14) Coordination and response (1.4, 2.2, 3.2/5) Flashcards
1.1 What do electrical impulses travel along?
Neurones
1.2. Describe the mammalian nervous system
CNS (brain, spinal cord) and PNS (spinal cord, nerves outside brain)
1.3. Describe the role of the nervous system
Coordination and regulation of bodily functions
Sensitivity: ability to detect and respond to changes in the internal and external environment
1.4. Identify the parts of neurones
1.5. Describe a simple reflex arc
Stimulus -> receptor -> sensory neurone -> relay neurone -> motor neurone -> effector
1.6. Describe a reflex action
Automatically and rapidly integrating and coordinating and stimuli with the response of effectors (muscles and glands)
1.7. Describe a synapse
A junction between two neurones
1.8. Describe the structure of a synapse
Vesicles in presynaptic bulb contain neurotransmitters
Synaptic gap separates neurones
Receptors in the postsynaptic membrane specific for neurotransmitter
1.9. Events at a synapse
- An impulse travels down the axon of a neurone and arrives at the synaptic bulb
- It stimulates the vesicles to release neurotransmitters into the synaptic gap
- Neurotransmitters diffuse across the synaptic gap
- They bind with receptors at the postsynaptic membrane
- An impulse is stimulated in the next neurone
1.10. What is the function of synapses?
To ensure that impulses travel in one direction only
2.1. Describe sense organs
A group of receptor cells that respond to specific stimuli (light, touch, sound, temperature, chemicals)
2.2. Structure of the eye
2.3. Describe the functions of each part of the eye
Cornea: refracts light
Iris: controls how much light enters pupil
Lens: focuses light onto retina
Retina: Contains light receptors, sensitive to light of all colours
Optic nerve: Carries impulses to the brain
2.4. Explain the pupil reflex in terms of pupil diametre
Pupil constricts in bright light to protect the retina and dilated in the dark to protect us from not seeing objects
2.5. Explain the pupil reflex in terms of antagonistic action
Radial muscles and circular muscles - antagonist muscles (when one contracts, the other relaxes)
Dark: Radial contract, circular relax, more light
Light: Radial relax, circular contract, less light
2.6. Explain accommodation to view near and distant objects
Near: ciliary muscles contract, causing suspensory ligaments to loosen, lens becomes fatter and more light is refracted
Far: ciliary muscles relax, causing suspensory ligaments to tighten, lens become thinner and less light is refracted
2.7. Describe the distribution of cone and rod cells in the retina
Found all over retina except blind spot where the optic nerve attaches to the retina
No rod cells in fovea, has the most cone cells
2.8. Describe the function of rods and cones
Rods: night vision
Cones: colour vision
2.9. State the function of the fovea
Where you can see in the best detail (most cone cells)
3.1. Describe a hormone
A chemical substance secreted by a gland and carried by the blood that affects one or more specific target organs
3.2/5. Identity in diagrams specific endocrine glands
3.3/6. Describe adrenaline
The hormone secreted by the adrenal gland in “fight or flight” situations
Can cause increased breathing rate, heart rate, blood glucose concentration, pupil diametre
3.4. Compare nervous and hormonal control
Nervous system faster speed of action but shorter duration of effect (electrical vs chemical)
4.1. Describe homeostasis
The maintenance of a constant internal environment
4.2/4. Describe the control of blood glucose concentration by the liver
Insulin is produced in the pancreas when blood glucose rises and stimulates the liver to convert excess glucose into glycogen to be stored
Glucagon is produced in the pancreas when blood glucose falls and stimulates the liver and muscles to convert stored glycogen into glucose
4.3. Describe negative feedback
Occurs when conditions change from an ideal set point and returns conditions back to the set point
4.5. Outline the treatment of Type 1 diabetes
Injecting insulin into the patient
Taking blood glucose tests, controlling blood glucose level through exercise and diet
4.7. Describe the maintenance of a constant internal body temperature in mammals
Brain contains receptors sensitive to blood temperature
Skin has temperature receptors, sends impulses to the brain via sensory neurones
Brain sends nerve impulses to effectors to maintain the optimum temperature
Fatty tissue acts as insulation
Sweat secreted when hot so the body loses heat energy as it evaporates
Hairs lie flat to let air circulate, increasing heat transfer to environment by radiation
Skeletal muscles contract rapidly and causes shivering. These involuntary contractions need energy from respiration, and some is released as heat
Erect hairs to trap a layer of air around the skin for insulation
4.8. Describe vasodilation and vasoconstriction of arterioles
Vasoconstriction: arterioles get narrower, blood flow in capillaries slower, reduces amount of blood flowing through skin surface and heat lost by radiation
Vasodilation: arterioles get wider, blood flow in capillaries faster, increases amount of blood flowing through skin surface and heat lost by radiation
5.1. Describe gravitropism
A response in which plants grow towards (positive) or away (negative) from gravity
5.2. Describe phototropism
A response in which plants grow towards (positive) or away (negative) from light
5.3. Investigate and describe gravitropism and phototropism in shoots and roots
Shoots: positive phototropism, negative gravitropism
Grow upwards for more light and photosynthesise and grow more
Roots: negative phototropism, positive gravitropism
Grow downwards into soil, absorb water and minerals and anchor the plant
5.4/5. Explain phototropism and gravitropism of a shoot and the role of auxin in controlling shoot growth
- Auxin is produced in the apical meristem at the shoot tip
- It diffuses to the plant towards (a side)
- Auxin is unevenly distributed in response to light/gravity
- Auxin stimulates cell elongation
- (Side) becomes longer and causes the shoot to bend
