Coordination And Response Flashcards
Name the steps of the reflex arc in order of how the electrical impulse moves (7)
- Stimulus
- Receptor
- Sensory neurone
- Relay neurone
- Motor neurone
- Effector
- Response
Which parts of the reflex arc are in the coordinator (brain or spinal chord)
- Sensory neurone
- Relay neurone
- Motor neurone
Which parts of the reflex arc are in the coordinator (brain or spinal chord)
- Sensory neurone
- Relay neurone
- Motor neurone
Which neurone is fully within the coordinator (brain or spinal chord)
Relay neurone
How does the body’s reflexes react when you touch a burning candle
- Receptor cells in the skin detect a stimulus (the heat of the candle)
- Sensory neurone sends impulses to relay neurone in the spinal chord
- The relay neurone connects to the motor neurone (and also sends a message to the brain)
- The motor neurone sends impulses to the effector
- The effector produces a response (the muscle contracts to move the hand away)
How is the spinal chord structured
Impulses enter through neurones in the dorsal (back) root. They leave through the motos neurones in the ventral (front) root. Axons and fatty myelin sheaths are on the outside of the spinal cord and are white. Great matter is on the inside - cell bodies. The sensory neurones are in the dorsal root ganglion
What do neurons consist of
Elongated cells consisting of a cell host and long, thin axon
What is a synapse
A synapse is the small gap between two nerve cells (neurons) where nerve impulses are transferred from one neuron to another.
How does a synapse work
- An electrical impulse travels down the axon of the first neuron
- When the impulse reacher the end of the neuron it triggers the release of chemicals called neurotransmitters
- Neurotransmitters diffuse across the synaptic gap to the next neuron
- The neurotransmitters bind to receptors on the surface of the next neuron, triggering a new electrical impulse
What are dendrites
Thin projections that extend from the cell body and connect with other neurones, allowing electrical impulses to pass from one nerve to the other
What are axons of neurones wrapped in
The myelin sheath - an insulating lipid layer
Why does the reflex arc go through the spinal chord instead of the brain
It is quicker
What do sensory neurones transmit
Messages from sense receptors (eyes, nose etc) to the brain or spinal chord
What do sensory neurones transmit
Messages from sense receptors (eyes, nose etc) to the brain or spinal chord
Draw a nerve
See Nerve Cells note
Draw a nerve
See Nerve Cells note
What is the definition of reflexes
Fast, automatic protective biological control systems that link a stimulus to a response
Do reflexes require thinking
No
Why are reflexes involuntary
The CNS sends electrical signals to the muscles before the brain can pick up the message
What 4 parts make up a motor neurone and how to draw them
- Cell body (radial graph shape with black nucleus inside)
- Dendrites - tiny hair like things coming off all corners of the cell body except 1
- Axon - a long line coming off the last spot in the cell body, with dendrites at the end
- Myelin sheath - blocks that run along the axon, surrounding/protecting it
See Nerve Cells note
How to simply draw a sensory neuron
- Axon - line
- Myelin sheath - blocks protection the axon
- Cell body - a line coming off the axon connecting to a large circle with a nucleus in
- Dendrites at each end of the axon
See Nerve Cells note
Where do motor neurons transmit messages to and from
Messages from the brain and spinal chord to the muscle and glands
What is a hormone
A chemical that is released into the blood from a gland
What is the release of hormones known as
Secretion
What are the two types of gland
Endocrine and exocrine
What does an endocrine gland do
Releases hormones straight into the blood
What do endocrine glands do
Release blood into the organs
Which is faster - an electrical nervous signal or a chemical hormonal signal
Nervous§
What type of transmission is used for nervous signals and for hormonal signals
Nervous - electrical impulses
Hormonal - chemical
Which is more widespread with its effect: hormones or nerves
Hormones
What is the duration of the effect of nervous signals and hormones
Nervous signals - short
Hormones - long
Where is adrenaline produced
The adrenal gland (kidneys)
Where is insulin produced
Pancreas
Where is testosterone produced
Testes
Where is oestrogen produced
The ovary
Name 4 hormones and their functions
- Adrénaline - prepare body for physical activity
- Insulin - lower glucose level in blood
- Oestrogen - regulating the menstrual cycle
- Testosterone - controls the development of male secondary sexual characteristics
What is a plant response to light called
Phototrophism
What is a plant response to water called
Hydrotrophism
What is a plant response to gravity called
Geotrophism
How can coleoptiles be used to show plant responses
