2Cells Tissues Organs Organ systems Organism Cells are not found by themselves; they’re with others. These are called tissues.TISSUE: A group of cells, usually similar, which share a particular function.ORGAN A group of tissues which share a particular function.ORGAN SYSTEM: A group of organs which share a particular function (digestive system, nervous system).
3Cell DifferentiationThrough the process of cell differentiation, each cell develops a characteristic set of structural features.Each cell has to contribute one piece toward the overall function of the organism, so that all the vital functions can be covered.During differentiation, cells in nearby locations become able to work together.After differentiation, cells do not change their function throughout their life cycle
4TYPES OF TISSUES WE’LL DISCUSS: EPITHELIUM: a sheet of cells that makes up the surface of the skin and also lines tubes in the body.CONNECTIVE TISSUE: deep to the epithelium; supplies oxygen and nutrients to epithelium.Fibrous (Proper) Connective TissueSpecial Connective Tissue (cartilage, bone, blood, muscles, nerves)MUSCLE TISSUE: makes up muscles, and these cells are able to contract, unlike fibrous connective tissue. It is bound together by areolar connective tissue. (discussed in later lectures)NERVOUS TISSUE: makes up brain and nerves (discussed in later lectures)
5EPITHELIA: (plural form of epithelium): a sheet of cells that makes up the surface of the skin and also lines tubes in the body.Function of epithelia:The epithelial cells are the type of tissue that protects the underlying structuresWhat is the difference between epithelium and epidermis?Epidermis is the outermost layer of skin. It consists of epithelial cells, but epithelium is also found in areas lining the tubes of the body (digestive, respiratory, urinary systems, etc)
6EpitheliumEpithelium is the tissue that covers the outside of the body (the top layer of the skin), and it also lines the tubes within the body.Digestive tractRespiratory tractCardiovascular systemUrinary tractReproductive tractSweat glands and other exocrine glands
7MicrovilliThe presence of large numbers of microvilli on the exposed surfaces of epithelial cells indicates that this is the area where absorption and secretion take place.These cells are transportation specialists.They are probably located along portions of the digestive and urinary tracts
8Kidney Sweat glands Trachea The hollow space within each of these tubes is called a lumen.The lumens are always lined by epithelial cells.KidneySweat glandsTrachea
9Basement MembraneAll epithelia sit on top of connective tissue, and is connected to it by a BASEMENT MEMBRANE (which is not a cell membrane), made of protein fibers that connect to epithelium.The only function of the basement membrane is to attach the epithelium to the connective tissue beneath it.Epithelia get oxygen and nutrients from the blood vessels in the connective tissue beneath the basement membrane.
13SIMPLE EPITHELIUM SIMPLE EPITHELIUM has only one cell layer. SIMPLE SQUAMOUS EPITHELIUM:SIMPLE CUBOIDAL EPITHELIUMSIMPLE COLUMNAR EPITHELIUMPSEUDOSTRATIFIED EPITHELIUM
14SIMPLE SQUAMOUS (thin) EPITHELIUM SIMPLE SQUAMOUS (thin) EPITHELIUM are flat cells that allow diffusion of materials between the cells.This type of epithelium is in regions where a lot of diffusion is needed from one compartment to another, such as the lungs and a region in the kidney called the glomerulus.
15Simple Squamous Epithelium Found in the lungsFigure 4.3a
16Simple Squamous Epithelium Found in the lungsFound in the kidneys (glomerulus)
17SIMPLE CUBOIDAL EPITHELIUM SIMPLE CUBOIDAL EPITHELIUM is cube shaped and is also found in areas where there is a lot of material going across from one compartment to another.This cell type has plenty of room for organelles.This epithelium is found in the intestines, and a region of the KIDNEY called the convoluted tubules, and places that need diffusion as well as room for cell organelles.
18Simple Cuboidal Epithelium Found in the kidneys (convoluted tubules)Figure 4.3b
19Tubules are simple cuboidal Glomerulus is simple squamous KIDNEYTubules are simple cuboidalGlomerulus is simple squamous
20SIMPLE COLUMNAR EPITHELIUM SIMPLE COLUMNAR EPITHELIUM is shaped like a column and are found in areas where the cells are needed for secretion and absorption (intestines).When they are differentiated into GOBLET CELLS, they produce mucus.
