Chapter 16 -Mekyle

The Origins of Medical Science

• Early healers used superstition and magic for treatments.
• Observation and experimentation led to new anatomical and physiological terminology.
• Cadaver dissection provided groundbreaking knowledge about the human body.
• Andreas Vesalius revolutionized anatomy in the 16th century with detailed dissections and illustrations.

Anatomy and Physiology: Structure and Function

• Anatomy studies the structure of the human body, a term derived from the Greek word for "a cutting up."
• Physiology studies the functions of the human body, derived from the Greek for "relationship to nature."
• Structure directly determines function.

Levels of Organization: From Atoms to Organisms

• Subatomic particles include protons, neutrons, and electrons.
• An atom is the smallest unit of an element (e.g., hydrogen, carbon).
• A molecule consists of two or more atoms (e.g., water (H2OH_2OH2​O), glucose (C6H12O6C_6H_{12}O_6C6​H12​O6​)).
• Macromolecules are large molecules formed by smaller molecules (e.g., DNA, proteins).
• An organelle is a specialized structure within a cell (e.g., mitochondria, lysosomes).
• Cells are the basic unit of structure and function (e.g., muscle cells, nerve cells, blood cells).
• Tissues are groups of similar cells performing a specific function (e.g., adipose tissue).
• An organ is composed of different tissues performing a function (e.g., heart, kidney, stomach).
• An organ system is a group of organs performing a function (e.g., digestive system).
• An organism is a complete living being with interacting organ systems (e.g., a human).

Noninvasive Imaging Techniques

• Ultrasound creates images of soft internal structures using high-frequency sound waves and is used for fetal sonograms.
• Magnetic Resonance Imaging (MRI) uses magnetic fields to produce high-resolution images of internal structures, especially the brain.

Core Themes of Anatomy and Physiology

• The cell is a fundamental unit of life.
• The internal environment differs from the external environment.
• Homeostasis is the maintenance of a stable internal environment.
• Cells depend on each other for survival and function.
• Structure and function are inextricably linked.
• Cells move substances down pressure and concentration gradients across permeable membranes.
• Cellular differentiation is the specialization of cells through gene expression.
• Cell membrane mechanisms regulate substance entry/exit and respond to external signals.
• Cell-to-cell communication occurs through membrane receptors.
• Feedback loops are homeostatic mechanisms that respond to changes.
• The body balances substance replacement and elimination.
• Energy is required for metabolic reactions within cells.

Characteristics of Life

• Growth is the increase in cell number and size.
• Reproduction is the production of new cells and organisms.
• Responsiveness is reaction to environmental changes.
• Movement is a change in body position or motion of internal organs.
• Metabolism is the sum of all chemical reactions in a living system.
• Respiration is the process of making energy, involves the intake of oxygen and the release of carbon dioxide.
• Digestion is the breakdown of food into usable nutrients.
• Circulation is the movement of chemicals and cells through body fluids.
• Excretion is the removal of waste products.

Requirements of Organisms

• Water is the most abundant substance and supports metabolic processes and temperature regulation.
• Food supplies nutrients for energy, growth, and repair.
• Oxygen releases food energy through cellular respiration.
• Heat maintains body temperature and influences metabolic rate.
• Pressure, including atmospheric and hydrostatic pressure, is essential for breathing and blood flow.

Homeostasis: Maintaining a Stable Internal Environment

• Homeostasis maintains a stable internal environment.
• Homeostatic mechanisms are self-regulating systems.

Components of a Homeostatic Mechanism

• Receptors detect changes and send information.
• The control center processes information and determines response.
• Effectors carry out the response.

Feedback Mechanisms: Regulating Homeostasis

• Negative feedback is the most common mechanism, counteracting initial changes to maintain stability; examples include body temperature, blood pressure, and glucose.
• Positive feedback amplifies initial changes for a specific outcome, such as blood clotting and childbirth.

Organization of the Human Body

• The axial portion includes the head, neck, and trunk.
• The appendicular portion includes the upper and lower limbs.

Major Body Cavities of the Axial Portion

• The cranial cavity houses the brain.
• The vertebral canal contains the spinal cord.
• The thoracic cavity encloses the lungs and thoracic viscera.
• The abdominopelvic cavity contains the abdominal and pelvic viscera.
• The diaphragm separates the thoracic and abdominopelvic cavities.
• The mediastinum is the region between the lungs, containing the heart, esophagus, trachea, and thymus gland.

Abdominopelvic Cavity Subdivisions

• The abdominal cavity extends from the diaphragm to the pelvis, including the stomach, liver, spleen, kidneys, small intestine, and most of the large intestine.
• The pelvic cavity is enclosed by pelvic bones, containing the end of the large intestine, urinary bladder, and internal reproductive organs.

Small Cavities of the Head

• The oral cavity is the mouth.
• The nasal cavity is the nose.
• Orbital cavities are eye sockets.
• Middle ear cavities are in the temporal bones of the skull.

Thoracic and Abdominopelvic Membranes

• Serous membranes are double-layered membranes that line cavities and secrete serous fluid.
• The visceral layer covers an organ.
• The parietal layer lines the cavity wall.
• The pleura surrounds the lungs.
• The pericardium encloses the heart.
• The peritoneum lines abdominopelvic organs.

Organ Systems: Body Covering, Support, and Movement

• The integumentary system includes skin, hair, nails, and glands and functions in protection, temperature regulation, sensation, and vitamin D production.
• The skeletal system includes bones, ligaments, and cartilage and functions for the provision of support, movement, protection, mineral storage, and blood cell production.
• The muscular system includes muscles and provides support, movement, heat production, and posture maintenance.

