Coordination and response Flashcards
Describe a reflex arc
Receptor detects …
Impulse moves along sensory neurone to central nervous system (relay neurone)
Neurotransmitters diffuse across synapse
Motor neurone to effector
Effector carries out response (muscle contraction)
What is the central nervous system?
Consists of the brain and spinal cord. Coordinates all responses (movement and reflexes)
Name the 3 different types of neurones and their purpose
Sensory neurones - carry impulses to central nervous system
Relay neurones - decreases response time between sensory and motor
Motor neurones - carry neurones away from central nervous system, to the effector
What is an effector?
Usually a muscle, carries out a response
What is a synapse?
A small gap between 2 neurones
Describe what happens at the synapse
Release of neurotransmitters
Diffuse across the gap (synapse)
Transmitting the impulse between neurones
Advantages of reflexes
Fast
No brain involvement/involuntary
Less damage/harm
How does the eye adjust to looking at a distant object?
Suspensory ligaments contract
Ciliary muscles relax
Lens becomes long and thin (less convex shape)
Less refraction of light
How does the eye adjust to looking at a close object?
Suspensory ligaments relax
Ciliary muscles contract
Lens becomes thicker with a more convex shape
More refraction of light
How does the eye adjust to bright light?
Circular muscles contract
Radial muscles relax
Iris becomes wider
Pupil constricts, letting less light in
How does the eye adjust to dim/no light?
Radial muscles contract
Circular muscles relax
Iris becomes narrower
Pupil dilates to let more light in
What happens if blood glucose is too high?
Pancreas produces the hormone insulin.
Insulin stimulates cells to take glucose in from the bloodstream (particularly from the liver and muscles cells)
In liver and muscle cells excess glucose is converted into glycogen for storage.
What happens if blood glucose is too low?
Pancreas produces the hormone glucagon.
Stimulates liver and muscle cells to convert stored glycogen into glucose to be released into the bloodstream, increases the blood glucose levels.
How does the body respond when it is cold?
Piloerection - Hair stands on end. Warm air becomes trapped underneath the hairs, creating a convection current that acts as a warm insulating layer.
Vasoconstriction - Arterioles supplying the capillaries near the surface of the skin constrict (get narrower). Less blood flows near the surface of the skin so less heat is lost by radiation.
Less sweat released so less heat lost by evaporation.
How does the body respond when it is hot?
Pilorelaxation - Hairs lie flat and so an insulating layer of air isn’t formed. More heat is lost.
Vasodilation - Arterioles supplying the capillaries near the surface of the skin dilate. More blood flows near the surface of the skin, so more heat is lost by radiation.
More sweat is released - When sweat evaporates, heat energy is taken away from the skin as the evaporation of water requires energy.