22PSEUDO-STRATIFIED COLUMNAR EPITHELIUM PSEUDO-STRATIFIED COLUMNAR EPITHELIUM is a single layer of cells that appears to be more than one layer thick, but it is not. The nucleus on one cell is at the top, and the nucleus of the next cell is at the bottom.Pseudostratified epithelium always has cilia on its apical surface. Each cilium is a hair-like structure that moves back and forth to move material in a certain direction.This type of epithelium needs goblet cells nearby to produce the mucus that contains the material to be swept. These cells will be found in the respiratory tract (the trachea), where the mucous catches the debris you inhale and the cilia sweeps the material up to your throat where you cough and swallow it.Its only functions are protection and mucous production.
23Pseudostratified Columnar Epithelium Found in the tracheaFigure 4.3d
25STRATIFIED EPITHELIUM STRATIFIED EPITHELIUM has more than one cell layer. The type of epithelium is named by the APICAL layer.STRATIFIED SQUAMOUS EPITHELIUM:1) Keratinized stratified squamous epithelium2) Non-keratinized stratified squamous epithelium STRATIFIED CUBOIDAL EPITHELIUMSTRATIFIED COLUMNAR EPITHELIUMTRANSITIONAL EPITHELIUM
26STRATIFIED SQUAMOUS EPITHELIUM STRATIFIED SQUAMOUS EPITHELIUM: the type is named by the apical cells. Stratified squamous epithelium is found in regions of the body where there is a lot of abrasions or wear-and tear, and it is the most protective (it is the thickest).1) KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM has apical cells that contain a protein called keratin, which is waterproof. All of our dry skin is this type, and it is especially thick in the palms and soles. It is very good at resisting abrasions.2) NON-KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM does not have the keratin, so it will be moist skin, like what is found lining the mouth and esophagus.
27Stratified Squamous Epithelium (keratinized) Found in dry skin
28Stratified Squamous Epithelium (non-keratinized) Found in moist skin (mouth and esophagus)Figure 4.3e
29STRATIFIED CUBOIDAL EPITHELIUM STRATIFIED CUBOIDAL EPITHELIUM usually consists of only two layers, and there is almost no diffusion between them.It is found in sweat glands.
30Stratified Cuboidal Epithelium Found in sweat glandsFigure 4.3f
31Stratified Cuboidal Epithelium Found in Sweat Glands
32STRATIFIED COLUMNAR EPITHELIUM STRATIFIED COLUMNAR EPITHELIUM usually has just a few layers and this type of epithelium inhibits diffusion of materials.It is relatively rare, providing protection along portions of the pharynx, urethra, and anus.
34TRANSITIONAL EPITHELIUM TRANSITIONAL EPITHELIUM can stretch and change shape.This type is what lines the urinary bladder and it looks like this as it goes from empty to full.
35Transitional Epithelium Found in the urinary bladderFigure 4.3h
36Connective Tissues Types of Connective Tissues FIBROUS (PROPER) Connective tissuesSPECIAL CONNECTIVE TISSUEFunctions of Connective TissuesDefend the body from invasion by microorganismsProvide protection for delicate organsEstablish a structural framework for the body
37FIBROUS (PROPER) Connective tissues ADIPOSE (fat)RETICULAR (lymph nodes)LOOSE (aka AREOLAR; upper dermis)DENSEREGULAR (tendons and ligaments)IRREGULAR (lower dermis and joint capsules)
38Adipose ADIPOSE Main cell type is an adipocyte (stores fat) Functions: Cushions organsFood StorageInsulation
40LipomaThese are benign fat nodules in the hypodermis, usually associated with high cholesterol levels. They are easily surgically excised (removed)
41LiposarcomaPatients usually note a deep seated mass in their soft tissue. Only when the tumor is very large do symptoms of pain or functional disturbances occur.Most frequent in middle-aged and older adults (age 40 and above), liposarcomas are the second most common of all soft-tissue sarcomas . Annually 2.5 cases occur per million population.The prognosis varies depending on the site of origin, the type of cancer cell, the tumor size, the depth, and proximity to lymph nodes. Well-differentiated liposarcomas treated with surgery and radiation have a low recurrence rate (about 10%) and rarely metastasize.
