Coordination and response Flashcards
What is excretion?
The removal of toxic materials, waste products and excess materials in both plants and animals
What does homeostasis do?
Maintains a constant internal environment
What internal conditions have to be controlled?
Skin - Core body temperature
Kidney - Water and ion content
Lungs - CO2 content in the blood
Pancreas & Liver - Blood glucose level
What is normal body temperature?
37 degrees
Why must the body remain at around 37.5 degrees?
So that enzymes working in the body work at their optimum temperature and don’t denature
What happens if the body gets too cold?
- Blood vessels narrow
(vasoconstriction) - Less blood flows near skins
- Hairs stand to trap insulating air
- Shivering = rapid muscle
contractions which creates heat
What happens if the body gets too hot?
- Blood vessels widen (vasodilation)
- More blood flows near skins surface
- More heat is lost by radiation
- More sweat produced and released
What does the nervous system do?
Detects changes in the environment (stimuli) and co-ordinate a response
What coordinates a response to
a stimulus in an animal?
They have receptors in their sense organs
What does a receptor do?
It’s a special type of cell that detects changes in the environment
What is a sense organ made up of?
lots of receptor cells
What is a stimulus?
change in the environment
What is a response?
A change in an organism triggered by a stimulus
Give 5 examples of sense organs and what they do.
- Mouth/tongue - detects food chemicals
- Eyes - detects light
- Ears - detects vibrations (sound)
- Nose - detects scent
- Skin- Detects pressure, heat + pain
What is the central nervous system made up of?
The brain and spinal cord which is protected by your skeleton
What do receptors do?
Sends an electrical impulse along nerve cells (neurones) to your central nervous system
What is the pathway of nerve impulses?
Stimulus, receptors, sensory neurone, CNS, motor neurone,
effector, response
What job does the long axon have in a nerve cell?
It carries messages over large distances quickly
What job does the Myelin Sheath have in a nerve cell?
increases the speed electrical impulses can travel
What job do dendrites have in a nerve cell?
connects to many other neurones
Name the 3 types of neurones
Sensory, motor and neurone
What is a synapse?
A tiny gap between two neurones
What is the electrical impulse converted to?
A chemical signal that is passed across the synapse
How do nervous impulses travel?
In one direction
Why do reflexes not require you to think about the response and are said to be involuntary/automatic?
To help protect the body from harm
Why does a reflex action bypass the brain?
To instead pass through a relay neurone in the spinal cord to make the action faster
What is the eye?
A sense organ containing receptors that detect change in light
What is the stimulus converted into in an eye?
Electrical impulses that are sent to the brain to form an image
What is the sclera?
The visible, white part of the eye that provides a tough and protective outer coating
What is the Iris?
The coloured ring of muscular tissue that controls the size of the pupil and the amount of light hitting the retina
What is the Cornea?
Curved, transparent section of the sclera in front of the eye that allows light to enter and refract it
What is the Pupil?
A hole in the middle of the iris that allows light to enter
What is the Lens?
A transparent disc that refracts light as it enters the eye and is able to change shape to focus on the retina
What are Ciliary muscles and suspensory ligaments?
A ring of muscle attached to ligaments that are connected to the lens that contract and allow us to focus on objects at different distances
What is the Retina?
Light sensitive layer containing the photoreceptors which initiate the nerve impulse that travels down the optic nerve to the visual centre in the brain
What is the Optic Nerve?
A nerve made of bundles of sensory neurones that connects the eye to the visual centre of the brain. Electrical impulses travel along it
What are the two types of photoreceptors?
Rods and cones
What do cones do?
Detect colour
What do rods do?
Detect dim light
What is a hormone?
Chemical release from a gland
What does homeostasis do?
Maintains a constant internal environment
