Neural

• Coordination is the process through which two or more organs interact and complement each other's functions to maintain homeostasis
• During physical exercises, energy demand increases for maintaining increased muscular activity, leading to increased supply of oxygen
• Increased supply of oxygen necessitates an increase in the rate of respiration, heart beat, and increased blood flow via blood vessels
• When physical exercise is stopped, the activities of nerves, lungs, heart, and kidney gradually return to their normal conditions
• The neural system and the endocrine system jointly coordinate and integrate all the activities of the organs in the body
• The neural system provides an organised network of point-to-point connections for quick coordination
• The endocrine system provides chemical integration through hormones
• The human neural system is divided into the central neural system (CNS) and the peripheral neural system (PNS)
• The CNS includes the brain and the spinal cord and is the site of information processing and control
• The PNS comprises all the nerves of the body associated with the CNS
• The PNS nerve fibres are of two types: afferent fibres and efferent fibres
• The PNS is divided into somatic neural system and autonomic neural system
• The somatic neural system relays impulses from the CNS to skeletal muscles, while the autonomic neural system transmits impulses to involuntary organs and smooth muscles
• The autonomic neural system is further classified into sympathetic neural system and parasympathetic neural system
• Visceral nervous system comprises the complex of nerves, fibres, ganglia, and plexuses transmitting impulses to and from the viscera and the central nervous system
• A neuron is composed of a cell body, dendrites, and axon
• Neurons are classified based on the number of axon and dendrites into multipolar, bipolar, and unipolar
• There are two types of axons: myelinated and non-myelinated
• Neurons are excitable cells due to their polarised membrane
• The resting potential is the electrical potential difference across the resting plasma membrane of a neuron
• A nerve impulse is generated by the depolarisation of the membrane at a specific site, leading to an action potential
• Nerve impulses are transmitted from one neuron to another through synapses, which can be electrical or chemical
• At chemical synapses, neurotransmitters are involved in the transmission of impulses between neurons
• The brain is the central information processing organ of our body
• It acts as the 'command and control system' controlling voluntary movements, balance, functioning of vital involuntary organs, thermoregulation, hunger, thirst, circadian rhythms, activities of endocrine glands, human behaviour
• The brain processes vision, hearing, speech, memory, intelligence, emotions, and thoughts
• The brain is protected by the skull and covered by cranial meninges: dura mater, arachnoid, pia mater
• The brain is divided into three major parts: forebrain, midbrain, hindbrain
• Forebrain consists of cerebrum, thalamus, and hypothalamus
• Cerebrum is divided into left and right cerebral hemispheres connected by corpus callosum
• Cerebral cortex covers the cerebral hemisphere and contains motor areas, sensory areas, and association areas
• Thalamus is a coordinating centre for sensory and motor signaling
• Hypothalamus controls body temperature, eating, drinking urges, and secretes hypothalamic hormones
• Midbrain is located between the thalamus/hypothalamus and pons
• Contains corpora quadrigemina
• Hindbrain comprises pons, cerebellum, and medulla
• Pons has fibre tracts interconnecting different brain regions
• Cerebellum has a convoluted surface for more neurons
• Medulla is connected to the spinal cord and controls respiration, cardiovascular reflexes, and gastric secretions
• Brain stem includes midbrain, pons, and medulla oblongata, forming connections between the brain and spinal cord