Response and regulation Flashcards
What are sense organs?
Sense organs are groups of receptor cells that respond to certain stimuli.
Which sense organs are there and what are their stimuli?
Eye - light
Ears - sound
Nose - chemicals (in the air)
Tongue - chemicals (in food)
Skin - touch, temperature and pressure
What is the nervous system?
The nervous system consists of the brain, spinal cord and nerves. When a stimuli is detected, it is sent as an electrical impulse along neurones to the central nervous system so that the brain can decide how to react.
What are the properties of reflex actions?
protective, automatic, fast
What are some examples of reflexes and what are they for?
Blinking - protection of the eye
Change in pupil diameter - protection of the retina
Withdrawal - protection from harm to the body
Describe a reflex arc
stimulus -> receptor -> sensory neurone -> co-ordinator -> motor neurone -> effector -> response
The co-ordinator is always either the brain or the spinal cord, and the effector is always a muscle or a gland.
There is a relay neurone and synapses between the sensory neurone and the motor neurone.
What would happen when you touch something hot?
The stimulus (heat) is detected by the receptors in the skin. The receptor responds by sending an electrical impulse along a sensory neurone to the co-ordinator (the spinal cord). The electrical impulse is passed to a relay neurone inside the spinal cord and then on to the motor neurone. Between each neurone is a tiny gap called a synapse. The motor neurone carries the impulse to the effector (the muscle). The hand then pulls away from the stimulus; this is the response.
What is homeostasis and why is it important?
Homeostasis means keeping the internal environment constant. This is important as body cells work most efficiently when they are at the appropriate temperature and pH, and are supplied with the correct concentrations of nutrients and water.
What is a hormone?
Hormones are proteins which act as chemical messengers that control many body functions. They are produced by glands and carried by the blood.
What happens when glucose levels in the blood increase?
Normal glucose level -> carbohydrate meal eaten -> glucose level in blood goes up -> pancreas starts releasing insulin into the blood -> liver starts turning the glucose into insoluble glycogen and stores it -> glucose level in blood decreases back to normal -> pancreas stops releasing insulin -> normal glucose level
What happens when glucose levels in the blood decrease?
normal glucose level -> exercise undertaken -> glucose level in blood goes down -> pancreas starts releasing glucagon into the blood -> blood glucose levels increase back to normal -> pancreas stops releasing glucagon -> normal glucose level
What is diabetes?
Diabetes is a condition where the level of glucose in the blood cant be controlled, meaning that glucose in the blood can rise to a dangerous level.
What are the types of diabetes?
Type 1 diabetes is when a person’s pancreas cannot produce insulin.
Type 2 diabetes is when a person’s pancreas can produce insulin, but their body cells do not respond. It is linked with being overweight.
What are the symptoms of diabetes?
- urinating frequently as more glucose must be excreted (glucose is excreted in urine)
- feeling thirsty as a lot of water has been lost in the urine
- loss of weight and feeling weak because glucose isn’t stored and used by the body
- in extreme cases, diabetic coma
What are the treatments for diabetes?
- regular injections of insulin into the body
- controlling the carbohydrate and fat content of a diet
- sufficient exercise
- transplant of pancreatic tissue
