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UNIT 4: ENDOCRINE SYSTEM (CHEMICAL COORDINATION)
(Campbell et.al, 2010 – CHAPTER 45)
ENDOCRINE SYSTEM The nervous system and the endocrine system work together
To regulate the activities of the other systems in the body.
Both systems use chemical signals when they respond to changes.
But they have different means of delivering the signals
Differences between the CNS and the endocrine system
Central nervous system
Endocrine system
Transmits electrical impulses
Transmits chemical biological messengers
Impulse send through neurons through neurotransmitters
Transmits message through bloodstream by means of hormones
Fast reaction Slow reactionReaction doesn’t last a long time
Reaction lasts a long time
ENDOCRINE GLANDSEndocrine system consist of different endocrine glands in the body.
Endocrine glands are ductless .And produce and secrete hormones. That are transported through the blood
in the blood vessels of the body.Towards a specific target organ where
it has a specific function.
ENDOCRINE GLANDSThe target cells only respond to specific hormones secreted by specific endocrine glands.
If the cell can respond to the hormone, the hormone and the receptor proteins bind together as a key fits into a lock.
EXOCRINE GLANDS Exocrine glands have ducts
and secrete chemicals like enzymes into these ducts which takes it to the lumen of organs or to the outside of the body.
HORMONES (CHEMICAL SIGNALS)
• Hormones are biological chemical messengers that help cells, body parts and even individuals to communicate with one another.
• Most hormones are proteins, but the steroids are fats.
• Hormones can inhibit or stimulate a reaction.
• Hormones are temperature, pH and substrate sensitive
ENDOCRINE GLANDS1. PITUITARY GLAND2. THYROID3. ADRENAL GLAND4. PINEAL GLAND5. PARATHYROID GLAND6. THYMUS7. PANCREAS8. GONADS
ENDOCRINE GLANDS
HYPOTHALAMUS AND PITUITARY GLAND
The hypothalamus controls the glandular secretions of the pituitary gland
PITUITARY GLAND Attached to a stalk onto the hypothalamus. Consist of a posterior- and anterior
pituitary. Posterior- (Pars nervosa) produce and
secrete the following hormones: ADH and Oxytocin.
Anterior- (Pars distalis) produce and secrete the following hormones: TSH, ACTH, prolactin, growth hormone, FSH and LH.
Posterior pituitary gland hormones: ADH and Oxytocin
ADH: Regulate the water reabsorption through the kidneys by changing the permeability of the renal tubules.
Oxytocin: Stimulates the uterus wall to contract during the process of giving birth and stimulates milk production during pregnancy.
How ADH functions
Anterior pituitary gland hormones: TSHACTH
prolactingrowth hormone
FSH LH.
TSH (THYROID STIMULATING HORMONE)
Stimulates the thyroid gland to secrete thyroxin.
Function by means of a negative feedback reaction.
TSH (THYROID STIMULATING HORMONE)
ACTH (Adrenocorticotropic hormone)
Stimulates the adrenal cortex to produce glucocorticoid that is released during stress.
PROLACTIN Control milk production in
females
Growth hormone
Promotes skeletal and muscular growth.
It stimulates the rate at which amino acids enter cells and protein synthesis occurs.
It promotes fat metabolism as opposed to glucose metabolism.
Growth hormone
DISORDERS CAUSED BY THE UNDERSECRETION OF GROWTH HORMONE
When a too little GH has been produced during childhood.
Normal proportions but small stature.
Low blood pressure. Can be rectified by
injecting the child with growth hormone
PITUITARY DWARFISM
DISORDERS CAUSED BY THE OVERSECRETION OF
GROWTH HORMONE
If too much GH have been produced during childhood.
Excessive growth of muscles and bones.
Usually have diabetes. Much taller than normal
children/adults.
GIGANTISM
Disorder of GH : ACROMEGALY
Caused by overproduction of GH in adults.
Enlargement of bones in the face, fingers and toes as a person ages.
FEEDBACK MECHANISMS CAUSED BY HORMONE ACTION
NEGATIVE FEEDBACK MECHANISM
FSH (follicle stimulating hormone) and LH
Stimulates the gonads (testis and ovaries) to produce sex hormones and gametes.
THYROID GLAND Located in the neck
around the trachea. Red – high blood volume 2 lobes connected by
isthmus. Uses Iodine to produce
the hormone thyroxin Thyroxin production is
stimulated by TSH secreted by the Hypophysis
Also secretes the hormone calcitonin
STRUCTURE OF THYROID GLAND
FUNCTIONS OF THYROXIN
Increase the metabolic rate of a person.
No specific target organ, they stimulate all cells of the body to metabolize at a faster rate.
Promotes the metabolism of glucose so that more energy is released.
DISORDERS OF THE THYROID GLAND
Disorder caused by the lack of Iodine in the diet.
Without iodine the thyroid is unable to produce thyroxin and continued anterior pituitary stimulation causes the gland to enlarge.
