HAPP111 Lecture Notes - Introduction PDF

Two complementary branches of science - Deals with structures too small to be seen Anatomy and Physiology provides the with the naked eye (requires a specific concepts that help us to understand the tool) human body. Includes:...

Two complementary branches of science - Deals with structures too small to be seen Anatomy and Physiology provides the with the naked eye (requires a specific concepts that help us to understand the tool) human body. Includes:  Cytology (cell) Studies the structure of body parts and  Histology (tissues) their relationships to one another. Deals with structural changes that occur Concerns the function of the body, in throughout the lifespan (from other words, how the body parts work and fertilization until death) carry out their life-sustaining activities. Although we use the reference values and common directional and regional terms to Sub-discipline of developmental anatomy refer to all human bodies, variability Concerns developmental changes that always exists - external anatomy, internal occur before birth. organs, etc. Although it is possible to study anatomy From fertilization until birth and physiology individually, they are inseparable because function always reflects structure (Principle of Pathology complementarity of structure and function). Studies structural changes caused by disease. Studies internal structures as visualized Macroscopic - can be seen by the naked by X-rays images or specialized scanning eye procedures. Can be approached in different ways:  REGIONAL ANATOMY - All the structures in a particular region of the body are examined  SURFACE ANATOMY - Study of The study of the functions of living cells, internal structures as they relate considered to be the cornerstone of to the overlying skin surface human physiology. (beneath the skin)  SYSTEMIC ANATOMY - body How does the cell work? structure is studied system by system (organs and accessory parts)  Ex. Water (H2O), Carbon Dioxide (CO2), Carbohydrates, Proteins and Lipids 2. It is the study of the functions of specific organs. Example cardiac physiology, the study of heart function. Smallest independent units of life Basic structural and functional units of an organism that are composed of Includes all aspects of the functions of chemicals specific organ systems, like cardiovascular physiology, respiratory physiology, Growth, metabolism, irritability, and reproductive physiology, etc. reproduction Cells vary in size from a sperm (which is about 5 um) long to a nerve cell with thin Pathophysiology fibers (which maybe a meter long). It is the study of the effects of diseases Ex. Muscle cells, Nerve cells, Epithelial cells on organ or organ system functions. Made up of many similar cells that perform a specific function. Four basic types of tissues: Epithelial Tissues - covers body surfaces, lines hollow organs and cavities, and forms glands; protection and secretion function Connective Tissues - connects, supports, and protects body organs while distributing blood vessels to other tissues. Nervous Tissues - carries information from one part of the body to another through nerve impulses; receives stimulus Atoms - simplest level, the body is composed of atoms (indivisible) o the Muscular Tissues - contracts to make body basic and smallest unit of all matter. parts move and generates heat.  Ex. Oxygen atom Molecules - combination of two or more Tissues that are joined together atoms. Structures that are composed of two or  Ex. Oxygen atom + Oxygen atom = more different types of tissues Oxygen molecule (O), Carbon (C), They have specific functions and usually Hydrogen (H), Phosphorus (P), have recognizable shapes Calcium (Ca), DNA, etc. Compounds - a molecule containing atoms  Ex. stomach, skin, bones, heart, of more than one element. liver, lungs, and brain  As the fast-acting control system of the body, it responds to internal and external Consists of related organs with a common changes by activating appropriate function. muscles and glands.  Ex. Digestive system, which breaks Impulses down and absorbs food. Its organs include the mouth, salivary glands, Master system that controls other pharynx (throat), esophagus (food systems tube), stomach, small intestine, large intestine, liver, gallbladder, and pancreas. Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body Any living individual. cells. All the parts of the human body No ducts (no connection) functioning together constitute the total organism Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. The heart pumps blood. Skin and accessory parts Forms the external body covering, and Immunity protects deeper tissues from injury. Picks up fluid leaked from blood vessels Synthesizes vitamin D, and houses and returns it to blood. Disposes of debris cutaneous (pain, pressure, etc.) receptors in the lymphatic stream. and sweat and oil glands. Houses white blood cells (lymphocytes) involved in immunity. The immune response mounts the attack against Protects and supports body organs from foreign substances within the body. assault or trauma, and provides a framework the muscles use to cause movement. Blood cells are formed within Air passageway bones. Bones store minerals. Hematopoiesis (Hemopoiesis) - blood cell Acid base balance formation in bone marrow Keeps blood constantly supplied with oxygen and removes carbon dioxide. The gaseous exchanges occur through the Allows manipulation of the environment, walls of the air sacs of the lungs. locomotion, and facial expression. Maintains posture, and produces heat. Attached to the bone Breaks down food into absorbable units Motion/Action that enter the blood for distribution to body cells. Indigestible foodstuffs are It includes the activities promoted by eliminated as feces. muscular system like running, swimming, etc. Also, movement occurs when substances like blood, foodstuffs, urine, and feces are propelled. On the cellular Eliminates nitrogenous wastes from the level, the muscle cell's ability to move by body. Regulates water, electrolyte, and shortening is called contractility. acid-base balance of the blood. Capacity to react Overall function is production of The ability to sense changes (stimuli) in offspring. Testes produce sperm and male the environment and respond to them. For sex hormone, and male ducts and glands example, if you cut your hand on broken aid in delivery of sperm to the female glass, withdrawal reflex occurs. Likewise, reproductive tract. Ovaries produce eggs when carbon dioxide in blood rises, and female sex hormones. The remaining chemical sensors respond by by sending female structures serve as sites for messages to brain centers controlling fertilization and development of the respiration. Nerve cells are the most fetus. Mammary glands of female breasts involved with responsiveness. However, all produce milk to nourish the newborn. body cells are excitable to some extent. Reproduction of life Secondary sex characteristics The breaking down of ingested foodstuffs to simple molecules that can be absorbed into the blood, accomplished by the digestive system. The nutrient rich blood is distributed to all cells through the Definite structure, capable to define what actions of cardiovascular system. is internal and external Converting complex food product to Every living organism must maintain its simpler substance. boundaries so that Its Internal environment (inside remains distinct from the external environment (outside). Single-celled and multi-cellular organisms