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Quick Quiz - hormones
1. How do hormones move around the body?
2. What is the meaning of “target organ”?
3. List 3 endocrine glands.
4. Where is urine produced?
5. What is the chemical name and symbol for common salt?
6. Why are marathon runners in danger of loosing too much salt?
The role of hormones in our
body
Objectives:
To be able to explain:
•the source, role and regulation of thyroxine
•The source, role and regulation of ADH
•The source, role and regulation of aldosterone
•How the blood works as an electrolyte
•Homeostasis of sodium chloride
•Problems associated with too much salt / not enough salt
The role of hormones in our body
Hormones are released
in endocrine glands into
the blood stream.
They then travel around
the body in the blood to
the target organ.
You already know about
the actions of insulin and
glucagon.
The role of hormones in our body
The thyroid gland in our neck makes a hormone
called thyroxine.
The role of hormones in our body
The mineral iodine is needed to make thyroxine.
Deficiency of iodine causes the thyroid gland to
swell – this disease is called goitre.
The role of hormones in our body
Effects of thyroxine:
• Increases and regulates basal
metabolic rate
• Improves oxygen uptake
• Increases heart rate
• Regulates growth and
development
• Regulates body temperature
The role of hormones in our body
Hypothyroidism means a reduced level of thyroid
hormone (thyroxine) causing things to “slow down”.
This can cause various symptoms, the most
common being:
•tiredness,
•weight gain,
•constipation,
•aches,
•dry skin and lifeless hair
•feeling cold.
Treatment is usually easy by
taking a tablet each day to
replace the missing thyroxine.
Treatment usually works well
and symptoms usually go.
The role of hormones in our body
Antidiuretic hormone - ADH
The role of hormones in our body
Antidiuretic hormone - ADH
Roughly 60% of our body mass is water, and
despite wide variation in the amount of water taken
in each day, body water content remains incredibly
stable. This is a good example of HOMEOSTASIS.
Such precise control of body water and solute
concentrations is a function of several hormones
acting on both the kidneys and vascular system.
The main hormone involved in this is ADH.
The role of hormones in our body
Antidiuretic hormone - ADH
The role of hormones in our body
Antidiuretic hormone - ADH
1. Effects on the Kidney
The single most important effect of antidiuretic
hormone is to conserve body water by reducing the
loss of water in urine.
Antidiuretic hormone binds to receptors on cells in the
collecting ducts of the kidney and promotes
reabsorption of water back into the blood.
In the absence of antidiuretic hormone, the collecting
ducts are virtually impermeable to water, and it flows
out as urine.
The role of hormones in our body
Antidiuretic hormone - ADH
1. Effects on
the Kidney
The role of hormones in our body
Antidiuretic hormone - ADH
2. Effects on the Vascular (Blood) System
High concentrations of antidiuretic hormone also
cause constriction of arterioles (vasoconstriction),
which leads to increased arterial pressure.
A negative feedback loop exists so that increased
blood pressure blocks the secretion of more ADH.
The role of hormones in our body
Antidiuretic hormone - ADH
Some facts:
• ADH is made in the hypothalamus (in the brain)
• It is transported from here to the pituitary gland
(another part of the brain) via the nerves.
• It is then released into the blood
• Release of ADH is controlled by the hypothalamus
• The hypothalamus can detect changes in the
water potential of the blood and also changes in
pressure of the blood vessels
• The receptors in the hypothalamus that detect the
changes in water potential are called
osmoreceptors.
The role of hormones in our body
Antidiuretic hormone - ADH
The role of hormones in our body
Aldosterone
This hormone is
made in the adrenal
cortex of the adrenal
glands, near the
kidneys
The role of hormones in our body
Aldosterone
Aldosterone helps to control blood pressure and
concentrations of salt in the blood.
It is made in the adrenal cortex and is carried in the
blood to the kidneys where it acts on the tubules
and collecting ducts.
The role of hormones in our body
Aldosterone
A quick chemistry lesson!
•Na+ = sodium ion
• Cl- = chloride ion
• NaCl = sodium chloride (salt)
• K+ = potassium ion
These are all examples of
electrolytes.
The role of hormones in our body
Aldosterone
Aldosterone has 4 main effects on the kidneys:
•causes the conservation of sodium ions,
•secretion of potassium ions,
•increased water retention (because chloride ions
come with the sodium),
•increased blood pressure (due to water).
The overall effect of aldosterone is to increase
reabsorption of ions and water in the kidney.
The role of hormones in our body
Aldosterone
The blood is a mixture of aqueous electrolytes
which includes sodium and chloride ions.
These ions are important for normal body function
but if too much salt is in the diet it can cause
problems.
The role of hormones in our body
Importance of salt
"Salt" is sodium chloride. By weight, it is 40% sodium
and 60% chloride.
Sodium is an essential nutrient, a mineral that the
body cannot manufacture itself but which is required
for life itself and good health.
Sodium is the major electrolyte responsible for
regulating water balance, pH, and osmotic
pressure. It is also important in nerve conduction.
The role of hormones in our body
Importance of salt
Chloride too, is essential to good health. It preserves
acid-base balance in the body, aids potassium
absorption, supplies the essence of digestive stomach
acid, and enhances the ability of the blood to carry
carbon dioxide from respiring tissues to the lungs.
The role of hormones in our body
Sources of salt
Food is the main source of salt in the diet.
The recommended daily intake for adults is 6g per
day – equivalent to 2.5g of sodium
The role of hormones in our body
How salt is lost from the body
The role of hormones in our body
Consequences of salt deficiency
Severe and prolonged diarrhea can also cause salt deficiency.
Severe diarrhea results in the loss of large amounts of water,
sodium, and various nutrients.
Excessive drinking of beer, which is mainly water and low in
sodium, can also produce salt deficiency when combined with a
poor diet.
Marathon running, under certain conditions can lead to loss of
too much salt. Races can result in the loss of great quantities (8
to 10 liters) of sweat, which contains both sodium and water.
The role of hormones in our body
Consequences of salt deficiency
The role of hormones in our body
Problems of excess salt in the diet
Too much salt in the blood
Lowers the water potential of the blood
Water moves out of the body cells into the
blood by OSMOSIS
More water in the blood
Increased blood pressure
The role of hormones in our body
Hormone
Insulin
Glucagon
Thyroxine
ADH
Aldosterone
Endocrine
gland
Target
Organ
Effect