HHP3115 Unit 1 Notes Chapter 4 PDF

lOMoARcPSD|43571669 10 Chapter 4 – Tissues Tissue: group of closely associated cells that… - Perform related functions - Are similar in structure Epithelial tissue: covers and linings, glands Connective tissue: support Muscle tissue: movement Nervous tissue: control Epithelial tissues...

lOMoARcPSD|43571669 10 Chapter 4 – Tissues Tissue: group of closely associated cells that… - Perform related functions - Are similar in structure Epithelial tissue: covers and linings, glands Connective tissue: support Muscle tissue: movement Nervous tissue: control Epithelial tissues - Cover a body surface or line a body cavity - Forms most glands Functions of epithelial tissue: - Protection - Movement across it (absorption, secretion, ion transport, filtration) - Forms slippery surfaces (mucus-covered surfaces allow for the movement of things without friction being created) Characteristics of epithelia: - Densely packed cells - Contain specialized contacts (cell-cell junctions) - Polar - Supported by connective tissue - Avascular, yet innervated - Regenerate at extremely high rates (because they’re dying at high rates as well) o Skin cells die in a month because they lose connection with connective tissues’ blood supply, gut cells die in a week because of harsh environment o Regeneration at such high rates is possible because the connective tissue below it is SO supportive Epithelial surface features: - Microvilli: projections that maximize surface area for increased movement across it - Cilia: projections that aid in movement of mucus and other substances o Move via whip-like movements (“power stroke”), and recover like a balloon man o Moves contaminated mucus to either the gut (which can better handle it) or to be coughed/sneezed out o Smokers (and maybe even alcoholics) have deadened cilia - Cell junctions: connect adjacent cells - Basal lamina: bottom layer of the epithelium, which anchors it to the connective tissue First name of tissue indicates number of cell layers - Simple = 1 layer - Stratified = multiple layers - Pseudostratified = one layer, but appears as multiple Last name of tissue indicates shape of cells Downloaded by Connor Ward ([email protected])  lOMoARcPSD|43571669 11 - Squamous: plate-like (wider than tall) - Cuboidal: cube-shaped (as wide as tall) - Columnar: column-like (taller than wide) What is our skin? - Stratified, cuboidal on the bottom layers and squamous on the outer layers o This is actually named stratified squamous epithelial, because the rule is that you name it based off apical surface - This is because, as they get further away from a blood supply and die, the organelles will deteriorate Benefits of each type of epithelial tissue: - Simple: ease of movement o Simple squamous: respiratory tract, glomerulus, and other places that rely on diffusion/filtration (which requires no energy or organelles/structures)  Literally 1/15 the depth of tissue paper o Simple cuboidal: thick enough cells to house the organelles/structures that facilitate absorption/secretion (which requires energy and machinery)  Found in kidney tubules, ducts, etc. o Simple columnar: thick enough to house the organelles/structures that facilitate absorptions/secretion  Found in most of digestive system, etc. - