Nervous and Endocrine Systems

Overview

• Nervous System
  • Involves nerves.
  • Fast response system.
• Endocrine System
  • Involves hormones (chemicals).
  • Slower response system.
• Both systems work together to maintain homeostasis by responding to environmental changes.

Human Nervous System

• Functions:
  • Sensory Function: Receptors detect stimuli.
  • Integrative Function: CNS processes and reacts to stimuli.
  • Motor Function: Effectors (muscles & glands) respond.
• Stimuli: Physical or chemical changes in environments causing organism response.

Neurons

• Neurons make up the nervous system.
• Require a large amount of energy and oxygen and do not replace themselves via mitosis.
• Structure:
  • Dendrites: Conduct impulses to the cell body.
  • Axon: Conducts impulses away from the cell body to synaptic knobs.
  • Schwann Cells: Insulate neurons with myelin to speed impulse conduction.
• Classes of Neurons:
  • Structurally: Multipolar, Bipolar, Unipolar.
  • Functionally: Sensory, Connector (Interneuron), Motor.

Parts of Nervous System

• CNS (Central Nervous System):
  • Brain and spinal cord protected by cranium, vertebral column, and meninges.
  • Meninges: Dura mater, Arachnoid mater, Pia mater.
  • Cerebrospinal Fluid (CSF): Cushions, nourishes, and hydrates the CNS.
• PNS (Peripheral Nervous System):
  • 43 pairs of nerves (12 cranial, 31 spinal).
  • Divided into: Somatic (voluntary control) and Autonomic (involuntary control).

Brain

• Cerebrum:
  • Largest part; surface folds increase cell area.
  • Functions: Voluntary movement, intelligence, memory, and sensory processing.
• Cerebellum:
  • Coordinates voluntary movements, balance, and posture.
• Medulla Oblongata:
  • Controls reflex actions and acts as a pathway for impulses.

Autonomic Nervous System

• Sympathetic NS: Prepares body for action/fight or flight.
• Parasympathetic NS: Recovery/rest and digest.
• Both systems have antagonistic effects.

Reflex Arcs

• Pathway for fast involuntary responses to stimuli.
• Components: Receptor, Sensory neuron, Interneuron, Motor neuron, Effector.

Impulses and Synapses

• Impulse: Electrical wave along neuron membrane.
• Synapse: Gap between neurons, transmitting chemically via neurotransmitters.
• Synapses ensure one-directional flow, impulse dispersion, and filter unimportant stimuli.

Disorders

• Alzheimer’s Disease:
  • Incurable, causes dementia.
  • Symptoms: Memory loss, confusion, mood swings.
• Multiple Sclerosis:
  • Autoimmune, affects myelin sheaths.
  • Symptoms: Muscle control issues, visual problems.

Note: Brain/spinal cord injuries and drug effects on CNS are not included in the syllabus.