Human Anatomy and Physiology Prelims PDF

HUMAN ANATOMY AND PHYSIOLOGY WITH PATHOPHYSIOLOGY PROFESSOR INTRODUCTION TO HUMAN ANATOMY LECT 1 1. Chemical...

HUMAN ANATOMY AND PHYSIOLOGY WITH PATHOPHYSIOLOGY PROFESSOR INTRODUCTION TO HUMAN ANATOMY LECT 1 1. Chemical Smallest level OUTLINE Atoms, chemical bonds I. Anatomy and Physiology II. Importance of Anatomy and physiology 2. Cellular Cells: basic units of life III. Types of anatomy Compartments and organelles IV. Structural and functional organization Examples are mitochondria, nucleus V. Major organs of the body 3. Tissues VI. Organs systems of the body Group of cells with similar structure and VII. Characteristics of life function plus extracellular substances they VIII. Homeostasis release IX. Terminology and the body plan Four broad types: X. Directional terms o Epithelial XI. Body planes o Connective XII. Body regions o Muscular XIII. Body cavities o Nervous XIV. Serous membranes 4. Organs XV. Pericardium and pericardial cavity Two or more tissue types acting together to XVI. Pleura and pleural cavity perform function(s) XVII. Peritoneum and peritoneal cavity Examples: stomach, heart, liver, ovary, bladder, kidney ANATOMY & PHYSIOLOGY 5. Organ-system: Anatomy Group of organs contributing to some function It investigates body structure For example, digestive system, reproductive The term means to “dissect” system 6. Organism: Physiology All organ systems working together Investigate processes and functions Includes associated microorganisms such as Human physiology: intestinal bacteria Studies the human organism Systemic physiology Studies body organ-systems Cellular Physiology studies body cells IMPORTANCE OF ANATOMY AND PHYSIOLOGY Understand how the body: responds to stimuli environmental changes environmental changes environmental cues diseases injury MAJOR ORGANS OF THE BODY TYPES OF ANATOMY Systemic: studies body organ-systems Regional: studies body regions (medical schools) Surface: studies external features, for example, bone projections Anatomical imaging: using technologies (x-ray, ultrasound, MRI) STRUCTURAL AND FUNCTIONAL ORGANIZATION KENNETH JOMEL A. RODRIGUEZ | BSMT1 1  TRANS: CHARACTERISTICS OF LIFE ORGAN SYSTEM OF THE BODY ORGANIZATION Functional interrelationships between parts METABOLISM Sum of all chemical and physical changes sustaining an organism Ability to acquire and use energy in support of these changes RESPONSIVENESS (MOVEMENT) Ability to sense and respond to environmental changes Includes both internal and external environments DEVELOPMENT Changes in form and size Changes in cell structure and function from generalized to specialized-differentiation REPRODUCTION Formation of new cells or new organisms Generation of new individuals Tissue repair HOMEOSTASIS Maintenance of constant internal environment despite fluctuations in the external or internal environment Variables: measures of body properties that may change in value Examples of variables: body temperature, heart rate, blood pressure, blood glucose levels Normal range: normal extent of increase or decrease around a set point Set point: normal, or average value of a variable Over time, body temperature fluctuates around a set point KENNETH JOMEL A. RODRIGUEZ | BSMT1 2  TRANS: Set points for some variables can be temporarily adjusted depending on body activities, as needed: examples Common cause of change Body temperature fever Heart rate, blood pressure, exercise respiratory rate NEGATIVE FEEDBACK POSITIVE FEEDBACK Positive feedback mechanisms occur when the initial stimulus Is the main mechanism used in homeostatic regulation. further stimulates the response A negative feedback response involves: o System response causes progressive deviation away o Detection: of deviation away from set point from the set point, outside of the normal range o Correction: reversal of deviation toward set o Not directly used for homeostasis point and normal range o Some positive feedback occurs under normal The components of feedback: conditions. Example: childbirth 1. Receptor: detects changes in variable o Generally associated with injury, disease 2. Control center: receives receptor signal, establishes o Negative feedback mechanism unable to maintain set points, sends signal to effector homeostasis 3. Effector: directly causes a change in variable TERMINOLOGY AND THE BODY PLAN ANATOMICAL POSITION o Person standing erect with face and palms forward o All relational descriptions based on the anatomical position, regardless of the body orientation NEGATIVE FEEDBACK CONTROL OF BODY TEMPERATURE KENNETH JOMEL A. RODRIGUEZ | BSMT1 3  TRANS: DIRECTIONAL TERMS o Superior: above o Inferior: below o Anterior: front (also: ventral) o Posterior: back (also: dorsal) Note: in four-legged animals, the terms ventral (belly) and dorsal (back) correspond to anterior and posterior in humans o Medial: close to midline o Lateral: away from midline o Proximal: close to the point of attachment o Distal: far from the point of attachment o Superficial: structure close to the surface o Deep: structure toward the interior of the body BODY PLANES o Sagittal plane: separates the body into right and left parts o Median plane: a sagittal plane along the midline that divides the body into equal left and right halves o Transverse plane: a horizontal plane that separates the body into superior and inferior parts o Frontal/ Coronal plane: a vertical plane that separates the body into anterior and posterior parts KENNETH JOMEL A. RODRIGUEZ | BSMT1 4  TRANS: BODY REGIONS Cavity: a fluid-filled space between the membranes o Upper limbs: arm, forearm, wrist, hand o Lower limbs: thigh, leg, ankle, foot o Central region: head, neck, trunk THREE SETS OF SEROUS MEMBRANES AND CAVITIES Membrane Cavity Pericardium Pericardial cavity Around heart Pleura Pleural cavity Around lungs Peritoneum Peritoneal cavity Around abdominopelvic cavity and its organs PERICARDIUM AND PERICARDIAL CAVITY PERICARDIUM Visceral pericardium: covers heart Parietal pericardium: thick fibrous Pericardial cavity: reduces friction BODY CAVITIES Thoracic cavity o Space within the chest wall and diaphragm o Contains heart, lungs, thymus gland, esophagus, trachea Mediastinum Space between lungs Contain heart, thymus gland, esophagus, trachea Abdominal cavity Space between diaphragm and pelvis Contains