WEEK 4

• The nervous system consists of the central nervous system (CNS) and the peripheral nervous system (PNS).
• Sensory neurons carry sensory information from sensory receptors to the CNS.
• Nerve cells, or neurons, are the basic units of the nervous system.
• The nervous system is compromised of three kinds of neurons, sensory neurons, motor neurons, and interneurons.
• Sensory neurons transmit information from sensory cells in the body called receptors to the brain, either directly or by way of the spinal cord.
• Receptors are cells that receive sensory information.
• The output is received by interneurons, nerve cells that connect other neurons with one another.
• The vast majority of neurons in the brain and spinal cord are interneurons.
• Motor neurons transmit commands from interneurons to the glands and muscles of the body, most often through the spinal cord.
• Motor neurons carry out both voluntary actions, such as grabbing a glass of water, and vital bodily functions, such as digestion and heartbeat.
• Sensory neurons are sometimes called afferent neurons.
• Motor neurons are sometimes called efferent neurons.
• Motor neurons transmit commands from the brain to the glands and muscles of the body.
• Interneurons connect neurons with one another.
• Neurons generally have a cell body, dendrites (branch-like extensions of the cell body), and an axon that carries information to other neurons.
• When a neuron is at rest (its resting potential), it is polarised, with a negative charge inside the cell membrane and a positive charge outside.
• Graded potentials are the spreading voltage changes along the cell membrane that occur as the neuron is excited by other neurons.
• An action potential is the “firing” of the neuron or a nerve impulse.
• Neurotransmitters transmit information from one neuron to another as they are released into the synapse. They bind with receptors in the membrane of the post-synaptic neuron, which produces graded potentials that can either excite or inhibit the post-synaptic neuron from firing.
• The endocrine system is a collection of glands that controls various bodily functions through the secretion of hormones.
• The endocrine system sends global messages through the bloodstream.
• Neurons of the PNS carry messages to and from the CNS.
• The PNS has two subdivisions: the somatic nervous system (carries sensory information to the brain and motor neurons that direct the action of skeletal muscles) and the autonomic nervous system (controls basic life processes such as heartbeat, digestive system and breathing).
• The autonomic nervous system consists of two parts: the sympathetic nervous system (activated in response to threats) and the parasympathetic nervous system (involved in routine activities).
• The design of the human nervous system reflects its evolution. The most primitive vertebrate brain, or brainstem, included a forebrain, a midbrain, and a hindbrain. The forebrain of humans includes an expanded cerebrum and cortex, which allows much more sophisticated sensory, cognitive, and motor processes.
• The CNS consists of the brain and the spinal cord.
• The spinal cord carries out reflexes, transmits sensory information to the brain and transmits messages from the brain to the muscles and organs.
• The hindbrain consists of the medulla oblongata or medulla, the cerebellum and parts of the reticular formation. These structures link the brain to the spinal cord, sustain life by controlling the supply of air and blood to cells in the body and regulate arousal level.
• The midbrain consists of the tectum and tegmentum; these structures help humans orient to visual and auditory stimuli with eye and body movements.
• The forebrain is involved in complex sensory, emotional, cognitive, and behavioural processes and consists of the hypothalamus, thalamus, the subcortical structures of the cerebrum and the cerebral cortex.
• The cerebral cortex consists of two hemispheres, each of which has four sets of lobes: occipital lobes, parietal lobes, frontal lobes, and temporal lobes. The primary and association areas of the cerebral cortex are involved in complex mental processes such as perception and thinking.
• Neuroplasticity suggests that the brain is a dynamic organ that continues to develop and change itself in response to neural, environmental, and behavioural experiences.
• Neurogenesis is the process by which neurons can be produced or repair themselves structurally or biochemically in the CNS.
• Cognitive neuropsychology is a branch of cognitive psychology that aims to understand how the structure and function of the brain relate to specific psychological processes.
• Heritability refers to the proportion of variability among individuals on an observed characteristic (phenotypic variance) that can be accounted for by genetic variability (genotypic variance).
• Branch-like extensions of the neuron, called dendrites, receive inputs from other cells.
• The cell body includes a nucleus that contains the genetic material of the cell (the chromosomes).
• The nucleus, with its genetic blueprints, is the “brain” of the operation, which determines how that particular neuron will manipulate the input from the dendrites of other neurons through its axon.
• The axon is a long extension from the cell body - occasionally as long as one metre - whose central function is to transmit information to other neurons.
• Axons often have two or more offshoots, or collateral branches.