Includes all chemical reactions that occur are surrounded by a selectively permeable within body cells. Metabolism includes membrane. breaking down substances into simpler molecules (catabolism) and synthesizing Similarly, the human body is enclosed and more complex from simpler substances protected by integumentary system (anabolism). Metabolism depends on the against drying-out, microorganisms, and digestive and respiratory systems to make damaging effects of sunlight, chemicals, nutrients and oxygen available to the etc. blood, cardiovascular distributes them, while endocrine regulates metabolism through hormone secretion. The process of removing wastes or excreta, non-useful substances produced during digestion and metabolism. Several Energy supply organ systems participate in excretion such as digestive systems (indigestible Without energy = bodily functions is food residues), urinary system (nitrogen- impossible containing metabolic wastes like urea and Obtained from the diet, chemical creatinine), respiratory system (by- substances used for energy and cell product of cellular respiration in the form building. Most plant-derived foods are rich of carbon dioxide), integumentary system carbohydrates, vitamins, and minerals, (cellular wastes products like urea, whereas most animal foods are richer in ammonia, lactic acid). proteins and fats. It occurs at the cellular and organismal All the nutrients in the world are useless level. In cellular, the original cell divides, unless oxygen is also available. Because producing identical daughter cells, used the chemical reactions that release energy for body growth or repair. In organismal, are oxidative reactions that require making a whole new person (offspring), oxygen. Human cells can survive for only a major task of the reproductive system few minutes without oxygen. but regulated by hormones of the Approximately 20%of the air we breathe endocrine system. is oxygen. Both respiratory and Growth by intussusception cardiovascular systems make oxygen available to the blood and body cells. Aerobic respiration - with oxygen and An increase in size (hypertrophy) of a releases more energy but slow body part or accomplished by increasing Anaerobic respiration - without oxygen the number of cells (hyperplasia). For and releases less energy but quick true growth to occur, constructive activities must occur at a faster rate than destructive ones. It accounts for 50-60% of our body weight and is the single most abundant chemical substance in the body. It The process whereby unspecialized cells provides the watery environment become specialized cells. Specialized cells necessary for chemical reactions and the differ in structure and function from the fluid base for body secretions and unspecialized cells that give rise to them. excretions. We obtain water chiefly from ingested Intussusception - growth by adding new foods or liquids and lose it from the body materials between existing components by evaporation from the lungs and skin of cell walls. and in body excretions. Unspecialized cells undergoes cell maturation to become specialized cells. Evaporates from lungs and skin   Effector provides the means for the control center's response If chemical reactions are to continue at (output) to output. The results of life-sustaining rates, normal body the response then feedback to temperature must be maintained. As body influence the effect of the temperature drops below or exceeds above stimulus, either reducing or 37'C (98.6'F) metabolic reaction are enhancing. affected. At either extreme, death occurs.  Stimulus → Receptor → Afferent The activity of muscular system generates most body heat. → Control Center → Efferent → Effector → Feedback American Physiologist, spoke of the "wisdom of the body" and he coined the word homeostasis, to describe the ability of the body to maintain relatively stable internal conditions even though the outside world changes continuously. Although the literal translation of FEEDBACK LOOPS homeostasis is unchanging, the term does not really mean static rather, it indicates a dynamic state of equilibrium or balance. Virtually every organ system plays a role in maintaining the constancy of the Most homeostatic control mechanism are internal environment. negative feedback mechanism. In these Communication within the body is systems, the output shuts off the original essential for homeostasis. Communication effect of the stimulus or reduces its accomplished chiefly by the nervous and intensity; Opposite to that of the initial endocrine systems, which use neural and change, returning to ideal value. electrical impulses or bloodborne All negative feedback mechanisms have hormones as information carriers. the same goal: preventing severe changes Regardless of the factor or event being within the body. Body temperature and regulated - the variable - all homeostatic blood sugar are only two of the variables control mechanisms are processes that need to be regulated. involving at least three (3) components that work together:  Receptor - it is some type of sensor that monitors the environment and responds to changes called stimuli, by sending information (input) to the control center.  Control center analyzes the input it receives and determines the appropriate response.  It is the process when the receptor In Positive feedback mechanisms, the detect change and initiate response result or response enhances the original that will go against the change. stimulus so that the response is  EXAMPLE: Blood glucose rise after accelerated. The feedback mechanism is sugar meal positive because the change that results ♦ Increase of glucose, proceeds in the same direction as initial decrease in insulin change Positive feedback mechanism are often referred to as cascades. Two familiar examples are the enhancement of labor It is the process by which stimulus contractions during birth and blood causes a response which will increase clotting. the stimulation. Oxytocin, a hypothalamic hormone,  EXAMPLE: The contraction of Intensities labor contractions, more uterine during childbirth frequent and more powerful. The ♦ Increase of oxytocin increased contractions cause more oxytocin to be released, until the baby is OXYTOCIN - Hormone that manages key born. The birth ends the stimulus for aspects in both male and female oxytocin release and shuts off positive reproductive systems feedback mechanism. ♦ Female, contraction ♦ Male, ejaculation Homeostasis is important that most disease can be regarded as a disturbance, a condition called homeostatic imbalance. As we age, our body's control systems become less efficient, and our internal A process of nervous and hormonal environment become less stable. These regulation by which the body maintains events increase our risk for illness and levels. produce the changes we associate with It is done to either increase or dampen aging the initiate response that will go against the change. Another important source of homeostatic imbalance occurs when the usual negative feedback mechanisms are overwhelmed, and destructive positive feedback mechanisms take over. Some instances of heart failure reflect this phenomenon. In the anatomical position, the person is:  Standing erect  Head and eyes facing forward  Feet are flat on the floor, slightly apart and directed forward  Arms at the sides with palms turned forward Abdominal - anterior body trunk inferior to ribs Acromial - point of shoulder Antebrachial - forearm Antecubital - Anterior surface of elbow Axillary - armpit Brachial - arm Buccal - cheek area Carpal - wrist Cervical - neck region Coxal - hip Crural - anterior leg; the shin Deltoid - curve of shoulder formed by large deltoid muscle Digital - fingers, toes Femoral - thigh (applies to both Popliteal - posterior knee area anterior and posterior) Sacral - area between hips at base of Fibular - lateral part of leg spine Frontal - forehead Scapular - shoulder blade region Inguinal - area where thigh meets body Sural - the posterior surface of leg; the trunk; groin calf Mental - chin Vertebral - area of spinal column Nasal - nose area NOTE: The plantar region, or the sole of the foot, actually on the inferior body Oral - mouth surface, is illustrated with the posterior body landmarks Orbital - eye area Otic - ear Patellar - anterior knee Pectoral - relating to, or occurring in or on, the chest Pelvic - area overlying the pelvis anteriorly Pubic - genital region Sternal - breastbone area Tarsal - ankle region Thoracic - area between the neck and abdomen, supported by the ribs, sternum and costal cartilages; chest Umbilical - navel Calcaneal - heel of foot Cephalic - head Femoral - thigh Gluteal - buttock Lumbar - area of back between ribs and hips; the loin Occipital - posterior surface of head or base of skull Olecranal - posterior surface of elbow  PRONATION - means rotating the forearm and hand medially so that the palm faces posteriorly while SUPINATION - means rotating the forearm and hand laterally so that the palm faces anteriorly. DORSIFLEXION - occurs when the ankle bends raising the toes upward, and this decreases the angle between the dorsal side of the foot and the tibia. FLEXION - decreases the angle of a joint; PLANTAR FLEXION - occurs when the ankle bending bends in the direction that points the toes and plantar side of the foot downward. EXTENSION - straightens a joint and returns a body part to the anatomical position HYPEREXTENSION - is extension of a joint beyond 180 degrees INVERSION - involves the movement of the sole towards the median plane - so that the sole faces in a medial direction. Eversion involves the movement of the sole away from the median plane - so that the sole faces in a lateral direction. PROTRACTION - means gliding motion anteriorly and retraction means moving the structure back to anatomic position ABDUCTION - is movement away from the or even further posteriorly. body, while adduction is movement toward the body. CIRCUMDUCTION - is the movement of the limb, hand, or fingers in a circular pattern, using the sequential combination of flexion, adduction, extension, and abduction motions. ROTATION - means moving around the long DEPRESSION AND ELEVATION - are downward axis (lateral, medial) and upward movements of the scapula or mandible. OPPOSITION - a small hand movement consisting of the thumb touching the tips of the other digits.  (Principle of complementarity of structure and function). Cells can only arise from other cells. Cells are the structural units of all living things, from one-celled "generalists" like DNA is found in the nucleus of the cell. amoebas to complex multicellular organisms like humans, animals, and trees. Contain membrane - bound organelles which include mitochondria, endoplasmic The human body has 50 to 100 trillion cells reticulum, and Golgi complex. with over 250 different cell types that vary greatly in shape, size, and function. Cell division involves mitosis. Whatever its form, the cell is the microscopic package that contains all the parts necessary to survive in an ever- DNA is not enclosed within the membrane. changing world. Lack membrane - enclosed organelles. Usually divide by binary fission The first person to use the term "cell". He referred to the small empty chambers in the structure of cork as cells. Concluded that all plant and animal tissues were composed of cells. Proposed the theory of biogenesis where cells only arise from pre-existing cells. A cell is the basic structural and functional unit of living organisms. When you define cell properties, you define the properties of life. The activity of an organism depends on both the individual and the combined activities of its cells. MITOSIS - cell replicates its chromosomes and segregates them to The biochemical activities of cells are produce two identical nuclei for cell dictated by their shapes or forms, and division by the relative number of the subcellular structures they contain BINARY FISSION - cell dividing into two  Prokaryotes (Eubacteria and Archeabacteria) are the most abundant organisms on earth. A prokaryotic cell does not contain a membrane-pound nucleus. Each prokaryotic cell is surrounded by a plasma membrane. The cells has no subcellular organelles, only infoldings of the plasma membrane called mesosomes. The deoxyribonucleic acid (DNA) is condensed within the cytosol to form the nucleold. Some prokaryotes have tail-like flagella. Regardless of differences, all cells have the same basic parts and some common functions (generalized or composite cell)  The plasma membrane as the outer boundary of the cell  Cytoplasm, the intracellular fluid packed with organelles  Nucleus, an organelle that controls cellular activities Water accounts for about 70-75% of the weight of the cell. Organic compounds accounts for 25-30% of the cell weight. They are nucleic acids, polysaccharides (carbohydrates) proteins, and lipids. Inorganic compounds account for the rest of the cell weight. The flexible plasma membrane (cell membrane) separates two of the body's major fluid compartment - the intracellular fluid (ICF) within cells and extracellular fluid (ECF) outside cells. Plasma membrane proteins allows the cell to communicate with its environment. There are two distinct two populations of membrane proteins, integral (firmly inserted, transmembrane proteins) and peripheral (loosely attach) The fluid mosaic model of membrane structure depicts the plasma membrane as thin (7-10nm) structure composed of a double layer (bilayer) of lipid molecules with proteins plugged into or dispersed in it. It is constructed largely or phospholipids with smaller amounts of glycolipids and cholesterol. It is constructed largely of phospholipids Although certain cell types - blood cells, with smaller amounts of glycolipids and sperm cells, and some immune cells - are cholesterol. Each lollipop-shaped footloose in the body, many other types phospholipid molecule has polar (charged, are knit together. Junctions are the most hydrophilic) head and non-polar important factor securing cells together. (uncharged, hydrophobic) tall, made of two fatty acid chains. Interstitial Fluids - fills the narrow spaces between cells of tissues Blood Plasma - within blood vessels Lymph Fluid - within lymphatic vessels Cerebrospinal Fluid - within brain and spinal cord Synovial Fluid - joints Aqueous Humor and Vitreous Body - eyes Substances move through the plasma membrane in essentially two ways - passively or actively. In passive processes, substances cross the membrane without any energy input from the cell. In active processes, the cell provides the metabolic energy (usually ATP) needed to move substances across the membrane. The two (2) main types of passive transport are diffusion and filtration.   