Lecture 36 Flashcards
Where is the adrenal gland located? What is its structure?
The adrenal glands are found on top of the kidneys and are composed of two regions, the adrenal cortex and medulla. The cortex is composed of 3 layers, the glomerulosa (outermost), fasciculata (middle) and reticularis (inner layer). The medulla has no layers.
What hormones are secreted by the adrenal cortex layers and medulla?
Glomerulosa secretes aldosterone, fasciculata secretes cortisol, reticularis secretes androgens. The medulla secretes epinephrine and norepinephrine.
What is the common link between the adrenal cortex hormones and what family does each hormone fall under?
The three hormones (aldosterone, cortisol and androgens are all linked by their formation from a cholesterol backbone. The aldosterone is a mineralocorticoid, the cortisol is a glucocorticoid and the androgens are sex steroids.
What is the mechanism by which cortisol reaches the target cell? What metabolic effects does it tend to have?
Cortisol is a lipid soluble hormone and as such must be carried by a carrier protein and follows all the same steps as other lipid soluble hormones. Effects include: increases expression of enzymes involved in gluconeogenesis in the liver, causing the liver to make and release more glucose, stimulates muscle protein breakdown in the muscles and increases fat mobilisation. Also increases glucose uptake by many cells (e.g muscles).
What two factors causes cortisol secretion? What factor will stop the cortisol secretion negative feedback? What are three of the overall effects which cortisol causes which are not metabolic?
Abnormal stress and normal daily variation (low blood glucose levels) will both cause cortisol secretion, of these abnormal stress will cause the secretion to not be affected by the normal negative feedback loop.
Other effects of cortisol include helping cope with stress, suppressing the immune system long term and is essential for maintaining normal blood pressure.
What are 7 specific cortisol functions?
helps influence changes that occur in response to stress such as blood glucose levels, fat, protein and carbohydrate metabolism in order to maintain that blood glucose level, immune responses, anti inflammatory actions, blood pressure , heart and blood vessel tone and contraction and central nervous system activation.
What weffects does low cortisol lead to?
brain fog, cloudy headedness, mild depression, low thyroid function, blood sugar imbalances (hypoglycemia), fatigue (primarily in the morning and mid afternoon), sleep disruption, low blood pressure and inflammation.
What is Addison’s disease?
A disease caused by not enough cortisol or aldosterone. A low cortisol or aldosterone concentration causes adrenocorticotropic hormone secretion to not be inhibited and hence it is secreted heavily, melanocyte-stimulating hormone is released as a byproduct of this and stimulates the synthesis and pigmentation of the skin. Also leads to other effects in common with low cortisol secretion.
What is too much cortisol refered to as?
Cushing’s syndrome.
What family of hormones do Aldosterone, cortisol, epinephrine and norepinephrine fall into?
The water soluble hormones catecholamines.
What causes the medulla to start secreting hormones and what part of the body sends the signal? What process tends to happen at the same time via the same pathway that communicated with the medulla?
The medulla is triggered by stress through the actions of the sympathetic nerve fibers, when it recieves a signal from these fibers it will secrete norepinephrine and epinephrine into the blood stream. At the same time the sympathetic nerve fibers will also send a signal to specific target organs.
What effects does the secretion of epinephrine and norepinephrine lead to? Which cells secrete epinephrine?
Epinephrine and norepinephrine secretion leads to increased heart and respiratory rates, more perspiration, more blood flow to muscles, more muscle strength, more cognitive ability and less gastrointestinal activity. Chromaffin cells are responsible for secreting epinephrine.
What is a key thing to keep in mind about the hypothalamus in regards to nerve stimulation and hormone secretion under stress?
The hypothalamus can do two actions at once, e.g under stress among other things it can stimulate both the sympathetic nervous system and secrete cortisol releasing hormone.
