Anatomy of lung and spinal cord Hand made Notes

Download now Report

Anatomy of Lung and Spinal Cord, Function of Spinal Cord - Handmade Notes

Download handmade notes covering the anatomy of the lung and spinal cord, with a dedicated section on the function of the spinal cord. These notes provide detailed structural descriptions of the lungs and spinal cord, along with a comprehensive explanation of the spinal cord's roles in the nervous system. Suitable for B.Pharm and related health science programs. Available in PDF/PPT format.

Keywords: Lung Anatomy, Spinal Cord Anatomy, Spinal Cord Function, Respiratory System, Central Nervous System, CNS, B.Pharm, Human Anatomy and Physiology, Handmade Notes, PDF, PPT, Download.

Anatomy and Function of the Lung and Spinal Cord

1. Anatomy of the Lung

The lungs are the primary organs of respiration, located in the thoracic cavity. Key anatomical features include:

• Paired Organs: Humans have two lungs, a right lung and a left lung.
• Lobes: The right lung has three lobes (superior, middle, inferior), while the left lung has two lobes (superior, inferior). The left lung is smaller to accommodate the heart.
• Pleura: The lungs are surrounded by a double-layered serous membrane called the pleura:
  • Visceral Pleura: Covers the surface of the lungs.
  • Parietal Pleura: Lines the thoracic cavity.
  The pleural cavity, the space between the visceral and parietal pleura, contains a small amount of pleural fluid, which reduces friction during breathing.
• Bronchial Tree: Air enters the lungs through the trachea (windpipe), which branches into two primary bronchi (one for each lung). The primary bronchi further divide into secondary bronchi (one for each lobe), then tertiary bronchi, and finally into smaller and smaller bronchioles.
• Alveoli: The bronchioles terminate in tiny air sacs called alveoli, which are the sites of gas exchange. Alveoli are surrounded by a network of capillaries.
• Hilum: The region on the medial surface of each lung where the bronchi, blood vessels, lymphatic vessels, and nerves enter and exit.
• Apex- Top most part.
• Base:- The base of lung located just above the diaphragm.

2. Anatomy of the Spinal Cord

The spinal cord is a long, cylindrical structure that extends from the brainstem (medulla oblongata) to the lumbar region of the vertebral column. It's part of the central nervous system (CNS). Key anatomical features include:

• Protection: The spinal cord is protected by the vertebral column (bones), meninges (membranes), and cerebrospinal fluid (CSF).
• Meninges: Three layers of connective tissue membranes surround the spinal cord:
  • Dura Mater: The outermost, tough layer.
  • Arachnoid Mater: The middle layer, with a web-like appearance.
  • Pia Mater: The innermost layer, which adheres closely to the spinal cord.
  The subarachnoid space, between the arachnoid mater and pia mater, contains CSF.
• Gray Matter: The inner core of the spinal cord, shaped like a butterfly or the letter "H." It contains neuron cell bodies, dendrites, and unmyelinated axons. The gray matter is divided into horns:
  • Dorsal (Posterior) Horns: Contain sensory neuron cell bodies.
  • Ventral (Anterior) Horns: Contain motor neuron cell bodies.
  • Lateral Horns: Present in the thoracic and upper lumbar regions; contain cell bodies of autonomic motor neurons.
• White Matter: Surrounds the gray matter. It contains myelinated axons, which are organized into tracts (bundles of axons with similar functions).
  • Ascending Tracts: Carry sensory information *up* the spinal cord to the brain.
  • Descending Tracts: Carry motor commands *down* the spinal cord from the brain.
• Spinal Nerves: 31 pairs of spinal nerves emerge from the spinal cord, connecting it to the peripheral nervous system. Each spinal nerve is formed by the union of a dorsal root (containing sensory fibers) and a ventral root (containing motor fibers).
• Central Canal: A small canal that runs through the center of the spinal cord, containing CSF.
• Conus Medullaris: The tapered, lower end of the spinal cord.
• Cauda Equina: A bundle of nerve roots that extend inferiorly from the conus medullaris.
• Filum terminale:- fibrous tissue that provide support to spinal cord.

3. Function of the Spinal Cord

The spinal cord has two primary functions:

1. Pathway for Sensory and Motor Information:
   • Sensory (Afferent) Pathways: Sensory information from the body travels *up* the spinal cord to the brain via ascending tracts in the white matter. This information includes touch, pressure, pain, temperature, and proprioception (body position).
   • Motor (Efferent) Pathways: Motor commands from the brain travel *down* the spinal cord via descending tracts in the white matter. These commands control voluntary movements (via the somatic nervous system) and involuntary functions (via the autonomic nervous system).
2. Reflex Center: The spinal cord integrates and coordinates *reflexes*, which are rapid, involuntary responses to stimuli. A reflex arc typically involves:
   • Receptor: Detects the stimulus.
   • Sensory Neuron: Carries the sensory information to the spinal cord.
   • Integration Center: Usually within the gray matter of the spinal cord. May involve interneurons.
   • Motor Neuron: Carries the motor command from the spinal cord to the effector.
   • Effector: The muscle or gland that carries out the response.
   Examples of spinal reflexes include the stretch reflex (e.g., knee-jerk reflex), the withdrawal reflex (e.g., pulling your hand away from a hot object), and the crossed-extensor reflex.

In summary, the spinal cord serves as a crucial link between the brain and the peripheral nervous system, transmitting both sensory and motor information, and it also plays a vital role in coordinating reflexes.

Info!
If you are the copyright owner of this document and want to report it, please visit the copyright infringement notice page to submit a report.