FACILITATED DIFFUSION ♦ The movement of large molecules like glucose through the cell membrane larger molecules must be “helped” ♦ Proteins in the cell membrane form channels for large molecules to pass through. ♦ Proteins that form channels (pores) are called protein channels. Requires energy - Adenosine Triphosphate (ATP) ATP - energy currency No energy required  ENDOCYTOSIS ♦ Moves into the cell  SIMPLE DIFFUSION ♦ Food products ♦ The movement of small particles across a  EXOCYTOSIS selectively permeable ♦ Moves out of the cell membrane like the cell ♦ Waste/cell products membrane until equilibrium is reached. Diffusion is the tendency of the molecules ♦ These particles move or ions to move from an area where they from an area of high are in higher concentration to an area concentration to an area where they are in lower concentration, of low concentration. down or along concentration gradient. ♦ Equal concentration, The driving force for diffusion is the equal solute (tinutunaw), equal solvent kinetic energy of the molecules, the speed (tumutunaw) of diffusion is influenced by molecular  OSMOSIS size (the smaller, the faster) and ♦ The diffusion of water temperature (the warmer, the faster). (H2O) through a Although there is continuous traffic selectively permeable across the plasma differential, it is a membrane like the cell selectively, differentially permeable membrane. barrier. ♦ ONLY diffuses water. ♦ Water diffuses across a membrane from an area of high concentration to an area of low concentration. ♦ Semi-permeable membrane is permeable to water, but not to sugar Tonicity refers to the ability of a solution For cells, the control center is the gene- to change the shape or tone of cells by containing nucleus. As the genetic library, altering the cells' internal water volume. it contains the instructions needed to build nearly all the body's proteins. The osmolarity and tonicity are not the Additionally, it dictates the kinds and same. A solution's osmolarity is based amounts of proteins to be synthesized at solely on its total solute concentration. In any one time in response to signals. contrast, tonicity is based on (1) solute concentration and (2) solute permeability Most cells have only one nucleus, but of the plasma membrane. some, including skeletal muscles, bone destruction cells, and some liver cells are Osmolarity is expressed as osmol/L and destruction multinucleate. All of our body osmolality as osmol/Kg. cells have nuclei except for mature red blood cells (anucleate), whose nuclei are ejected before the cells enter bloodstream. Nucleus is often spherical or oval, its shape usually conforms to the shape of the cell. The nucleus has three recognizable structures or regions: (1) nuclear membrane or envelope (2) Nucleoli and (3) chromatin. NUCLEAR MEMBRANE - is a double membrane barrier separated by fluid filled space. The outer membrane is continuous with the rough ER. The inner membrane is lined by nuclear lamina, network of lamins that maintains shape of nucleus. Nuclear membrane is punctuated by nuclear pores. Nuclear envelope encloses jellylike substance nucleoplasm in which other nuclear elements are suspended. NUCLEOLI - are dark staining spherical bodies that contains the DNA that issues genetic instructions synthesizing ribosomal RNA. CHROMATIN - a system of bumpy threads cells; pigment (melanin) granules in weaving through the nucleoplasm. certain skin and hair cells. Chromatin is composed of 30% DNA, 60% globular histone proteins and 10% RNA chains. Cytoplasm is the cellular material between the plasma membrane and the nucleus, the site most cellular activities. Electron microscopy reveals that cytoplasm consists of three major elements: (1) The cytosol (2) organelles and (3) Mitochondria are typically threadlike or inclusions. lozenge-shaped membranous organelles. CYTOSOL - the viscous, semitransparent They are the power plants of a cell, fluid in which the cytoplasmic elements providing most of its ATP supply. The are suspended. Dissolved in the cytosol, density of mitochondria in a particular which is largely water, are proteins, salts, cell reflects that cell's energy sugars, and a variety of other solutes. requirement, and generally cluster where the action is. Busy cells like kidney and ORGANELLES (LITTLE ORGANS) - are liver cells have hundreds of mitochondria metabolic machinery of the cell. Each type whereas relatively inactive cell like certain of organelle carries out a specific lymphocytes have just few. function for the cell. Compartmentalization is crucial to cell Mitochondrion is enclosed by two functioning, without this biochemical membranes; the outer membrane is activity would be chaotic. smooth and featureless but the inner membrane folds inward forming shelflike INCLUSIONS - are chemical substances that cristae that protrudes into matrix, gel-like may or may not be present, depending on substance within the mitochondrion. cell type. Examples include stored Teams of enzymes, some dissolved in the nutrients like glycogen granules in liver matrix, and others forming part of the and muscle cells; lipid droplets in fat cristae membrane, break down intermediate products of food fuels like The lysosomal membrane is adapted to glucose and others to water and carbon serve lysosomal functions into two dioxide and releases energy (aerobic important ways: cellular respiration)  Lysosome contains H ion pumps Mitochondria are complex organelles, that maintains the organelle's containing own DNA, RNA, ribosomes and acidic pH able to reproduce themselves.  Lysosomes retains dangerous lysosomal enzymes (acid hydrolases) Endoplasmic reticulum is an extensive Lysosomes (disintegrator bodies) are system of tubes and membranes enclosing spherical membranous organelles fluid filled cavities known as cisterns. The containing activate digestive enzymes. ER is continuous with the outer nuclear Lysosomes are large an abundant in membrane and accounts for about half of phagocytes, the cells that dispose of the cell's membranes. There are two invading bacteria and cell debris. distinct varieties: rough ER (rER) and Lysosomal enzymes can digest almost all smooth ER (sER). kinds of biological molecules.  The external surface of the reR is Lysosomal membrane is ordinarily stable studded with ribosomes, hence the but becomes fragile when the cell is name rough. Proteins are injured or deprived of oxygen and when assembled on these ribosomes, excessive amount of vitamin A are delivered to fluid-filled ER cisterns, present. When lysosome rupture, the cell and eventually enclosed in vesicles digest itself, a process called autolysis. for their journey to Golgi apparatus where they undergo  further processing. The rER is regulator" for cellular proteins. Its major particularly abundant and well function is to modify, concentrate, and developed in most secretory cells, package the proteins and lipids made at antibody-producing immune cells, ER and destined for export from the cell. and liver cells  The sER is continuous with rER. Its enzymes play no role in protein synthesis. Instead, involved in (1) metabolizing lipids, synthesizing cholesterol and phospholipids (2) synthesize steroid-based hormones like sex hormones (3) Absorb, synthesize, and transport fats (4) Detoxify drugs, certain pesticides and cancer-causing chemicals (5) Break down stored glycogen to form free glucose.  