stomach, intestines, liver, spleen, pancreas, kidneys. Pelvic Cavity PLEURA Space within pelvis Visceral pleura: covers lungs Contains urinary bladder, reproductive organs, part of Parietal pleura: lines inner wall of thorax large intestine Pleural cavity: reduces friction, adheres lungs to thoracic wall SEROUS MEMBRANE Line trunk cavities, cover organs Structure: Visceral serous membrane: cover organs Parietal serous membrane: is the outer membrane KENNETH JOMEL A. RODRIGUEZ | BSMT1 5  TRANS: PERITONEUM AND PERITONEAL CAVITY PERITONEUM Visceral peritoneum: covers, anchors organs; double layers called mesenteries Parietal peritoneum: lines inner wall of abdominopelvic cavity Peritoneal cavity: reduces friction KENNETH JOMEL A. RODRIGUEZ | BSMT1 6  HUMAN ANATOMY AND PHYSIOLOGY WITH PATHOPHYSIOLOGY PROFESSOR CELL STRUCTURES AND FUNCTIONS LECT 2 CELL MEMBRANE OUTLINE The cell membrane, or plasma membrane, is the I. outermost component of a cell. II. It forms a boundary between material in inside the cell III. and the outside. Materials inside the cell are intracellular and those IV. outside are extracellular. It acts as a selective barrier. CELL STRUCTURE ORGANELLES CELL MEMBRANE STRUCTURE Specialized structure in cells that perform specific functions The fluid-mosaic model is the model used to describe Example: nucleus, mitochondria, ribosomes the cell membrane structure. The membrane contains phospholipids, cholesterol, CYTOPLASM proteins, and carbohydrates. Jelly-like substance that holds organelles Phospholipids form a bilayer. Phospholipids contain 2 regions: polar and nonpolar. CELL MEMBRANE Also termed the plasma membrane PHOSPHOLIPID STRUCTURE A structure that encloses the cytoplasm A phospholipid molecule has a polar head region that is hydrophilic and a nonpolar tail region that is GENERALIZED CELL hydrophobic. The polar region is exposed to water around the membrane. The nonpolar region is facing the interior of the membrane. THE CELL MEMBRANE MOVEMENT THROUGH THE CELL MEMBRANE FUNCTIONS OF THE CELL The cell membrane has selective permeability, which Smallest units of life allows only certain substances to pass in and out of the Cell metabolism and energy use cell. Synthesis of molecules Substances such as enzymes, glycogen, and Communication potassium are found in higher concentrations inside Reproduction and inheritance the cell. KENNETH JOMEL A. RODRIGUEZ | BSMT1 1  TRANS: Substances such as sodium, calcium, and chloride are LEAK AND GATED CHANNELS found in higher concentrations outside the cell. Lipid soluble substances can diffuse directly through the phospholipid bilayer. CELL MEMBRANE PASSAGE Water-soluble substances, such as ions, can diffuse across the cell membrane only by passing through cell Some substances, like O2 and CO2, can pass directly membrane channels. through the cell membrane’s phospholipid bilayer. Two classes of cell membrane channels include leak Some substances must pass through transmembrane channels and gated channels. protein channels, such as Na+ through its channels. Leak channels constantly allow ions to pass through. The route of transport through the membrane depends Gated channels limit the movement of ions across the on the size, shape, and charge of the substance. membrane by opening and closing. Some substances require carrier molecules to transport them across the cell membrane, such as glucose. Some substances require vesicular transport across the membrane. The vesicle must fuse with the cell membrane for transport. ACTIVE TRANSPORT AND PASSIVE TRANSPORT Passive membrane transport does not require the cell to expend energy. Active membrane transport does require the cell to expend energy, usually in the form of ATP. Passive membrane transport mechanisms include diffusion, osmosis, and facilitated diffusion. Active membrane transport mechanisms include active transport, secondary active transport, endocytosis, and exocytosis. DIFFUSION Diffusion generally involves the movement of substances in a solution down a concentration gradient. DIFFUSION THROUGH THE CELL MEMBRANE A solution is generally composed of two major parts, solutes and the solvent. Solutes are substances dissolved in a predominant liquid or gas, which is called the solvent. Solutes, such as ions or molecules, tend to move from an area of higher concentration of a solute to an area of lower concentration of that same solute in solution. This movement from a high concentration to a low concentration is diffusion. OSMOSIS CONCENTRATION GRADIENT Osmosis is the diffusion of water (a solvent) across a A concentration gradient is the difference in the selectively permeable membrane from a region of concentration of a solute in a solvent between two higher water concentration to one of lower water points divided by the distance between the two points. concentration. The concentration gradient is said to be steeper when Osmosis exerts a pressure, termed osmotic the concentration difference is large and/or the pressure, which is the force required to prevent the distance is small. movement of water across the cell membrane KENNETH JOMEL A. RODRIGUEZ | BSMT1 2  TRANS: CARRIER-MEDIATED TRANSPORT Some water-soluble, electrically charged or large sized particles cannot enter or leave through the cell membrane by diffusion. These substances include amino acids, glucose, and some polar molecules produced by the cell. Carrier molecules are proteins within the cell membrane involved in carrier-mediated transport. OSMOTIC PRESSURE AND THE CELL Carrier-mediated transport mechanisms include facilitated diffusion and Active transport. Osmotic pressure depends on the difference of Facilitated diffusion does not require ATP for energy. solution concentrations inside a cell relative to those Active transport does require ATP for transport outside the cell. A cell may be placed in either hypotonic, isotonic, or hypertonic solutions compared to the cell cytoplasm. FACILITATED DIFFUSION HYPOTONIC Facilitated diffusion is a carrier-mediated transport process that moves substances across the cell membrane from an area of higher concentration to an A hypotonic solution has a lower concentration of area of lower concentration of that substance. solutes and a higher concentration of water relative to Because movement is with the concentration gradient, the cytoplasm of the