Components of the Nervous System.

• The nervous system - a specialised network of cells in the human body and is our primary internal communication system

• The two main functions of the Nervous System: 1) To collect, process and respond to information in the environment. 2) to co-ordinate the working of different organs in the body.

• The nervous system is split into the ‘Central Nervous System’ and the ‘Peripheral Nervous System’

• Central nervous system - made up from the brain and the spinal cord. The brain is the centre of all conscious awareness. The cerebral cortex is highly developed and is what distinguishes us from animals. The brain is divided into two hemispheres. The spinal cord is an extension of the brain and is responsible for reflex actions such as pulling away your hand from something hot.

• Peripheral nervous system (PNS) - transmits messages via million s of neuron’s to and from the CNS. The PNS is divided into the ‘Autonomic Nervous System’ and ‘Somatic Nervous System’.

• Autonomic nervous system - governs vital functions in the body such as breathing, heart rate, digestion, sexual arousal etc. The Autonomic nervous system is then divided into the ‘Sympathetic Nervous System’ and the ‘Parasympathetic Nervous System’

• Somatic Nervous System - controls muscle movement and receives information from sensory receptors.

• Parasympathetic nervous system - Involved inn preparing the body for a fight or flight response.

• Sympathetic nervous system - Returns the body to its normal resting state. Slows down the heart and breathing rate and other functions are restored e.g. digestion.

• Difference between somatic nervous system and the autonomic nervous system - the Somatic nervous system has sensory and motor pathways whereas the Autonomic Nervous System is purely motor.

Neurons

• We have roughly 86 million neutrons. 80% of which are in the brain.

• Sensory neurones - transmits sensory information from receptors via the spinal cord to the brain

• Relay neurons - transmits information between neuron’s to allow for communication between different parts of the central nervous system.

• Motor neurons - transmits information to muscles and glands from the central nervous system.

Synapses

• Synaptic transmission - action potential reaches the end of the presynaptic neuron and triggers the release of neurotransmitters from the vesicles. The neurotransmitters diffuse across the synapse and bind to the receptors on the postsynaptic neuron. Excitatory neurotransmitters make it more likely that the postsynaptic neuron will generate an action potential. Inhibitory neurotransmitters will make it less likely that the postsynaptic neuron will generate an action potential . Neurotransmitters are removed from the synapse by being broken down by enzymes.

• Excitation - when a neurotransmitter such as adrenaline, increases the positive charge of the post synaptic neuron. this increases the likelihood that the neuron will pass on the electrical impulse.

• Inhibition - when a neurotransmitter such as serotonin, increases the negative charge of the post synaptic neuron. This decreases the likelihood that the neuron will pass on the electrical impulse.

• Distinguish between sensory and relay neurons - sensory neurons transmit sensory information from the receptors via the spinal cord, to the brain where as a relay neuron transmits information between neurons to allow communication between different parts of the central nervous system.

Endocrine system

• Hypothalamus - regulates hunger, thirst, sleep and wakefulness. Also regulates involuntary mechanisms such as body temperature.

• Pituitary glands - controls all other endocrine glands: influences growth, metabolism and regeneration.

• Thyroid gland - regulates energy and metabolism

• Thymus - builds resistance to disease

• Adrenal glands - secrets adrenaline to prepare body for fight or flight response to help react to emergencies

• Ovaries / testes - influences how your blood circulates and determines your mental vigor and sex drive.

• Endocrine system - bodies major information systems that instructs glands to release hormones and carried towards target organs.

• Glands - an organ in the body that synthesises substances such as hormones.

Example of a gland - hypothalamus

Hormone produced - oxytocin

Effects of hormone produced - increases positive emotions such as love

Example of gland - adrenal gland

Hormone produced - adrenaline

Effects of hormone produced - prepares body for fight or flight response