Additionally, skeletal and cardiac muscle cells have an elaborate smooth ER (called sarcoplasmic reticulum) that stores and release calcium ions during muscle contraction. Resembling small lysosomes, peroxisomes are spherical membranous sacs containing a variety of powerful enzymes, the most important of which are oxidases and catalases. Recent evidence suggests that most new peroxisomes form by budding off of the ER via special machinery that differs from that used for vesicles destined for modification in the Golgi apparatus. Oxidases use molecular oxygen to detoxify harmful substances like alcohol and formaldehyde. And to neutralize free radicals, highly reactive chemicals with unpaired electrons. Peroxisomes are especially numerous in liver and kidney cells which are very active in detoxification. They also play a role in energy metabolism by breaking Golgi apparatus consists of stacked and down and synthesizing fatty acids. flattened membranous sacs. Golgi apparatus is the principal "traffic  The cell cycle is the series of changes a cell goes through from the time it is formed until it reproduces. Interphase (in green), in which the cell grows and carries on its usual activities Cell division or the mitotic phase (in yellow), during which it divides into two cells Cytoskeleton (cell skeleton) is an elaborate network of rods running through the cytosol and hundreds of Before a cell can divide, its DNA must be accessory proteins that link these rods to replicated exactly, so that identical copies other cell structure. of the cell's genes can be passed to each of its offspring. During the s-phase, Cytoskeleton acts as cell's bones, muscles replication until all the DNA has been and ligaments. replicated. Cell division is essential for body growth and tissue repair. Some cells reproduce almost continuously (skin, intestinal linings), some divide more slowly (liver cells), and others lose the ability to divide (nervous tissue, skeletal muscle, and heart muscle) when they are fully mature, and repairs are made with scar tissue (fibrous type of connective tissue)  as “immortality enzyme” found in certain specialized cells, has the ability to lengthen previously shortened telomeres. Cell aging is complicated and has many causes. The exact nature of human aging is still a mystery, but there are several current theories on aging: Holds that the cumulative effect of assaults such as environmental toxins, leads to accelerated rates of cell death throughout the body. Places the blame on damage caused by free radicals, resulting in diminished energy production by damaged mitochondria. Holds that aging results from a progressive weakening of the immune system; the body loses its ability to fight off pathogens or systemic inflammation. Holds that cell aging is programmed into our genes. Telomeres are non-sensical strings of nucleotides that cap the ends of chromosomes. Telomeres are vital for chromosomal survival. With each cycle of DNA replication, telomeres gets a bit shorter. Telomerase is an enzyme dubbed  Absence of blood vessels among cells (avascularity but innervated) Tissues (histology) are group of cells that Equipped with high regenerative capacity are similar in structure and perform a common or related function Fundamental Types of Tissues  Epithelial  Connective  Muscular  Nervous If we summarized the role of each primary tissue in a single word, we could say that epithelial tissue covers, connective tissue supports, muscle tissue produces movement, and nervous tissue Epithelial Tissue - forms the covering of controls. the surfaces of the body located in internal and external parts Extracellular Substance - outside the One of the fundamental types of tissue of cell the body Intercellular (intracellular) Substance - COMPOSITION: inside the cell  Epithelial Cells Interstitial Fluid - fluid found in the spaces around the cells  Extracellular or Intercellular substance Apical-basal Polarity - essential for epithelial cell form and function, as it determines the localization of the adhesion molecules that hold the cells together laterally and the occluding junctions that act as barriers to paracellular diffusion Avascularity but innervated - no blood vessels but has presence of nerves Forms a boundary layer that controls the movement of substances between the external and internal environment May be specialized for absorption and secretion Exhibits apical-basal polarity On the exterior of the body, resists Cells are arranged in sheets or layers abrasion and dehydration Cells rest on a continuous extracellular layer called basal lamina  Classification based on the number of layers of cells SIMPLE EPITHELIUM  One layer of epithelial cells on a basement membrane or basal lamina; Found where absorption, secretion, and filtration occur STRATIFIED EPITHELIUM  Describe two or more layers of epithelial on top of a basement membrane; Common in high abrasion areas where protection is important PSEUDOSTRATIFIED EPITHELIUM  Describe one layer of epithelial cell on basement membrane but cells have different sizes, nucleus are in different areas inside the cell (has different heights, thus showing a stratified appearance) Ectoderm - Epidermis, Glandular appendages of the skin Mesoderm - Vascular endothelium, Kidneys, Reproductive tracts Endoderm - Intestinal tract, Liver, Pancreas, Lungs Membranous (Covering, Lining) Epithelium  Epithelial cells covering surfaces and lining cavities Classification based on the shape of the Glandular Epithelium cells of the uppermost number of layers  Fashions the glands of the body SQUAMOUS  Flattened and scale-like CUBOIDAL  Boxlike, approximately as tall as they are wide  COLUMNAR LOCATION: Kidney glomeruli; air sacs of  Tall and column-shaped lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body TRANSITIONAL EPITHELIUM cavity (serosae).  The thickness of the layer of epithelial cells varies when the organ functions at rest, the layer is thick; when in function it becomes thin (vice-versa) DESCRIPTION: Single layer of cube-like cells with large, spherical central nuclei. FUNCTION: Secretion and absorption. LOCATION: Kidney tubules; ducts and secretory portions of small glands; ovary surface. DESCRIPTION: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia. FUNCTION: Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae.  Location: Non-ciliated type in males' sperm-carrying ducts and ducts of large DESCRIPTION: Single layer of tall cells with glands; ciliated variety lines the trachea, round to oval nuclei; many cells bear most of the upper respiratory tract. microvilli, some bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells). FUNCTION: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action. LOCATION: Non-ciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus. DESCRIPTION: Thick membrane composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers. Description: Single layer of cells of FUNCTION: Protects underlying tissues in differing heights, some not reaching the areas subjected to abrasion. free surface; nuclei seen at different levels; may contain mucus-secreting cells LOCATION: Non-keratinized type forms the and bear cilia. moist linings of the esophagus, mouth, and vagina; keratinized variety forms the Function: Secrete substances, particularly epidermis of the skin, a dry membrane. mucus; propulsion of mucus by ciliary action.  DESCRIPTION: Two or more layers of cells in which the cells in the apical layer are cube-shaped. LOCATION: Ducts of adult sweat glands and esophageal glands and part of male urethra. FUNCTION: Protection and limited secretion and absorption. DESCRIPTION: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamous-like, depending on degree of organ stretch. FUNCTION: Stretches readily, permits DESCRIPTION: Several layers of irregularly stored urine to distend urinary organ. shaped cells; only the apical layer has LOCATION: Lines the ureters, bladder, and columnar cells. part of the urethra. LOCATION: Lines part of urethra, large excretory ducts of some glands, such as esophageal glands, small areas in anal mucous membrane, and part of the conjunctiva of the eye. FUNCTION: Protection and secretion.  