- They grew and bent towards light normally
- When a cap is put on the tip, they grow upwards but do not bend towards the light
What happens when the tip of a coléoptile is cut and a 1. Mica sheet and 2. Gelatine block is placed between it and the rest of the plant
- When the tip is removed and put on a mica sheet, there is no bending
- When the tip is removed and put on a gelatine block, it bends towards the light like normal
What happens when the tip of a coléoptile is removed and only put on one side of the stem
The cells on the side with the tip elongate more but the cells on the side without the tip do not, so it bends, without the light direction influencing the direction of bending
What happens when the tip of a coléoptile is removed, put on an agar block for many hours and then the agar block is put on where the tip once was
Bending occurs towards the light
How to label an eye diagram
See The Human Eye note
What is the sclera and what does it do
A tough outer area connected to muscles to move the eye
What is the cornea and what is its function
Clear outer area that refracts light
What are the suspensory ligaments and what do they do
They are controlled by the ciliary muscle to relax or tighten the lens to change its shape
What is the ciliary muscle and what is its function
A circular right muscle next to the iris that changes the shape of the lens
What does the lens do
Refracts light
What does the optic nerve do and where is it
Behind the eye - it contains sensory neurons to transmit impulses from the retina to the brain
What is the retina and what does it do
Tissue at the back of the eye that contains photoreceptor cells.
What are rod cells sensitive to
Light levels
What are cone cells sensitive to
Colour
What is the vitreous humour and what is its function
It is a liquid in the middle of the eye. It gives the eye shape - without it the eye would not have the area required to be spherical
What happens when the eye sees bright light
The circular muscles contract to reduce the pupil size
What does the eye do in response to dim light
The radial muscles contract to increase the size of the pupil
How does the eye focus on distant objects
The lens becomes less convex (flatter), the ciliary muscles relax and the suspensory ligaments are pulled tight
How does the eye focus on close objects
The lens becomes more convex (rounded), the ciliary muscles contract and the suspensory ligaments slack
What orientation are light rays from far objects and what does this mean for the lens
Almost parallel to each other once they reach the eye - they do not need to be refracted as much
What angle do light rays from nearby object come at and what does this mean for the lens
They come at angles (not parallel), so need to be refracted more, so the lens must become rounded
Where are the rod cells found
The periphery of the retina
Where are cone cells found
The centre of the retina
What are the optimal light conditions for rod and cone cells
Rod - dim (night)
Cone - bright (day)
What is the resolution of cone and rod cells
Rod - low
Cone - high
How is resolution of eye cells measured
The number of cells : one bipolar cell
More cells : 1 bipolar = lower resolution
What wavelengths can cone cells do
Red, green blue
What wavelengths can rod cells do
All
How many types of rod and cone cells are there
Rod - one
Cone - three
Which is more abundant - cone or rod cells
Rod
Which is more abundant - cone or rod cells
Rod
See The Human Eye note (bottom of it) for diagrams of rod and cone cells
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What is the role of the kidneys (2)
Excretion - the removal of waste products from the blood e.g. urea
Osmoregulation - controlling water balance of the blood/tissue fluid by removing excess water or excess salt
How do we excrete nitrogen from amino acids
Urine
Where does urine form, go to and how
Forms in the kidneys
Passes through tubes called the ureters
Passes to the bladder
Label a kidney diagram from google
Ok (see The Kidneys note for help)
Label a nephron diagram from google
Ok (see The Kidneys note for aid
How does the nephron help to regulate water levels in blood when we are dehydrated / too hydrated
- ADH is released by the pituary gland when we are dehydrated
- ADH makes the walls of the collecting duct more permeable to water (less if too hydrated)
- Water passes back into blood from the collecting duct (water passes from blood to collecting duct when we are too hydrated)
- The urine is Lower in volume and more concentrated (greater in volume and more diluted if too hydrated)
What are ions
Salts
Which blood vessel brings blood to the kidney
The renal artery
Which blood vessel brings blood away from the kidney
The renal vein
What happens to the blood when it enters the kidney
It is put under pressure so small molecules like water, salts, glucose, amino acids and urea are forced out of the capillaries.
