Origins of Medical Science, Anatomy & Physiology

• Chapter 1 includes a lecture outline and figures

Origins of Medical Science

• Early healers practiced superstition and magic.
• Observations of injuries, wound healing, and dead bodies were made.
• Experimentation and new terminology evolved for anatomy & physiology.
• Cadaver dissection and the study of corpses led to new knowledge of the human body.
• Vesalius made illustrations from 1543.

Anatomy & Physiology

• Anatomy studies the structure/morphology of the human body and its parts, derived from the Greek "a cutting up."
• Physiology studies the functions of the human body and its parts and is derived from the Greek for "relationship to nature."
• The structure of organs and body parts determine the function.

Levels of Organization

• All materials, living or non-living, consist of chemicals, which are composed of atoms.
• Subatomic particles like protons, neutrons, and electrons make up cells.
• Atoms are tiny particles making up chemicals, such as hydrogen and carbon.
• Molecules are particles of atoms joined together, such as water and glucose.
• Macromolecules are large particles of molecules, examples include DNA and protein.
• Organelles support the function of a cell, such as the mitochondrion and lysosome.
• A cell is the basic unit of structure and function, examples are muscle, nerve, and blood cells.
• Tissue is a layer or mass of cells with specific functions, such as adipose tissue.
• An organ is a group of different tissues, for example, the heart, kidney, and stomach.
• An organ system is a group of organs with a common function, such as the digestive system.
• An organism is composed of interacting organ systems, such as a human.

Clinical Applications

• Noninvasive procedures provide images of internal structures.
• Ultrasound uses high-frequency sound waves to produce images of soft internal structures, like a fetus sonogram in the uterus.
• Magnetic Resonance Scan (MR): Magnetic field changes alignment, spins certain atoms, and provides high-resolution images of internal structures.

Core Themes of Anatomy & Physiology

• Cells: All living things consist of cells
• Internal environment: The environment within the body
• Homeostasis: the Maintenance of a constant internal environment
• Interdependency of cells: Cells depend on each other
• Interrelated structures and functions

Mechanisms and Processes

• Gradients and permeability move cells from high to low pressure across permeable membranes.
• Cellular differentiation is the process of specialization of cells due to gene expression.
• The cell membrane mechanism determines the entry of substances and responds to signals.
• Cell-to-cell communication occurs through membrane receptors.
• Feedback loops are homeostatic mechanisms for stability.
• Maintaining Balance through replacement of lost substances and the elimination of excesses
• The energy processes keep cells active.

Characteristics of Life

• Growth: Increased cell number, size, and body size
• Reproduction: Production of new cells and organisms
• Responsiveness: Reaction to a change inside or outside of the body
• Movement: change of body position and/or motion of internal organs
• Metabolism: The sum of all chemical reactions in a living system related to energy production and nutrient cycling
• Respiration: Making energy, primarily by taking in oxygen and expelling carbon dioxide
• Digestion: Breaking down food into usable nutrients for absorption into the blood
• Circulation: Moving chemicals and cells through body fluids
• Excretion: Removing waste products

Requirements of Organisms

• Life requires environmental factors like water, food, oxygen, heat, and pressure
• Chemicals in the body
• Water is the most abundant substance and supports metabolic processes, transport, and temperature regulation.
• Food provides necessary nutrients to supply energy.
• Oxygen releases energy from food.

Fluids

• Intracellular fluid is inside cells.
• Interstitial fluid is between cells.
• Blood plasma is fluid in blood vessels.
• Extracellular fluid includes interstitial fluid and blood plasma.

Organism Requirements

• Heat as a form of energy helps maintain body temperature and partly controls the rate of metabolic reactions.
• Pressure is the application of force on an object.
• Atmospheric pressure needed for breathing.
• Hydrostatic pressure keeps blood flowing.

Homeostasis

• Homeostasis maintains a stable internal environment.
• Homeostatic mechanisms are self-regulating systems that monitor and correct aspects of the internal environment.
• The receptor detects and provides information about the stimuli.
• The control center is the decision-maker that maintains the set point.
• The effector, a muscle or a gland responds to the control center by causing the necessary change in the internal environment.

Feedback

• Negative feedback is the most common type of homeostatic mechanism.
• With negative feedback, effectors return conditions toward a normal range, lessening the initial deviation.
• Negative feedback is named after the opposing direction of the variable from the deviation of the set point.
• Negative Feedback prevents sudden and severe changes in the human body.
• Examples: Negative feedback controls body temperature, blood pressure, and glucose levels.
• Positive feedback is an uncommon feedback mechanism in the body.
• Positive feedback intensifies the change/deviation instead of reversing it.
• Positve feedback increases the activity of the effectors.
• Positive feedback is short-lived.
• Postive feedback produce unstable conditions but may not lead to homeostasis.
• Examples: Blood clotting and uterine contractions during childbirth

Organization of the Human Body

• The human body consists of an axial portion (head, neck, and trunk) and an appendicular portion (upper and lower limbs).
• Major body cavities of the axial portion:
  • Cranial cavity houses the brain.
  • Vertebral canal/spinal cavity contains the spinal cord.
  • Thoracic cavity houses the lungs and thoracic viscera.
  • Abdominopelvic cavity contains abdominal and pelvic viscera

Major Body Cavities

• The diaphragm separates the thoracic and abdominopelvic cavities.
• The mediastinum, located between the lungs in the thoracic cavity, contains the heart, esophagus, trachea, and thymus gland.
• The abdominopelvic cavity contains 2 portions:
  • The abdominal cavity extends from the diaphragm to the top of the pelvis and contains several organs.
  • The pelvic cavity, enclosed by pelvic bones, contains the end of the large intestine, the urinary bladder, and internal reproductive organs.