cell. metabolic energy in the form of ATP is not required. The solution has less tone, or osmotic pressure, than the cell. Water moves by osmosis into the cell, causing it to swell. If the cell swells enough, it can rupture, a process called cell lysis. ISOTONIC A cell immersed in an isotonic solution has the same solute concentrations inside and outside the cell. The cell will neither shrink nor swell. HYPERTONIC The cytoplasm of a cell in a hypertonic solution has a lower solute concentration and higher water concentration than the surrounding solution. Water moves by osmosis from the cell into the hypertonic solution, resulting in cell shrinkage, or crenation KENNETH JOMEL A. RODRIGUEZ | BSMT1 3  TRANS: ACTIVE TRANSPORT Active transport is a carrier-mediated process, requiring ATP, that moves substances across the cell membrane from regions of lower concentration to those of higher concentration against a concentration gradient. Active transport processes accumulate necessary substances on one side of the cell membrane at concentrations many times greater than those on the other side. SODIUM-POTASSIUM PUMP A major example of active transport is the action of the sodium-potassium pump present in cell membranes. The sodium-potassium pump moves Na+ out of cells and K+ into cells. The result is a higher concentration of Na+ outside cells and a higher concentration of K+ inside cells. ENDOCYTOSIS Endocytosis is a process that brings materials into cells using vesicles. Receptor-mediated endocytosis occurs when a specific substance binds to the receptor molecule and is transported into the cell. Phagocytosis is often used for endocytosis when solid particles are ingested. Pinocytosis has much smaller vesicles formed, and they contain liquid rather than solid particles. RECEPTOR-MEDIATED ENDOCYTOSIS SECONDARY ACTIVE TRANSPORT Secondary active transport uses the energy provided by a concentration gradient established by the active transport of one substance, such as Na+ to transport other substances. No additional energy is required above the energy provided by the initial active transport pump. EXOCYTOSIS In cotransport, the diffusing substance moves in the Exocytosis involves the use of membrane-bound sacs same direction as the initial active transported called secretory vesicles that accumulate materials substance. for release from the cell. In countertransport, the diffusing substance moves in a The vesicles move to the cell membrane and fuse, direction opposite to that of the initial active transported ultimately releasing the material by exocytosis. substance. Examples of exocytosis are the secretion of digestive enzymes. KENNETH JOMEL A. RODRIGUEZ | BSMT1 4  TRANS: There are usually one to several nucleoli within the nucleus. The subunits of ribosomes, a type of cytoplasmic organelle, are formed within a nucleolus. These ribosomal components exit the nucleus through nuclear pores. GENERAL CELL STRUCTURE The interior of a cell is composed of the cytoplasm, which a jelly-like fluid that surrounds the organelles. Organelles are specialized structures that perform certain functions. Organelles include the nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, Chromosome Structure peroxisomes, mitochondria, cytoskeleton, centrioles, cilia, flagella, and microvilli. RIBOSOMES Generalized Cell Ribosome components are produced in the nucleolus. Ribosomes are the organelles where proteins are produced. Ribosomes may be attached to other organelles, such as the endoplasmic reticulum. Ribosomes that are not attached to any other organelle are called free ribosomes. CELL NUCLEUS Ribosome Production The nucleus is a large organelle usually located near the center of the cell. The nucleus is bounded by a nuclear envelope, which consists of outer and inner membranes with a narrow space between them. The nuclear membrane contains nuclear pores, through which materials can pass into or out of the nucleus. The nuclei of human cells contain 23 pairs of chromosomes which consist of DNA and proteins. During most of a cell’s life, the chromosomes are loosely coiled and collectively called chromatin. When a cell prepares to divide, the chromosomes become tightly coiled and are visible when viewed with a microscope. Within the nucleus are Nucleoli, which are diffuse bodies with no surrounding membrane. that are found ENDOPLASMIC RETICULUM within the nucleus The endoplasmic reticulum (ER) is a series of membranes forming sacs and tubules that extends KENNETH JOMEL A. RODRIGUEZ | BSMT1 5  TRANS: from the outer nuclear membrane into the cytoplasm. One example is white blood cells phagocytizing The rough ER is involved in protein synthesis and is bacteria. rough due to attached ribosomes. Lysosome action The smooth ER has no attached ribosomes and is a site for lipid synthesis, and cellular detoxification, and it stores calcium ions in skeletal muscle cells. PEROXISOMES Peroxisomes are small, membrane-bound vesicles containing enzymes that break down fatty acids, amino acids, and hydrogen peroxide (H2O2). Hydrogen peroxide is a by-product of fatty acid and amino acid breakdown and can be toxic to a cell. The enzymes in peroxisomes break down hydrogen. MITOCHONDRIA Mitochondria (singular mitochondrion) are small organelles responsible for producing considerable amounts of ATP by aerobic (with O2) metabolism. GOLGI APPARATUS They have inner and outer membranes separated by a space. The Golgi apparatus, also called the Golgi complex, The outer membranes have a smooth contour, but the consists of closely packed stacks of curved, inner membranes have numerous folds, called cristae, membrane-bound sacs. which project into the interior of the mitochondria. It collects, modifies, packages, and distributes proteins The material within the inner membrane is the and lipids manufactured by the ER. mitochondrial matrix and contains enzymes and The Golgi apparatus forms vesicles, some of which are mitochondrial DNA (mtDNA). secretory vesicles, lysosomes, and other vesicles Cells with a large energy requirement have more mitochondria than cells that require less energy. A mitochondrion THE CYTOSKELETON LYSOSOMES The cytoskeleton gives internal framework to the cell. It consists of protein structures that support the cell, Lysosomes are membrane-bound vesicles formed hold organelles in