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KS4 Biology
Hormones
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Contents
Hormones
The endocrine system
Endocrine glands
Blood glucose regulation
Summary quiz
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Hormones and the endocrine system
What exactly are hormones?
What effect do hormones have on the body?
To understand hormones you need to know about the
endocrine system and how it works.
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The endocrine system
The endocrine system coordinates the
body’s organs so that they work together.
The endocrine system is based on the
production of chemical messengers
called hormones.
Hormones are produced by glands
(endocrine glands) in different parts of
the body. These chemical messengers
are produced in very small quantities
and are transported in the blood.
Hormones control body processes that require several
organs of the body to interact for a combined effect.
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What do hormones do?
Hormones travel slower than nervous
impulses but cause longer-lasting effects.
They are delivered to all parts of the
body but can have local effects.
Hormones are used to stabilize the
body’s internal environment through
homeostasis and also coordinate
longer-term processes such as
growth and sexual development.
Over- or under-activity of some endocrine glands
can cause functional disorders such as diabetes.
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Which body system?
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Contents
Hormones
The endocrine system
Endocrine glands
Blood glucose regulation
Summary quiz
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Endocrine glands – thyroid
Produces the hormone thyroxine:
thyroid
 Regulates rate of metabolism.
 Excess causes hyperactivity.
 Deficiency causes weight gain
and sluggishness.
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Endocrine glands – adrenal glands
Produce the hormone adrenalin.
Adrenaline causes the ‘fight or flight’
response resulting in:
 Increased heart rate and breathing
rate.
adrenal
glands
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 Blood diverted to the muscles.
 Increased respiration to increase
the amount of glucose in the blood.
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Endocrine glands – reproductive organs
In females, ovaries produce several
hormones:
oestrogen
 Controls the development of female
secondary sexual characteristics.
 Regulates menstrual cycle.
ovaries
progesterone
 Thickens uterine wall.
 Prevents contractions until a baby is
being born.
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Endocrine glands – reproductive organs
In males, testes produce the hormone
testosterone:
 Promotes the development of male
secondary sexual characteristics.
testes
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Endocrine glands – pancreas
Produces the hormone insulin:
 Controls the conversion of blood
glucose to insoluble glycogen,
which is stored in the liver.
 Increases metabolic rate by
stimulating cellular glucose uptake.
pancreas
 Increases protein synthesis in some
cells.
 Deficiency causes the condition
“sugar diabetes”, where the blood
sugar level is unregulated.
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Endocrine glands – pancreas
Produces the hormone glucagon:
 Controls the conversion of
insoluble glycogen to glucose
in the liver.
pancreas
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Endocrine glands – pituitary gland
pituitary
gland
Produces several hormones:
growth hormone
 Promotes bone and muscular
growth.
antidiuretic hormone (ADH)
 Controls reabsorption of water into
the blood by kidneys.
thyroid stimulating hormone (TSH)
 Controls the endocrine function of
the thyroid gland.
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Endocrine glands – pituitary gland
pituitary
gland
Produces several specific hormones
in females:
follicle stimulating hormone (FSH)
 Causes the follicle in the ovary to
develop and secrete oestrogen.
luteinizing hormone (LH)
 With FSH and other hormones
causes ovulation.
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Name that gland
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Match hormones to glands
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Contents
Hormones
The endocrine system
Endocrine glands
Blood glucose regulation
Summary quiz
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Negative feedback
Some hormones affect only one target organ,
but most affect more than one.
When the hormone has had the desired
effect, further production of the hormone
needs to be controlled.
Hormone production is controlled by a
process called negative feedback.
The regulation of blood glucose level is an
example of negative feedback.
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Negative feedback – blood glucose
Which of these parts of the body are involved in the
negative feedback process that regulates blood glucose?
The brain, the pancreas and the liver are all involved
in regulating blood glucose.
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Negative feedback – high blood glucose
The brain detects the level of glucose in the blood.
When the level of blood glucose increases above normal,
what hormone does the pancreas release?
increased blood glucose
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Negative feedback – high blood glucose
The pancreas is stimulated to release insulin.
What effect does this have?
The insulin stimulates the liver to take glucose from the
blood and convert into glycogen, which is stored in the liver.
increased blood glucose
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insulin
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Negative feedback – high blood glucose
The level of glucose in the blood decreases, causing the
pancreas to stop producing insulin.
What would happen if the pancreas kept on producing insulin?
increased blood glucose
insulin
blood glucose
returns to normal
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Negative feedback – low blood glucose
Negative feedback also occurs when the blood glucose level
decreases below normal.
This time the brain detects decreased blood glucose and so
the pancreas is stimulated to release which hormone?
decreased blood glucose
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Negative feedback – low blood glucose
The pancreas produces the hormone glucagon.
Glucagon stimulates the liver to convert glycogen back to
glucose and release this glucose into the bloodstream.
decreased blood glucose
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glucagon
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Negative feedback – low blood glucose
The level of glucose in the blood increases, causing the
pancreas to stop producing glucagon.
What would happen if the pancreas kept on producing
glucagon?
decreased blood glucose
glucagon
blood glucose
returns to normal
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Blood glucose activity
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When hormones go wrong – diabetes
What happens if the pancreas
is unable to produce the
hormone insulin?
Lack of insulin production
means that the blood glucose
level is unregulated and causes
the condition known as “sugar diabetes”.
After a person with diabetes has eaten, their blood glucose
level increases. What happens to this glucose?
The absence of insulin means that glucose is not converted
to glycogen and stored in the liver, so the blood of a
diabetic contains extra glucose.
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When hormones go wrong – diabetes
Glucose is essential for
the body, so why is excess
glucose a danger for
people with diabetes?
The ability of the kidneys to
absorb glucose is also exceeded,
so the excess is excreted in urine.
When the glucose is used up, coma and convulsions may
occur. So how is diabetes controlled?
Regular insulin injections and a careful diet can control
the condition.
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Contents
Hormones
The endocrine system
Endocrine glands
Blood glucose regulation
Summary quiz
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Multiple-choice quiz
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