Adrenals: Anatomy & Function
Adrenal glands, which are also called suprarenal glands, are
small, triangular glands located on top of both kidneys.
An adrenal gland is made of two parts: the outer region is
called the adrenal cortex and the inner region is called the
adrenal medulla.
The adrenal glands work interactively with the hypothalamus
and pituitary gland in the following process:the hypothalamus
produces corticotropin-releasing hormones, which stimulate
the pituitary gland.the pituitary gland, in turn, produces
corticotropin hormones, which stimulate the adrenal glands
to produce corticosteroid hormones.
What is the Adrenal
Cortex
The adrenal cortex, the outer portion of the adrenal gland, secretes
hormones that have an effect on the body's metabolism, on chemicals in the
blood, and on certain body characteristics.
The adrenal cortex secretes corticosteroids and other hormones directly into
the bloodstream.
The hormones produced by the adrenal cortex include:mcorticosteroid
hormoneshydrocortisone hormone - this hormone, also known as cortisol,
controls the body's use of fats, proteins, and carbohydrates.corticosterone this hormone, together with hydrocortisone hormones, suppresses
inflammatory reactions in the body and also affects the immune
system.aldosterone hormone - this hormone inhibits the level of sodium
excreted into the urine, maintaining blood volume and blood
pressure.androgenic steroids (androgen hormones) - these hormones have
minimal effect on the development of male characteristics.
What is the Adrenal Medulla
The adrenal medulla, the inner part of the adrenal gland, is
not essential to life, but helps a person in coping with
physical and emotional stress.
The adrenal medulla secretes the following
hormones:epinephrine (also called adrenaline) - this hormone
increases the heart rate and force of heart contractions,
facilitates blood flow to the muscles and brain, causes
relaxation of smooth muscles, helps with conversion of
glycogen to glucose in the liver, and other
activities. norepinephrine (also called noradrenaline) - this
hormone has little effect on smooth muscle, metabolic
processes, and cardiac output, but has strong
vasoconstrictive effects, thus increasing blood pressure.
Organ Interactions:
When you are (or feel) threatened physically or
emotionally, your sympathetic nervous system
brings about the “flight-or-flight” response to
help you cope with the stressful situation. One of
the organs it stimulates is the adrenal medulla,
which literally pumps its hormones into the
bloodstream to enhance and prolong the effects
of the neurotransmitters of the sympathetic
nervous system.
Organs Interactions:
An organ that interacts with the adrenals glands are the kidneys.
Mineralocorticoids, mainly aldosterone, are a steroid hormone released by the adrenal
cortex. This steroid hormone regulates the mineral (salt) content of the blood.
Mineralocorticoids regulate the concentrations of sodium and potassium ions. By
regulating the salt content of the blood, mineralocorticoids target the kidney tubules.
When blood levels of aldosterone rise, the kidney tubule cells regain increasing
amounts of sodium ions and secrete more potassium ions into the urine. When sodium
is reabsorbed, water follows. Mineralocorticoids control water and electrolyte balance
in the body.
Another organ that interacts with the adrenal glands is the heart.
A hormone released by the heart, atrial natriuretic peptide (ANP), prevents aldosterone
release. ANP’s goal is to reduce blood volume and blood pressure.
Addison’s Disease
Also known as Adrenal Insufficiency.
Occurs when your adrenal glands do not secrete adrenal cortex
hormones such as cortisol (helps in regulating blood sugar & blood
pressure, decreases immune responses) and aldosterone (increases
reabsorbing water & sodium and secreting of potassium).
Symptoms of Addison’s include fatigue, weight loss, weak muscles, low
blood pressure, and changes in skin color, as well as hypoglycemia (low
blood sugar) and difficulty managing stress.
Addison’s is treated by taking pills that contain the hormones needed.
In some cases, surgery is necessary and injections of hormones are
given. If Addison’s remains untreated, it can be deadly.
Hyperpigmentation
Pheochromocytoma
Currently, this tumor is the only noted disease of the adrenal
medulla. It can occur in one or both of the adrenal glands.
It can release large amounts of epinephrine and norepinephrine.
Patients can experience symptoms of reoccurring phases of high
blood pressure, anxiety, headaches, & heart palpitations. Others
experience constant hypertension.
Some signs can be treated with medicines that inhibit the activity
of the epinephrine and norepinephrine. Surgery is the beneficial
option because the entire tumor is removed.
Conn’s Syndrome
Also known as primary hyperaldosteronism.
Occurs when the adrenal glands produce too much
aldosterone.
The main cause is hypertension and it is usually the only
symptom.
This disease can be found if a person has larger adrenals
or has a benign tumor on an adrenal.
It can be treated with a diet low in salt and potassium
supplements.