place, and enable the cell to change from the Golgi apparatus. shape. They contain a variety of enzymes that function as These protein structures are microtubules, intracellular digestive systems. microfilaments, and intermediate filaments. Vesicles formed by endocytosis may fuse with lysosomes in order to breakdown materials in the MICROTUBULES endocytotic vesicles. Microtubules are hollow structures formed from protein subunits. KENNETH JOMEL A. RODRIGUEZ | BSMT1 6  TRANS: The microtubules perform a variety of roles, including Cilia are cylindrical structures that extend from the cell helping to support the cytoplasm of cells, assisting in and are composed of microtubules. cell division, and forming essential components of FLAGELLA certain organelles, such as cilia and flagella. MICROFILAMENTS Flagella have a structure similar to that of cilia but are much longer, and they usually occur only one per cell. Microfilaments are small fibrils formed from protein Sperm cells each have one flagellum, which propels subunits that structurally support the cytoplasm, the sperm cell. determining cell shape. Some microfilaments are involved with cell movement. MICROVILLI Microfilaments in muscle cells enable the cells to shorten, or contract. Microvilli are specialized extensions of the cell membrane that are supported by microfilaments. INTERMEDIATE FILAMENTS They do not actively move as cilia and flagella do. Microvilli are numerous on cells that have them and they increase the surface area of those cells. Intermediate filaments are fibrils formed from protein subunits that are smaller in diameter than microtubules They are abundant on the surface of cells that line the but larger in diameter than microfilaments. intestine, kidney, and other areas in which absorption is an important function. They provide mechanical support to the cell. A specific type of intermediate filament is keratin, a WHOLE CELL ACTIVITY protein associated with skin cells. A cell’s characteristics are determined by the type of The cytoskeleton proteins produced. The proteins produced are in turn determined by the genetic information in the nucleus. Information in DNA provides the cell with a code for its cellular processes. DNA DNA contains the information that directs protein synthesis; a process called gene expression. A DNA molecule consists of nucleotides joined together to form two nucleotide strands. The two strands are connected and resemble a ladder that is twisted around its long axis. Each nucleotide consists of a 5-carbon sugar, a phosphate group, and a nitrogenous base. Each nucleotide on one DNA strand has a specific CENTRIOLES bonding pattern to another nucleotide on the opposite strand. The centrosome is a specialized area of cytoplasm A gene is a sequence of nucleotides that provides a close to the nucleus where microtubule formation chemical set of instructions for making a specific occurs. protein. It contains two centrioles, which are normally oriented perpendicular to each other. Each centriole is a small, cylindrical organelle GENE EXPRESSION composed of microtubules. Gene expression, which is protein synthesis, involves The centriole is involved in the process of mitosis. transcription and translation. Transcription involves copying DNA into messenger RNA. Translation involves messenger RNA being used to produce a protein. TRANSCRIPTION Transcription takes place in the nucleus of the cell. DNA determines the structure of mRNA through transcription. During transcription, the double strands of a DNA CILIA segment separate, and DNA nucleotides of the gene pair with RNA nucleotides that form the mRNA. Cilia project from the surface of certain cells. They are DNA contains one of the following organic bases: responsible for the movement of thymine, adenine, cytosine, or guanine. materials over the top of cells, such as mucus. Messenger RNA (mRNA) contains uracil, adenine, cytosine, or guanine. KENNETH JOMEL A. RODRIGUEZ | BSMT1 7  TRANS: DNA nucleotides pair only with specific RNA The process continues until the entire polypeptide is nucleotides. completely formed. DNA’s thymine pairs with RNA’s adenine. DNA’s adenine pairs with RNA’s uracil. Translation of mRNA in Protein Synthesis DNA’s cytosine pairs with RNA’s guanine DNA’s guanine pairs with RNA’s cytosine. Overview of Gene Expression TRANSLATION Translation occurs in the cell cytoplasm after mRNA has exited the nucleus through the nuclear pores. The mRNA attaches to a ribosome. THE CELL CYCLE Codons (3 nucleotide bases) on the mRNA are read by anticodons (3 nucleotide bases) on transfer RNA During growth and development, cell division occurs to (tRNA). increase the number of cells or replace damaged or Transfer RNA transports specific amino acids from the dying ones. cytoplasm to the ribosome-mRNA complex and This cell division involves a cell cycle. initiates formation of the polypeptide chain. KENNETH JOMEL A. RODRIGUEZ | BSMT1 8  TRANS: The cell cycle includes two major phases: a Microtubules, termed spindle fibers, form to assist in nondividing phase, called interphase, and a cell breaking the centromere between the chromatids and dividing phase, termed mitosis. move the chromosomes to opposite sides of the cell. A cell spends most of its life cycle in interphase The nuclear membrane dissolves. performing its normal functions. METAPHASE During interphase, the DNA (located in chromosomes During metaphase, the chromosomes align near the in the cell’s nucleus) is replicated. center of the cell. The two strands of DNA separate from each other, and The movement of the chromosomes is regulated by the each strand serves as a template for the production of attached spindle fibers. a new strand of DNA. ANAPHASE Nucleotides in the DNA of each template strand pair with new nucleotides that are subsequently joined by At the beginning of anaphase, the chromatids separate enzymes to form a new strand of DNA. and each chromatid is called a chromosome. Each of The sequence of nucleotides in the DNA template the two sets of 46 chromosomes is moved by determines the sequence of nucleotides in the new the spindle fibers toward the centriole at one of the strand of DNA. poles of the cell. Replication of DNA gives two identical chromatids At the end of anaphase, each set of chromosomes has joined at a centromere; both form one