6.1 response to stimuli

• sensory neurones transmit electrical impulses from receptors to the central nervous system
• the central nervous systeem is made up of the brain and spinal cord
• motor neurones transmit electrical impulses from the CNS to effectors
• relay neurones transmit electrical impulses between sensory neurones and motor neurones
• a stimulus is detected by receptor cells and an electrical impulse is sent to the central nervous system
• receptors detect stimuli
• effectors are cells that bring a response to a stimulus to produce an effect
• receptors communicate with effectors via the nervous system or the hormonal system
• the peripheral nervous system is made up of the neurones that connect the CNS to the rest of the body
• the somatic nervous system controls conscious activites
• the autonomic nervous system controls unconscious activities
• the sympathetic nervous system gets the body ready for action
• the parasympathetic nervous system calms the body down
• reflects are rapid, automatic responses to stimuli
• what are the stages of the reflex arc in order?

  stimulus, sensory neurone, relay neurone, motor neurone, effector, response
• a tropism is a plants growth response to external stimuli
• phototropism is the growth of a plant in response to light
• gravitropism is the growth of plant in response to gravity
• taxes?

  the organisms move towards or away from a directional stimulus
• kineses?

  the organisms' movement is affected by a non-directional stimulus
• in phototropism IAA moves to the more shaded parts of the shoots and roots, so there's uneven growth
• in gravitropism IAA moves to the underside of shoots and roots, so there's uneven growth
• pacinian corpuscles are pressure receptors in your skin
• the muscles of the iris control the amount of light that enters the eye
• lens on the retina focus light rays
• the fovea is the area of the retina that contains lots of photoreceptors
• the optic nerve is a bundle of neurones
• photoreceptors convert light into an electrical impulse
• what two photoreceptors are is in the human eye?

  rods and cones
• control of the basic heart beat is myogenic
• the sinoatrial node initiates a wave of depolarisation that causes the atria to contract
• The sinoatrial node sets the rhythm of the heartbeat by sending out regular waves of electrical activity to the atrial walls
• the atrioventricular node is responsible for passing the waves of electrical impulses from the atria to the ventricles
• The bundle of His is a group of muscle fibres responsible for conducting waves of electrical activity between the ventricles and the apex of the heart
• the rate at which the SAN fires is unconsciously controlled by a part of the brain called the medulla oblongata
• there are blood pressure receptors called baroreceptors in the aorta and the carotid arteries
• there are chemical receptors called chemoreceptors in the aorta, the carotid artery and in the medulla
• what receptor detect high or low blood pressure?

  bracoreceptors
• what receptors detect low blood pressure?

  chemoreceptors
• the autonomic nervous system is responsible for involuntary functions such as heart rate and breathing