Topic 7 – Animal Coordination, Control and Homeostasis-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)
2 marks
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
2 Marks
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? (higher)
A hormone 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) (higher)
● Increases heart rate
● Increases blood pressure
● Increases blood flow to muscles
● Increases blood glucose levels
Describe how adrenaline increases heart rate and blood pressure (higher)
● 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
● ∴ heart rate increases, blood pressure increases
Describe how adrenaline increases respiration at muscle tissues (higher)
● Adrenaline binds to specific receptors on cells in the liver
● Triggers breakdown of glycogen stores and release of glucose ∴ blood glucose levels increase
● Increased heart rate causes greater blood flow to muscles ● ∴ muscle cells receive more oxygen and glucose for respiration
What is negative feedback? (higher)
● 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
What is the thyroid gland?
Endocrine gland that produces thyroxine
Where is the thyroid gland located?
In the neck
What is thyroxine? (higher)
A hormone secreted by the thyroid gland that controls metabolic rate, heart rate and temperature.
What is metabolic rate? (higher)
The rate at which biochemical reactions occur in cells
