Chapter 2 - Cells And Control Flashcards
What is a stimulus/ are stimuli ?
Any change to the internal (chemical reactions inside body) or external (outside the body) environment
What do receptors do?
Detect stimuli, they are located in the sense organs (eyes, ears, nose, tongue and skin) and are groups of cells.
Give an example of receptors: eg in the eye…
Rod and cone cells are used in the eye to detect changes in light, rods for dimmer black light, cones for colour
What are effectors?
Cells that bring about a response to to stimuli which can be on many different ways, these include muscle cells which contract and glands which secrete hormones
How do receptors communicate with effectors?
Via the nervous system, the hormonal system or sometimes both
What is the CNS? What parts of the body make up this?
The central nervous system, the brain and the spinal cord
What is the nervous system? Hat is it made up of
The system that receptors and effectors mostly use to communicate, it is made up of neurones
What receptors detect a stimuli what do they do?
Send electrical impulses along sensory neurones to the CNS
Where does the CNS send the electrical impulses from a receptor? Then what happens?
To an effector along a motor neurone, the motor neurone responds accordingly
What are the 3 types of neurone?
Motor, relay and sensory
What neurone responds to the electrical impulses from receptors accordingly?
Motor neurones
What is the job of the CNS?
To coordinate a response, a stimulus, receptor and effector is needed for this to happen
What enables the nervous system to bring about very rapid responses?
The high speed of electrical impulses
What is a synapse?
The connection between 2 neurones
How is the electrical impulse passed between 2 neurones over the synapse? Why is this?
Because there is a gap between neurones the nerve signal is transferred by chemicals called neurotransmitters which diffuse across the gap, this chemicals set of a new electrical signal in the next neurone
What are the chemicals transferred across a synapse called?
Neurotransmitters
What is a reflex? What do we have this?
An automatic response to a certain stimuli, they reduce your chance of being injured as it takes less time than waiting for your brain to respond
Give an example of a reflex
When a bright light is shone in your eyes your pupils automatically contact/ get smaller so less light is let in therefore less damage of the eyes occur
What is a reflex arc?
The route the electrical impulse (receptor to effector) takes in a reflex
What is the natural reflex if you get a shock?
Your body releases hormone adrenaline automatically
What are the main stages in a reflex arc?
Stimulus, receptor, sensory neurone, CNS (and synapse to relay neurone then synapse back to next stage), motor neurone, effector, response
What is homeostasis?
The maintenance of a constant internal environment
What ways is water lost from the body?
Via the skin as sweat, the kidneys as urine and the lungs as breath, some water is also lost in faeces
How does the balance between water being lost from the body vary between sweat and urine?
On what you are doing and the weather
What would the balance between sweat and urine been like if I you were exercising or it was a hot day?
You would sweat more therefore urinate less but when you do it would be more concentrated, deeper in colour, and you would lose more water through your breath when exercising as you breath faster
What would the balance between sweat and urine be like on a cold day or not exercising?
You don’t sweat much and produce more urine which will be paler as it is more dilute
What are hormones?
Chemical messages that are sent through the blood slowly that only effect certain cells and can be long lasting
Where are hormones produced?
In glands
What are the key differences between nerves and hormones?
Nerves send a very fast message, Act for a very short time, Act on a very precise area
Hormones send a slower message, Act for a long time, Act in a more general way
What is the temperature enzymes work best at called?
The optimum temperature
What temperature does the human body try to remain as the enzymes work best at this temperature?
37 degrees Celsius
What is the source, role and effect of adrenaline?
The adrenaline gland, it readies the body for fight or flight, this is done by increasing the heart rate, blood flow to muscles and blood sugar level
What is the source, role and effect of insulin?
Formed in the pancreas, it helps control the bodies blood sugar level and stimulates the liver to turn glucose into glycogen for storage
What is the source, role and effects of testosterone?
Sourced is the testes it is a male sex hormone that promotes male secondary characteristics, such as facial hair
What is the source, role and effect of progesterone?
Sourced in the ovaries, it supports pregnancy by maintaining the lining of the uterus
What is the source, role and effect of oestrogen?
Sourced in the ovaries, it is the main female sex hormone which controls the menstrual cycle and promotes secondary female sexual characteristics such as widening of the hips
What is the source, role and effect of ADH (Anti-Diuretic Hormone)?
It is sourced in the pituitary gland (in the brain) and controls water content, increases the permeability of the kidney tubules to water
What is the source, role and effect of FSH?
It is sourced in the pituitary gland (in the brain) and it is a female sex hormone which causes an egg to mature n an ovary, it stimulates to produce oestrogen
What is the source, role and effect of LH?
Sourced in the pituitary gland (in the brain) and is a female sex hormone which stimulates the release of an egg from an ovary
What happens when the radial muscles in the eye contract? What about when the circular muscles contract?
When the radial muscles contract the pupil gets bigger whereas when the circular muscles contract the pupil gets smaller, this controls how much light enters the pupil and is a reflex
Name all the main parts of the eye
The lens, the retina, the pupil, the iris, the optic nerve, the cornea, the sclera, the conjunctiva
What does the optic nerve do?
Carries impulses from the receptors to the brain (eye receptors)
What does the iris do?
Control the diameter of the pupil, therefore how much light enters the eye
What does the lens do?
Focus the light on the retina, where all the receptors are
What is the sclera?
The tough outer layer that protects the eye
What is the conjunctiva ?
What lubricates and protects the surface of the eye
What do your ciliary muscles do when looking at a close object? What about a far away one?
Whilst looking at near objects it contracts which slackens the suspensory ligaments making the lens more fat/curved which increases the amount by which light refracts making the object clearer, distant objects are the exact opposite where the ciliary muscles relax and the suspensory muscle is tight ,light refracts by a smaller amount as the lens is thinner/smaller
What does positively phototropic mean? What about negative phototropic?
Positive is when a plant or part of a plant grows towards light, negative is the opposite
What is what is positively geotropic? What about negative?
Positive is when a plant or part of a plant grows towards gravity, negative is the opposite
What are plant growth hormones called?
Auxins
What is it called when an animal can reproduce asexually, they are both male and female? It is very rare and sometimes happens in bugs or Komodo dragons
Parthenogenesis
Other than the central nervous system what is the other type of nervous system? What does this control?
Peripheral nervous systems (PNS), it controls the automatic and the somatic (voluntary and involuntary) responses