Organ Systems: Integration and Coordination

• The nervous system includes the brain, spinal cord, nerves, and sense organs; it detects changes, interprets sensory information, and stimulates muscles and glands with rapid, short-term effects.
• The endocrine system includes hormone-secreting glands and controls metabolic activities with slower, longer-lasting effects.

Organ Systems: Transport

• The cardiovascular system includes the heart, arteries, capillaries, and veins and transports gases, nutrients, blood cells, hormones, and wastes.
• The lymphatic system includes lymphatic vessels, lymph nodes, the thymus, and the spleen; it returns fluid to the blood, carries absorbed food molecules, and defends against infection.

Organ Systems: Absorption and Excretion

• The digestive system includes the mouth, tongue, teeth, and associated organs as well as the stomach, intestines, liver and gallbladder, and pancreas; it receives, breaks down, and absorbs food and eliminates waste.
• The respiratory system includes the nasal cavity, pharynx, larynx, trachea, bronchi, and lungs and enables gas exchange.
• The urinary system includes kidneys, ureters, the urinary bladder, and the urethra; it removes blood wastes, regulates electrolyte balance and blood pressure, and produces and excretes urine.

Organ Systems: Reproduction

• The male reproductive system includes the scrotum, testes and associated organs, urethra, and penis; it produces and transfers sperm cells.
• The female reproductive system includes ovaries, uterine tubes, the uterus, the vagina, and external genitalia (vulva); it produces egg cells, receives sperm, supports embryo development, and functions in childbirth.

Organ Systems Summary

• Integumentary: Skin, hair, nails, sweat glands, and sebaceous glands. Protect tissues, regulate body temperature, support sensory receptors.
• Skeletal: Bones, ligaments, cartilages. Provide framework, protect soft tissues, provide attachments for muscles, produce blood cells, store inorganic salts.
• Muscular: Muscles. Cause movements, maintain posture, produce body heat.
• Nervous: Brain, spinal cord, nerves, sense organs. Detect changes, receive and interpret sensory information, stimulate muscles and glands.
• Endocrine: Glands that secrete hormones (pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries, testes, pineal gland, and thymus). Control metabolic activities of body structures.
• Cardiovascular: Heart, arteries, capillaries, veins. Move blood through blood vessels and transport substances throughout body.
• Lymphatic: Lymphatic vessels, lymph nodes, thymus, spleen. Return tissue fluid to the blood, carry certain absorbed food molecules, defend the body against infection.
• Digestive: Mouth, tongue, teeth, salivary glands, pharynx, esophagus, stomach, liver, gallbladder, pancreas, small and large intestines. Receive, break down, and absorb food; eliminate unabsorbed material.
• Respiratory: Nasal cavity, pharynx, larynx, trachea, bronchi, lungs. Intake and output of air, exchange of gases between air and blood.
• Urinary: Kidneys, ureters, urinary bladder, urethra. Remove wastes from blood, maintain water and electrolyte balance, store and eliminate urine.
• Reproductive: Male: scrotum, testes, epididymides, ductus deferentia, seminal vesicles, prostate gland, bulbourethral glands, urethra, penis; Female: ovaries, uterine tubes, uterus, vagina, clitoris, vulva. Produce and maintain sperm cells, transfer sperm cells into female reproductive tract; Produce and maintain egg cells, receive sperm cells, support development of an embryo, and function in birth process.

Lifespan Changes: The Aging Process

• Hair loses pigment.
• Skin wrinkles due to decreased subcutaneous fat and stiffens due to decreased collagen and elastin.
• Body fat tissue increases.
• Joints stiffen.
• Blood pressure may increase.
• Increased risk of type 2 diabetes.
• Organs shrink.
• Cells lose ability to divide.
• Metabolic rate slows down.
• Protein production is reduced.
• Increased risk of neurological conditions like dementia or Alzheimer’s disease.

Anatomical Terminology: Describing Body Position and Structure

• Anatomical Position: Erect stance, facing forward, with upper limbs at the sides and palms facing forward.
• Superior (above) / Inferior (below): Vertical relationships.
• Anterior or ventral (toward the front) / Posterior or dorsal (toward the back): Front-to-back relationships.
• Medial (toward the midline) / Lateral (away from the midline): Relationships to the midline.
• Bilateral (paired structures; on both sides): Structures on both sides.
• Ipsilateral (same side) / Contralateral (opposite sides): Structures on the same or opposite sides.
• Proximal (close to point of attachment to trunk) / Distal (farther from point of attachment to trunk): Relationships to attachment point.
• Superficial (close to body surface) / Deep (more internal): Relationships to the body surface.

Body Sections or Planes

• Sagittal Section: Divides the body into left and right portions.
• Mid-sagittal/Median Section: Divides the body into equal left and right portions.
• Parasagittal Section: Divides the body into unequal left and right portions.
• Transverse or Horizontal Section: Divides the body into superior and inferior portions.
• Coronal or Frontal Section: Divides the body into anterior and posterior portions.

Sections of Cylindrical Organs

• Cross Section: Cut across the structure.
• Oblique Section: Angular cut.
• Longitudinal Section: Lengthwise cut.

Explore the impact of observation on medical science and Vesalius's anatomical contributions. Understand the structure-function relationship in organ systems, and levels of organization in the human body. Learn about the relationship between macromolecules and smaller molecules.