Bio 103: Introduction to Anatomy and Physiology

Introduction to Anatomy and Physiology

• Definition of Anatomy and Physiology:     * Anatomy: The study of structure. The term originates from the Greek phrase meaning ‐a cutting up.‑     * Physiology: The study of function. The term originates from the Greek phrase meaning ‐relationship to nature.‑     * The Principle of Complementarity: Structure is always related to function; the way something is built determines what it can do.

Characteristics of Living Organisms

• Distinct Properties of Living Organisms:     * Cellular Composition: Cells are the basic units of life. They are the smallest unit that can carry out functions of life, and all living organisms are composed of them.     * Metabolism: This refers to the collection of chemical reactions carried out by living organisms.         * Anabolism: Known as ‐building‑ processes, where smaller molecules are combined to form larger ones.         * Catabolism: Known as ‐breaking down‑ processes, where large molecules are broken down into smaller subunits.     * Growth: This occurs when building (anabolism) outweighs breaking down (catabolism) processes. It takes two forms:         * An increase in the size of individual cells.         * An increase in the total number of cells.     * Excretion: The process an organism uses to eliminate potentially harmful waste products created by metabolic processes.     * Responsiveness or Irritability: The ability of organisms to sense and react to changes or stimuli in their environment.     * Movement: The ability of an entire organism to move, or the movement of individual cells or materials within/between cells.     * Reproduction: In multicellular organisms, this occurs in two ways:         * Individual cells reproduce within the organism for growth and to replace old or damaged cells.         * The organism itself reproduces to yield similar offspring.

Levels of Structural Organization

• Chemical Level: The smallest level and the foundation for each successive level. It ranges from atoms to complex molecules.     * Atom: Examples include the hydrogen atom and lithium atom.     * Molecule: Examples include the water molecule and glucose molecule.     * Macromolecule: Examples include protein molecules and DNA molecules.
• Cellular Level: Formed by groups of many different types of molecules combined in specific ways to form cellular structures.     * Organelle: Subcellular structures such as the mitochondrion, Golgi apparatus, and nucleus.     * Cell: Examples include muscle cells and nerve cells. The cell is the smallest unit of life.
• Tissue Level: Two or more cell types cooperate to perform a common function.     * Components: Consists of cells and the surrounding extracellular matrix.     * Variations: Ranges from membrane sheets covering body cavities to irregularly shaped cartilage found in the nose.
• Organ Level: Consists of two or more tissue types combined to form a structure or organ.     * Examples: Skin, femur, heart, and kidney.
• Organ System Level: The body’s organs are grouped into organ systems.     * Definition: Consists of two or more organs that together carry out a broad function in the body.     * Quantity: The human body has $11$ organ systems.
• Organism Level: The highest level where organ systems function together to make up a working human body (an organism).

Overview of the 11 Organ Systems

• Integumentary System:     * Components: Hair, skin, and nails.     * Functions: Protects the body from the external environment, produces vitamin D, retains water, and regulates body temperature.
• Skeletal System:     * Components: Bones and joints.     * Functions: Supports the body, protects internal organs, provides leverage for movement, produces blood cells, and stores calcium salts.
• Muscular System:     * Components: Skeletal muscles.     * Functions: Produces movement, controls body openings, and generates heat.
• Nervous System:     * Components: Brain, spinal cord, and nerves.     * Functions: Regulates body functions and provides for sensation, movement, automatic functions, and higher mental functions via nerve impulses.
• Endocrine System:     * Components: Pineal gland, hypothalamus, pituitary gland, thyroid gland, thymus gland, adrenal glands, pancreas, ovaries (female), and testes (male).     * Functions: Regulates body functions and regulates the functions of muscles, glands, and other tissues through the secretion of chemicals called hormones.
• Cardiovascular System:     * Components: Blood vessels and heart.     * Functions: Pumps and delivers oxygen-poor blood to the lungs and oxygen-rich blood to the tissues, removes wastes from tissues, and transports cells, nutrients, and other substances.
• Lymphatic System:     * Components: Tonsils, lymph nodes, thymus, spleen, and lymphatic vessels.     * Functions: Returns excess tissue fluid to the cardiovascular system and provides immunity (protection against disease).
• Respiratory System:     * Components: Nasal cavity, pharynx, larynx, trachea, and lungs.     * Functions: Delivers oxygen to the blood, removes carbon dioxide from the body, and maintains the acid-base balance of the blood.
• Digestive System:     * Components: Mouth, salivary glands, esophagus, liver, stomach, gallbladder, pancreas, large intestine, and small intestine.     * Functions: Digests food, absorbs nutrients into the blood, removes food waste, and regulates fluid, electrolyte, and acid-base balance.
• Urinary System:     * Components: Kidneys, ureters, urinary bladder, and urethra.     * Functions: Removes metabolic wastes from the blood, regulates fluid, electrolyte, and acid-base balance, and stimulates blood cell production.
• Reproductive System (Male):     * Components: Prostate gland, ductus deferens, testis, and penis.     * Functions: Produces and transports sperm, secretes hormones, and sexual function.
• Reproductive System (Female):     * Components: Mammary glands, uterine tube, ovary, uterus, and vagina.     * Functions: Produces and transports eggs, site of fetal development, nourishment, childbirth, and lactation, secretes hormones, and sexual function.

