Notes on Human Anatomy Lecture

Introduction to the Brain

• Considered the most complex organ in the universe.
• Acts as the cockpit of the body, controlling all functions.
• Processes nerve impulses, emotions, and thoughts.
• Consumes 25% of body's energy, despite being only 5% of body weight.
• In danger, prioritizes self-preservation over other body parts.

Brain Structure

• Divided into two hemispheres: Right and Left.
• Three main parts:
  • Cerebrum: Largest part; coordinates movement and regulates temperature.
  • Cerebellum: Assists with balance.
  • Brain Stem: Controls basic life functions (consciousness, breathing, sleep).

The Heart

• Functions as the body's engine, essential for pumping blood.
• Comprised of:
  • Two upper chambers (Atria)
  • Two lower chambers (Ventricles)
• Blood flow process:
  1. Blood enters right atrium from veins.
  2. Moves to right ventricle.
  3. Flows to lungs via pulmonary artery for oxygenation.
  4. Oxygen-rich blood returns to left atrium, then left ventricle.
  5. Pumped out to the body through arteries.

The Lungs

• Essential for oxygenating the blood.
• Large surface area for gas exchange (size of a tennis court).
• Without functioning lungs, oxygen delivery to organs fails, risking damage.

The Liver

• Converts nutrients for bodily functions and filters blood from digestion.
• Produces bile, proteins, and aids in detoxification and immune response.
• Can regenerate even after significant removal (up to 75%).

The Kidneys

• Pair of bean-shaped organs for filtering waste from blood.
• Contain filtration units called nephrons that produce urine.
• One kidney can suffice for normal function, leading to organ donations.

The Spleen

• Located in the upper belly, it filters out old blood cells and foreign objects.
• Functions similarly to an air filtration system for the bloodstream.

The Gallbladder

• Stores and releases bile produced by the liver, aiding in fat digestion.
• Not vital, but can develop gallstones affecting digestion.

The Pancreas

• Located in the upper left abdomen; functions as both exocrine and endocrine gland.
• Produces digestive enzymes and insulin to regulate blood sugar.

The Stomach

• Breaks down and digests food with enzymes like pepsin, converting proteins to amino acids.
• Stores food as chyme before it moves to the intestines.
• Size adjusts based on food intake.

The Intestines

• Comprised of small and large intestines.
• Most digestion and absorption occurs in the small intestine.
• Waste is formed into feces in the large intestine and expelled.

The Skin

• Largest organ, part of the integumentary system (includes nails, hair, fat).
• Regulates temperature, protects from danger, and produces vitamin D.
• Composed of three layers:
  • Epidermis: Outermost layer.
  • Dermis: Middle layer.
  • Subcutaneous: Deepest layer.
• Skin color variations due to melanin levels.

Sensory Organs

Eyes

• Responsible for vision; capture light and send signals to the brain for processing.
• Remain the same size from birth to death.

Ears

• Detect sound and help maintain balance.
• Self-cleaning mechanism to manage earwax.

Tongue

• Sensory and muscular organ aiding in taste, digestion, speaking, and breathing.

Reproductive Organs

• Male: Testes (located in scrotum) produce sperm and testosterone.
• Female: Ovaries produce eggs, estrogen, and progesterone; crucial for reproduction.