HUMAN
ENDOCRINE SYSTEM
BY:M.SAIDI
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TOPIC COVARAGE
Introduction
endocrine and an exocrine gland
hormones
Negative feedback mechanism
Introduction:
Homeostasis
Homeostasis through negative
feedback
Thermoregulation
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INTRODUCTION
endocrine system is the collection
of glands that produce hormones that
regulate metabolism, growth and
development, tissue function, sexual
function, reproduction, sleep, and
mood, among other things.
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ENDOCRINE GLANDS
(Ductless)
release chemical
(hormones) substances
directly into the
bloodstream or tissues of
the body.
EXOCRINE GLANDS
release chemical
substances through ducts
to outside the body or onto
another surface within the
body ThunderEDUC
HORMONES:
These are organic compounds proteins
in nature that act as messengers
needed in small amounts in the body.
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(hypophysis)
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Pituitary gland):
Hypothalamus: GH -Controls growth
ADH-Controls the TSH -Stimulates thyroid gland to secrete
concentration of water in thyroxin
the blood FSH – stimulates the development of the
follicle in the ovaries
LH – stimulates ovulation, and
stimulates development of the corpus
Adrenal gland: luteum
Adrenalin -Increases, Prolactin – stimulates the mammary
heartbeat, blood glands to secrete milk
pressure ,conversion from
glycogen to glucose, Thyroid gland:
skeletal muscle tone, rate Thyroxin: Controls basic
and depth of breathing , metabolic rate
diameter of pupils etc
Aldosterone -Regulates
salt concentration in the
blood Pancreas:
Glucagon -Stimulates
conversion of glycogen to
Ovary: glucose
Oestrogen– stimulates Insulin- Stimulates
puberty in females, conversion of glucose to
promotes thickening of glycogen.
the endometrium
Progesterone – Testes:
promotes thickening of Testosterone-Stimulates the
the endometrium, maturation of sperm cells
maintains pregnancy ThunderEDUC Stimulates puberty in males
Questions
Study the diagram below and answer the
questions that follow.
A hormone secreted by one of the glands
labelled A to D has the following effects:
Heartbeat increases
Vasoconstriction of blood vessels to the gut
Dilation of pupils
2.2.1 Give the letter and name of the gland
that secretes the hormone which brings
about the changes listed above. (2)
2.2.2 Explain the significance of each of the
following changes:
(a) Heartbeat increases (2)
(b) Pupils dilate (2)
2.2.3 Explain the relationship between
gland A and the kidney on a hot day.
(6)
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MEMORANDUM ThunderEDUC
2.2.1 C adrenal gland (2)
2.2.2 (a) More blood can be pumped to organs that need
it to supply oxygen and glucose (2)
(b) More light can be directed to the retina for
better vision (2)
2.2.3 On a hot day, the body will produce sweat for
thermoregulation
So water that would be lost in urine needs to be
conserved
Gland A (pituitary) releases ADH / vasopressin when
the water level of the blood passing through the
hypothalamus is detected to be lower
ADH travels via the blood to its target organ, the
kidney
ADH causes the collecting ducts to become more
permeable to water
So more water is thus re-absorbed from the urine /
less is lost in urine (any 6) (6)
NEGATIVE FEEDBACK MECHANISM
Is a mechanisms operate in the human body to
detect changes or imbalances in the internal
environment and to restore the balance.
general sequence of events in a negative
feedback mechanism
an imbalance is detected by the receptor
a control centre is stimulated
the control centre responds
a message sent to target organ/s (effectors)
the effectors responds it opposes (reverses) the
imbalance
balance is restored
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Negative feed back
mechanism
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THYROXIN
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DISORDERS OF THYROID GLAND
1. Hyperthyroidism
(overactive thyroid) occurs when thyroid gland produces
too much of the hormone thyroxine.
Hyperthyroidism can accelerate the body's metabolism,
causing weight loss and a rapid or irregular heartbeat
Examples include Goitre, is a swelling in the neck
resulting from an enlarged thyroid gland caused by iodine
deficiency
2. 1. Hypothyroidism
Occurs thyroid gland can't make enough thyroid
hormone to keep the body running normally eg
Myxoedema
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EACH STEP AHEAD
MAKES A DIFFERENCE
BY:M.SAIDI
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