The Structure and Function of the Nervous System and Brain

The Structure and Function of the Nervous System and Brain

The Nervous System

The Nervous System can be categorised into Central Nervous System (CNS) and Peripheral Nervous System (PNS).

  • The CNS consists of the brain and spinal cord. This system processes information received from the peripheral nervous system and coordinate a response.
  • The PNS involves two main parts: the somatic nervous system and the autonomic nervous system.
    • Somatic Nervous System controls voluntary actions like movement of muscles.
    • Autonomic Nervous System controls involuntary functions like heartbeat and digestion. It’s divided into sympathetic and parasympathetic divisions.

Structure and Function of the Brain

The brain, the command centre of the nervous system, can be classified into three main parts: Forebrain, Midbrain, and Hindbrain.

  • The Forebrain consists of the cerebrum, thalamus, and hypothalamus.
    • Cerebrum is the largest part of the brain and responsible for functions such as thought, behaviour, emotion, and complex sensory and motor function.
    • Thalamus acts as a relay station, transmitting information to and from the cerebral hemispheres.
    • Hypothalamus regulates functions like temperature control, thirst, appetite and sleep patterns.

  • The Midbrain connects the forebrain and the hindbrain. It contains the reticular activating system, which controls arousal and sleep.

  • The Hindbrain includes the pons, medulla oblongata, and cerebellum.
    • Pons aids in control of sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expression, and posture.
    • Medulla oblongata is responsible for regulating heart rhythm, blood flow, breathing rate, digestion, vomiting and swallowing.
    • Cerebellum helps in maintaining balance and coordination of voluntary movements.

Neurons and Nerve Impulse Transmission

  • Neurons are the basic units of the nervous system. They carry messages in the form of electrical impulses.
  • Each neuron consists of a cell body (or soma), dendrites, and an axon.
  • Dendrites receive signals from other neurons and transmit them towards the cell body.
  • Axons transmit the signals away from the cell body to other neurons or target cells.
  • Synapse is the tiny gap between two neurons where signal transmission occurs. It involves the release of chemicals known as neurotransmitters.

Sensory and Motor Neurons

  • Sensory Neurons transmit signals from sensory receptors to the CNS.
  • Motor Neurons carry signals from the CNS to the muscles or glands to initiate a response.
  • Interneurons relay signals between sensory and motor neurons.

Nervous System and Homeostasis

  • The nervous system plays a crucial role in maintaining homeostasis by coordinating response to changes in the internal or external environment.
  • It utilises feedback mechanisms to monitor and adjust the physiological processes. For example, the regulation of body temperature, blood pressure and glucose level.

Brain Disorders

  • Stroke, occurs when the blood supply to parts of the brain is disrupted, causing brain cells to die.
  • Epilepsy, a neurological disorder characterised by recurrent seizures.
  • Alzheimer’s Disease, a form of dementia that causes problems with memory, thinking and behaviour.
  • Parkinson’s Disease, a degenerative disorder of the nervous system that affects movement.
  • Multiple Sclerosis, a disease in which the immune system eats away at the protective covering of nerves.