Anatomical Terminology and Position

• Anatomical Position: A common frame of reference used to describe body parts and regions regardless of the actual position of the body.     * Criteria: Body standing upright, feet shoulder-width apart, upper limbs at the sides of the trunk, head and palms facing forward.     * Context: The body is always referred to as if it were in this position. ‐Right‑ and ‐left‑ always refer to the sides of the body being described, not the observer's own right or left.
• Directional Terms:     * Anterior (Ventral): Toward the front. Examples: The palms are on the anterior side of the body; the esophagus is anterior to the spinal cord.     * Posterior (Dorsal): Toward the back. Examples: The occipital bone is on the posterior cranium; the spinal cord is posterior to the esophagus.     * Superior (Cranial): Toward the head. Examples: The nose is superior to the mouth; the neck is superior to the chest.     * Inferior (Caudal): Toward the tail. Examples: The nose is inferior to the forehead; the umbilicus (belly button) is inferior to the chest.     * Proximal: Closer to the point of origin (generally the trunk). Examples: The knee is proximal to the ankle; the shoulder is proximal to the elbow.     * Distal: Farther away from the point of origin (generally the trunk). Examples: The foot is distal to the hip; the wrist is distal to the elbow.     * Medial: Closer to the midline of the body or body part; on the inner side of. Examples: The ear is medial to the shoulder; the index finger is medial to the thumb.     * Lateral: Farther away from the midline of the body or body part; on the outer side of. Examples: The shoulder is lateral to the chest; the thumb is lateral to the index finger.     * Superficial: Closer to the surface. Examples: The skin is superficial to the muscle; muscle is superficial to bone.     * Deep: Farther below the surface. Examples: Bone is deep to skin; bone is deep to muscle.

Regional Terms and Body Divisions

• Major Body Regions:     * Axial Region: Includes the head, neck, and trunk.     * Appendicular Region: Includes the upper and lower limbs or appendages.
• Specific Regional Terms:     * Cephalic: Head region (includes Cranial, Occipital, Frontal, Ocular, Otic, Nasal, Buccal, Oral, and Mental).     * Cervical: Neck region.     * Thoracic: Chest region (includes Sternal, Axillary, Mammary, and Costal).     * Abdominal: Region over the stomach.     * Pelvic: Region over the pelvis (includes Inguinal and Pubic).     * Manual: Hand region (includes Carpal, Metacarpal, Palmar, Pollex, and Digital).     * Pedal: Foot region (includes Tarsal, Metatarsal, Plantar, Hallux, and Digital).     * Upper Limb: Includes Acromial (shoulder), Brachial (arm), Antecubital (front of elbow), Antebrachial (forearm), and Carpal.     * Lower Limb: Includes Coxal (hip), Femoral (thigh), Patellar (kneecap), Popliteal (back of knee), Crural (leg), Sural (calf), and Tarsal.     * Back/Dorsal Side: Includes Vertebral, Lumbar, Sacral, and Gluteal.

Anatomical Planes of Section

• Sagittal Plane: Divides the body into right and left sections.     * Midsagittal (Median) Plane: Divides the body into equal right and left sections.     * Parasagittal Plane: Divides the body into unequal right and left sections.
• Frontal (Coronal) Plane: Divides the body into anterior (front) and posterior (back) sections.
• Transverse (Horizontal/Cross Section): Divides the body into superior (top) and inferior (bottom) sections, or proximal and distal sections for limbs.
• Oblique Plane: A section taken at an angle; used less frequently.

Body Cavities

• Posterior (Dorsal) Body Cavity: Located on the posterior side of the body.     * Cranial Cavity: Houses the brain.     * Vertebral (Spinal) Cavity: Houses the spinal cord.
• Anterior (Ventral) Body Cavity: Divided by the diaphragm into two main divisions:     * Thoracic Cavity: Superior to the diaphragm. It is subdivided into:         * Pleural Cavities: Each surrounds a lung.         * Mediastinum: The central region; houses the heart, great vessels, trachea, and esophagus. It is not delimited by a serous membrane.         * Pericardial Cavity: Located within the mediastinum; surrounds the heart.     * Abdominopelvic Cavity: Inferior to the diaphragm. It is subdivided into:         * Abdominal Cavity: Superior portion containing digestive organs.         * Pelvic Cavity: Inferior portion within the bony pelvis.

