17: THE ENDOCRINE SYSTEM Flashcards
what is the endocrine system
a collection of glands that produce hormones which carry info/instructions from one set of cells to another
what are hormones
chemicals made by specialist cells (usually within an endocrine gland) and released into the blood stream to send a message to another part of the body
what is homeostasis
the body’s way of regulating or maintaining a steady internal environment
what is the function of the endocrine system
to provide the body with a sensory system to react to the environment, a slower method of maintaining homeostasis than the nervous system
list the endocrine glands
Pituitary
Thyroid
Thymus
Adrenal
Pancreas
Ovary
Teste
how is the regulation of homeostasis achieved
through feedback loops - either positive or negative
what does a positive feedback loop do
amplifies change
what does a negative feedback loop do
reduces change
hormones are slower to create a response than nerves?
true
what are hormones made from
lipids (fats) and amino acids (protein)
what are the two different types of hormones
Steroid
Peptide
what are catabolic hormones
they break things down
what are anabolic hormones
they build things up
what are steroid hormones
Slow acting and long lasting hormones that control themselves by means of feedback
what are peptide hormones
made of protein, fast acting and short-lived
where is the hypothalamus located
base of the brain, above the pituitary gland
what does the hypothalamus do
master gland, controls activity of the pituitary gland. forms the link between the nervous and endocrine system
where is the pituitary gland
base of the brain, below the pituitary gland
what does the anterior part of the pituitary gland do
secretes growth hormones under the control of the hypothalamus
what does the posterior part of the pituitary gland do
secretes a number of important hormones that control factors such as blood matter content and lactation
what does the pituitary gland do
secretes a range of hormones known as ‘tropic’ hormones that act as messengers and controllers of other endocrine glands
what are growth hormones
powerful anabolic hormones, important in tissue growth. Lots in children, lower levels in adults
where is the thyroid situated
in the neck
what does the thyroid do
secretes thyroxine
what does thyroxine affect
heart and digestive function
metabolism maintenance
brain development
bone health
muscle control
what happens if you have low levels of thyroxine
retarded growth and development
reduced basal metabolism
rapid weight gain in adults
where is the parathyroid located
situated in the neck behind the thyroid glad - usueally have 4
what does the parathyroid do
secretes parathyroid hormone (PTH) which regulates levels of calcium in the blood (essential for muscle contraction and nerve impulse transmission)
what happens when blood calcium levels fall
PTH is released to increase calcium absorption from the gut and breaking down bone to release calcium
where are the adrenal glands located
on the kidneys
what do the adrenal glands do
secrete powerful hormones in response to stress, fear and excitement (sympathetic activity of the autonomic nervous system)
what does each adrenal gland release
Catecholamines - hormones; adrenaline and noradrenaline. Quick acting to prepare the body for fight or flight
what is the outer layer of the adrenal glands called
the cortex
what happens in the cortex of the adrenal glands
cortisteroid hormones (such as cortisol) are made and released into the blood
where are ovaries situated
inside female pelvic region and part of reproductive organs
what do ovaries do
secrete oestrogen and progesterone which promotes feminine characteristics such as breasts, less body hair and increased body fat
where is the pancreas located
near the stomach
what is the role of the pancreas
dual role:
1. Digestive gland - producing enzymes that help break down fat, carbs and protein
2. Endocrine gland: produces hormones insulin and glucagon
when is insulin realised into the blood
in response to rising blood sugar levels
what does insulin do
promotes transport of blood sugar into the cells to be used for energy or to be stored as glycogen. it reduces blood sugar levels.
what happens when blood sugar levels fall
glucagon breaks down stored glycogen to release glucose and increase blood sugar levels
what is the relationship between insulin and glucagon
they work antagonistically to keep blood sugar levels in a healthy range
where are testes located
male pelvic region and involved in reproductive system of the body. outside rather than inside to keep them cool enough for effective sperm production
what do the testes do
secretes testosterone (anabolic hormone) which promotes masculine characteristics - increased muscle size, increased body hair, decreased body fat, increased red blood cell count
what happens to cortisol levels during exercise
they rise due to the stress placed on the body
what causes cortisol levels to rise too much
overtraining stress and lifestyle stressors
what happens if cortisol levels are too high
impaired cognitive performance
suppressed thyroid function
blood sugar imbalances
decreased bone density
decrease muscle tissue
higher blood pressure
lowered immunity and inflammatory responses
increased tummy fat
benefits of growth hormones during exercise
stimulates protein synthesis (muscle tone development)
strength of bones, tendons, ligaments and cartilage
decreased the use of glucose and increases the use of fat as fuel (reduced body fat)
what happens to growth hormones if overtraining
can increase the release of this hormone. cortisol can inhibit protein synthesis if levels rise out of control
what happens to testosterone during normal exercise
helps gain muscle, strengthen bones and lose fat. Although exercise can increase levels, cortisol can have an inhibiting effect so important to have rest times
what happens to testosterone in overtraining
the body regulates T output through negative feedback loops. If artificially injected then natural outputs will lower and the glands will shrink
what happens to oestrogen during training
increase fat breakdown from body fat stores to be used as fuel
increase basal metabolic rate
elevate mood
increase libido
what happens to oestrogen in over training
can lead to reduction in levels produced. low body fat in women can result in loss of periods
benefit of exercise for thyroid disorders
can reduce symptoms and increase circulation of thyroid hormones
what happens to thyroid during exercise
increases blood flow and improves metabolic rate
minimises chance of weight gain
increases energy levels
thyroid and over training
can have adverse effect in the functioning of the thyroid and make it over produce (hyperthyroidism) or under product (hypothyroidism)
what is hyperthyroidism
over producing thyroid
feel mentally/physically drained after exercise
weight gain
sore joints
constant fatigue
what is hypothyroidism
under producing thyroid
can result in heart conditions, brittle bones and eye problems
what happens to insulin and glucagon levels during exercise
blood insulin levels drop and blood glucagon levels rise. insulin sensitivity is increased so your cells are better able to use any available hormone that helps the body use glucose for energy. When muscles contract, it allows your cells to take up glucose and use it for energy when insulin is available or not
insulin and glucagon and over training
causes blood sugar levels to rise. can activate fight or flight which stimulates adrenal glands. Stress hormones are then released which stimulate the liver to product glucose at a faster rate than normal.
