Chapter 2: Chemical Messengers Flashcards
What do exocrine glands do?
Secrete into a duct that carries the secretion to the body surface or to a body cavity
What do endocrine glands do?
Secrete hormones into the extracellular fluid that surrounds the cells and makes up the gland. It is then transported by the blood
What is a hormone?
A chemical messenger that effects the functioning of a cell
What is a paracrine
A local hormone that works in its adjacent cells
How do protein and amine hormones work?
By attaching to a receptor in the plasma membrane and then sending a secondary messenger substance to diffuse through the cell.
How do steroid hormones work?
By entering the cell directly and combining with a receptor protein inside the cell.
3 functions of hormones?
- Activate certain genes
- Change the shape or structure of an enzyme
- Change the rate of production of an enzyme
What is meant by the term “enzyme amplification”
That one hormone molecule does not stimulate just one enzyme molecule, it stimulates thousands.
What is meant by the term, “hormone clearance”
Hormone clearance is the breakdown of the hormone once it has had the desired effect.
What controls the regulation of these things?
releasing and inhibiting factors
Where is the hypothalamus located?
Base of the brain
What structure connects the hypothalamus to the pituitary?
The infundibulum
What hormones are secreted by the anterior lobe of the pituitary gland
- Follicle stimulating hormone
- Luteinising Hormone
- Growth hormone
- Thyroid stimulating hormone
- Adrenocorticotropic Hormone
- Prolactin
What hormones are RELEASED from the posterior pituitary?
- Oxytocin
- Antidiuretic Hormone
Where are the hormones released by the posterior pituitary produced?
The hypothalamus
Where is the pineal gland located?
Deep inside the brain
What hormone is released by the pineal gland?
Melatonin
Where is the thyroid gland located?
in the neck
What hormones is released from the thyroid?
Thyroxine
Calcitonin
What is the effect if thyroxine and how is its release stimulated?
Controls the body metabolism
Thyroid stimulating hormone
Where are the parathyroid glands and how many are there
Behind the thyroid gland
There are 4 of them
What is the effect of the parathyroid hormone?
It controls calcium and phosphate levels in the blood
Where is the thymus located?
In chest, just above the heart
What is secreted by the thymus?
Thymosins
What is the role of thymosins?
Influence the maturation of T-lymphocytes
What are the two adrenal glands?
Adrenal cortex and the adrenal medulla
Which is the inner section of the adrenal gland?
The medulla
What does the adrenal medulla produce?
Adrenaline and Noradrenaline
What does the adrenal cortex produce?
Aldosterone and Cortisol
What does the hormone adrenaline do?
Helps prepare the body for a fight or flight response
What does the hormone noradrenaline do?
Similar to adrenaline, in particular it increases the rate and force of the heartbeat.
What is the role of cortisol in the body?
Promotes normal metabolism
What does the hormone aldosterone do?
Increases the amount of potassium and decreases sodium in the urine
What are the clusters of cells called in the pancreas that produce hormones?
Islets of Langerhans
What are the two types of cells in the Islets of Langerhans?
Alpha and Beta cells
What do alpha cells produce?
Glucagon
What do beta cells produce?
Insulin
What is the effect of insulin on the blood sugar levels?
Decreases them
What is the effect of Glucagon on blood sugar levels?
Increases them
What hormone is produced by the testes?
Androgens
What do androgens do?
Development and maintenance of male sex characteristics.
What hormones do the ovaries produce?
Oestrogen and progesterone
What is the role of oestrogen and progesterone?
Stimulate the maintenance and development of female sex characteristics and also regulate the menstrual cycle.
Target cells of thyroxine?
Most cells
Target cells of parathyroid hormone?
Bones and kidneys
Target cells of thymosins?
T-lymphocytes
Target cells of aldosterone?
Kidney
Target cells of cortisol?
most cells
Target cells of adrenaline and noradrenaline?
most tissues
Target cells of insulin
Most cells
Target cells of glucagon
liver and fat storage tissues
Target cells of androgens
Many tissues
Target cells of oestrogen
many tissues
Target cells of progesterone
uterus and mammary glands