MUCOUS GLAND  Secretes a thick and viscid product Classification based on the presence or absence of ducts  Goblet cells ENDOCRINE GLANDS SEROUS GLAND  Ductless glands like thyroid,  Secretes a thin and watery pituitary, parathyroid product  Parotid gland EXOCRINE  Duct-containing glands like sweat MUCO-SEROUS GLAND gland, salivary glands  Mixed secretions  Submandibular and sublingual Classification based on the number of glands cells CYTOGENIC GLANDS UNICELLULAR GLAND  Glands that produce cells  Goblet cells  Testis and ovaries MULTICELLULAR GLAND Classification based on the fate of  All other cells except goblet cells secretory cells during active secretion MEROCRINE GLAND  There is no destruction of the secretory cells  Sweat gland APOCRINE GLAND  There is partial destruction of secretory cells  Mammary gland HOLOCRINE GLAND  There is total destruction of secretory cells  Sebaceous gland Classification based on the Glands according to Morphology Classification based on the nature of  Whether branched (compound) secretions or unbranched (simple)  Shape of the secretory portion ♦ Tubular  ♦ Alveolar/acinar collagen fibers are seen in the light ♦ Tubulo-alveolar microscope. An important component is proteoglycans made TYPES: up of protein and polysaccharide Simple Tubular - Glands in the Large Intestine Simple Branched Tubular - Gastric glands Simple Coiled Tubular - Sweat glands SIMPLE ACINAR - Glands of the penile urethra Simple Branched Acinar - Sebaceous gland Compound Tubular - Bulbo-urethral (Cowper's gland) Compound Acinar - Mammary gland Compound Tubuloacinar - Acinar glands of pancreas Connective Tissue - kind of tissue that use to connect, bind, holds, and support one part to another part of the body. They are the most vascularized and widely distributed in the body. FUNCTIONS OF THE CONNECTIVE TISSUE:  Supporting the muscle to Characterized by large amounts of produce movement extracellular materials that separate cells  Protects the internal and from one another delicate organs  Connects the tissues of the body Characterized by a large percentage of living cells and non-living material  Protein fiber known as matrix ♦ Collagen Matrix - made of ground substance and ♦ Reticular fibrous structures ♦ Elastic  Ground substance is the shapeless background against which cells and  Cells of connective tissues are widely a particular area: between the skin and apart with each other in a form of muscles) matrix LOCATION: Widely distributed under Extracellular Matrix - A large network of epithelia of body, e.g., forms lamina proteins and other molecules that propria of mucous membranes; packages surround, support, and give structure to organs; surrounds capillaries. cells and tissues in the body SPECIALIZED CELL: Fibroblasts Polysaccharides - Complex carbohydrates rich in vitamins, MATRIX: Collagen structure and elastic minerals and fiber. It is a long chain of monosaccharide Proteins - building blocks of life All connective tissues arise from mesenchyme, an embryonic tissue Connective tissues run the gamut of vascularity; Cartilage is avascular, dense connective is poorly vascularized while others are highly vascularized Connective tissues are largely nonliving extracellular matrix Consists of collage and elastic fiber but is not a typical connective tissue Adipose cells are filled with lipids and function to store energy It also acts as a pad and thermal insulator Consists of collagen and elastic fiber SPECIALIZED CELL: Adipocytes Most common cells found are fibroblast MATRIX: Reticular structure with Fibroblast are responsible for the collagenous fibers production of the fibers of the matrix FUNCTIONS: Storage of lipids for energy DESCRIPTION: Gel-like matrix with all three building; insulator fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells. FUNCTION: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid. (Holds the organs in  forms joints, costal cartilages that attach ribs to sternum Consists of densely packed fibers  Fibrocartilage - has more collagen than does hyaline It is what makes up tendons and ligaments cartilage. It is found in the disks between vertebrae and some Two types: joints  DENSE COLLAGENOUS - has  Elastic - contains elastic fibers extracellular matrix consisting that appear as coiled fibers mostly of collagen fibers; Examples among bundles of collagen. The external ear, epiglottis, and are tendons, ligaments, dermis, auditory tube contain elastic capsule fibers  DENSE ELASTIC - has abundant elastic fibers among collagen fibers; Examples are vocal cords, walls of large arteries, elastic DESCRIPTION: Amorphous but firm matrix; ligaments collagen fibers form an imperceptible network; chondroblasts produce the DESCRIPTION: Primarily parallel collagen matrix and when mature (chondrocytes) fibers: a few elastic fibers; major cell lie in lacunae. type is the fibroblast FUNCTION: Supports and reinforces; FUNCTION: Attaches muscles to bones or serves as resilient cushion; resists to muscles. Attaches bones to bones. compressive stress. Withstands great tensile stress when pulling force is applied in one direction. LOCATION: Forms most of the embryonic skeleton; covers the ends of long bones in LOCATION: Tendons, most ligaments, joint cavities; forms costal cartilages of aponeuroses. the ribs; cartilages of the nose, trachea, and larynx. DESCRIPTION: Matrix similar to but less Composed of cartilage cells or firm than that in hyaline cartilage; thick chondrocytes collagen fibers predominate. TYPES: FUNCTION: Tensile strength allows it to  Hyaline - most abundant of the absorb compressive shock. cartilages and it covers bones, LOCATION: Intervertebral discs; pubic  Cancellous bone symphysis; discs of knee joint. DESCRIPTION: Hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae. Very well vascularized. FUNCTION: Supports and protects (by enclosing); provides levers for the muscles to act on; stores calcium and other minerals and fat; marrow inside bones is the site for blood cell formation (hematopoiesis). LOCATION: Bones DESCRIPTION: Similar to hyaline cartilage, but more elastic fibers in matrix. FUNCTION: Maintains the shape of a structure while allowing great flexibility. LOCATION: Supports the external ear (pinna); epiglottis Blood is unique because the matrix is liquid, enabling blood cells to move Bone (Osseous) is a hard connective tissue through blood vessels that consists of living cells and a It is classified as connective tissue mineralized matrix because it develops from mesenchyme and Bone cells or osteocytes are located within consists of blood cells surrounded by a the spaces in the matrix called lacunae non-living fluid matrix called blood plasma Two types of bone: Blood cells include the red blood cells (erythrocytes), white blood cells  Compact bone (leukocytes), and platelets (thrombocytes). The fibers of blood are soluble protein molecules that precipitate during blood clotting. Transport vehicle for nutrients, wastes, Muscle tissues are highly cellular, well- gases, substances and many other vascularized tissues that are responsible for most types of body movement. DESCRIPTION: Red and white blood cells in Muscle cells possess myofilaments, a fluid matrix (plasma). elaborate networks of actin and myosin FUNCTION: Transport respiratory gases, filaments that bring about movement or nutrients, wastes, and other substances. contraction in all cell types LOCATION: Contained within blood vessels.  