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Anatomy and Physiology
Fundamentals for Medical
Students
Human Organism
Anatomy
The study of the structure or morphology of the body and how the body parts are organized. Means to cut the body parts to study, or to dissect. Subdivisions of Gross Anatomy: Systemic Anatomy Regional Anatomy Surface Anatomy
Systemic Anatomy
The study of organs per system.
Regional Anatomy
The study of organs per region.
Surface Anatomy
The study of external features.
Why is it important to study anatomy?
It is for students who plan to take up medical courses to have a background knowledge on the human body. It provides the basis to understand diseases and pathologies.
Physiology
The study of the functions of body parts, what they do, and how they do it. Helps to understand and predict the body's response to stimuli.
Pathology
The study of the diseases of the body. Any changes in the body are called symptoms.
Anatomy is not changing, rather it is improving
To facilitate uniformity of terms, scientists have adopted the four basic reference systems of bodily organization: A. Directions B. Planes C. Cavities D. Structural units
Anatomical Position
The human body must be in its anatomical position when describing the 4 basic reference systems: Erect position of the body Face directed forward Arms at the side Palms of the hand facing forward Feet facing forward
A. Terms of Direction
Superior - upper or above Inferior - lower or below Anterior or Ventral - toward the front of the body Posterior or Dorsal - toward the back of the body Superficial - towards the surface Deep - away from the surface Cephalad or Cranial - skull or head end Caudal - tail end Medial - towards the middle or midline of the body Lateral - away from the midline of the body Proximal - closer or towards to the point of attachment Distal - farther from the point of attachment
Body Parts and Regions
Head
Frontal, Orbital, Nasal, Oral, Otic, Buccal, Mental, Cranial
Neck
Cervical, Clavicular, Occipital, Nuchal
Trunk
Thoracic, Abdominal, Umbilical, Pelvic, Inguinal, Pubic, Dorsal, Scapular, Vertebral, Lumbar, Sacral, Gluteal, Perineal
Upper Limb
Axillary, Brachial, Antecubital, Antebrachial, Carpal, Manual (Palmar, Digital), Acromial, Olecranon, Dorsum
Cavity Coverings
Parietal - covers the walls of a cavity (pleural and pericardium) Visceral - covering of an organ
D. Structural Units
Atoms Molecules Cells Tissues Organs Systems Human Organism
Organ Systems
Integumentary System Skeletal System Muscular System Lymphatic System Respiratory System Digestive System Nervous System Endocrine System Cardiovascular System Urinary System Female Reproductive System Male Reproductive System
Homeostasis
Maintenance of the body's internal environment within varying narrow limits. Most homeostatic mechanisms are governed by the endocrine and nervous systems.
Negative Feedback Loop
Any homeostatic process that changes the direction of the stimulus. It may either increase or decrease the stimulus, but is not allowed to continue as it did before the receptor sensed it.
Positive Feedback Loop
Maintains the direction of the stimulus, possibly accelerating it.
Cell Structure, Metabolism, and Reproduction
Cell Structure
The basic unit of biological organization. Prokaryotic vs. Eukaryotic cells.
Prokaryote
Has no nucleus. Has no membrane-bound organelles. Has a circular DNA.
Eukaryote
Has a nucleus. Have membrane-bound organelles. Has a linear DNA.
Basic Composition of the Cell
Protoplasm Cell membrane Organelles
History of the Cell Theory
Proposed in the 1830s by Matthias Schleiden and Theodor Schwann.
Modern Cell Theory
Cells are the smallest complete living things. All organisms are composed of one or more cells. Cells arise only from other cells. All existing cells are descendants of the first cells.
Functions of the Cell
Cell metabolism Synthesis of molecules Communication Reproduction and Inheritance
Cell Organelles
Cell or Plasma Membrane Cytoplasm Nucleus Ribosome
Marker Molecules and Attachment Proteins
Glycoproteins
Glycoproteins are cell surface markers that allow cells to identify other cells or molecules. Examples include sperm cell recognition of egg cells and immune cells' ability to recognize foreign bodies.
Attachment Proteins
Attachment proteins, such as cadherins and integrins, anchor cells to other cells or to extracellular molecules. Cadherins attach cells to other cells, while integrins attach cells to extracellular molecules.