chromosome. reached an opposite pole of the cell, and the cytoplasm begins to divide. TELOPHASE DNA Replication During telophase, the chromosomes in each of the daughter cells become organized to form two separate nuclei, one in each newly formed daughter cell. The chromosomes begin to unravel and resemble the genetic material during interphase. Following telophase, cytoplasm division is completed, and two separate daughter cells are produced. The Cell Cycle CELL GENETIC CONTENT Each human cell (except sperm and egg) contains 23 pairs of chromosomes, a total of 46. The sperm and egg contain 23 chromosomes in total. One pair of chromosomes are the sex chromosomes, which consist of two X chromosomes if the person is a female or an X and Y chromosome if the person is a male. MITOSIS Mitosis involves the formation of 2 daughter cells from a single parent cell. Mitosis is divided into four phases: prophase, metaphase, anaphase, and telophase. DIFFERENTIATION A sperm cell and an oocyte unite to form a single cell, PROPHASE then a great number of mitotic divisions occur to give During prophase the chromatin condenses to form the trillions of cells of the body. visible chromosomes. The process by which cells develop with specialized structures and functions is called differentiation. KENNETH JOMEL A. RODRIGUEZ | BSMT1 9  TRANS: During differentiation of a cell, some portions of DNA are active, but others are inactive. Diversity of Cell Types APOPTOSIS Apoptosis, termed programmed cell death, is a normal process by which cell numbers within various tissues are adjusted and controlled. In the developing fetus, apoptosis removes extra tissue, such as cells between the developing fingers and toes. In some adult tissues, apoptosis eliminates excess cells to maintain a constant number of cells within the tissue. CELLULAR ASPECTS OF AGING There are various causes for cellular aging. Existence of a cellular clock Presence of death genes DNA damage Formation of free radicals Mitochondrial damage TUMORS Tumors are abnormal proliferations of cells. They are due to problems occurring in the cell cycle. Some tumors are benign and some are malignant (cancer). Malignant tumors can spread by a process, termed metastasis. KENNETH JOMEL A. RODRIGUEZ | BSMT1 10  HUMAN ANATOMY AND PHYSIOLOGY WITH PATHOPHYSIOLOGY Jaques Celaje TISSUES LECT 3 FUNCTIONS OF EPITHELIAL TISSUE OUTLINE 1. Protects underlying structures I. 2. Act as a barrier II. 3. Permits passage of substances III. 4. Secretes substances IV. 5. Absorption of substances CLASSIFICATION OF EPITHELIA TISSUES Epithelial tissues are classified primarily according to the number of cell layers and the shape of the A tissue is a group of cells with similar structure and superficial cells. function, plus the extracellular substance surrounding The cell layers can be simple, stratified, or them. pseudostratified. Histology is the study of tissues. The cell shapes can be squamous, cuboidal, columnar, TYPES OF TISSUES or a special transitional shape, that varies with the degree of stretch. 1. Epithelial – a covering or lining tissue Simple epithelium consists of a single layer of cells, 2. Connective – a diverse primary tissue type that makes with each cell extending from the basement membrane up part of every organ in the body to the free surface. 3. Muscle – a tissue that contracts or shortens, making movement possible Stratified epithelium consists of more than one layer 4. Nervous – responsible for coordinating and controlling of cells, but only the basal layer attaches the deepest many body activities layer to the basement membrane. Pseudostratified columnar epithelium is a special EPITHELIAL TISSUES type of simple epithelium, that appears to be falsely stratified. Epithelium, or epithelial tissue, covers and protects It consists of one layer of cells, with all the cells surfaces, both outside and inside the body. attached to the basement membrane. Included under the classification of epithelial tissue are Due to variations in the shape of the cells, the epithelia the exocrine and endocrine glands. appear stratified. EPITHELIAL TISSUE CHARACTERISTICS 1. Mostly composed of cells There are three types of epithelium based on the idealized 2. Covers body surfaces shapes of the epithelial cells: 3. Distinct cell surfaces 1. Squamous: cells that are flat or scalelike 4. Cell and matrix connections 2. Cuboidal: cells are cube-shaped-about as wide as 5. Nonvascular they are tall 6. Capable of regeneration 3. Columnar: cells tend to be taller than they are wide Characteristics of epithelium SIMPLE SQUAMOUS EPITHELIUM Simple squamous epithelium is a single layer of thin, flat cells. Some substances easily pass through this thin layer of cells, but other substances do not. The lungs, simple squamous epithelium, allow for gas exchange. The kidneys, simple squamous epithelium, helps filter wastes from the blood while keeping blood cells inside the blood vessels. Simple squamous epithelium KENNETH JOMEL A. RODRIGUEZ | BSMT1 1  TRANS: Tissues SIMPLE CUBOIDAL EPITHELIUM PSEUDOSTRATIFIED COLUMNAR EPITHELIUM Pseudostratified columnar epithelium secretes mucus, Simple cuboidal epithelium is a single layer of cube-like which covers its free surface. cells that carry out active transport, facilitated diffusion, Cilia in the airways move the mucus and accumulated or secretion. debris toward the throat, where it is swallowed. They have a greater secretory capacity than simple squamous epithelial cells. Simple Cuboidal Epithelium STRATIFIED SQUAMOUS EPITHELIUM Stratified squamous epithelium forms a thick epithelium because it consists of several layers of cells. Though the deepest cells are cuboidal or columnar and are capable of dividing and producing new cells, the naming is based on the shape of the surface cells. SIMPLE COLUMNAR EPITHELIUM There are two types of stratified squamous epithelia: keratinized stratified squamous and nonkeratinized Simple columnar epithelium is a single layer of tall, thin stratified squamous epithelia. cells. The large size of these cells enables them to perform KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM complex functions, such as secretion. The outer layer of the skin is comprised of a keratinized The simple columnar epithelium of the small intestine squamous epithelium. produces and secretes mucus and