Nervous system and Hormones Flashcards
What is the difference between the nervous and hormonal systems?
The nervous system sends messages quickly in the form of electrical impulses.
The hormonal system sends information in the form of chemicals in the blood to organs and this is much slower.
What is a stimulus?
a response our body makes because of a change in the environment
What is a receptor?
A structure which can detect a stimulus e.g. skin
Give 2 examples of effectors
Muscles and glands
What is an effector?
Responds to a stimulus
What is a neurone?
A single nerve cell
What is the pathway in which an electrical impulse travels through the nervous system?
stimulus –> receptor –> sensory neurone –> CNS –> Motor neurone –>Effector
What makes up the Central Nervous System (CNS)?
Brain and spinal cord
Which part of the eye: is the protective outer coating?
Conjunctiva
Which part of the eye: refracts light onto the retina?
Lens
Which part of the eye: contains the light sensitive cells?
Retina
Which part of the eye: contains neurones that carry electrical impulses to the brain?
Optic nerve
Which part of the eye: helps to maintain the shape of the eye and keeps the retina against the wall of the eye
Vitreous humour
Which part of the eye: allows light to enter and most refraction of light occurs here?
Cornea
Which part of the eye: controls how much light enters?
Iris
What is accommodation?
When the lens changes shape to focus light onto the retina
Explain what happens in the eye when looking at a distant object
Ciliary muscles are relaxed, suspensory ligaments are taut and the lens is thinner
Explain what happens in the eye when looking at a near object
Ciliary muscles contract, suspensory ligaments are slack and the lens is thicker
What is an adaptation of the axon in a neurone?
They are 1m long so that electrical impulses can be transmitted from the CNA to the extremities by one cell quickly
What is the function of the myelin sheath?
It speeds up electrical impulses
What is the function of the branches ends?
Allows the neurone to make junctions with other neurones
What is the junction between 2 neurones called?
Synapse
Explain what happens at a synapse
An electrical impulse travels down the neurone towards the end of the axon.
Vesicles contains transmitter substance move towards the gap.
The transmitter diffuses across the gap and attached to the receptors.
If enough the to the receptor then it triggers an electrical impulse In the next neurone
What is a voluntary action?
Involves conscious thought i.e. involves the brain
What is a reflex action?
This response does not involve conscious thought and so the information bypasses the brain. These reactions are much faster and protects the body from danger.
What is homeostasis?
The maintenance of a constant internal environment
What are hormones produced by?
Glands
What hormone is produced by the pancreas to lower blood sugar levels?
Insulin
What does insulin cause the liver to do in order to reduce blood glucose levels?
The liver converts glucose into glycogen. Glycogen is a storage molecule in animals
What do muscles do with excess glucose?
Use it in respiration
What is negative feedback?
Is a homeostatic mechanism where the body detects a change and returns it to the normal level (set point)
What is type 1 diabetes?
The pancreas doesn’t produce insulin
What are the symptoms of diabetes?
Thirst, weight loss, fatigue, frequent urination
What are the long term effects of diabetes if blood sugar levels are not managed?
Eye damage, heart disease, strokes and kidney damage
How is type 1 diabetes treated?
Insulin injections
What is type 2 diabetes?
Insulin is produced by the body has become resistant to it so it no longer works effectively
What causes type 2 diabetes?
Poor diet, obesity and lack of exercise
What are the 2 functions of the kidney?
Controls water levels (osmoregulation) and removes waste (excretion)
How does the body gain water?
Drinking, eating and cells respiring
How does the body lose water?
Urine, sweat, breathing and faeces
What hormone controls water levels in the body?
ADH (Antidiuretic hormone)
What does an increase of ADH hormone do to the kidney?
Signals to the kidney to reabsorb more water back into the blood. This causes a larger volume of dilute urine to be produce.
What causes an increase in ADH production?
Sweating or exercising
What causes a decrease in ADH production?
Drinking water
What is phototropism?
Is the response of a plant to light
Where is the hormone auxin produced?
Shoot tip
What is the function of auxin?
It causes cell elongation