Skeletal muscle  Cardiac muscle  Smooth muscle Muscle Tissues - composed of muscle cells that are designed for contraction and movement Also called as muscle fibers Consists of: Sarcolemma - cell membrane Sarcoplasm - cytoplasm of the muscle cell Cell Body - contains nucleus at the center Involuntary Muscles - can't be controlled Voluntary Muscles - can be controlled TYPES OF WHITE BLOOD CELLS Striated - with muscle fibers (LEUKOCYTES) Non-Striated - without muscle fibers Monocytes - has longer life span/ helps to break down bacteria Lymphocytes - antibodies/ associated with immunity (T and B cells) DESCRIPTION: Long, cylindrical, Granulocytes - small granules/ multinucleate cells; obvious striations. neutrophil (first line of defense), eosinophil (combat for pathogens), FUNCTION: Voluntary movement; basophil (for allergens) locomotion; manipulation of the environment; facial expression; voluntary control. LOCATION: In skeletal muscles attached to bones or occasionally to skin. DESCRIPTION: Branching, striated, generally uninucleate cells that DESCRIPTION: Spindle-shaped (elongated) interdigitate at specialized junctions cells with central nuclei; no striations; (intercalated discs). cells arranged closely to form sheets. FUNCTION: As it contracts, it propels blood FUNCTION: Propels substances or objects into the circulation; involuntary control. (foodstuffs, urine, a baby) along internal LOCATION: The walls of the heart. passageways; involuntary control. LOCATION: Mostly in the walls of hollow organs.  NEURAL TISSUE HAS 2 BASIC TYPES OF CELLS: Nervous tissue forms the brain, spinal Neurons or nerve cells which cord. It is responsible for coordinating transmit signals and controlling many bodily activities. Neuroglia or supporting cells And this dependent on the ability of the which has the following cell to communicate to one another by functions: electrical signals called action potential  Provide a supporting framework Nervous tissue contains very important for neural tissue. cells which are neurons (nerve cell) and  Acts as phagocytes, thus neuroglia (glial cells) defending the neural tissue from pathogens. DESCRIPTION: Neurons are branching cells;  Help in repair of injuries. cell processes that may be quite long extend from the nucleus-containing cell  Regulate the composition of the body; also contributing to nervous tissue interstitial fluid and isolate and are non-excitable supporting cells. protect the cell membranes of the neurons. FUNCTION: Neurons transmit electrical signals from sensory receptors and to effectors (muscles and glands); supporting cells support and protect Concerned about the direction of the neurons. nerve impulse travels to the CNS (Central Nervous System), from CNS to sensory LOCATION: Brain, spinal cord, and nerves. receptors. Neurons that carry impulses to the brain to the visceral or muscles and glands. Neurons that connect between sensory and motor neurons following the neutral pathways. Single process emerging from the cell body This tissue is specialized for the One dendrite, one axon reception of stimuli and transmission of impulses. Majority of the neural tissue in the body is concentrated in the brain Many dendrites, one axon and spinal cord (Central Nervous System). Soma or cell body containing the nucleus Protoplasmic processes:  Dendrite - transmit impulses towards the soma  Axon - transmits impulses from soma to synapse Synapse - is a specialized intercellular junction where the axon ends. CYCLE OF TRANSMISSION: Dendrite - Cell Body - Axon - Synapse - Another Neuron HEMATOPOIESIS/HEMOPOIESIS - blood production PLASMA - fluid component RED BLOOD CELL (RBC) - erythrocytes - oxygen - hemoglobin WHITE BLOOD CELL (WBC) - leukocytes - defense system PLATELETS - thrombocytes - blood coagulation (clotting)  SCIENCE OF DERMATOLOGY  Epidermis  Dermis Skin - largest organ in the body; also Weighs 20 lbs, or more depending on the called integument; simply means covering size of the body Skin appendages Used to determine body fat (hypodermis - fats)  Oil gland  Sweat gland  Ceruminous gland Superficial protective layer of the skin  Mammary gland  Hairs Composed of keratinized, squamous epithelium that stratified varies in  Nails thickness Composed of 4-5 layers, depending on its location within the body Protects body from mechanical damage (bumps & cuts), chemical damage (from All but the deepest layers of epidermis are acids and bases), thermal damage (heat composed of dead cells and cold), ultraviolet radiation, and Palms and soles have five layers because external foreign agents an (bacteria, these areas are exposed to most friction parasites) Keeps water and other precious molecules in the body Process in which new cells (with keratin) Keeps water out (so one can swim for push old cells to surface hours without becoming waterlogged) 40 - 56 days for new cells to reach Insulates and cushions deeper body organs surface Regulates heat loss from body surface Acts as a mini-excretory system during perspiration, urea, salt and water are lost Manufactures several proteins important to immunity Storage of Vitamin D precursor Contains cutaneous receptors that serve as sensors for touch, pressure, temperature, and pain   Langerhans cells (Non-pigmented granular dendrocytes) - protective macrophagic cells that ingest bacteria and other foreign debris Spiny, Prickly layer Contains several stratified layer of cells Spiny appearance due to changed shape of keratinocytes With limited mitosis This layer plus stratum basale are collectively called Stratum Germinativum Layers with cells slightly separated by tissue fluid but joined by delicate extensions of cytoplasm (skin, strength, and flexibility). Granular layer Consists of only 3-4 flattened rows of cells Cells here appear granular due to the presence of keratoyalin granules Germinativum (other term) Several layers of cells filled with granules Basal layer containing keratohyalin (keratin), nerve Composed of single layer of cells in endings and epidermal pigments. contact with the dermis KERATINOCYTE - major cell type of the Layers of actively dividing cells which epidermis / keratin replaces the cells that are shed off. KERATIN - type of protein that helps to Primarily made up of basal cell. form tissues of the hair, nails, and the Four (4) types of cells in the stratum outer layer of the skin. They are also basale found on cells in the lining of organs, glands, and other parts of the body.  Keratinocytes - produces keratin Stratum lucidum which toughens and waterproofs skin Clear layer  Melanocytes - synthesize the Nuclei, organelles, and cell membranes are pigment melanin providing no longer visible, so this layer appears protective barrier to UV radiation clear in sunlight  Tactile cells (Merkel cells) - aid in Exists only in the lips and thickened skin touch (tactile) reception of soles and palms Contains a translucent substance called eleidin Translucent layer where nails originate Caused by expression of a combination of (palm of the hands, fingertips, and sole of three (3) pigments the feet).  