B5 - Infection and Response Flashcards
What is homeostasis and what is the purpose of it
regulation of the internal conditions of a cell or organism to maintain
optimum conditions for function in response to internal and external changes and also enzyme action and cell function
Name the uses of homeostasis
Blood glucose concentrations
Water levels
Body temperature
Describe the different parts of negative feedback and what they do ( 4 marks)
Receptor - detects a stimulus
Co-ordination centre - receives and processes the information, then organises a response
Effector - produces a response which counteracts the change and restores the optimum level
Describe the different parts of the nervous system (6 marks)
CNS - vertebrates brain/spinal cord only, mammals CNS connected to the body by sensory neurones and motor neurones
Sensory Neurones - carries information as electrical impulses from receptor to the CNS
Motor Neurones - carries electrical impulses from the CNS to effectorsed
Effectors - all muscles and glands that respond to nervous impulses
Explain the reflex arc
stimulus detected by receptors - impulses are sent along a sensory neurone to relay neurone in the CNS
When impulses reach a synapse between sensory and relay, they trigger chemicals to be released, chemicals cause impulses to be sent along the relay neurone
When the impulses reach a synapse between the neurone and a motor neurone, the same thing happens. Chemicals released and cause impulses to be sent along the motor neurone
Impulses travel along motor neurone to effector
Effector contracts
What is a reflex action.
automatic and rapid responses that doesn’t involve the conscious part of the brain
Explain how a student can investigate the effect of caffeine on a persons reaction time
Person being tested should sit with their arm resting on the edge of a table
Hold a ruler vertically between their thumb and forefinger, make sure that the zero end of the ruler is level with their thumb and finger
Let go without any warning
Person should attempt to catch the ruler as fast as they can
Reaction time is measured by the number on the ruler where its caught - number should be read from the top of the thumb
Further down the ruler is caught, the slower the reaction time
Repeat test several times calculate a mean
Person should drink a caffeinated drink e.g 300ml of cola
After ten minutes, repeat the test
Same person each test, same hand same height, before the initial test no caffeine should have been consumed
Too much caffeine can cause unpleasant side-effects so the person being tested should not drink anymore
Describe how information passes from the relay neurone to motor neuron (3 marks)
release of chemical from relay neurone
chemical crosses synapse
chemical attaches to motor neurone causing an impulse
What does decreasing the effect of the chemical on the motor neurone do
Decreases contraction
Describe the function of receptors in the skin (2 marks)
Detect changes in surroundings or detect stimuli
Converts information to impulse
What are hormones
Chemical molecules released directly into the blood
Function of:
Pituitary Gland
Ovaries
Testes
Produces many hormones that regulate body conditions - head
Produces oestrogen - pelvic region
Produces testosterone - pelvic region
What are the difference between hormones and nerves ( 3 marks)
nerves:
fast
Act for a very short time
Act on a very precise area
Hormone:
slower action
Act for a long time
Act in a more general way
Why is the pituitary gland called the master gland
Hormones produced act on other glands
Function of:
Thyroid
Adrenal Gland
Pancreas
Produces thyroxine - regulates rate of metabolism, heart rate and temperature
Produces adrenaline
Produces insulin - regulates bgc