Retarded growth during infancy.
Body is short and stocky with mental retardation
SIMPLE GOITERCONGENITAL HYPOTHYROIDISM
Disorder of Thyroid Gland: Exophthalmic goiter
This goiter is due to an overactive thyroid gland
The eyes of a person protrudes because of edema in the eye socket tissue
Person is hyperactive, nervous, irritable, suffers from insomnia.
Sweat excessively and is heat sensitive.
Enlarged thyroid can be surgically removed and treated with radioactive iodine.
FUNCTIONS OF CALCITONIN
Regulates the Calcium level in the blood.
Calcitonin brings about the deposit of calcium in the bones when the level of calcium in the blood is too high.
When the blood calcium level lowers to normal, the release of calcitonin by the thyroid is inhibited.
This lower level of calcium in the blood, stimulates the release of parathyroid hormone (PTH) by the parathyroid glands.
PARATHYROID GLAND 4 parathyroid glands are located on the
thyroid. Secretes the hormone: Parathyroid
Hormone (PTH) PTH corrects a low blood calcium level PTH promotes the release of calcium by
the bones PTH promotes the reabsorption of
calcium from the kidneys PTH brings about the activation of
Vitamin D.
PARATHYROID GLAND
DISORDERS OF THE PARATHYROID GLAND
Insufficient PTH secreted.
Dramatic drop in blood calcium levels.
The body shakes from continuous muscle contraction
The blood calcium level becomes abnormally high.
Bones become soft and fragile.
Person irritable and prone to get kidney stones
TETANY HYPERPARATHYROIDISM
CALCITONIN AND PTH – ANTAGONISTIC HORMONES
These 2 hormones (Calcitonin and PTH) are antagonistic.
Both hormones work together regulate the blood calcium level.
When the blood calcium level is high – the thyroid gland secretes calcitonin.
When the blood calcium level is low – the parathyroid gland releases PTH
ADRENAL GLAND
Located ontop of the kidneys.
Consist of an inner part the adrenal medulla and outer part called the adrenal cortex.
The adrenal medulla secretes 2 hormones: adrenalin and nor-adrenalin.
STRUCTURE
FUNCTIONS OF ADRENALIN AND NOR-ADRENALIN
Brings about all the bodily changes that occur when an individual reacts to an emergency situation.
Effect of this hormone is short term. Released during fright,
anxiousness and anger. Increase heart rate. Increase blood flow and blood
pressure.
ADRENALIN and NOR-ADRENALIN
FUNCTIONS OF ADRENALIN AND NOR-ADRENALIN
Muscles absorb glucose for energy to react.
More blood (oxygen) to brain. Actions of the digestive system
inhibited. Pupils dilate to observe clearly
ADRENALIN and NOR-ADRENALIN
MALFUNCTION OF THE ADRENAL CORTEX
Bronzing of the skin
Excess amount of ACTH.
This lead to a buildup of melanin.
Excess cortisol in blood
Sub-cutaneous fat deposits.
ADDISON DISEASE CUSHING SYNDROME
PANCREAS The pancreas consist of exocrine tissue
with ducts that produce and release digestive juice (pancreatic sap) into the duodenum, and endocrine tissue without ducts that secrete hormones directly into the bloodstream.
The endocrine tissue is know as the Islets of Langerhans and it secretes two hormones: Insulin and glucagon (antagonistic hormones).
PANCREAS
FUNCTIONS OF INSULIN IN THE PANCREAS
If blood sugar (glucose) level is high. Insulin is secreted. Insulin stimulates the uptake of glucose
by the cells (liver, muscle and adipose) In the liver and muscles it is stored as
glycogen. Muscle cells break it down for energy. Fat cells convert it to glycerol for the
forming of fat. Therefore insulin lowers the blood
sugar level.
FUNCTIONS OF GLUCAGON
When the blood sugar level is low.
Glucagon is secreted into the blood.
Glucagon stimulates the liver cells to convert glycogen into glucose for energy production.
Therefore glucagon raises the blood sugar level.
DIABETES MELLITUS Type 1 Diabetes: Pancreas is not
producing insulin Islets of Langerhans
damaged. Glucose accumulate
in blood. Coma results if not
treated with insulin injections.
Treatment of Diabetes:
Self study
TESTIS AND OVARIES Testis produce
testosterone (male sex hormone)
Stimulates the formation of male traits during puberty
Stimulates oil and sweat glands.
Stimulates hairloss (baldness)
Ovaries produce estrogen and progesterone (female sex hormones)
Estrogen stimulates growth of the uterus and vagina during puberty and secondary sexual female traits.
Stimulate egg production and preparation of the uterus for pregnancy.
Progesterone prepare the uterus wall for possible implantation of an embryo.
HORMONES PRODUCED BY THE TESTIS HORMONES PRODUCED BY THE
OVARIES
Effects of testosterone on males
Effects of estrogen and progesterone in females