digestive enzymes. Keratin reduces the body's loss of water. Simple columnar epithelium NON-KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM Stratified squamous epithelium of the mouth is a moist nonkeratinized stratified squamous epithelium. This nonkeratinized stratified squamous epithelium provides protection against abrasion and acts as a mechanical barrier. Water, however, can move across it more readily than across the skin (keratinized stratified squamous). KENNETH JOMEL A. RODRIGUEZ | BSMT1 2  TRANS: Tissues Stratified squamous epithelium The free surface can be smooth or lined with microvilli or cilia. Cilia move materials over the top of the cell. Microvilli increase surface area. CELL CONNECTIONS Cells have several structures that hold one cell to one another or to the basement membrane. These structures do three things: mechanically bind the cells together, help form a permeability barrier, and provide a mechanism for intercellular communication. Desmosomes are mechanical links that bind cells together. Hemidesmosomes are half desmosomes that anchor cells to the basement membrane. Tight junctions prevent the passage of materials between epithelial cells because they completely surround each cell, similar to the way a belt surrounds the waist. Materials that pass through the epithelial layer must STRATIFIED COLUMNAR EPITHELIUM pass through the cells, so those cells regulate what Stratified columnar epithelium consists of more than materials can cross. one layer of epithelial cells; the surface cells are Tight junctions are found in the lining of the intestines. columnar but the deeper cells are irregular or cuboidal Gap junctions are small channels that allow small in shape. molecules and ions to pass from one epithelial cell to Like stratified cuboidal epithelium, stratified columnar an adjacent one. epithelium is relatively rare, found in the mammary Most epithelial cells are connected to one another by gland ducts, the larynx, and a portion of the male gap junctions, and researchers believe that molecules urethra. or ions moving through the gap junctions act as This epithelium carries out secretion, protection, and communication signals to coordinate the activities of some absorption. the cells. TRANSITIONAL EPITHELIUM Transitional epithelium is a special type of stratified Cell Connections epithelium that can be greatly stretched. The shape of the cells change as the epithelium is stretched. Transitional epithelium lines cavities that can expand greatly, such as the urinary bladder. It also protects underlying structures, like the urinary bladder, from the caustic effects of urine. Transitional Epithelium GLANDS Glands are secretory organs that secrete substances onto a surface, into a cavity, or into the bloodstream. FREE CELL SURFACES Glands are composed primarily of epithelium, with a Most epithelia have a free surface that is not in contact supporting network of connective tissue. with other cells and faces away from underlying Glands with ducts are called exocrine glands. Both tissues. the gland and its ducts is lined with epithelium. The characteristics of the free surface reflect its Endocrine glands are ductless glands; they secrete functions. their products (termed hormones) into the bloodstream. KENNETH JOMEL A. RODRIGUEZ | BSMT1 3  TRANS: Tissues Most exocrine glands are multicellular, comprised of Connective tissue differs from the other three tissue many cells. types in that it consists of cells separated from each Some exocrine glands are composed of a single cell, other by abundant extracellular matrix. like goblet cells, that secrete mucus. Connective tissue is diverse in both structure and Multicellular exocrine glands can be classified function. according to the structure of their ducts and secretory Connective tissue is comprised of cells, protein fibers, regions. and an extracellular matrix. Simple glands have a single, non-branched duct, FUNCTIONS OF CONNECTIVE TISSUE some have branched ducts. Compound exocrine glands have multiple, branched 1. Enclose and separate other tissue ducts. 2. Connecting tissues to one another Glands with secretory regions shaped as tubules 3. Supporting and moving parts of the body (small tubes) are called tubular, whereas those 4. Storing compounds shaped in saclike structures are called acinar or 5. Cushioning and insulating alveolar. 6. Transporting Tubular glands can be straight or coiled. Glands with a 7. Protection combination of the two are called CONNECTIVE TISSUE CELLS tubuloacinar or tubuloalveolar. The specialized cells of the various connective tissues produce the extracellular matrix. Exocrine Gland Structure The name of the cell identifies the cell functions. Osteoblasts form bone, osteocytes maintain it, and osteoclasts break it down. Fibroblasts are cells that form fibrous connective tissue, and fibrocytes maintain it. Chondroblasts form cartilage and chondrocytes maintain it. Found in connective tissue are cells associated with the immune system, such as white blood cells. Macrophages are large cells that are capable of moving about and ingesting foreign substances, including microorganisms in the connective tissue. Mast cells are nonmotile cells that release chemicals, such as histamine, that promote inflammation. EXTRACELLULAR MATRIX The extracellular matrix of connective tissue has three Exocrine glands can also be classified according to major components: protein fibers, ground substance, how products leave the cell. and fluid. Merocrine secretion involves the release of secretory Ground substance consists of non-fibrous protein and products by exocytosis. other molecules. Apocrine secretion involves the release of secretory The structure of the matrix is responsible for the products as pinched-off fragments of the gland cells. functional characteristics of connective Holocrine secretion involves the shedding of entire tissues—for example, they enable bones and cartilage cells. to bear weight. MATRIX PROTEIN FIBERS Exocrine Glands and Secretion Three types of protein fibers—collagen, reticular, and elastic—help form most connective tissues. Collagen fibers, which resemble microscopic ropes, are very flexible but resist stretching. Reticular fibers are very fine, short collagen fibers that branch to form a supporting network. Elastic fibers have the ability to