into glucose in the liver
What is the general role of the ovary and the hormones it releases?
-produes oestrogen which controls ovulation and secondary sexual characterstics
- progesterone + oestrogen which controls ovualtion and secondary sexual characteristics
-progesterone prepares uterus lining for recieving an embryo
Do endocrine glands secrete hormones or enzymes?
endocrine glands release hormones into the bloodstream
How does hormonal communication occur?
- endocrine gland secrete hormones into the blood stream
- the hormones travel to target cells
- the target cells have specific (to hormone) receptors
- after binding they coordinate a specific response
What are the 2 types of hormones?
-Steriod hormones
-Non-steriod hormones
Can steriod or non-steriod (peptide) hormones pass through the cell surface membrane?
- steriod hormones can pass through the cell surface membrane
Why can non steriod hormones not pass through the cell surface membrane?
What do non-steriod hormones work? (mechanism)
- non-steriod hormones cannot pass through because they are hydrophilic and the cell surface membrane has a hydrophobic core
Instead:
1. horomone binds to specific receptor (1st messenger) on c.s.m of target cell
2. hormone binding to receptor activated enzyme on c.s.m to turn ATP into cAMP (second messenger)
3. cAMP triggers cascade of reactions
e.g. adrenaline
Why can steriod hormones pass through the cell surface membrane?
How do steriod hormones work? (mechanism)
- they are lipid soluble so can diffuse through the lipid component of the c.s.m
- hormones diffuse through cell surface membrane
- hormones bind to steriod hormone receptors in cytoplasm/nucleus (dependant on which hormone)
- now there is a hormone receptor complex
- if receptor in nucleus: the hormone receptor complex acts as a transcription factor (facilitates/inhibits DNA transcription)
What is the location of the adrenal gland in the body?
- adrenal gland found ontop of each kidney
What is the structure of the adrenal gland
- adrenal gland has 2 sections
- the inner region is the adrenal medulla (produces non essential hormones)
- the outside is the adrenal cortex (produces vital hormones)
Which hormones does the adrenal medulla produce?
adrenal medulla: (produces non-essential hormones)
- produces peptide hormones (non-steriod)
-
Which 2 hormones does the adrenal medulla release? and what are their roles?
1) adrenaline
- increases heart rate
- increases blood glucose concentration
-2) noradrenaline
- increases heart rate
- widens pupils
- widens air passages to lungs
- vasoconstriction in blood vessels in non-essential organs = higher blood pressure
Which hormones does the adrenal cortex produce?
adrenal cortex: (vital to life hormones)
- produces steriod hormones
Which 3 hormones does the adrenal cortex release? and what are their roles?
1) glucocorticoids
regulates:
- glucose+protein metabolism
- blood pressure
- immune response
- suppress inflammatory reactions
2) mineralocorticoids
- maintain salt and water conc
3) androgens
- release small amounts of sex hormones which have v.little impact
Define Histology
the study of the microscopic anatomy of cells and tissues
What are the 2 roles of the pancreas?
Acts as:
- exocrine gland
- endocrine gland
What does the exocrine gland do (pancreas) ?
(4 steps)
exocrine gland:
1. produces enzymes
2. enzymes are secreted into ducts
3. ducts lead to pancreatic duct
4. enzymes are released into duodenum (top of s. intestine)
What does the endocrine gland do (pancreas)?
endocrine tissue (the islets of langerhans):
- produce and secretes hormones insulin and glucagon into the bloodstream
Draw a labelled diagram of a pancreas section and label it
snaprevise
on flashcard
What shape and colour do the pancreatic acini (exocrine tissue) appear under the microscope?
colour: darker stained
shape: small berry like clusters