B.Pharm 1st Semester HAP Unit 4 Notes PDF Download: Peripheral Nervous System & Special Senses

1st Semester

Download B.Pharm 1st Semester HAP Unit 4 Notes PDF with detailed explanation of Peripheral Nervous System, spinal and cranial nerves, and special senses (eye, ear, nose, tongue). Covers structure, functions, and common disorders — perfect for pharmacy students.

HAP-1

✅ Peripheral Nervous System (PNS)

The peripheral nervous system connects the central nervous system (CNS — brain and spinal cord) to the rest of the body. It acts like a communication highway between the brain/spinal cord and the limbs, organs, and tissues.

Classification of PNS

The PNS is classified into:

1️⃣ Somatic Nervous System

  • Controls voluntary body movements
  • Supplies skeletal muscles
  • Carries conscious sensations

2️⃣ Autonomic Nervous System (ANS)

  • Controls involuntary functions
  • Supplies smooth muscles, cardiac muscle, glands
  • Maintains internal balance (homeostasis)

The ANS is further divided into:

  • Sympathetic Nervous System
  • Parasympathetic Nervous System

✅ Sympathetic Nervous System

Origin

  • Arises from the thoracolumbar segments (T1–L2) of the spinal cord.

Structure

  • Short preganglionic fibers, long postganglionic fibers
  • Ganglia arranged in a chain alongside the vertebral column

Functions

  • Prepares the body for emergencies (“fight or flight”)
  • Increases heart rate
  • Dilates pupils
  • Inhibits digestion
  • Increases blood supply to muscles

✅ Parasympathetic Nervous System

Origin

  • Arises from the craniosacral segments (cranial nerves III, VII, IX, X and sacral S2–S4).

Structure

  • Long preganglionic fibers, short postganglionic fibers
  • Ganglia near or within the target organ

Functions

  • Maintains normal body functions (“rest and digest”)
  • Slows heart rate
  • Promotes digestion
  • Stimulates secretion of digestive juices
  • Conserves energy

✅ Spinal Nerves

  • 31 pairs of spinal nerves
    • 8 cervical
    • 12 thoracic
    • 5 lumbar
    • 5 sacral
    • 1 coccygeal
  • Each arises from the spinal cord
  • Carries both sensory and motor fibers
  • Controls movement and reflexes of the trunk and limbs

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Unit 4 Notes

✅ Cranial Nerves

  • 12 pairs originating directly from the brain
  • Responsible for special senses and movements of the head/neck

Examples:

  • Optic nerve (vision)
  • Olfactory nerve (smell)
  • Facial nerve (facial expressions)
  • Vagus nerve (heart, lungs, digestive tract)

Special Senses

Special senses let us interact with the world around us. These include:
✅ Vision (eye)
✅ Hearing (ear)
✅ Smell (nose)
✅ Taste (tongue)

✅ Eye: Structure and Function

The eye is the organ of vision.

Structure:

  • Cornea
  • Lens
  • Retina (photoreceptors)
  • Iris and pupil
  • Optic nerve

Functions:

  • Receives light
  • Focuses it on retina
  • Converts it into nerve signals for the brain to interpret as images

Common Eye Disorders:

  • Cataract
  • Glaucoma
  • Conjunctivitis

✅ Ear: Structure and Function

The ear helps in hearing and balance.

Structure:

  • Outer ear (pinna, auditory canal)
  • Middle ear (eardrum, ossicles)
  • Inner ear (cochlea, semicircular canals)

Functions:

  • Converts sound waves to nerve impulses
  • Maintains body balance

Common Ear Disorders:

  • Deafness
  • Otitis media
  • Tinnitus

✅ Nose: Structure and Function

Structure:

  • External nostrils
  • Nasal cavity lined with olfactory receptors

Functions:

  • Smell perception
  • Warming, humidifying air
  • Filtering dust and microbes

Common Disorders:

  • Rhinitis
  • Sinusitis

✅ Tongue: Structure and Function

Structure:

  • Skeletal muscle covered with taste buds (papillae)

Functions:

  • Taste (sweet, salty, bitter, sour, umami)
  • Assists in speech
  • Helps in swallowing

Common Disorders:

  • Glossitis
  • Loss of taste