return to their original shape after being stretched or compressed, giving tissue an elastic quality The ground substance consists of non-fibrous molecules and is shapeless. It consists of proteoglycans, which are large molecules that consist of a protein core attached to many long polysaccharides. Proteoglycans trap large quantities of water between CONNECTIVE TISSUE the polysaccharides, which allows them to return to their original shape when compressed or deformed. Connective tissue is a diverse primary tissue type that makes up part of every organ in the body. TYPES OF CONNECTIVE TISSUES KENNETH JOMEL A. RODRIGUEZ | BSMT1 4  TRANS: Tissues ▪ The two main types of connective tissue are Dense Regular Collagenous Connective Tissue embryonic and adult connective tissue. ▪ By eight weeks of development, most of the embryonic connective tissue has become specialized to form the types of connective tissue seen in adults. ▪ Loose connective tissue consists of relatively few protein fibers that form a lacy network, with numerous spaces filled with ground substance and fluid. ▪ Three subdivisions of loose connective tissue are areolar, adipose, and reticular. ▪ Areolar connective tissue primarily consists of collagen fibers and a few elastic fibers. ▪ The most common cells in loose connective tissue are the fibroblasts. ▪ Adipose tissue consists of adipocytes, or fat cells, which contain large amounts of lipid for energy storage. ▪ Adipose tissue pads and protects parts of the body and acts as a thermal insulator. ▪ Reticular tissue forms the framework of lymphatic tissue, such as in the spleen and lymph nodes, as well ▪Dense elastic connective tissue has abundant elastic as in bone marrow and the liver. fibers among its collagen fibers. Areolar connective tissue ▪ The elastic fibers allow the tissue to stretch and recoil. ▪ Examples include the dense elastic connective tissue in the vocal cords. ▪ A genetic condition called Marfan syndrome results from, in part the inability to properly maintain and form elastic fibers. Dense Regular Elastic Connective Tissue Adipose Tissue CARTILAGE ▪ Cartilage is composed of chondrocytes, located in spaces called lacunae within an extensive matrix. ▪ Dense connective tissue has a relatively large number ▪ Collagen in the matrix gives cartilage flexibility and of protein fibers that form thick bundles and fill nearly strength. all of the extracellular space. ▪ Cartilage is resilient because the proteoglycans of the ▪ There are two major subcategories of dense matrix trap water. connective tissue: collagenous and elastic. ▪ Cartilage provides support, but if bent or slightly ▪ Dense collagenous connective tissue has an compressed, it resumes its original shape. extracellular matrix consisting mostly of collagen fibers. ▪ There are three types of cartilage: hyaline, ▪ Dense collagenous connective tissue has an ▪ fibrocartilage, and elastic cartilage. extracellular matrix consisting mostly of collagen fibers. ▪ Hyaline cartilage is the most abundant type of cartilage ▪ Dense collagenous connective tissue having the and has many functions, such as covering the ends of collagen fibers oriented in the same direction is termed bones, where they form joints. dense regular. ▪ Fibrocartilage has more collagen than does hyaline ▪ Examples of dense regular are tendons and ligaments. cartilage and is able to withstand compression and ▪ Dense collagenous connective tissue having the resist tearing or pulling. collagen fibers oriented in the multiple directions is ▪ Fibrocartilage is found in the intervertebral disks. termed dense irregular. ▪ Examples of dense irregular are in the dermis of the Hyaline cartilage skin and in organ capsules. KENNETH JOMEL A. RODRIGUEZ | BSMT1 5  TRANS: Tissues Bone ▪ Fibrocartilage has more collagen than does hyaline BLOOD cartilage and is able to withstand compression and ▪ Blood is a liquid connective tissue resist tearing or pulling. ▪ It contains a liquid matrix, termed the plasma, along ▪ Fibrocartilage is found in the disks between the with formed elements. vertebrae (bones of the back) and in some joints, such ▪ The formed elements are erythrocytes, leukocytes, and as the knee and temporomandibular (jaw) joints. platelets. ▪ Elastic cartilage contains elastic fibers in addition to ▪ It functions in transport of food, oxygen, waste, collagen and proteoglycans. hormones, and other substances. ▪ The elastic fibers appear as coiled fibers among Blood bundles of collagen fibers. ▪ Elastic cartilage is able to recoil to its original shape when bent. ▪ The external ear, epiglottis, and auditory tube contain elastic cartilage. Fibrocartilage and Elastic Cartilages MUSCLE ▪ The main function of muscle tissue is to contract, or shorten, making movement possible. ▪ Muscle contraction results from contractile proteins located within the muscle cells. ▪ The three types of muscle tissue are skeletal, cardiac, and smooth. ▪ Skeletal muscle attaches to the skeleton and enables the body to move. ▪ Skeletal muscle cells are striated, or banded, because of the arrangement of contractile proteins within the cells. Skeletal Muscle BONE ▪ Bone is a hard connective tissue that consists of living cells and a mineralized matrix. Osteocytes are located within lacunae. ▪ The strength and rigidity of the mineralized matrix enables bones to support and protect other tissues and organs. ▪ Two types of bone tissue exist: spongy bone and compact bone. ▪ Spongy bone has spaces between trabeculae or plates, of bone and therefore resembles a sponge. ▪ Compact bone is more solid, with almost no space between many thin layers of mineralized matrix. KENNETH JOMEL A. RODRIGUEZ | BSMT1 6  TRANS: Tissues ▪ Cardiac muscle is the muscle of the heart; it is responsible for pumping blood. ▪ Cardiac muscle cells are cylindrical but much shorter than skeletal muscle cells. ▪ Cardiac muscle cells are striated and usually have one nucleus per cell. ▪ They are often branched and connected to one another by intercalated disks. CARDIAC MUSCLE TISSUE MEMBRANES ▪ A tissue membrane is a thin sheet or layer of tissue that covers a structure or lines a cavity. ▪ Most membranes consist of epithelium and the connective tissue on which the epithelium rests. ▪ There are four tissue membranes in the body: cutaneous, mucous, serous, and synovial. ▪ The skin, termed