3. ● What regulates our body activities ?
● The activities in our bodies are highly complex and need to be regulated so
that every activity takes place at a correct time and in a correct sequence
● For example gastric juice bile and pancreatic juice should be poured only
when food is in it
● This kind of regulation is done by the nervous system and chemical
regulators known as hormones
4. Nervous control
● It is usually immediate or rapid
● Effect is only short lived
● Cannot affect growth
● Transmitted electrochemically
through the nerve fibres and
chemically across synapses
Hormonal control
● Usually slow
● Effect is short term or long lasting
● Can affect growth
● Transmitted chemically through the
blood
Difference between hormonal control and nervous control
5. General properties of hormones
1. Hormones are secreted from their source directly into the blood
2. They act on target organs usually away from their source
3. Hormones are not stored in the body are excreted from the
system
4. Hormones are produced in one species usually show similar
influence in other species
7. Endocrine vs exocrine glands
Endocrine glands
1. Endocrine glands are the type of glands
that secrete into blood stream
2. Are a type of ductless glands
3. Secrete into blood
4. Secrete hormones
Exocrine glands
1. Exocrine glands are the type of glands
which release their secretions at the
surface of an organ
2. May or may not have ducts
3. Pour their secretions directly at the site
of action
4. Secrete enzymes
10. Location, shape, and hormones secreted of
adrenal glands
● Adrenal glands are like caps on top of each kidney
● Each adrenal gland consists of 2 parts adrenal medulla and adrenal cortex
Adrenal medulla
1. Adrenal medulla secretes adrenaline
2. It is a hormone which prepares the
body to meet any fight (face danger) or
flight situations (run away from it)
3. Adrenaline Increases heart rate
4. Increases blood supply to the muscles
decreasing it to the skin
5. More glucose is released by the liver
Adrenal cortex
1. Adrenal cortex secretes cortisone
2. There are 2 types of cortisones
mineralocorticoids and glucocorticoids
3. Mineralocorticoids regulates mineral
metabolism (Na+ and K+ ions)
4. Glucocorticoids regulates carbohydrates,
proteins and fat metabolism
11. Hypo and hypersecretion of adrenal
glands
● So in general cortical hormones
○ Increase blood glucose concentration
○ Influence fat and protein metabolism
○ Regulate salt and water balance
○ Adapt the body to extreme heat or cold , burns and infections
● Hyposecretion of cortisone
○ Hyposecretion of cortisone causes addison’s disease
○ The symptoms are weight loss, nausea, hypoglycemia (low blood sugar)
○ Increased susceptibility of infections
● Hypersecretion of cortisone
○ Hypersecretion of cortisone causes Cushing’s syndrome
○ Symptoms are obesity and hyperglycemia (high blood sugar)
12. Location, shape, and hormones
secreted by pancreas● The pancreas is located behind the stomach in the upper left abdomen.
● Islets of Langerhans are islands of endocrine cells scattered throughout the pancreas.
● It is shaped like a flat pear across the abdomen
● Pancreas is both a duct and ductless gland
● As a duct gland
○ It pours it secretions into the duodenum for digestion
● As a ductless gland
○ It has special group of cells called islets of langerhans in the entire gland
○ They produce 3 type of hormones from 3 different types of cells - insulin from the beta cells,
glucagon from the alpha cells, and somatostatin from the delta cells
13. Functions of Insulin
Hyposecretion and hypersecretion of
insulin
● Functions of insulin
○ Promotes glucose utilisation by the body cells thereby reducing blood sugar level
○ It stimulates deposition of excess glucose of the blood as glycogen in liver and
muscles
● Hyposecretion of insulin
○ Causes diabetes mellitus / hyperglycemia
○ High concentration of sugar in blood
○ Excretes great deal of urine loaded with sugar
○ Feels thirsty frequently because of the loss of water through frequent urination
● Hypersecretion of insulin
○ Causes hypoglycemia
○ Sugar level in blood is low
○ The brain may enter a state of coma if the level becomes too low even for a few
minutes
14. Function of glucagon
● Glucagon is secreted by the alpha cells of the islets of langerhans
● It stimulates breakdown of glycogen in the liver to the glucose
● Thus it raises sugar level in the blood
15. Location, shape, and hormones
secreted by the thyroid gland
● The thyroid gland is a bilobed structure
● It is situated in front of the neck below the larynx]
● The 2 lobes are joined by a narrow connection called isthmus
● It secretes the hormone thyroxine and calcitonin
● Thyroxine regulates the basal metabolism [the rate of cellular oxidation resulting in
heat production at rest]
● An increase in secretion increases metabolism and a decrease in secretion reduces it
● It also influences the general growth of the body
16. Hyposecretion of the thyroid gland
● Hyposecretion of the thyroid gland may lead to 3 conditions - simple
goitre, cretinism, and myxoedema
Simple goitre
● It is the enlargement of the
thyroid is seen as a swelling in
the neck
● It is due to the insufficient
quantity of iodine in food
● This condition is common for
people living in hilly areas
because the soil there does not
contain any iodine and so does
the food
Cretinism
● It is a condition which affects
growth of children showing
dwarfism and mental
retardation
● It is due to defective
development or early
degeneration
myxoedema
● It is a condition which affects
adults if his thyroid does not
function properly
● Person becomes sluggish with
swelling of face and hands.
17. Hypersecretion of the thyroid gland
● Excess of thyroxine secretion causes exophthalmic goitre
● Symptoms include
○ Forms a goitre in the neck
○ Rapid heartbeat
○ Shortness of breath
○ Eyes are protruded
18. Location and shape of the pituitary
gland
● The pituitary gland is also called the master gland
● It is the size of a pea and hangs from the base of the midbrain below the thalamus
● It is called the master gland because it seems to control all the other glands
● The pituitary gland has 2 distinct lobes the anterior pituitary and posterior pituitary
19. Hormones secreted by the anterior
pituitary
● Growth hormone is essential for normal growth
● It is also called the somatotropin [somatic = body, tropic = stimulating]
● The deficiency of the growth hormone in childhood results in dwarfism
● The oversecretion of the growth hormone in childhood results in gigantism (the Long bones lengthen beyond the
normal)
● If oversecretion of growth hormone suddenly occurs in an adult there will be excessive growth of bones In the
face, hands, ad feet
● The person also develops a large nose and thick lips
Thyroid stimulating hormone activates thyroid to secrete thyroxin
Gonad-stimulating hormones regulate the activities of the testes and ovaries
Adrenocorticotropic hormone regulates the activity of the adrenal Cortex
20. Hormones secreted by the posterior
pituitary
● The posterior lobe produces 2 hormones - vasopressin and oxytocin
● The antidiuretic hormone or vasopressin constricts blood vessels with rise in blood
pressure
● It also acts on the kidneys increasing reabsorption of water from the kidney tubules
● Deficiency of vasopressin causes diabetes insipidus in which urination is frequent
● This results in loss of water from the body
● Another hormone secreted by the posterior pituitary is oxytocin
● It stimulates vigorous contractions leading to the birth of a baby
● Also stimulates milk ejection
