co-ordination and response ✓ Flashcards
how are organisms able to respond to changes in their environment ?
the changes are detected by the receptors (sense organs) a response is then co-ordianted by the brain and a response is carried out by the effector (usually muscles or glands)
what is homeostasis ?
is the maintenance of a constant internal environment
what are some examples of homeostasis ?
- body water content
- body temperature
what is the role of the skin in temperature regulation, in vasodilation ?
in hot weather the muscle cells in the walls of the arterioles relax, this causes dilation of blood vessels, more blood flows through the capillaries, more heat is lost by radiation and the skin appears red
what is the role of the skin in temperature regulation, in vasoconstriction ?
in cold weather the muscles cells in the walls of the arterioles contract, this causes constriction of blood vessels, less blood flows through capillaries, less heat is lost by radiation and skin appears pale
what is the role of the skin in temperature regulation, in sweating ?
the evaporation of the sweat takes heat away from the body cooling you down
what does a co-ordinated response require ?
- stimulus
- receptor
- effector
how does nervous system control responses ?
the sensory neurones take messages from the receptors to the central nervous system (brain and spinal cord), the relay neurones transfer messages from sensory neurones to other nerve cells and the motor neurones take messages from the central nervous system to the effector
how does the hormonal system control responses ?
allow responses if there are changes
what is the difference between the nervous and hormonal system ?
NERVOUS- fast responses, short lasting, nerve cells involved, electrical impulses go along nerves
HORMONAL- slow responses, long lasting, glandular cells that make hormones are involved, hormones transported in the blood
what does the central nervous system consist of ?
- the brain
- the spinal cord
- and is linked to the sense organs by nerves
how does a rapid response occur ?
the stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the CNS
what is the role of the neurotransmitters at synapses ?
they diffuse across the synapses and trigger an impulse in the next neurone
what is the function of a simple reflex arc ?
to make an unthinking action which protects the body from harm
what happens in a reflex arc ?
SENSORY NEURONE receives signal and sends it to a motor neurone through a RELAY NEURONE, MOTOR NEURONE receives signal and creates an instant unthinking action
