Biology Grade 10 Science Reviewer - 3rd Quarter

Nervous System

• The human nervous system is a complex network that enables us to experience the world around us and respond to various stimuli.
• It involves various parts working together to send, receive, and process signals.

Brain Anatomy

• The brain is divided into three main sections: the cerebrum, the cerebellum, and the brainstem.
• The cerebrum is the largest part of the brain, controlling higher thought processes, speech, voluntary muscle movements, and interpreting sensory information.
• The cerebrum has two hemispheres that communicate with each other via the corpus callosum.
• Each hemisphere can be further divided into lobes:
  • Frontal lobe: controls reasoning
  • Parietal lobe: interprets sensory input
  • Temporal lobe: processes sound
  • Occipital lobe: associated with sight

Cerebellum

• The cerebellum sits below the brainstem and above the neck's spinal cord.
• It plays a crucial role in coordinating movement, maintaining balance, and regulating body posture.

Brainstem

• The brainstem connects the brain to the rest of the nervous system.
• It encompasses several structures, including the midbrain, pons, medulla oblongata, and reticular formation.
• The brainstem controls automatic functions like:
  • Breathing
  • Heart rate
  • Blood pressure
  • Swallowing
  • Digestion
  • Eye movements

Autonomic Nervous System

• The autonomic nervous system controls involuntary processes that occur without conscious thought.
• It has two main branches: sympathetic and parasympathetic.
• The sympathetic nervous system (also known as the fight or flight response):
  • Prepares the body for action by increasing heart rate, respiration, pupil dilation, and sweating.
  • Enables the body to respond quickly to stressful situations.
• The parasympathetic nervous system:
  • Slows the heart rate, lowers blood pressure, and increases gastric secretions.
  • Activates digestion and recovery from stress.

Peripheral Nervous System

• The peripheral nervous system is responsible for conveying information between different parts of the body.
• It consists of sensory neurons that transmit signals towards the central nervous system and motor neurons that carry signals away from it.

Somatic Nerve Fibers

• These nerve fibers provide sensation such as:
  • Touch
  • Temperature
  • Pain
  • Vibration
  • Pressure
  • Position sense
  • Muscle control
• Each somatic fiber consists of axons encased in myelin sheaths for efficient signal transmission and Schwann cells for protection and support.

Autonomic Nerve Fibers

• Unlike somatic nerves, autonomic nerves extend deep into internal organs.
• They play a vital role in controlling visceral functions like:
  • Blood flow regulation
  • Gut motility
  • Body temperature maintenance

Central Nervous System

• The central nervous system primarily consists of the brain and spinal cord.
• These organs work together to process incoming sensory information, coordinate voluntary movements, and control other essential physiological processes.

Spinal Cord

• The spinal cord runs down the back through vertebrae, acting as a bridge between the brain and the rest of the body.
• It relays messages between the brain and various regions of the body via its 31 pairs of spinal nerves.
• Injuries to the spinal cord can affect motor and sensory function depending on their location along the spine.