43Are you more drunk than you think?, http://fxn.ws/TqUdz9 Women have a higher fat-to-water ratio than men do.A 150-pound man holds more water than a 150-pound woman; after one drink, the woman will have a higher concentration of booze in her blood. That leads to greater intoxication. And her liver has to work harder to metabolize that alcohol, prolonging her buzz. For every drink a woman has, it’s the equivalent of a drink and a half for a same-sized man.
44Reticular Connective Tissue Found in lymph nodeFigure 4.12d
46Loose Connective Tissue LOOSE (AREOLAR) connective tissueThis is the least specialized connective tissue.The main cell type in loose and dense connective tissue is a FIBROBLAST (a type of cell, not just a part of a cell). Fibroblasts are what make collagen and elastic fibers, and they also and repair wounds.Areolar is common in areas just deep to epidermis (upper dermis).It does NOT have much collagen as dense because it does not have many fibroblasts.
47Areolar Connective Tissue Found in dermisFigure 4.12b
48Dense Regular Connective Tissue Dense regular and irregular connective tissue has lots of COLLAGEN FIBERSDense regular has more collagen than irregular.Dense regular fibers have a pattern, and run in same directionEven more strong than irregular, but only in one directionLigaments and tendons are dense regular CT.Note: tendons are not muscle tissue; they are dense regular connective tissue.
50NOTE: If you get injured, you’d rather break a bone than tear a ligament, why? The number of fibroblasts is the same, but the ligament has a lot more collagen to be made by each fibroblast.And the blood supply to bone is much better than a ligament.
51Dense Irregular DENSE IRREGULAR connective tissue Has lots of COLLAGEN FIBERSFibers have irregular position; no patternExtremely strong in all directionsFound in areas of body where strength is needed (joint capsules and deeper layer of the dermis).
52Dense Irregular Connective Tissue Found in joint capsules and dermisFigure 4.12e
53SclerodermaScleroderma is a chronic systemic autoimmune disease (primarily of the skin) characterized by fibrosis (or hardening), vascular alterations, and autoantibodies. There are two major forms:Limited systemic sclerosis/scleroderma involves cutaneous manifestations that mainly affect the hands, arms, and face. It was previously called CREST syndrome in reference to the following complications: Calcinosis, Raynaud's phenomenon, Esophageal dysfunction, Sclerodactyly, and Telangiectasias. Additionally, pulmonary arterial hypertension may occur in up to one-third of patients and is the most serious complication for this form of scleroderma.Diffuse systemic sclerosis/scleroderma is rapidly progressing and affects a large area of the skin and one or more internal organs, frequently the kidneys, esophagus, heart, and lungs. This form of scleroderma can be quite disabling. There are no treatments for scleroderma itself, but individual organ system complications are treated.
55GranulomaA granuloma is an inflammation found in many diseases. It is a collection of immune cells known as macrophages.Granulomas form when the immune system attempts to wall off substances that it perceives as foreign but is unable to eliminate.Such substances include infectious organisms such as bacteria and fungi as well as other materials such as keratin and suture fragments.
57Special Connective Tissue CartilagesHyaline cartilage (most joints)Elastic cartilage (ear)Fibrocartilage (intervertebral discs)Bone tissuesCompact bone (shaft of long bones)Spongy bone (ends of long bones)BloodMuscles (discussed more in later lectures)Nerves (discussed more in later lectures)
58Cartilage There are three types of cartilage: Cartilages Main cell type is CHONDROCYTEExtracellular matrix is dense collagen; almost solid, very rigidAvascular (no blood vessels. Torn cartilage won’t heal).There are three types of cartilage:HYALINE CARTILAGEELASTIC CARTILAGEFIBROCARTILAGE
59Hyaline CartilageFound in most jointsFigure 4.12g
68Bone Bone tissues Main cell type is OSTEOCYTE = “bone cell” Extracellular matrix is solid, full of minerals (instead of fluid)Minerals are: Calcium carbonate and Calcium phosphate (same as limestone)
69Bone Tissue: Compact Bone Found in shaft of long bonesFigure 4.12j
74Synovial MembranesThis membrane lines the inside of fluid-filled joints.The cellular layers are incomplete, with gaps between adjacent cells to allow the fluid to escape into the joint to serve as a cushion.