Transport Proteins
Channel Proteins
Channel proteins form passageways through the plasma membrane, allowing specific ions or molecules to enter and exit the cell. Channel proteins may be gated (opened or closed by chemical signals or voltage) or non-gated (allowing constant leakage).
Carrier Proteins (Transporters)
Carrier proteins move ions or molecules across the membrane by undergoing changes in shape when binding to specific chemicals. The carrier proteins then transport the specific chemical across the membrane.
ATP-Powered Pumps
ATP-powered pumps move specific ions or molecules across the membrane, requiring ATP molecules to function.
Receptor Proteins
Receptor proteins function as binding sites for chemical signals in the extracellular fluid. Binding of chemical signals to receptors triggers cellular responses.
Selective Permeability and Transport
Mechanisms
Selective Permeability
The cell membrane is selectively permeable, allowing only certain substances to pass through it.
Passive Transport Mechanisms
Diffusion : The movement of molecules from areas of higher to lower concentration, driven by the concentration gradient and not requiring ATP. Lipid-soluble molecules can dissolve and diffuse through the lipid bilayer. Ions and small molecules can diffuse through membrane channels. Osmosis : The movement of water molecules across the membrane, driven by differences in solute concentration and not requiring ATP. Isotonic: Balanced extracellular and intracellular concentration. Hypertonic: Higher concentration of solute outside the cell, causing the cell to shrink. Hypotonic: Lower concentration of solute outside the cell, causing the cell to swell. Facilitated Diffusion : The movement of substances across the membrane with the help of carrier proteins, without the use of ATP.
Active Transport Mechanisms
Active Transport : ATP-powered pumps that combine with substances and move them across the plasma membrane, requiring ATP. Secondary Active Transport : Ions are moved across the plasma membrane by active transport, establishing an ion concentration gradient that drives the movement of other substances.
Vesicular Transport
Endocytosis
The process by which molecules enter the cell by vesicles, requiring ATP. Phagocytosis: Engulfing of solid materials (cell eating). Pinocytosis: Engulfing of dissolved or liquid substances (cell drinking).
Exocytosis
The process by which molecules exit the cell by vesicles, requiring ATP. Secretions accumulate within the secretory vesicles, which then migrate to the plasma membrane, fuse with it, and release their contents from the cell.
Cytoskeleton
The cytoskeleton supports the cell, holds the nucleus and other organelles in place, and is responsible for changes in cell shape and movement. Microtubules, intermediate filaments, and actin filaments are the three groups of proteins in the cytoskeleton.
Centrioles, Centrosomes, Cilia, and Flagella
Centrioles form spindle fibers during cell division and guide duplicated chromosomes to daughter cells. Centrosomes are composed of two centrioles at right angles to each other. Cilia and flagella are hair-like protrusions from the cell membrane, with cilia moving materials across the cell surface and flagella propelling the cell. Microvilli are specialized extensions of the cell membrane that increase the cell surface area and support the cilia.
Cell Metabolism and Reproduction
Metabolism
Metabolism is the total cellular chemical changes, including anabolism (building up) and catabolism (breaking down). ATP is the most common energy source available to the cell, produced through cellular respiration.
Cell Division and the Cell Cycle
The cell cycle includes interphase (G1, S, G2) and cell division (mitosis or meiosis). Mitosis is the duplication of genetic material, resulting in two diploid daughter cells. Meiosis is a reduction division, resulting in four haploid daughter cells. Gametogenesis (spermatogenesis and oogenesis) is the formation of sex cells.
Integumentary System
The integumentary system provides a covering for the body, with the skin as the largest external organ. Accessory structures of the skin include hair, nails, and glands.
The Integumentary System
Dermis
The dermis is the layer of skin that lies beneath the epidermis. It is a tough, connective tissue layer composed of two sublayers:
Papillary Layer : This layer is adjacent to the epidermis and is composed of loose connective tissue. It brings blood vessels close to the epidermis, providing nutrients and regulating temperature. Reticular Layer : This is the main layer of the dermis, providing strength and elasticity to the skin. It is composed of dense, irregular connective tissue containing hair follicles, sweat glands, and oil glands.
