Mind map Neural Control and Coordination Best notes and Brain map for Free
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The neural system coordinates and integrates functions as well as metabolic and homeostatic activities of all the organs. Neurons, the functional units of neural system are excitable cells due to a differential concentration gradient of ions across the membrane.
The human Central Nervous System (CNS) is a network of over 100 billion individual nerve cells that regulate our actions, sense our environment and process our thoughts. The CNS includes the brain and the spinal cord, which together coordinate and control the movement and activities of the body. The Central Nervous System is responsible for sensory input, integration, control of muscle and glands, homeostasis, and mental activities. Sensory input is detected by the nervous system through sensory receptors that detect external and internal stimuli. These stimuli range from vision, hearing, smell, touch, pain, body position and temperature, to unconscious processes such as blood pH, blood gases, or blood pressure. The CNS is also responsible for sending signals from the brain and spinal cord to other parts of the body. These signals are sent through pathways which have projecting reticular neurons that affect the cerebral cortex, cerebellum, thalamus, hypothalamus, and spinal cord. The pathways communicate with each other through many neural pathways, and the pathways allow the brain and spinal cord to analyze information and prepare body responses accordingly. The CNS also helps to maintain homeostasis, which is the balance between the body’s internal environment and its external environment. Homeostasis is accomplished through the activities of the autonomic nervous system, which is composed of the sympathetic and parasympathetic nervous systems. The sympathetic nervous system is responsible for the body’s “fight or flight” response, while the parasympathetic nervous system helps to restore the body back to a state of equilibrium. Finally, the CNS is responsible for the conscious and unconscious mental activities of the body. Conscious mental activities include the ability to think, reason, remember, and perceive. Unconscious mental activities include the automatic processes that occur in the body, such as the regulation of heart rate, respiration, and digestion. In conclusion, the Central Nervous System is an intricate and complex network of neurons that enable us to sense the external and internal environment, coordinate and control our bodies, and maintain homeostasis. It is responsible for conscious and unconscious mental activities, as well as the body’s “fight or flight” response. Without the CNS, our bodies would not be able to function properly.
The electrical potential difference across the resting neural membrane is called the ‘resting potential’. The nerve impulse is conducted along the axon membrane in the form of a wave of depolarisation and repolarisation.
A synapse is formed by the membranes of a pre-synaptic neuron and a post-synaptic neuron which may or may not be separated by a gap called synaptic cleft. Chemicals involved in the transmission of impulses at chemical synapses are called neurotransmitters.
Human neural system consists of two parts : (i) central neural system (CNS) and (ii) the peripheral neural system. The CNS consists of the brain and spiral cord. The brain can be divided into three major parts : (i) forebrain, (ii) midbrain and (iii) hindbrain. The forebrain consists of cerebrum, thalamus and hypothalamus.
The midbrain receives and integrates visual, tactile and auditory inputs. The hindbrain comprises pons, cerebellum and medulla. The cerebellum integrates information received from the semicircular canals of the ear and the auditory system. The medulla contains centres, which control respiration, cardiovascular reflexes, and gastric secretions. Pons consist of fibre tracts that interconnect different regions of the brain. The entire process of involuntary response to a peripheral nervous stimulation is called reflex action.
The cerebrum is longitudinally divided into two halves that are connected by the corpus callosum. A very important part of the forebrain called hypothalamus controls the body temperature, eating and drinking. Inner parts of cerebral hemispheres and a group of associated deep structures form a complex structure called limbic system which is concerned with olfaction, autonomic responses, regulation of sexual behaviour, expression of emotional reactions, and motivation.
Information regarding changes in the environment is received by the CNS through the sensory organs which are processed and analysed. Signals are then sent for necessary adjustments. The wall of the human eye ball is composed of three layers. The external layer is composed of cornea and sclera. Inside sclera is the middle layer, which is called the choroid. Retina, the innermost layer, contains two types of photoreceptor cells, namely rods and cones. The daylight (photopic) vision and colour vision are functions of cones and twilight (scotopic) vision is the function of the rods.
The light enters through cornea, the lens and the images of objects are formed on the retina. The ear can be divided into the outer ear, the middle ear and the inner ear. The middle ear contains three ossicles called malleus, incus and stapes. The fluid filled inner ear is called the labyrinth, and the coiled portion of the labyrinth is called cochlea. The organ of corti is a structure which contains hair cells that act as auditory receptors and is located on the basilar membrane. The vibrations produced in the ear drum are transmitted through the ear ossicles and oval window to the fluid-filled inner ear.
Nerve impulses are generated and transmitted by the afferent fibres to the auditory cortex of the brain. The inner ear also contains a complex system located above the cochlea called vestibular apparatus. It is influenced by gravity and movements, and helps us in maintaining balance of the body and posture.
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