The Central Nervous System

Biology 8

• The theme for this course is "Live 5Cs" (Competence, Character, Commitment to Achieve, Collaboration, Creativity)
• This theme will be explored through academic rigor, growth mindset, and grit.
• The unit is about the nervous system.

Unit 02: Life Processes of Living Things - Nervous System

• The Nervous System has three primary functions:
  • Receiving information from the environment and inside the body.
  • Interpreting the received information.
  • Making the body respond to the information.

Introduction to the Nervous System

• The nervous system is a complex network in the human body that plays a crucial role in controlling and coordinating bodily functions.
• Its primary function is to receive, process, and respond to information from the environment.

Nervous System Overview

• The structure of the nervous system includes the central nervous system (CNS) and the peripheral nervous system (PNS).
• The CNS consists of the brain and spinal cord; the PNS consists of nerves.
  • CNS receives and processes information and initiates action.
  • PNS transmits signals between the CNS and the rest of the body.
  • The brain, spinal cord, and nerves work together to transmit nerve impulses to coordinate movement, sensations, cognition, and all other bodily functions.

Central Nervous System (CNS)

• The Central Nervous System (CNS) is responsible for:
  • Receiving and sorting information from the environment and the body's internal state.
  • Making decisions about appropriate responses to stimuli.
• Two major components of CNS are:
  • The brain.
  • The spinal cord.

Brain

• The brain is one of the largest organs and controls most bodily activities.
• It is the centre for all thought, memory, judgment and emotion.
• Each part of the brain controls distinct functions (e.g., temperature regulation, breathing).
• The brain is composed of sections called the forebrain, midbrain, and hindbrain.

Forebrain

• The forebrain is composed of the cerebrum, thalamus, and hypothalamus.
  • The cerebrum is the largest part of the forebrain.
  • The cerebral cortex, the outer layer of the cerebrum, has many specialized areas associated with thoughts, judgment, memory, problem-solving, and language.
  • The cerebrum is divided into the left and right cerebral hemispheres, each with four lobes.
  • The thalamus receives sensory information from the body and transmits it to the cortex.
  • The hypothalamus controls automatic bodily processes, including the pituitary gland, which regulates metabolism, digestion, sexual maturity, and response to stress.

Midbrain

• The midbrain is located beneath the middle of the forebrain.
• It acts as a coordinator for messages going in and out to the spinal cord.

Hindbrain

• The Hindbrain is located underneath the back of the cerebrum.
• It consists of the cerebellum, pons and medulla oblongata. These structures are critical for vital body functions like heartbeat and breathing. -The cerebellum coordinates voluntary body movements and maintains balance.
  • The brainstem (medulla oblongata and pons) sends out and coordinates all brain messages, and controls automatic body functions like breathing, heart rate, blood pressure, swallowing, and blinking.

Spinal Cord

• The spinal cord is the bridge between the peripheral nervous system and the brain.
• It serves as a pathway of information from and to the brain
• The spinal cord has various regions, including cervical, thoracic, lumbar, sacral, and coccygeal..
• It handles some sensory information and provides motor responses.
• These are called reflex actions.

Meninges

• The meninges are the three layers of membranes that surround the brain and spinal cord.
• They protect the CNS.
  • Dura mater (outermost layer)
  • Arachnoid mater (middle layer)
  • Pia mater (innermost layer)

Sulci & Gyri

• Sulci and gyri are grooves and ridges, respectively, in the cerebral cortex; characteristic of the brain. They increase the surface area of the cerebral cortex.
• These grooves and bumps increase surface area and make the functions of the brain more efficient.

Fissure

• Fissures are deep grooves or clefts in the brain that divide the brain into various parts.
  • One important fissure in the brain is the longitudinal fissure.

Cerebrospinal Fluid

• Cerebrospinal fluid (CSF) is a clear, colorless liquid that surrounds and cushions the brain and spinal cord.
• It provides a protective barrier against shock.
• It's produced by the choroid plexus in the brain’s ventricles.

Peripheral Nervous System (PNS)

• The PNS transmits signals between the CNS and the rest of the body.
  • Somatic nervous system: handles voluntary movements and sensory information from receptors in the skin, body wall and limbs.
  • Autonomic nervous system: handles involuntary movements and processes. It has two further branches:
    • Sympathetic division (fight or flight response)
    • Parasympathetic division (rest and digest response)

Spinal Nerves

• Spinal nerves branch off the spinal cord and pass out through openings in the vertebrae called foramina
• These nerves carry information to and from the spinal cord to the rest of the body.

Cranial Nerves

• Cranial nerves arise directly from the brain.
• In humans, there are traditionally twelve pairs of cranial nerves. Some are sensory, some motor, and some mixed.

Nerve Cells

• Neurons, also called nerve cells, are the active components of the nervous system.
• They communicate with each other using electrical signals and transmit information throughout the body.
• A neuron has three major components:
  • Dendrites
  • cell body (soma)
  • axon
  • myelin
  • synaptic terminals

Synapses

• Synapses are junctions where neurons communicate with each other or with other cells.
• They're the sites where nerve impulses are transmitted.

Test your knowledge of the central nervous system's functions. This quiz covers brain regions like the cerebrum, cerebellum, and occipital lobe. Explore the roles of these key areas and their impact on motor control, sensory processing, and vital functions.