The dermis also contains blood and lymph vessels, nerve endings, and receptors, as well as muscles. It connects the skin to the underlying fat and muscle tissues.
Epidermis
The epidermis is the upper or superficial layer of the skin. It is composed of epithelial tissue divided into several sublayers:
Stratum Corneum : The outermost layer, composed of 25 or more layers of dead, keratinized cells. It serves as a barrier to light, heat, chemicals, and microorganisms, and prevents water loss. Stratum Lucidum : A thin, transparent layer found only in the hairless parts of the body, such as the palms and soles. Stratum Granulosum : The layer where active keratinization takes place, with flattened, diamond-shaped cells losing their nuclei and producing keratohyalin granules. Stratum Spinosum : Composed of 8 to 10 layers of spiny-shaped cells, producing keratin fibers and responsible for the skin's strength and flexibility. Stratum Germinativum (or Stratum Basale) : The deepest layer of the epidermis, resting on the basement membrane attached to the dermis. It is the site of cell division, producing new cells that move upward and undergo keratinization.
The epidermis contains four main cell types:
Keratinocytes : Produce keratin, making the cells more durable and resistant to abrasion. Melanocytes : Contribute to skin, eye, and hair color by producing melanin. Langerhans Cells : Part of the immune system. Merkel Cells : Responsible for light touch and superficial pressure sensation.
The epidermis does not contain blood vessels, but it exchanges gases, nutrients, and waste products with the blood vessels in the dermis.
Muscle Tissue : Responsible for movement and contraction, including skeletal, cardiac, and smooth muscle. Nervous Tissue : Composed of neurons and supporting cells, it is responsible for transmitting and processing information throughout the body.
The three embryonic germ layers (endoderm, mesoderm, and ectoderm) give rise to all the tissues of the body.
Transitional Epithelial Tissues
Classifications of Epithelial Tissues based on Arrangement
Simple Epithelium : One cell layer thick. Stratified Epithelium : Several layers thick. Pseudostratified Epithelium : Appears to be several layers but is not. The arrangement is usually seen in columnar cells. Transitional Epithelium : Several layers of easily stretched cells.
Types of Epithelial Tissues
Mucous Membrane Exocrine Glands Endocrine Glands Endothelium Mesothelium
Classification of Epithelial Tissues based on Function
Mucous Membrane : Responsible for mucus production and lines all body cavities that open to the outside. Exocrine Glands : Have excretory ducts. Simple Tubular Simple Branched Tubular Simple Coiled Tubular Simple Acinar Simple Branched Acinar
Types of Simple Exocrine Glands
Simple Tubular : Glands in the stomach and colon. Simple Branched Tubular : Glands in the lower portion of the stomach. Simple Coiled Tubular : Glands in the lower portion of the stomach and small intestine. Simple Acinar : Sebaceous glands of the skin. Simple Branched Acinar : Sebaceous glands of the skin.
Types of Compound Exocrine Glands
Compound Tubular : Mucous glands of the duodenum. Compound Acinar : Mammary glands. Compound Tubuloacinar : Pancreas.
Exocrine Glands by Type of Secretion
Merocrine Gland : Cells of the gland produce secretions by active transport or produce vesicles that contain secretory products, and the vesicles empty their contents into the duct through exocytosis. Apocrine Gland : Secretory products are stored in the cell near the lumen of the duct, and a portion of the cell near the lumen containing secretory products is pinched off the cell and joins secretions produced by a merocrine process. Holocrine Gland : Secretory products are stored in the cells of the gland, and entire cells are shed by the gland and become part of the secretion. The lost cells are replaced by other cells deeper in the gland.
Other Epithelial Tissues
Endocrine Glands : Ductless and secrete hormones to the blood. Endothelium : Lines the circulatory system, specifically the blood vessels and lymphatic vessels. Endocardium : Lines the heart. Mesothelium (Serous) : Lines great cavities that have no openings to the outside.
Connective Tissue
Major Components of the Connective Tissue Matrix
Protein Fibers : Includes collagen, reticular, and elastin. Collagen: Most abundant protein of the body, about 6% of the body weight. Type I Collagen is the most abundant, and Type II Collagen is the major collagen found in cartilage. Reticular: Composed of type III collagen. Ground Substance : Fluid component of the matrix. Fluid : Fills the spaces between the fibers and cells.
