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14. Coordination and response

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Topic 14.1

14.1 Coordination and response

Objectives in this topic

State that electrical impulses travel along neurones

Describe the mammalian nervous system in terms of: (a) the central nervous system (CNS) consisting of the brain and the spinal cord (b) the peripheral nervous system (PNS) consisting of the nerves outside of the brain and spinal cord

Describe the role of the nervous system as coordination and regulation of body functions

Identify in diagrams and images sensory, relay and motor neurones

Describe a simple reflex arc in terms of: receptor, sensory neurone, relay neurone, motor neurone and effector

Describe a reflex action as a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands)

Describe a synapse as a junction between two neurones

Describe the structure of a synapse, including the presence of vesicles containing neurotransmitter molecules, the synaptic gap and receptor proteins

Describe the events at a synapse as: (a) an impulse stimulates the release of neurotransmitter molecules from vesicles into the synaptic gap (b) the neurotransmitter molecules diffuse across the gap (c) neurotransmitter molecules bind with receptor proteins on the next neurone (d) an impulse is then stimulated in the next neurone

State that synapses ensure that impulses travel in one direction only

Topic 14.2

14.2 Sense organs

Objectives in this topic

Describe sense organs as groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals

Identify in diagrams and images the structures of the eye, limited to: cornea, iris, pupil, lens, retina, optic nerve and blind spot

Describe the function of each part of the eye, limited to: (a) cornea – refracts light (b) iris – controls how much light enters the pupil (c) lens – focuses light on to the retina (d) retina – contains light receptors, some sensitive to light of different colours (e) optic nerve – carries impulses to the brain

Explain the pupil reflex, limited to changes in light intensity and pupil diameter

Explain the pupil reflex in terms of the antagonistic action of circular and radial muscles in the iris

Explain accommodation to view near and distant objects in terms of the contraction and relaxation of the ciliary muscles, tension in the suspensory ligaments, shape of the lens and refraction of light

Describe the distribution of rods and cones in the retina of a human

Outline the function of rods and cones, limited to: (a) greater sensitivity of rods for night vision (b) three different kinds of cones, absorbing light of different colours, for colour vision

Identify in diagrams and images the position of the fovea and state its function

Topic 14.3

14.3 Hormones

Objectives in this topic

Describe a hormone as a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs

Identify in diagrams and images specific endocrine glands and state the hormones they secrete, limited to: (a) adrenal glands and adrenaline (b) pancreas and insulin (c) testes and testosterone (d) ovaries and oestrogen

Describe adrenaline as the hormone secreted in ‘fight or flight’ situations and its effects, limited to: (a) increased breathing rate (b) increased heart rate (c) increased pupil diameter

Compare nervous and hormonal control, limited to speed of action and duration of effect

State that glucagon is secreted by the pancreas

Describe the role of adrenaline in the control of metabolic activity, limited to: (a) increasing the blood glucose concentration (b) increasing heart rate

Topic 14.4

14.4 Homeostasis

Objectives in this topic

Describe homeostasis as the maintenance of a constant internal environment

State that insulin decreases blood glucose concentration

Explain the concept of homeostatic control by negative feedback with reference to a set point

Describe the control of blood glucose concentration by the liver and the roles of insulin and glucagon

Outline the treatment of Type 1 diabetes

Identify in diagrams and images of the skin: hairs, hair erector muscles, sweat glands, receptors, sensory neurones, blood vessels and fatty tissue

Describe the maintenance of a constant internal body temperature in mammals in terms of: insulation, sweating, shivering and the role of the brain

Describe the maintenance of a constant internal body temperature in mammals in terms of vasodilation and vasoconstriction of arterioles supplying skin surface capillaries

Topic 14.5

14.5 Tropic responses

Objectives in this topic

Describe gravitropism as a response in which parts of a plant grow towards or away from gravity

Describe phototropism as a response in which parts of a plant grow towards or away from the direction of the light source

Investigate and describe gravitropism and phototropism in shoots and roots

Explain phototropism and gravitropism of a shoot as examples of the chemical control of plant growth

Explain the role of auxin in controlling shoot growth, limited to: (a) auxin is made in the shoot tip (b) auxin diffuses through the plant from the shoot tip (c) auxin is unequally distributed in response to light and gravity (d) auxin stimulates cell elongation

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