2j Coordination and Response Flashcards
What is the CNS?
Central Nervous System
is the spinal cord and brain
What is the PNS?
Peripheral Nervous System
is the collection of neurons connected to the CNS
What are neurons?
Neurons carry electrical impulses to carry messages from place to place
What do hormones do?
- Long term effects - slower responses
- Travels in the blood
- Released from endocrine glands
- Some examples are ADH and adrenaline
- Responsible for fight and flight
What do Neurons do?
Short term effects - faster response
- Responsible for transmitting information about sounds and smells
- Responsible for transmitting information about pain
- Travel in the nerves - pass messages as electrical signals
- Found in the brain and spinal cord
- Involved in reflex actions
Why is the axon long?
Because it is responsible for carrying the electrical impulses around the body
What happens in the synapses so they are able to pass an impulse from one neurone to the next?
1) Electrical impulse comes towards the synapse
2) Neurotransmitters are stored there, the electrical impulses travel there and become neurotransmitters
3) Neurotransmitters are released from the end of one neurone which diffuses from the synapse
4) When the neurotransmitters reach the next neurone they cause a new electrical impulse to be sent
What are the 3 types of neurones called?
Sensory neurone
Relay neurone
Motor neurone
What is a sensory neurone?
Carry out nerve impulses from receptor cells in the body towards the CNS
What are relay neurones?
Make connections between neurones inside your brain and your spinal cord
What are motor neurones?
Carry nerve impulses from your brain to your muscles / glands (effectors)
What is the sense organ?
It is the receptor
- eye
- skin
- nose
- tongue/taste buds
- ears
What are the names of the 5 senses?
- Sight
- Touch
- Taste
- Smell
- Hearing/balance
What is the stimulus detected by the sense organs?
Sight/eye - light
Touch/skin - Particles (temperature/pressure)
Smell/nose - chemicals in the air
Taste/tongue/taste buds - chemicals in the food
Hearing/balance/ears - Frequencies, vibrations
What is a stimulus?
A change in the surroundings
What is a receptor?
An organ or cell detecting a stimulus
What is an effector?
A muscle or gland
What is a response?
A reaction to the change
A person hears music playing and decides to change the radio station. How does the person respond and coordinate?
1) A radio plays a song and sends out the sound wave (stimulus)
2) A receptor cell in the ear senses the stimulus
3) An electrical impulse is sent along a sensory neurone
4) The impulse reaches the brain via the spinal cord
5) The brain processes the information
6) The brain sends out an impulse along a motor neurone
7) The impulse reaches an effector cell in the muscle in the finger
8) The finger moves towards the radio to change the channel (response)
What is a reflex?
A rapid and automatic response to a stimulus - no brain involvement
What is the order of the reflex arc?
1) A stimulus is a change in the environment of an organism
2) This is detected by a receptor such as the eye
3) Impulses from a receptor pass along a sensory neurone…
4) to the central nervous system (the co-ordinator)
5) The message is passed from a sensory neurone to a relay neurone
6) Then the message passes between a rely neurone and…
7) a motor neurone
8) The motor neurone carries an impulse to an effector…
9) which can be a muscle or a gland…
10) A muscle responds by contracting, a gland responds by releasing chemical substances
What is the eye?
The eye is the sensory organ which allows us to see. It contains receptor cells which pick up information about light, they convert this information into an electrical signal and then send the information to the brain
What is the role of the iris?
The eye needs to control the amount of light coming into the eye. It does this by changing the size of the iris
What does the pupil do?
Light travels from an object into the eye through the pupil
What is the pupil covered by?
The pupil is covered by a clear protective layer called the cornea
What does the cornea do?
The cornea is involved in refracting the light
Where does the light travel through?
The light travels through the lens
What does the lens do?
- The lens focuses the light onto the retina at the back of the eye
- It is flexible and can change shape to cause more or less refraction of light
What is the most sensitive part of the retina called?
The fovea
What cells does the retina contain?
The retina contains cells called photo receptors which convert light into an electrical signal
What does the optic nerve do?
The electrical signal is sent along the optic nerve and to the brain
The eye is hollow so how does it keep its shape?
It is full of liquid: The aqueous humour (in front of the lens) and the vitreous humour (behind the lens)
What is the order of how light enters your eye and enables you to see?
Your iris (the coloured part) controls the amount of light that enters your eye. The rays of light are refracted by the cornea and lens so that they converge (come together) at a single point and produce a clear image on your retina. The light-sensitive receptor cells on your retina then cause electrical impulses to pass along sensory neurones in the optic nerve to your brain
What is the retina?
The retina lines the back of the eye and contains all of the light sensitive receptor cells which convert the light energy into electrical energy
What is the fovea?
- The most sensitive part of the retina
- Contains a high density of colour receptor cells
What is the blind spot in an eye?
- The area of the eye where the nerves join together
- Does not contain any light sensitive cells
What are the two types of light sensitive cells in the retina?
Cone cells and rod cells
What do cone cells do?
Cone cells respond to light of a certain wavelength (colour). Only work in white light. These cells are mostly clustered around the fovea on the retina, where most light falls in bright conditions
What do rod cells do?
Rod cells respond to differences in light intensities, not wavelengths. More sensitive at low light intensities than cone cells. Give us images that are mainly black and white. These cells are found all over the retina
Does a thick lens bend the light more?