Cell Types in Connective Tissue
-blast : Create the matrix. -cyte : Maintain the matrix. -clast : Break the matrix down for remodeling.
Subgroups of Connective Tissue
Loose Connective Tissue : Fills spaces between and penetrates organs.
Dentin : Another specialized connective tissue that forms our teeth, related to bone in structure but is harder and denser. Enamel : The outer covering of the crown of the tooth with a white appearance.
Blood and Hemopoietic Tissue
Blood : Fluid portion (plasma) and formed elements (erythrocytes, leukocytes, and thrombocytes). Hemopoietic Tissue : Forms blood cells, found in the bone marrow of adults. Lymphoid : Involved in antibody production (B lymphocytes) and disease protection. Reticuloendothelial System : Consists of specialized connective tissue cells that perform phagocytosis, including Kupffer cells, histiocytes, neuroglia, alveolar macrophages, and osteoclasts.
Functions of Connective Tissue
Support Nourishment Transportation Connection Movement Protection and Insulation Storage Attachment and Separation
Muscle Tissue
Muscle tissue has the ability to shorten and thicken, allowing for contraction and movement. The length of muscle fibers is greater than their width.
Types of Muscle Tissue
Smooth Muscle Skeletal Muscle Cardiac Muscle
Muscle Tissue
Skeletal Muscle
Skeletal muscle, also known as "muscle" or "meat", constitutes about 40% of a person's body weight. It enables movement by pulling on bones. Skeletal muscle has long, thin cells that move under conscious control or voluntary control. It is multinucleated and striated, containing actin and myosin.
These muscles are attached to the movable parts of the skeleton and are capable of rapid, powerful contraction and long states of partially sustained contractions, allowing for voluntary movement. Skeletal muscle is striated or has transverse bands that run down the length of the muscle fiber.
Cardiac Muscle
Cardiac muscle is the muscle of the heart and is responsible for blood pumping. It is uninucleated and striated, and is under unconscious control or involuntary control by the Autonomic Nervous System (ANS). Cardiac muscle cells are cylindrical in shape and shorter than skeletal muscle cells. Contractions of cardiac muscle cells help the heart contract to pump blood through and out of the heart. Cardiac muscle is a striated, involuntary muscle that makes up the walls of the heart. Cardiac muscle cells are connected to other cardiac muscle cells by intercalated disks with gap junctions, which are important in coordinating cardiac muscle cells.
Smooth Muscle
Smooth muscle is spindle-shaped with a single nucleus, and is the only type of muscle that is not striated. It is under involuntary control by the Autonomic Nervous System (ANS). Smooth muscle forms the walls of hollow organs like the digestive tract, arteries and veins, and ureters. It is also found in the skin and eyes. Smooth muscle is responsible for several functions like peristalsis by contraction of outer and inner layers, and emptying of the bladder. Smooth muscle is non-striated because it lacks the obvious striations (bands) of skeletal muscles. Smooth muscle makes up the walls of the digestive, genitourinary, respiratory tracts, blood vessels, and lymphatic system.
Comparison of Muscle Tissue Types
| Characteristic | Skeletal Muscle | Cardiac Muscle | Smooth Muscle | | --- | --- | --- | --- | | Location | Attached to bones | In the heart | In the walls of hollow organs, blood vessels, eyes, glands, skin | | Cell Shape | Very long, cylindrical cells | Cylindrical cells that branch | Spindle-shaped cells | | Nucleus | Multinucleated, peripherally located | Single, centrally located | Single, centrally located | | Striations | Yes | Yes | No | | Function | Moves the body | Provides the major force for moving blood through the blood vessels | Moves food through the digestive tract, empties the urinary bladder, regulates blood vessel diameter, changes pupil size, contracts many gland ducts, moves hair | | Special Features | None | Branching fibers, intercalated
Types of Tissue Repair
Primary Union: Tissue repair occurs when the edges of the wound are close together. Secondary Union: Tissue repair occurs when the edges of the wound are far apart.