Abdominopelvic Quadrants and Regions

• Quadrants:     * Right Upper Quadrant (RUQ)     * Right Lower Quadrant (RLQ): Contains the appendix, right ovary (in females), first section of the large intestine, and the last part of the small intestine.     * Left Upper Quadrant (LUQ): Contains the stomach, spleen, pancreas, and parts of the large intestine.     * Left Lower Quadrant (LLQ)
• Regions:     * Right and Left Hypochondriac Regions: Superior lateral regions.     * Epigastric Region: Superior middle region.     * Right and Left Lumbar Regions: Middle lateral regions.     * Umbilical Region: Center region around the navel.     * Right and Left Iliac (Inguinal) Regions: Inferior lateral regions.     * Hypogastric Region: Inferior middle region.

Serous Membranes

• Definition: Thin sheets of tissue that form certain cavities within the ventral cavity and surround organs like the heart, lungs, and stomach.
• Structure:     * Visceral Layer: The inner layer in direct contact with the organ.     * Parietal Layer: The outermost layer attached to surrounding body structures or the cavity wall.     * Serous Fluid: An extremely thin layer of fluid found in the cavity between the two layers to reduce friction.
• Specific Membranes:     * Pleural Membranes: Surrounds the lungs (‐Pleural cavity‑).     * Pericardial Membranes: Surrounds the heart (‐Pericardial cavity‑). The parietal pericardium separates the heart from the mediastinum; the visceral pericardium lies directly on the heart muscle.     * Peritoneal Membranes: Surrounds some abdominal organs (‐Peritoneal cavity‑).
• Retroperitoneal Organs: Organs not covered by the peritoneum, including the kidneys, duodenum, and pancreas.

Homeostasis and Feedback Loops

• Homeostasis: The maintenance of a stable internal environment.     * Homeostatic Imbalance: Disturbances that can lead to disease or death if not corrected.     * Controlled Variables: Variables maintained within a narrow range close to a normal value (‐set point‑).
• Components of Feedback Loops:     * Stimulus: A change in a regulated variable.     * Receptor: Provides information about the stimulus.     * Control Center: Detects that the variable is out of range and compares it to the set point (often the brain or endocrine glands).     * Effector: Carries out a response to correct the change.
• Negative Feedback Loops: Oppose the initial change in a regulated variable to reduce output and return the variable to the set point. Examples include:     * Body Temperature: Normal range is approximately $36.1-37.2^{\circ}C$ ($97-99^{\circ}F$). If temperature rises, receptors in the brain detect it, the control center processes it, and effectors trigger sweating and blood vessel dilation to release heat.     * Thermostat Analogy: If a room rises above the set point of $70^{\circ}F$ to $73^{\circ}F$, the thermostat switches the air conditioner on until the room returns to $70^{\circ}F$.
• Positive Feedback Loops: Less common; the effector activity increases and reinforces the initial stimulus, amplifying the effect. Examples include:     * Blood Clotting: Injury to a vessel is detected by receptors on platelets. Activated platelets release chemicals that attract and activate more platelets until the vessel is sealed.     * Childbirth: The baby's head stretches the cervix (stimulus). The brain (control center) signals the uterus (effector) to produce oxytocin. Oxytocin stimulates contractions, which move the baby's head further, causing more stretching and more oxytocin release until birth is complete.     * Pitocin: Synthetic oxytocin used to induce labor by initiating this positive feedback loop.

Core Principles in Anatomy and Physiology

• Structure and Function: The form of a structure is always such that it best suits its function (‐form follows function‑). Example: The tissues in the lungs are thin to allow gases to cross rapidly. If they were thick, homeostasis would fail.
• Gradients: A gradient exists when more of something is in one area than another and the two are connected. Gradients drive physiological processes.     * Temperature Gradient: Heat concentrated near a heater and dissipating further away.     * Concentration Gradient: A dissolving pill is highly concentrated at the source and decreases in concentration further away.     * Pressure Gradient: Higher air pressure inside a compressed syringe compared to the lower pressure outside.
• Cell-Cell Communication: Cells communicate via electrical signals or chemical messengers to coordinate activities and maintain homeostasis. Example: Nerve cells release chemical messengers to trigger responses in muscle cells.