Hormonal Control Flashcards
What is the endocrine system?
A network of glands that produce and
secrete hormones into the bloodstream
What is a hormone?
● A cell signalling molecule produced by
endocrine glands and released into the blood
● Travels to a target organ and binds to
receptors on effectors initiating a response
Compare the endocrine and nervous systems (4)
What they use?
What travels where?
Speed of Response?
How long it lasts?
Endocrine system:
-Uses hormones
-Hormones travel in the bloodstream to
the target organ
-Slower response
-Lasts until all hormones have broken
down which takes a long amount of time
Nervous system:
-Uses nerve impulses
-Nerve impulses travel via neurones to
the effectors
-Faster response
-Lasts until the nerve impulse stops which
takes a short amount of time
What is the pituitary gland?
Described as the ‘master gland’
Endocrine gland that produces hormones which
control other glands (e.g. adrenal glands)
What are the adrenal glands?
Endocrine glands that produce
adrenaline
Where are the adrenal glands located?
Above the kidneys
What is adrenaline?
Ahormone produced by the adrenal glands
that is involved in the ‘fight or flight’
response (where the body prepares to
confront danger or flee from it)
State the effects of adrenaline on the body (4)
● Increases heart rate
● Increases blood pressure
● Increases blood flow to muscles
● Increases blood glucose levels
Describe how adrenaline increases heart rate and blood pressure
● Secreted by the adrenal glands, travels in the blood to the heart
● Binds to specific receptors on cells in the heart
● Causes heart muscle to contract more forcefully and frequently
● Therefore, heart rate increases, blood pressure increases
Describe how adrenaline increases respiration at muscle tissues
● Adrenaline binds to specific receptors on cells in the liver
● Triggers breakdown of glycogen stores and release of glucose
therefore blood glucose levels increase
● Increased heart rate causes greater blood flow to muscles
● Therefore muscle cells receive more oxygen and glucose for respiration
What is negative feedback?
● A corrective mechanism that allows only small shifts
from a set point
● It reverses a change in conditions e.g. if the concentration
of a hormone increases, negative feedback systems work
to reduce the concentration back to normal level
Where is the thyroid gland located?
In the neck
What is thyroxine?
A hormone secreted by the thyroid gland
that controls metabolic rate, heart rate
and temperature
What is metabolic rate?
The rate at which biochemical reactions
occur in cells
Describe how thyroxine is released
● Hypothalamus secretes TRH
● TRH stimulates secretion of TSH from pituitary gland
● TSH stimulates the release of thyroxine from the
thyroid gland