75Mucous MembranesMucous membranes are covered in epithelium, which are involved in absorption and secretion.They line cavities that are exposed to the external environment and internal organs.They are located at the nostrils, the mouth, the lips, the eyelids, the ears, the genital area, and the anus.
76Serous Membranes Serous membranes secrete a watery fluid. The fluid reduces friction from muscles or organs rubbing against each other. Its major function is to produce tiny amounts of watery liquid on their opposing surfaces to reduce friction.The serous membrane covering the heart is the pericardium. Inflammation here is called pericarditis.The serous membrane surrounding the lungs is the pleura. Inflammation here is called pleuritis.The serous membrane lining the abdominal cavity is the peritoneum. Inflammation here is called peritonitis.
77Another way to classify epithelium 1. MOIST EPITHELIUM: there are two types:a. MUCOSA is the cell type that produces mucous. Therefore, pseudo-stratified columnar epithelium is a mucous epithelium, or a mucosa.b. SEROSA is an epithelium that has watery secretions on the surface. This is found in sweat glands.2. DRY EPITHELIUM is keratinized stratified squamous epithelium.
78CollagenCOLLAGENThis is a type of fiber that is found in all connective tissues (other than blood).It gives connective tissues an elastic consistency.It has very little blood supply, so it does not regenerate well.It does not interfere with diffusion of materials from one area to another; it just provides support for connective tissues.
80Types of Glands Exocrine Gland Endocrine Gland Secretes substances into a duct (a tunnel) and then excretes it into the lumen or onto the skin (e.g. sweat, oil)Endocrine GlandSecretes substances into the blood to be transported to another part of the body, where it is used (e.g. hormones). Endocrine glands are ductless. We will discuss endocrine glands in a separate lecture.
81Exocrine Glands Classification of Exocrine Glands Type of secretion Method of secretionStructure
82Exocrine Glands EXOCRINE GLANDS 1. Classified based on the type of secretiona. SEROUS GLANDS secrete water, as found in sweat glands.b. MUCOUS GLANDS secrete mucous, as found in goblet cellsc. MIXED GLANDS secrete mucous and water as found in salivary glands.d. OIL GLANDS secrete waxy and oily substances, as found in sebaceous glands and ear wax.
83Glands 2. Classified by the method of secretion Merocrine (Eccrine) glandsApocrine glandsHolocrine glands
84Merocrine Gland Exocytosis 2. Classified by the method of secretion a. MEROCRINE (Eccrine) GLANDS produce a secretion by a process called EXOCYTOSIS. Example is sweat glandCell of merocrine glandVesicle with green secretion insideThe vesicle moves to and binds with the cell membrane, pops open and releases the secretion
85Merocrine Gland Functions ThermoregulationInhibiting the growth of bacteria on the skinExcretion of water, electrolytes, and some drugsThey do not function as a lubricant for the skin.
86Apocrine Glandsb. APOCRINE GLANDS accumulate material in the apical section, the top of the cell breaks off, and the material is released. The cells that broke down will grow again. Examples are the mammary glands and oil glands associated with pubic hairs. Apocrine glands are also considered to be a type of sweat gland, but only in the axilla and pubic regions.
87Holocrine Glandsc. HOLOCRINE GLANDS are those where the entire cell breaks off with all the contents inside, such as sebaceous (oil) glands. After the cell breaks off, the other cells move in quickly and close up the gap.
88Exocrine Glands3. Classified by their structure (what they look like)a. UNICELLULAR GLANDS, for example a GOBLET CELL.Goblet cells are found in the trachea and secrete mucous to trap debris; then you cough it up.