Unit 5: Week 1 Flashcards
What is the endocrine system?
It controls/regulates the body using chemical signals called hormones
What are hormones?
They are messenger molecules that have specific shapes that are recognised by binding sites on hormone receptors of target cells to modify behaviour or physiology. - transport substances across membranes , cellular enzymes, cell genetic information
What is an example of antagonist pairs of molecules?
Insulin decreases BGL
Glucagon increases BGL
What are -ve feedback loops?
An action takes place to move the body away from equilibrium. This stimulates the production and release of a hormone to act on target organs to move the body back to the set point. This reverse the change and stops further hormone release.
What is a +ve feedback loop?
An action takes place to move the body away from equilibrium. This stimulates the production and release of a hormone to act on target organs to reinforce the change (away from equilibrium). This continues until the stimulus stops.
What are the two main groups of hormones
Water soluble- they cannot diffuse through lipid (cell) membranes and use the second messenger system- amino acid derivative hormones (epi, insulin, glucagon)
Lipid soluble- steroid are lipid and thyroixine and are insoluble in water. They can diffuse into a cell and act on intercellular receptors.
What are two other types of hormones?
Paracrine- hormones act on nearby cells (sometimes called cell to cells signalling) Estrogen- in ovaries involved in ovarian folical stimulation
Autocrine- hormone acts on autocrine receptors of the cells that secretes it eg cytokines interleukin important in the inflammatory response
What are the different secretion patterns?
Pulstile
Diurnal
What are the main endocrine glands in the body-
Pineal Pituitary Hypothalamus Thyroid Parathyroid Thymus Adrenal Pancreas Gonads- ovaries testes
What does the hypothalamus do?
It produces tropic hormones to control the pituitary gland- which in turn produces hormones to affect other glands. it regulates temp, hunger, thirst, sleep cycles, gastrointestinal activity, controls the ANS and the endocrine system via the pituitary gland (master endocrine gland) (controls anterior and stores hormones in posterior).
What does the thyroid do?
Uses iodine to produce hormones that effect metabolism- body temp/weight
it there is not enough Iodine the body enlarges the gland resulting in a condition known at goiter.
Hormones: T4 thyroxin T3 triiodothyronine. (calcitonin which increases BCL)
What does the parathyroid do?
secrete parathyroid hormone - involved in bone reabsorption to increase blood calcium/phosphate
Increases production of vit D- four glands behind thyroid
What does the pancreas do?
endo/exocrine gland. its endocrine function relates to insulin and glucagon.
Glucagon is a 29 amino acid chain that act mainly on the liver to break down glycogen and form of glucose synthesis. Release triggered by fasting secreted from alpha cells
Insulin is a 51 amino acid chain that inhibits glycogen breakdown and glucose synthesis triggered by eating secreted from beta cells
What does the thymus do?
The thymus gland, located behind your sternum and between your lungs, is only active until puberty.
After puberty, the thymus starts to slowly shrink and become replaced by fat.
Thymosin is the hormone of the thymus, and it stimulates the development of disease-fighting T cells- protects the body against autoimmune response.
What does the adrenal gland do?
Sits on top of kidneys and produces hormones. Made up of two parts cortex and medulla.
Zone glomerulosa- mineralcorticoids
Zone fasciultata- glucocorticoids
Zone reticularis- gonadocorticoids
Medulla- chromafin cells epi/norepinephrine