Small Cavities of the Head

• Found in the head
• Oral cavity
• Nasal cavity
• Orbital cavities
• Middle ear cavities

Thoracic and Abdominopelvic Membranes

• Thoracic and abdominopelvic cavities which are lined by double-layered serous membranes, secrete serous fluid.
• The serous fluid reduces friction.
• Serous membranes consist of two layers:
  • Visceral layer that covers an organ.
  • Parietal layer that lines the cavity wall.
• Serous membrane examples:
  • Visceral and parietal pleura (around lungs in thorax)
  • Visceral and parietal pericardium (around heart in thorax)
  • Visceral and parietal peritoneum (around abdominopelvic organs)

Organ Systems: Body Covering, Support, and Movement

• Integumentary System: Body covering, protection, body temperature regulation, sensory reception, production of Vitamin D
• Skeletal System: Support and movement, framework, protection, attachment sites, storage of inorganic salts, production of blood cells
• Muscular System: Support and movement, main source of body heat, and posture

Organ Systems: Integration & Coordination

• Nervous System: Integration and coordination of organ function through nerve impulses and neurotransmitters with rapid short-term effects
• Endocrine system: Integration and coordination of organ function through chemical messengers called hormones, slower, longer-lasting effects

Organ Systems: Transport

• Cardiovascular System: Transportation of gases, nutrients, blood cells, hormones, and wastes
• Lymphatic System: Transportation of fluids from tissue spaces to blood. Carries fats from the digestive system and defends the body against infection

Organ Systems: Absorption & Excretion

• Digestive System: Receives food, breaks it down, absorbs digestion products, and excretes waste
• Respiratory System: Moves air in and out of the body, then exchanges gases (oxygen and carbon dioxide) between blood and air. It also absorbs oxygen.
• Urinary System: Removes blood wastes, regulates electrolyte & water balance and blood pressure, then produces urine and excretes it by transporting it to outside of the body.

Organ Systems: Reproduction

• Reproductive System: Male and female systems produce and transport sex cells, produce hormones, and produce new like organisms. Females also provide for fetal development and childbirth.

Organ Systems Table

• Major systems, organs, and functions include:
  • Integumentary, which includes skin, hair, nails, sweat glands, and sebaceous glands for protection and temperature regulation.
  • Skeletal includes bones, ligaments, and cartilages for providing a framework and protecting soft tissues.
  • Muscular includes muscles for movement and maintain posture producing body heat.
  • Nervous includes the brain, spinal cord, nerves, and sense organs for sensory information interpretation.
  • Endocrine which includes the pituitary, thyroid, parathyroid, adrenal glands, pancreas, ovaries, testes, pineal gland, and thymus to control metabolic activities.
  • Cardiovascular involving the heart, arteries, capillaries, and veins to move blood and substances.
  • Lymphatic consists of lymphatic vessels, lymph nodes, thymus and spleen to return fluid, absorb food molecules, and defend against infection
  • Digestive including the mouth, tongue, teeth, salivary glands, pharynx, esophagus, stomach, liver, gallbladder, pancreas, and intestines for receiving, breaking down, absorbing food, and eliminating unabsorbed material.
  • Respiratory involving nasal cavity, pharynx, larynx, trachea, bronchi, and lungs for air intake and gas exchange.
  • Urinary including kidneys, ureters, urinary bladder, and urethra for removing wastes, maintaining water and electrolyte balance.
  • Reproductive organs in males and females for reproduction.

Lifespan Changes due to Aging

• Gray or white hair due to loss of pigment
• Skin wrinkles result from a decrease in subcutaneous fat
• Stiffening of the skin due to decreased elastin and collagen
• Joints become stiff
• Increased percentage of fats in the tissues
• Blood pressure may progress to hypertension
• Increased blood glucose may result in type 2 diabetes mellitus
• Tissues atrophy and organs shrink
• Cells have limited ability to undergo cell division as they lose tips of chromosomes
• Low metabolic rate
• Reduced enzyme and protein production
• increased risk of developing dementia/Alzheimer's disease

Anatomical Terminology

• Body erected with a forward-facing position, upper limbs on the sides, and palms facing forward.
• Anatomic terms expressing relative position are based on a person standing in the anatomical position.

Terms of Relative Position

• Superior described as above/ Inferior described as below
• Anterior describes toward the front/ Posterior describes toward the back
• Medial describes the direction towards the midline/ Lateral describes the direction away from the midline
• Bilateral describes paired structures on both sides
• Ipsilateral is when something is located to the same side/ Contralateral is when something is on opposite sides
• Proximal describes where something is situated close to the point of attachment to the trunk/ Distal describes farther from the point of attachment to the trunk
• Superficial is something close to the body surface / Deep is more internal

Body Sections or Planes

• Sagittal: longitudinal cut separating the body into left and right portions
• Mid-Sagittal cut separates body into equal left and right portions
• Parasagittal: Lateral midline sagittal sectioning the body into unequal left and right portions
• Transverse/Horizontal: divides into superior/inferior portions
• Coronal/Frontal: longitudinal cut that divides into anterior and posterior portions

Sections of Cylindrical Organs

• Cross section is a cut across the structure.
• Oblique section is an angular cut.
• Longitudinal section is a lengthwise cut.

Lecture notes on the origins of medical science. Includes topics such as the evolution of terminology for anatomy and physiology. Also includes the levels of organization in the human body.