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Coordination and response (Excretion (Plants (Day (Plants excrete oxygen…
Coordination and response
Excretion
Nephron Structure and Function
2) These glomerular capillaries sit in a cup-shaped structure called a Bowman's capsule
3) This leads to the proximal convoluted tubule which coils many times. After this comes the uncoiled loop of Henlé and then the coiled distal convoluted tube
Millions of nephrons make up the bulk of each kidney
4) The distal convoluted passes into a collecting duct which eventually connects to the bladder
1) Inside each kidney the renal artery branches into smaller arteries and each of these lead to a knot of capillaries called a glomerulus.
Animals
Urea is a waste product made in the liver when amino acids are broken down, removed by the kidneys
carbon dioxide and water are waste products of aerobic respiration and are removed by the lungs
excess mineral ions can be removed by the skin or kidneys
Various other substances, including excess minerals absorbed from the diet and medical drugs as also considered metabolic waste.
Plants
Excretion in plants can't be described as active elimination because the movement of gases is irregular and it depends on the light intensity
Night
Plants excrete carbon dioxide and water (in transpiration)
Plants take in oxygen or aerobic respiration and mineral ions from the soil via active transport
Day
Plants excrete oxygen that is not being used in respiration and wate vapour
Plants take in water from the roots and mineral ions from the soil.
More carbon dioxide is used in photosynthesis than is made in respiration but there is also too much oxygen being produced in photosynthesis that is not needed in respiration. This process results in oxygen being excreted via stomata
Leaf cells constantly respire, however only photosynthesise during daylight
Carbon dioxide and oxygen can be both waste and useful substances depending on light intensity
Leaves that fall from trees can remove waste chemical substances from the plant because the plant will store unwanted, toxic chemicals in the dying leaf matter.
Structure of urinary system
Urine carried in the ureters to the bladder and from to bladder to outside the body in the urethra. The bladder is a muscular sac which expands to store urine and can hold it for several hours. When you relax the circle of sphincter muscles at the exit of the bladder, urine is forced down the urethra and the bladder empties.
Ureter: carries urine produced by the nephrons in the kidney to the bladder for storage
Excretion: removal of waste products of metabolism. Metabolic reactions are the main chemical reactions that take place in living cells. The waste products if these reactions can become toxic if they accumulate.
Ultrafiltration and Reabsorbtion
The blood pressure here is high because the diameter of the blood vessels leaving the glomerulus are narrower than the blood vessels entering the glomerulus.
This high pressure forces a lot of water as well as some small molecules into the bowman's capsule. Larger molecules remain in the blood. This is called ultrafiltration
The water and small molecules in the bowman's capsule form the glomerular filtrate.
As the filtrate passes along the tubule certain substances are taken back into the blood. This is called reabsorption.
As the filtrate passes along the proximal tubule, 100% glucose is reabsorbed by the blood
At the distal tube, more mineral ions are reabsorbed into the blood
When passing the loop of henlé, water is reabsorbed
At the collecting duct, the filtrate is shared with many other nephrons and even more water is taken back into the blood
The collecting ducts lead towards the centre of the kidney and the urine is carried from this region, along the ureter and to the bladder for temporary storage.
The volume of urine produced depends on the recent needs of the body.
Practical on urine
The eye
Quizlet
Eye Diagram
Stereo Vision: ability to use two eyes
Eyelid: protection
Parts of eye
Sclera:
tough white coat that keeps the eye in place and acts as a place of attachment for the muscles that move the eye.
Cornea:
transparent front to the eye that allows rays of light to pass into the eyeball
Iris:
varies diameter of pupil to regulate amount of light entering eye
Pupil:
aperture through which light rays pass into the back of the eye
Tear gland:
where tears come from, tears are a natural antiseptic enzyme which breaks down bacterial cell walls.
Aqueous Humour:
watery liquid
Lens:
focuses light rays
Vitreous humour:
jelly like substance behind lens
Choroid:
pigmented cells that stop light reflecting back into the eye
Retina:
made of receptor cells that pass electrical impulses along nerves to the brain. Two types of receptor cells rods for black and white and cones for colour
Optic Nerve:
leaves eye and links to CNS (blind spot because there are no receptor cells )
Fovea:
region of the retina with detailed colour vision
Accomodation
Close object: Ciliary muscles contract, suspensory ligaments become slack, lens gets fatter (more spherical)
Distant object: ciliary muscles relax, suspensory ligaments tighten, Lens gets flatter and thinner
Light rays enter the eye through transparent cornea, this is covered by a layer of thin protecting cells called conjunctiva. Light rays bend as they enter through the front of the eye and they eventually project the rays onto the retina.
Homeostasis
Osmoregulation
ADH
When a person exercises a lot they lose a lot more water in sweat. If this water is not restored by drinking then the body gets dehydrated. The receptors in the brain detect low water levels and send out signals to the body. This means that ADH is released from the pituitary gland and this means more water is reabsorbed from the collecting duct. This makes the urine more concentrated but it restores the body fluid
When you drink to much water the receptors in the brain detect this and stimulate the release of ADH from the pituitary gland. This results in the kidneys producing a larger volume of urine so that more water is excreted and the water content of the blood is returned to normal.
The control of water and salt concentration in the body fluids
Thermoregulation
Optimum body temperature for enzymes is 37˚C
Vital organs are maintained at 37˚C
Skin temperature can be up to 1˚ higher or 9˚ lower
A slight change in internal body temperature can be fatal. Low body temperatures may mean enzymes become too slow for reactions to take place and if body temperatures are too high enzymes could denature.
