Adrenal Cortex Flashcards
Location of the structure of adrenal glands
-sit on top of the kidneys and each gland consists of
an outer Cortex and
an inner Medulla
-The adrenal cortex is composed of regular endocrine tissue
-adrenal medulla is made of neurosecretory tissue
-Each of these tissues synthesizes and secretes a different set of hormones
Adrenal cortex structure
Secretes lipid-based steroid hormones, called “corticosteroids” – “cortico” as in “cortex”
MINERALOCORTICOIDS: Aldosterone is the main one
in Zona Glamerulosa
GLUCOCORTICOIDS: Cortisol (hydrocortisone) is the main one
in Zone faciculata
GONADOCORTICOIDS:Androgens
Testosterone is the main one
in Zona reticularis
Adrenal Medulla
Secretes catecholamine's such as epinephrine (adrenalin) and norepinephrine (noradrenalin)
Mineralocorticoids
(aldosterone)
- controls sodium balance
- Aldosterone reduces the secretion of sodium from the body
- the primary target is the distal parts of the kidney tubules
- increases sodium reabsorption and water retention in exchange for the elimination of potassium and hydrogen ions, when blood pressure drops
- adjusts sodium lvls and influences potassium and pH levels in the blood
- sodium ions cause water reabsorption, and aldosterone promotes water retention by the body
Aldosterone secreation is stimulated by decreasing
- blood volume
- blood pressure
- sodium loss
- rise in blood potassium lvls
what are the steps of the renin-angiotensin-aldosterone system
- bp or BV falls, cells from juxtaglomerular complex in kidneys are excited
- cells respond by releasing renin into the blood.
- Renin(enzyme) cleaves off part of the plasma protein angiotensinogen and turns into angiotensin I.
Angiotensin I circulates to lungs, where Angiotensin Converting Enzyme (ACE) turns it into angiotensin II. - Angiotensin II circulates to the adrenal cortex where it stimulates the zona glomerulosa cells to release aldosterone.
Negative feedback renin-angiotensin-aldosterone system
As water is retained, the volume of blood increases. The increased volume of blood creates higher blood pressure – which then causes the renin-angiotensin-aldosterone system to stop
Glucocorticoids
Cortisol (secreted in significant quantities) or hydrocortisone
Cortisone
Corticosterone
in Zona faciculata
Target organs for Glucocorticoids
widespread required for maintenance of: Arteriolar tone Blood pressure Glomerular filtration rate (GFR) Mobilisation of liver glycogen Body’s response to stress (mechanism unknown) Keep the blood glucose levels fairly constant
Cortisol can also cause weak mineralocorticoid activity (triggers aldosterone release in times of stress).
Hormonal stimulation of glucocorticoids
By the HPA axis hypothalamic/pituitary/adrenal axis
With stress, hypothalamus sends Corticotropin- Releasing Hormone/Factor(CRH or CRF) to anterior pituitary( adenohypophysis)
anterior pituitary secretes Adrenocorticotropic Hormone (ACTH) in a pulsatile fashion into the blood – not in a continuous stream
ACTH goes to the adrenal cortex where it stimulates glucocorticoid (cortisol) secretion
Cortisol is then carried in the blood, bound to a corticosteroid-binding protein all around the body for cells to use – it is essential for life
Corticotrophin Releasing Hormone/Factor
(CRH/CRF) negative feedback
secretion is inhibited by Increasing plasma concentrations of Corticosteroids (cortisol) and adrenocorticotrophic hormone concentration increase, it inhibits Corticotrophin Releasing Hormone (CRH) and Adrenocorticotropic Hormone (ACTH) releasing
Describe what Cortisol is
(Glucocorticoid receptors are found in the cells of most vertebrate tissues) - Cortisol is essential for life.
Enables the body deal with stressful situations within minutes
Physical: trauma, surgery, exercise
Psychological: anxiety, depression, crowding (sardine syndrome)
Physiological: fasting, hypoglycemia, fever, infection, inflammation
Regulates a variety of important cardiovascular, metabolic, immunologic, and homeostatic functions including water balance
People with adrenal insufficiency: these stresses can cause hypotension, shock and death.
Gonadocorticoids
sex hormones produced by the adrenal cortex
Zona Reticularis
weak androgens (male sex hormones) that convert to testosterone in the tissue cells or are convert into oestrogen in females
Small quantities of oestrogens are also produced by the adrenal cortex
Both (male & female) sex hormones promote skeletal muscle mass growth in adolescents
male hormones from adrenal gland stimulate the growth of axillary and pubic hair at puberty in females
male hormones help to sustain the sex drive, or libido, in both men and women
source of oestrogen after menopause
Production of Gonadocorticoids
The amount of gonadocorticoids produced by the adrenal cortex is insignificant compared to the amounts made by the gonads during late puberty and adulthood
Production is stimulated by Adrenocorticotropic Hormone (ACTH)
Hyposecretion from adrenal cortex
when deficiency of cortisol usually accompanied by a deficiency in aldosterone
ex: addisons disease
Addison’s Disease
signs and symptoms
Tiredness, weakness, and lethargy Anorexia and nausea Pigmentation (“bronzing” – suntan look) Weight loss Dizziness Postural hypotension Impotence or amenorrhoea