Melanin  Carotene  Hemoglobin Horny layer Composed of 25-30 layers of flattened, scale-like anucleated cells which are Brown-black pigment produced by the continuously shed as flake like residues of melanocytes of stratum basale cells (stratum disjunction) Guards skin against damaging effect of This surface layer is cornified and is the ultraviolet rays of sunlight real protective layer of the skin Gradual exposure to sunlight promotes Cornification is brought about by increased production of melanin hence, keratinization and the hardening, tanning of skin flattening process that takes place as the cells die and are pushed to the surface In albino, there is a normal number of melanocytes but lacks the enzyme Friction at the surface of skin stimulates tyrosinase that converts amino acid additional mitotic activity of stratum tyrosine to melanin basale, resulting in the formation of a callus for additional protection Freckles, caused by aggregated patch of melanin Outermost layers of flat, dead cells that are shed off at intervals; responsible for Vitiligo, lack of melanocytes in localized variations in skin thickness. areas of the skin causing distinct white spots A yellowish pigment found in epidermal cells and fatty parts of dermis Abundant in skin of Asians Together with melanin, accounts for the yellowish-tan color in Asians Not a pigment of the skin, rather it is the oxygen-binding pigment found in red blood cells Oxygenated blood flowing through the dermis, gives the skin its pinkish tones  FURROWS IN THE FOREHEAD AND FACE (WRINKLES) Produced by melanocytes Acquired from continual contraction of facial muscles, such as from smiling or Ranges from yellow to reddish-brown squinting in bright light or against the to black wind; facial lines become more strongly delineated as person ages Responsible for hair and eye color. LANGER LINES (CLEAVAGE LINE, SKIN TENSION Provides protection against UV Light. LINES) Amount produced determined by Lines of tension in the skin produced by genetics, UV light, hormones the orientation of collagen and elastic fibers in nan-random pattern of FRECKLES - are accumulation of melanin arrangement ALBINISM - absence of melanin Surgical incision should be made parallel to Langer lines to promote better wound MELANOCYTES - specialized cell of healing melanin SKIN COLOR AND VARIATIONS ARE DETERMINED BY:  Pigments  Genetics  Thickness of stratum corneum Melanocytes of darker skinned people produce more and darker melanin than fairer skinned people ALL RACES HAVE THE SAME NUMBER OF MELANOCYTES. FINGERPRINTS (FRICTION RIDGES) Present on the palms and soles (digits). Formed by the pull of elastic fibers within the dermis Function to prevent slippage when grasping objects DEEP FLEXION CREASES Found on the palms SHALLOW FLEXION LINES Seen on knuckles and surface of other joints  With numerous projections called dermal papillae, that extends from the upper Corium portion of the dermis into the epidermis Deeper and thicker than the epidermis Dermal papillae contain capillary loops which furnish nutrients to the epidermis; A strong and stretchy envelope that helps form the base for the friction ridges on to hold the body together the fingers and toes Blood vessels within the dermis nourish Some papillae house pain receptors (free the living portion of the epidermis nerve endings, nociceptor) and touch With numerous collagenous, elastic, and receptors (Meissner's corpuscles) reticular fibers that gives support to the skin Highly vascular and glandular Deepest skin layer Contains many nerve endings and hair Contains blood vessels, sweat, oil glands, follicles and deep pressure receptors (Pacinian corpuscles) Contains abundant touch receptors Many phagocytes are found here; they engulfed bacteria that have managed to get through the epidermis All are exocrine glands; they release secretions to skin surface via ducts SEBACEOUS (OIL) GLANDS Found all over the skin, except on palms and soles; Ducts usually empty into hair follicle but some open directly onto skin surface Secretion is called sebum, a mixture of oily substance and fragmented cells that keeps the skin soft and moist and prevents hair from becoming brittle If the drainage pathway for sebaceous glands become blocked for some reason, the glands may become infected, resulting in acne Sebum also contains chemicals that inhibit and kill some bacteria In contact with the epidermis Become very active when sex hormones are produced in increased amounts during Accounts for about 1/5 of the entire adolescence, thus skin is oilier during this dermis period of life SWEAT GLANDS  Secretion is mostly water with Also called sudoriferous glands few salts Widely distributed in the skin; numerous APOCRINE SWEAT GLAND in palms, soles, axillary and pubic regions  Much larger, localized gland found in axillary and pubic Secretion evaporates and cools the body regions where they secrete into CERUMINOUS GLANDS hair follicles  Not functional until puberty Modified sweat glands in the external ear  Secretion is thick and rich in that produce a waxy, yellowish, organic substances which is protective, lubricating substance called odorless when released but cerumen (earwax) quickly broken down by bacteria into substances responsible for Build-up and block earwax called impacted body odor cerumen MAMMARY GLAND Found within the breasts; specialized Characteristic of all mammals but its sudoriferous glands that secrete milk distribution, function, density, and during lactation; under the stimulus of texture varies across mammalian species pituitary gland Humans are relatively hairless, with only the scalp, face, pubis, and axilla being densely haired Men with more obvious hair because of the male hormone Certain regions of body are hairless, like the palms, soles, lips, nipples, penis, labia minora Lifespan 3-4 months for an eyelash, 3-4 years in scalp hair Primary function of hair is to offer protection against sunlight for example (scalp hair and eyebrows) SHAFT The visible but dead portion of hair projecting above surface of the skin ECCRINE SWEAT GLAND (MEROCRINE)  More numerous and found all ROOT over the body especially in Enclosed in the follicle forehead, back, palms, and soles  Secretion reaches the skin HAIR BULB MATRIX surface via a duct that opens The growth zone; contains melanocytes directly on surface of skin through sweat pores that give color to the hair  Growth of toenails and fingernails of non- dominant hands are slower Nails are transparent and nearly colorless, MEDULLA but they look pink because of the rich blood supply in the underlying dermis Inner part CORTEX Thick middle part NAIL BODY CUTICLE Visible attached portion Covers cortex and forms toughened outer NAIL ROOT portion Part of the nail covered by skin NAIL BED (HYPONYCHIUM) Where nail root and nail body are attached LANUGO FREE EDGE Fine, silky fetal hair that appears during the last trimester of development The distal exposed border attached to undersurface of hyponychium Usually not evident on a baby at birth unless it has been born prematurely EPONYCHIUM (CUTICLE) VELLUS HAIR Covers the nail root; frequently splits causing a hangnail Hairs that cover most of the body NAIL MATRIX TERMINAL HAIR Proximal part of the nail bed; the growth Heavily pigmented hair (Eyebrows, area of the nail eyelashes, scalp hair) LUNULA Sebaceous gland and arrector pili muscle are attached to the hair follicle; when the Whitish crescent-shaped (half-moon) area muscle involuntary contracts due to at the proximal aspects of nail thermal or psychological stimuli, the hair follicle is pulled into an upright position, causing the hair to "stand on its end" and producing goosebumps Found on distal dorsum of each fingers and toes Forms from a hardened, transparent stratum corneum of epidermis Fingernails grow at approximately 1 mm per week