When an object is close to the eye the light needs to be refracted a lot to focus on the retina and therefore the lens needs to be wider/thicker
How does the lens change shape?
- The lens is a clear, flexible bag of fluid
- It is surrounded by ciliary muscles that change the shape of the lens (accommodation)
- Suspensory ligaments attach the lens to the ciliary muscles
How do the eyes receive light from a near object?
- The ciliary muscles contract
- The suspensory ligament therefore loses tension
- As the ligament has slackened, the lens becomes short and fat to refract the light a lot
How do eyes receive light from a distant object
- The ciliary muscles relax
- The suspensory ligament tightens on the lens
- The lens becomes long and thin because the light only needs to be refracted a little
How does your pupil respond when you shine a bright light in your eyes?
The circular muscles in the iris contract to make the pupil size smaller -> protects the retina from damage
How does your pupil respond when you shine a dim light in your eyes?
In dim light the circular muscles relax and radial muscles contract and the pupil widens as the eyeball needs as much light to see clearly
Which things in the body need to be maintained at a constant level?
- Body temperature - so enzymes can function properly
- Water levels - ADH
- Heart rate
- Blood pressure
- Concentration of glucose
- Concentration of Carbon Dioxide
By what processes are water, blood glucose and temperature controlled by?
Water: Osmoregulation
Blood Glucose: Blood glucose regulation
Temperature: Thermoregulation
What temperature do your enzymes work best at?
37 degrees Celsius
- Essential to maintain core body temperature very close to this. Even your external body temp changes, your core body temp shouldn’t
What is heat produced by?
Heat produced through respiration and other chemical reactions is used to maintain body temperature
How do we monitor core body temperature?
- The temperature of the blood is monitored by the hypothalamus in the brain
- If the temperature varies too much from 37C, the hypothalamus causes changes to happen that bring the temperature back to about 37C
- The hypothalamus also receives electrical impulses from heat sensor cells in the skin surface
How can heat be gained or retained if you become cold?
- movement - shaking, tapping
- Increase rate of respiration
- Shivering
- Less sweating
- Less blood flow near skin surface - vasoconstriction - narrowing the blood vessels (arteries) near the surface of the skin
- More clothing
- Hairs stand on end - erector muscles contract - traps a layer of warm air next to your skin - causing insulation
- Loose less heat by radiation
What happens when you get too cold?
- Your muscles may start to make tiny contractions (shivering). These contractions need energy from respiration (heat is produced as a by-product)
- Moving around, eg. jumping up and down
- Extra layer of clothing. Clothes trap a layer of warm air next to your skin
- Arterioles (small arteries) that deliver blood to the skin surface get narrower (vasoconstriction). Less heat is lost by radiation
- Hypothermia is when the body temp drops too far below 37C. This causes unconsciousness and sometimes death
What happens when the body gets too hot?
Blood temperature is monitored by the hyperthalamus of the brain. If body temp gets too high, the blood vessels close to the skin widen so that heat energy can be transferred to the environment (otherwise known as vasodilation).
- This is also done by sweating - evaporation requires heat energy from the skin
- Getting too hot is very dangerous. If too much heat is lost through sweating, the body becomes dehydrated
- Can lead to heart stroke and even death
What hormone does the adrenal gland produce?
Adrenaline
What organs does adrenaline target?
Vital organs
eg. lungs, muscle, liver, heart
What effects on the body does adrenaline have?
- Increased heart rate
- Dilated pupils
- Increased depth of breathing and breathing rate
- Increased sweating
- Hair standing on end (goosebumps)
- Paling of the skin as blood is directed to muscles
What hormones do the ovaries produce?
Oestrogen, Progesterone
What organs does oestrogen target?
Ovaries, Pituitary gland
What effect does oestrogen have on the body?
- responsible for the development of secondary sexual characteristics in girls
- Controls puberty
- Stimulates production of LH and suppresses the production of FSH in the pituitary gland
- Helps control the menstrual cycle with progesterone
What organs does progesterone target?
Ovaries
What effects does progesterone have on the body?
- Helps control the menstrual cycle with oestrogen
- maintains the lining of the womb
- Suppresses FSH production in the pituitary gland
What hormones does the pancreas produce?
Insulin + glucogen
What are the organs that insulin targets?
Liver
What effects on the body does insulin have?
- Controls the concentration of glucose in the blood
- lowers blood glucose
- Causes the liver to take the glucose and store it as glycogen
What hormones does the pituitary gland produce?
ADH, FSH, LH
What organs does ADH target?
Kidneys
What effects on the body does ADH have?
- Helps regulate the body’s water content - triggering up take of water in kidneys
- It causes the kidney tubules to reabsorb more water in the blood by increasing the permeability of the collecting ducts
What organs does FSH and LH target?
Ovaries
What effect on the body does FSH have?
- Triggers egg ripening and oestrogen production in ovaries
- Work together with progesterone and oestrogen to control the menstrual cycle
What effect on the body does LH have?
- Work together with progesterone and oestrogen to control the menstrual cycle
- Progesterone production in ovaries triggers ovulation
What hormone do testes produce?
Testosterone
What organs does testosterone target?
Male reproductive organs
What effect on the body does testosterone have?
- Causes secondary sexual characteristics in boys
- Is needed for the production of sperm