What happens after the small molecules have been forced out of the blood in the kidneys
Some molecules are Selectively Reabsorbed to maintain the correct levels in the blood
What happens to molecules that are not selectively reabsorbed
They are put into the urine, which leaves the kidney via the ureter
How does blood leave the kidney
The renal vein
What is selective reabsorbsion
Only the small molecules that are required are reabsorbed, the ones that are in excess are disposed of via urine
Which substances are always reabsorbed in selective reabsorbsion
Sodium, amino acids and glucose
What is not reabsorbed into the blood
Urine
Where do non reabsorbed substances go
They pass through the nephron and enter the collecting duct, where they form urine, passing into the pelvis and then out into the ureters
What is negative feedback
A sine graph (peaks and troughs not always same height tho) with the optimal hydration level at the rest point - ADH is secreted at the troughs, so the levels go up, but then eventually they fall again, at which point ADH is again released
What is ultrafiltraiton
Small molecules are removed from the blood using the gin pressure to squeeze the molecule from the glomerulus to the Bowman’s capsule
What molecular weight molecules can be filtered via ultrafiltration
Less than 68,000 molecular weight
What does ADH do
Controls the water content of the blood
What are osmoreceptors
Receptors in the hypothalamus of the brain which stimulate the pituary gland to secrete ADH when blood is too concentrated
How does ADH work
ADH allows more water to pass from the collecting duct back into the blood around the loop of Henle by causing more water channels to appear in the wall of the collecting duct (aquaporins)
What happens if the blood is too diluted (more water than required)
- The pituary gland stops secreting ADH
- Excess water can move from the blood to the collecting duct
- So more water passes into the urine
What happens if the blood is too diluted (more water than required)
- The pituary gland stops secreting ADH
- Excess water can move from the blood to the collecting duct
- So more water passes into the urine
What is homeostasis
The maintenance of a constant internal environment
What are some homeostatic factors regulated in humans (3)
- Concentration of water in the blood
- Blood glucose levels
- Core body temperature
Why is homeostasis important in humans (2)
- A constant body temp is important because it allows enzymes to act at a near-optimal temperature without being denatured
- If too much water is lost, the blood will become too viscous, so the brain wont receive enough oxygen
What monitors and controls body temperature
Receptors in the skin and the brain
How do receptors in the skin and the brain detect changes in body temp
They detect changes in the temperature of the blood flowing through those areas
What is the thermoregulatory centre in the brain called
The Hypothalamus
What is the optimal body temp
37ºC
What happens if the body deviates from 37ºC
The hypothalamus and skin receptors send out electrical signals that trigger actions or behaviours that increase or decrease heat loss
What is the definition of negative feedback
A response to bring about the opposite of a stimulus (e.g. too much water, too cold, too much glucose in blood etc)
What are 3 things the body does when it is too hot
- Hair muscles relax; hairs lie flat to allow the escape of heat
- Sweat is secreted by sweat glands, which cools the skin by evaporation
- Blood flow in capillaries close to the skin surface increases
What are 3 things the body does when it is too cold
- Hair muscles pull on end, so they become erect, which traps a layer of air as an insulating layer
- Blood flow in capillaries close to surface of skin is decreased
- Shivering - constant involuntary contractions of muscles to generate kinetic energy which warms the body.
What is vasodilation
When we are too hot, more blood is sent to the capillaries closer to the skin, so more heat is radiated to the surroundings
What is vasoconstriction
When we are cold, less blood is sent to the capillaries near the surface of the skin, which means less heat is radiated to the cold air
What is vasoconstriction
When we are cold, less blood is sent to the capillaries near the surface of the skin, which means less heat is radiated to the cold air
What is a control
A baseline result that does not receive the effect of the experiment e.g. a plant that receives no fertiliser in an experiment to show the effect of fertiliser on the growth rate of a plant species
What is a control
A baseline result that does not receive the effect of the experiment e.g. a plant that receives no fertiliser in an experiment to show the effect of fertiliser on the growth rate of a plant species. This helps to show the natural growth rate, so you know for the fertiliser plants how much of the growth is due to the fertiliser and how much is natural
What is a control variable
A factor that is always constant
What is an independent variable
The one you change
What is a dependent variable
The one you measure
What is excretion
The removal of harmful waste products and products that are in excess of
