Human Anatomy: Body Membranes & Bones

Body Membranes

• Thin layers of tissue that cover, separate, and support visceral organs and line body cavities.
• Pleurae: covers the lungs
• Pericardium: covers the heart
• Peritoneum: covers the abdominal viscera

Locomotor System

• Consists of bones, joints, and muscles.

Bone

• Type of connective tissue formed of cells, fibers, and matrix.
• Hard due to calcification of its extracellular matrix.
• Elastic due to the presence of organic fibers.
• Functions:
  • Forms the supporting framework of the body.
  • Gives attachment to muscles and acts as levers.
  • Protects underlying structures (e.g., skull protects the brain).
  • Stores calcium and phosphorus.
  • Formation of blood cells by bone marrow.

Classification of Bones

• According to Structure:
  • Compact bone: appears as a solid mass.
  • Cancellous bone: Consists of a branching network of trabeculae.
• According to Shape:
  • Long bones: femur and humerus.
  • Short bones: carpal and tarsal bones.
  • Flat bones: scapula and bones of the skullcap.
  • Irregular bones: vertebrae and bones of the base of the skull.
  • Sesamoid bones: small bones found in certain tendons (e.g., patella).
  • Pneumatic bones: contain air cavities (e.g., some skull bones like the maxilla).

Regional Classification

• Axial skeleton:
  • Skull
  • Vertebral column
  • Thoracic cage
  • Pelvic cavity
• Appendicular skeleton:
  • Bones of the upper limb.
  • Bones of the lower limb.

Structure of Long Bones

• Shaft: tubular in shape, containing the marrow cavity with bone marrow.
• Ends: covered by articular cartilage.
• Epiphyseal plate: flat plate of hyaline cartilage between the ends and the shaft, responsible for growth of the bone in length.

Heart

• Chambers:
  • Right atrium: receives deoxygenated blood from the superior and inferior vena cava.
  • Right ventricle: pumps deoxygenated blood to the lungs via the pulmonary trunk.
  • Left atrium: receives oxygenated blood from the four pulmonary veins.
  • Left ventricle: pumps oxygenated blood to the body via the aorta.
• Surfaces:
  • Right surface: formed by the right atrium.
  • Left surface: formed mainly by the left ventricle and a small part by the left atrium.
• Differences between Atria and Ventricles:
  • Atrium: thin wall, occupies the upper part, receives blood from veins.
  • Ventricle: thick wall, occupies the lower part, pushes blood into arteries.
• Valves:
  • Atrioventricular valves: located between atria and ventricles.
    • Tricuspid valve: between right atrium and right ventricle.
    • Mitral valve: between left atrium and left ventricle.
  • Semilunar valves: located between ventricles and the vessels connected to them.
    • Pulmonary valve: between right ventricle and pulmonary trunk.
    • Aortic valve: between left ventricle and aorta.

Blood Supply of the Heart

• Supplied by two coronary arteries (right and left).
• Originate from the ascending aorta.

Nerve Supply of the Heart

• Supplied by sympathetic and parasympathetic autonomic nerves.

Conducting System of The Heart

• Consists of cardiac muscle cells and conducting fibers specialized for initiating and conducting impulses rapidly through the heart.
• Sino-atrial (SA) Node: initiates the heartbeat (pacemaker), located in the right atrium.

Trachea

• Structure:
  • Tubular structure about 10-12 cm long.
  • Composed of C-shaped hyaline cartilage rings.
  • Allows for air passage.
• Functions:
  • Conducts air to and from the lungs.
  • Warms, filters, and humidifies inhaled air before it reaches the lungs.

Primary Bronchi

• Two bronchi (right and left) arise from the lower end of the trachea.
• Each bronchus passes obliquely downward to the hilum of the corresponding lung.
• Differences:
  • Right bronchi: shorter (about 1 inch), wider, more vertical, divides into three bronchi (one for each lobe of the lung).
  • Left bronchi: longer (about 2 inches), narrower, more oblique, divides into two bronchi (one for each lobe of the lung).

Lungs

• Two lungs covered by the pleura, separated by the mediastinum.
• Shape: cone-shaped.
  • Apex: upper end.
  • Base: directed downward and resting on the diaphragm.
  • Surfaces:
    • Lateral surface: convex, related to the ribs.
    • Medial surface: concavo-convex, related to the heart.
    • Hilum: area where structures enter and leave the lung.
• Fissures and lobes:
  • Right lung: three lobes (superior, middle, and inferior) divided by two fissures (oblique and horizontal).
  • Left lung: two lobes (superior and inferior) divided by the oblique fissure.
  • Each lobe is further divided into segments.
• Alveoli: where gaseous exchange occurs between the air and blood.

Joints

• Types:
  • Fibrous Joints: immovable (e.g., sutures of the skull).
  • Cartilaginous Joints: slightly movable (e.g., intervertebral discs).
    • Primary Cartilaginous Joints: hyaline cartilage (e.g., epiphyseal plate).
    • Secondary Cartilaginous Joints fibrocartilage (e.g., intervertebral discs).
  • Synovial Joints: freely movable (e.g., shoulder joint).

Muscle Tissues

• Types:
  • Skeletal Muscle: attached to bones, voluntary control, striated appearance.
  • Smooth Muscle: found in walls of internal organs, involuntary control, not striated.
  • Cardiac Muscle: found in the heart, involuntary control, striated appearance.

Nervous System

• Parts:
  • Central Nervous System: brain and spinal cord.
  • Peripheral Nervous System: cranial and spinal nerves.
• Cranial Nerves: 12 pairs.
• Spinal Nerves: 31 pairs.
• Functions:
  • Sensory: receives information from the body.
  • Motor: sends signals to muscles and glands.
  • Integrative: processes and interprets information.

Digestive System

• Organs:
  • Mouth
  • Pharynx
  • Esophagus
  • Stomach
  • Small Intestine
  • Large Intestine
• Functions:
  • Ingestion
  • Digestion
  • Absorption
  • Elimination

Respiratory System

• Organs:
  • Nose
  • Pharynx
  • Larynx
  • Trachea
  • Bronchi
  • Lungs
• Functions:
  • Gas exchange (oxygen uptake, carbon dioxide removal).
  • Voice production.
  • Regulation of blood pH.

Urinary System

• Organs:
  • Kidneys
  • Ureters
  • Urinary bladder
  • Urethra
• Functions:
  • Filtration of waste products from blood.
  • Production of urine.
  • Regulation of blood volume and composition.

Reproductive System

• Male: testes, epididymis, vas deferens, prostate gland, seminal vesicles, penis.
• Female: ovaries, fallopian tubes, uterus, vagina.
• Functions:
  • Production of gametes.
  • Fertilization.
  • Development and birth of offspring.

Endocrine System

• Glands:
  • Pituitary gland
  • Thyroid gland
  • Parathyroid glands
  • Adrenal glands
  • Pancreas
  • Gonads
• Functions:
  • Production of hormones that regulate various bodily functions, including growth, metabolism, reproduction, and mood.

This quiz covers key concepts related to body membranes and the locomotor system, including the structure and function of bones. Delve into the different classifications of bones and their roles in the human body. Test your knowledge of anatomy and how these systems interact.