Endocrine system Flashcards
What does the endocrine system consist of?
-several endocrine glands
-many hormone-secreting cells in organs
What is the difference between the role of the endocrine system compared to the nervous system?
-endocrine system= release hormones into interstitial fluid and then into the bloodstream
-nervous system= controls body activities through the release of neurotransmitters at synapses
How do EXOCRINE glands work and give an example
-secrete their product into ducts that carry the secretions into a body cavity, into the lumen of an organ or onto the outer surface of the body
-e.g sweat glands
Give examples of endocrine glands
-pituitary
-thyroid
-parathyroid
-adrenal
-pineal
What’s the first main function of hormones?
- help to regulate: chemical composition, volume of internal environment, metabolism and energy balance, contraction of smooth and cardiac muscle, glandular secretions
What’s the second main function of hormones?
control growth and development
What’s the third main function of hormones?
regulate operation of reproductive systems
What’s the fourth main function of hormones?
help establish circadian rhythms
Where is your thyroid gland located?
middle of your neck just below the larynx (voice box)
Where is your adrenal gland located?
On top of your kidneys
Where is your pituitary and pineal gland located?
in your brain
How do hormones bring about an action within the body?
they only affect specific target cells that have the specific protein receptors to bind to a given hormone
How do lipid-soluble hormones affect cell function?
By altering gene expression
How do water-soluble hormones alter cell function?
by activating plasma membrane receptors which elicit production of a second messenger that activates various proteins inside the cell
What is hormone secretion controlled by?
signals from the nervous system, blood chemistry, and other hormones
Explain the mechanism of action of lipid-soluble hormones
- lipid-soluble hormone diffuses into cell
- activated receptor-hormone complex alters gene expression
- newly formed mRNA directs synthesis of specific proteins on ribosomes
- new proteins alter cell’s activity
Explain the mechanism of action of water soluble hormones
- binding of hormone to its receptor
- ATP is converted to cAMP
- cAMP serves as a second messenger to activate certain proteins
- activated proteins cause reactions that produce physiological responses
- cAMP is inactivated
What is a stressor? Give some examples
-Any stimulus that produces a stress response, may be pleasant or unpleasant and varies between people
-heat/cold
-environmental poisons
-bacteria toxins
-heavy bleeding from a wound
-strong emotional reaction
What are the three stages of the stress response?
- an initial fight or flight response
- slower resistance reaction
- exhaustion
Explain the process of the fight or flight response
-initiated by nerve impulses from the hypothalamus
- to the sympathetic division of the autonomic nervous system (including adrenal medullae)
= quickly mobilises the body’s resources for immediate physical activity
Explain how the fight or flight response helps the body to react
-brings huge amounts of glucose and oxygen to the organs that are most active in warding off danger:
-the brain becomes highly alert
-skeletal muscles
-the heart to work vigorously to pump enough blood to brain and muscles
What is the purpose of the resistance stage of the stress response?
-successful in seeing us through a stressful episode and our bodies then return to normal
When does exhaustion occur in the stress response?
-results from depletion of body resources in the resistance stage
-prolonged exposure to high levels of cortisol (stress hormone) and others involved causes wasting of muscles and suppression of the immune system
What 2 lobes does the pituitary gland consist of?
-the anterior pituitary
-the posterior pituitary
How are hormones of the pituitary gland controlled?
-by inhibiting and releasing hormones produced by the hypothalamus
What is the relationship between the hypothalamus and the pituitary gland?
the pituitary gland has a master (the hypothalamus) which is it attached to
What are the main hormones released by the anterior pituitary gland?
-hGh (human growth hormone)
-PRL (prolactin)
-TSH (thyroid-stimulating hormone)
-FSH (follicle-stimulating hormone)
-ACTH (adrenocorticotropic)
-MSH (melanocyte-stimulating hormone)
What are the main hormones made by the hypothalamus and released into the posterior pituitary?
-oxytocin (stimulates contraction of the uterus and ejection of milk from breasts)
-antidiuretic hormone (ADH) (stimulates water reabsorption by the kidneys)
What is the thyroid gland composed of and what does it secrete?
-butterfly shaped
-right and left lobes
-secreted hormones thyroxine (T4) and triiodothyronine (T3)
-and parafollicular cells which secrete calcitonin
What do thyroid hormones regulate?
-oxygen use and metabolic rate, cellular metabolism and growth and development
-secretion controlled by TRH from the hypothalamus
What is the function of the parathyroid hormone (PTH)?
-regulate the homeostasis of calcium, magnesium, and phosphate by increasing blood calcium and magnesium levels and decreasing blood phosphate level
Where is the pancreas located and explain the endocrine and exocrine functions it has?
-flattened organ located in the curve of the duodenum
-endocrine= islets of langerhan made up of alpha cells= secrete glucagon (increasing blood glucose levels) and beta cells= secrete insulin (lowers blood glucose levels)
What are the main physiological effects of hypothyroidism?
(under active thyroid gland)
-bradycardia
-cold intolerance
-constipation
-fatigue
-weight gain
What are the main physiological effects of hyperthyroidism?
(over active thyroid function)
-weight loss
-heat intolerance
-diarrhoea
-muscle weakness
