nerves

• baroreceptors and chemoreceptors are found in the aorta and the carotid arteries
• parasympathetic nervous system decreases heart rate
• sympathetic nervous system increases heart rate
• the sinoatrial node (SAN) aka pacemaker is found in the right atrium
• the atrioventricular node (AVN) is located in the septum between the two atria
• the purkyne tissue are specialised muscle fibres that make up the collective Bundle of His
• wave of excitation is released from the purkyne tissue which causes both ventricles to contract at the same time, from the bottom of the heart upwards
• the tip of the heart is called the apex
• when pressure is applied to a pacinian corpuscle it is deformed and the stretch mediated sodium channels widen, causing sodium ions to diffuse into the neurone. Influx of sodium ions causes the membrane to be depolarised and an action potential is generated
• rod cells cannot distinguish different wavelengths of light and so only see in black and white. On the other hand, there are three different types of cone cell which can all respond to a different wavelength of light, allowing them to see in colour
• cone cells are connected to their own bipolar cell so summation cannot occur as it can with rod cells. Therefore rod cells allow us to see in low light intensities.
• rod cells give a lower visual acuity compared to cone cells
• visual acuity is the sharpness of vision and how well you can distinguish between different objects
• cone cells have iodopsin and rod cells have rhodopsin
• cone cells are found at the fovea where no rod cells are found. Concentration of cone cells decreases as you move away from the fovea, meaning none are found at the periphery of the retina.
• rod cells are found at the periphery of the retina
• schwann cells make up the myelin sheath. They can also carry out phagocytosis
• nodes of ranvier are sections of the axon which are not myelinated
• neurones have large amounts of rough endoplasmic reticulum in their cell body to produce neurotransmitters
• motor neurones have a large cell body which is always at the end of the axon whereas in sensory neurones they are in the middle
• saltatory conduction is when the nerve impulse jumps from node to node. It is faster than conduction that has to occur along the whole length of the axon which has to happen when it is unmyelinated.
• noradrenaline increases heart rate
• acetylcholine decreases heart rate
• slow twitch muscles contain larger amounts of myoglobin. It can carry more oxygen than haemoglobin which allows aerobic respiration to continue for longer, making the fibres suitable for endurance
• fast twitch muscle fibres have phosphocreatine which rapidly generates ATP by donating an inorganic phosphate
• kinesis is when the speed or movement or rate of turning changes. It is to get away from an unfavourable stimulus as quickly as possible
• taxis is the movement towards a favourable stimulus like light or heat
• Indoleacetic acid (IAA) is a type of auxin that causes cell elongation so that a plant will bend towards a favourable stimulus
• cell elongation occurs by hydrogen ions being actively transported into spaces in the cell wall to increase plasticity
• the central nervous system is the brain and spinal cord
• the peripheral nervous system contains the sensory and motor nervous systems
• the motor nervous system contains the voluntary and autonomic nervous system
• the hormonal system produces longer lasting responses that may be permanent and widespread whereas the nervous system responses are rapid, localised and temporary
• hormones travel to all parts of the body but only target cells respond
• larger axon diameter = faster conduction speed.
• the refractory period ensures action potentials only move in one direction, that not too many action potentials are generated and that impulses are discrete (separated)
• temporal summation is when one neurone releases neurotransmitter many times
• spatial summation is when many neurones release enough neurotransmitter between them to reach threshold potential
• calcium ions are released from the sarcoplasmic reticulum and diffuse into the myofibril
• the H band only contains myosin in the middle