Download The Endocrine System

The Endocrine System
Lesson Objectives
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By the end of this lesson you should know:
The difference between endocrine and
exocrine glands
Define a hormone
The role of the principle endocrine glands
2 examples of hormone supplements
Exocrine and endocrine glands
Exocrine
glands
Endocrine glands
Definition
Have ducts
or tubes
Have no ducts or
tubes
Examples
Sweat, tear,
salivary
glands, the
liver
Pituitary, thyroid,
parathyroids,
adrenels, pancreas,
ovaries or testes
Hormones
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“A hormone is a chemical
messenger produced by
an endocrine gland and
transported in the
bloodstream to act in
another part of the body
where it has a specific
effect”
Many hormones are
proteins
Some are steroid or lipid
based such as those of
the reproductive system
Hormones are involved in
co-ordinating the body
They interact with the
nervous system in
achieving this function
Comparison of endocrine and nervous systems
Feature
Endocrine
system
Speed of action Slow acting
Nervous
system
Fast acting
Length of
action
Type of
message
Speed of
message
Areas affected
Action lasts a
long time
Chemical
Action lasts a
short time
Electrical
Slow delivery
Fast deliver
Affects many
areas
Affects one
area
The
Endocrine
System
The principal endocrine glands
Gland
Hormone
Function
Pituitary
Human growth
hormone (HGH)
Elongates bones in
the skeleton
Thyroid
Thyroxin
Controls metabolism
Parathyroid
Parathormone
Releases calcium
from bones
Pancreas
Insulin
Causes glucose to
be removed from the
blood
Adrenal
adrenalin
Allows us to respond
to stress
Ovaries or
testes
We will examine this
when studying
human reproduction
Pituitary gland
• Peanut sized gland in
the middle of the
head and is controlled
by the hypothalamus
• Produces many
hormones, e.g. GH,
ADH, TSH, LH, FSH
Hypothalamus
• Links nervous and
endocrine systems
• Secretes hormones that
control the pituitary gland
in response to messages
from the brain and other
hormones
• Releasing hormones &
inhibiting hormones
• e.g. GHRF
Pineal gland
• Tiny gland located
within the brain
• Produces a number of
hormones, best
known one is
melatonin
• Its function is not fully
understood but it
seems to play a role
in biological rhythms
e.g sleep
Thyroid
• Makes the hormone
thyroxin
• Iodine which is found
in seafood and sea
salt is needed to
make thyroxine
• Thyroxine controls
metabolism i.e. rate of
chemical reactions in
the body
Hormone Deficiency and Excess
Deficiency of Thyroxine
Symptoms
• Young children results in reduced physical
mental and physical development – cretinism
• In adults results in reduced metabolic rate,
tiredness, reduced mental and physical activity,
the build up of fluid under the skin and weight
gain (Myxoedema)– in addition the thyroid
glands swell – a condition called goitre
Treatment
• Involves taking tablets of thyroxine or iodine
Excess of Thyroxine
Symptoms
• Causes an increased metabolic rate,
which in turn causes hunger, loss of
weight, heat production, sweating, bulging
eyes and anxiety (Graves disease)
Treatment
• May involve removing a part of the thyroid
or killing part of it using radioactive iodine
Parathyroids
• 4 Parathyroids are
located in the thyroid
gland in the neck
• Produce
parathormone which
controls the release of
calcium from bone
• Problems with this
hormone can result in
brittle bones
Thymus
• The 2 lobes of the
thymus gland are
located behind the
breastbone in the
upper chest
• Produces a hormone
called thymosin which
causes lymphocytes
to mature and
become active
• The thymus begins to
degenerate around
puberty
Adrenals
• Located on top of the
kidneys in the lower
back
• Produce the hormone
adrenalin
Pancreas
Enzymes
Into pancreatic duct
Exocrine gland
Insulin
Into bloodstream
Endocrine gland
Pancreas
• Islets of Langerhans
cells
• Insulin
• Glycogen
• Diabetes
• Most of the cells in the
pancreas produce
enzymes (such as
amylase and lipase)
Hormone supplements
Insulin
• The inability to produce
insulin (or the inability of
cells to absorb insulin)
results in diabetes
Anabolic steroids
• Anabolic steroids
copy the action of the
male hormone
testosterone – in
particular they build
up muscle mass in
the body, reduce fat,
speed up the repair of
injuries and form
stronger bones
What have you learned?
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Do you know…
The difference between endocrine and
exocrine glands?
Can you define a hormone?
The role of the principle endocrine glands?
2 examples of hormone supplements?
Lesson Objectives – Higher
Level
By the end of this lesson you should
understand:
• The control of thyroxine levels through a
negative feedback mechanism
Control of thyroxine level
Goitre
• Caused by an
underproduction of
thyroxine (lack of Iodine
in the diet)
• Causes pituitary to
produce TSH
• Low concentration of
thyroxine in blood causes
the pituitary to produce
TSH
• TSH combines with
iodine to produce
thyroxine
• If there is a shortage of
iodine this can’t happen
• Cured by taking iodine
tablets
What have you learned?
Do you understand….
• The control of thyroxine levels through a
negative feedback mechanism?