the cutaneous membrane, is an external body surface membrane. ▪ The mucous membranes line cavities that open to the outside of the body, such as the digestive, respiratory, ▪ Smooth muscle forms the walls of hollow organs; it is and reproductive tracts. also found in the skin and the eyes. Smooth muscle is ▪ Mucous membranes consist of epithelial cells, their responsible for a number of basement membrane, and a thick layer of loose ▪ functions, such as moving food through the digestive connective tissue. tract and emptying the urinary bladder. ▪ Many, but not all, mucous membranes secrete mucus. ▪ Smooth muscle cells are tapered at each end, have a ▪ The functions of mucous membranes include single nucleus, and are not striated. protection, absorption, and secretion. SMOOTH MUSCLE ▪ Serous membranes line cavities that do not open to the exterior of the body, such as the pericardial, pleural, and peritoneal cavities. ▪ Serous membranes consist of three components: a layer of simple squamous epithelium, its basement membrane, and a delicate layer of loose connective tissue. ▪ Serous membranes do not contain glands, but they secrete a small amount of fluid called serous fluid, which lubricates the surface of the membranes. ▪ Synovial membranes line the cavities of freely movable joints. ▪ They are made up of only connective tissue and consist of modified connective tissue cells. ▪ Synovial membranes produce synovial fluid, which makes the joint very slippery, thereby reducing friction and allowing smooth movement within the joint. NERVOUS TISSUE Internal Membranes TISSUE INFLAMATION ▪ Nervous tissue forms the brain, spinal cord, and ▪ Inflammation is usually a beneficial nerves. process occurring when tissues are ▪ It is responsible for coordinating and controlling many damaged. body activities. ▪ When viruses infect epithelial cells of ▪ Nervous tissue consists of neurons and support cells, the upper respiratory tract, termed glial cells. inflammation and the symptoms of the ▪ The neuron is responsible for conducting action common cold are produced. potentials. ▪ The inflammatory process occurs in ▪ It is composed of three parts: a cell body, dendrites, stages. and an axon. ▪ Inflammation mobilizes the body’s defenses and isolates and destroys Nervous Tissue microorganisms, foreign materials, and KENNETH JOMEL A. RODRIGUEZ | BSMT1 7  TRANS: Tissues damaged cells so that tissue repair can proceed. ▪ Inflammation produces five major symptoms: redness, heat, swelling, pain, and disturbance of function. Inflammation TISSUE REPAIR ▪ Tissue repair involves substitution of dead cells for viable cells. ▪ Tissue repair can occur by regeneration or by fibrosis. ▪ In regeneration, the new cells are the same type as those that were destroyed, and normal function is usually restored. ▪ In fibrosis, or replacement, a new type of tissue develops that eventually causes scar production and the loss of some tissue function. ▪ Regeneration can completely repair some tissues, such as the skin and the mucous membrane of the intestine. In these cases, regeneration is accomplished primarily by stem cells. ▪ Stem cells are self-renewing, undifferentiated cells that continue to divide throughout life. ▪ Tissue repair occurs in sequential steps. Tissue Repair KENNETH JOMEL A. RODRIGUEZ | BSMT1 8  HUMAN ANATOMY AND PHYSIOLOGY WITH PATHOPHYSIOLOGY JAQUES CELAJE INTEGUMENTARY SYSTEM The dermis is a layer of dense connective tissue. LECT 4 The skin rests on the subcutaneous tissue, which is a layer of connective tissue. OUTLINE The subcutaneous tissue is not part of the skin. I. Epidermis and Dermis II. III. IV. INTEGUMENTARY SYSTEM The integumentary system consists of the skin and accessory structures, such as hair, glands, and nails. Integument means covering. The appearance of the integumentary system can indicate physiological imbalances in the body. INTEGUMENTARY SYSTEM FUNCTIONS 1. Protection. The skin provides protection against abrasion and ultraviolet light. 2. Sensation. The integumentary system has sensory receptors that can detect heat, cold, touch, pressure, and pain. 3. Vitamin D production. When exposed to ultraviolet EPIDERMIS light, the skin produces a molecule that can be The epidermis prevents water loss and resists transformed into vitamin D. abrasion. 4. Temperature regulation. The amount of blood flow The epidermis, known as the cutaneous membrane, is beneath the skin’s surface and the activity of sweat a keratinized stratified squamous epithelium. glands in the skin both help regulate body temperature. The epidermis is composed of distinct layers called 5. Excretion. Small amounts of waste products are lost strata. through the skin and in gland secretions. The stratum corneum, the most superficial stratum of SKIN the epidermis, consists of dead squamous cells filled The skin is made up of two major tissue layers: the with keratin. epidermis and the dermis. Keratin gives the stratum corneum its structural The epidermis is the most superficial layer of skin. It is strength. a layer of epithelial tissue that rests on the dermis. Cells of the deepest strata perform mitosis. KENNETH JOMEL A. RODRIGUEZ | BSMT1 1  TRANS: As new cells form, they push older cells to the surface, in parallel, curving ridges that shape the overlying where they slough, or flake off. epidermis into fingerprints and footprints. Excessive sloughing of stratum corneum cells from the SKIN COLOR surface of the scalp is called dandruff. Factors that determine skin color include pigments in In skin subjected to friction, the number of layers in the the skin, blood circulating through the skin, and the stratum corneum greatly increases, producing a thickness of the stratum corneum. thickened area called a callus. The two primary pigments are melanin and carotene. Over a bony prominence, the stratum corneum can Melanin is the group of pigments primarily responsible thicken to form a cone-shaped structure called a corn. for skin, hair, and eye color. DERMIS Carotene is a yellow pigment found in plants such as The dermis is composed of dense collagenous squash and carrots. connective tissue containing fibroblasts, adipocytes, Most melanin molecules are brown to black pigments, and macrophages. but some are yellowish or reddish. Nerves, hair follicles, smooth muscles, glands, and Melanin provi