Hypothermia below 36˚ or a 40˚ fever is fatal (hyperthermia)
Core body temperature is maintained by balancing heat loss and gain
Heat can be gained through:
exercise, shivering, vasoconstriction, extra clothing
Vasodilation
: core blood vessels get wider allowing a larger amount of blood to flow near the skin surface which means heat can transfer to the surroundings.
Sweating:
the production of sweat from sweat glands means as the sweat evaporates it transfers heat away from the body.
Heat can be lost though:
sweating, vasodilation, removing clothing
Shivering:
muscles begin to twitch and this rapid retraction and contraction of muscles generates heat.
Goosebumps:
tiny muscles at the base of body hair pulling hairs erect. The upright traps an insulating layer of air to stop heat loss
Vasoconstriction:
The muscular walls of blood vessels contract and get narrower, reducing the amount of blood flowing near the skin surface, therefore reducing heat loss.
Receptors
Receptors detect the change in temperature of blood flowing through those areas.
Thermoregulatory centre in brain is called hypothalamus. If the internal body temperature deviates by 1˚C the hypothalamus and receptors send electrical signals that trigger actions to increase/decrease heat loss.
Organs
Kidneys: regulates water and minerals
Heat or water regulation to maintain constant internal environment
Nerves and hormones
Neurotransmitters
Dopamine:
produces feelings of pleasure when it is released from the brain's reward centre, inhibitory
Serotonin:
affects mood, social behaviour, appetite, memory, digestion
Gaba:
decreases activity in nervous system, slows down responses, calms you down, locks and inhibits certain brain signals, main inhibitory neurotransmitter in the brain
Glutamate:
found in brain, form neural circuits to specific small scale functions like hearing, vision, movement
Glycine:
converts glucose into energy and creates muscle tissue. Mainly used by neurons in the spinal cord. Always acts as an inhibitory neurotransmitter
Norepinephrine:
acts as a neurotransmitter and a hormone
Chemicals that transfer an electrical impulse from one neuron to the next
Neurons
2) Carry electrical impulses from one place to another.
1) Have a long fibre called an axon which is protected by a fatty sheath
3) Have tiny branches called dendrons which branch further as dendrites at each end.
Sensory neurons:
bring impulses from eyes and fingers
Relay Neurons:
process information and make a decision.
The three neurons work together in a reflex action (a rapid and automatic response to a stimulus which minimises any danger to the body from potentially harmful conditions) Very fast because it avoids the brain and essential for survival
Reflex arc
1)
Receptor
in skin detects a stimulus
2)
Sensory neuron
sends an electrical impulse to
relay neuron
which is located in the spinal cord of the CNS
3)
Relay neurons
connect
sensory neurons
to
motor neurons
4)
Motor neurons
send an electrical impulse to an
effector
5)
Effector
produces a response.
Some reflexes can be conditioned and the brain can learn to ignore and reflex. Such as holding onto a hot pan.
Motor Neurons:
Takes impulses to arm and jaw muscles
Nervous system
CNS
is found in brain in spinal cord
PNS
nerves go from your spinal cord to legs, arms, hands and feet
Autonomic nerves
go from your spinal cord to your lungs, heart, stomach, intestines, bladder and sex organs
Cranial nerves
go from your brain to your eyes, ears, mouth, and other parts of the head.
Synaptic Transmission
5) The binding of a neurotransmitter to the receptors stimulates the second neuron to transmit an electrical impulse along its axon. therefore the signal has been carried from one neuron the next.
1) An electric nerve impulse travels along the axon
2)When the nerve impulse reaches the dendrites at the end of the axon, chemical messengers called neurotransmitters are released.
3) These diffuse across the synapse and bind with the receptors on the membrane of the next neuron
4) The receptors only bind to the specific neurotransmitters released by the first neuron.
Hormone control
Adrenaline: produced in the adrenal glands above the kidneys when the brain detects stress or fear. Prepares the body for physical activity often known as flight or fight response. The body produces more oxygenated blood in the lungs and sends to muscles to activate them. Blood vessels dilate to allow more blood to circulate. Fat cells under the skin breakdown. Glycogen breaks down into glucose for energy.
Insulin
Tropisms and Auxins
Plants respond to stimuli by making sure the leaves are in a good position for photosynthesis. This results in the shoot gradually turning towards the sun. Plants responses are slow taking minutes or hours.
Directional responses made by plants are caused by changes in the growth rates of plant tissues.
These responses enable plants to grow towards or away from stimulus.
Growth towards stimulus: positive
Seedling shoots grows towards light source: positive phototropism
Seedling roots grow away from a light source: negative phototropism
Growth away from stimulus: negative
Seeding roots grow down, towards centre of the earth: positive geotropism
Seeding shoots upwards, away from centre of the earth: negative geotropism
Eg: If plant cells on one side of the plant grow further than the cells on the other side then the shoot curves.
New cells are produced by cell division in the region of cell division. The region of cell division lies just below the shoot tip. Initially each new cell is tiny but gradually they elongate to their mature size. The process of this elongating is affected by plant growth regulators. Example plant growth regulator: auxin
Auxins are produced in the tip and transported to the region of cell expansion.
If concentration of auxin is equal on all sides of the shoot, the expansion of cells on all sides is the same and the shoot grows in a straight line.
If there is more auxin on one side then those cells elongate more and the shoot curves.
The stimulus to which a plant responds must be detected by receptor cells and these are usually located in the growing points such as root tips and shoot tips.
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Eye labelling, neuron labelling, synaptic transmission drawing, urinary system labelling, kidney labelling, nephron labelling, urine practical, auxin diagram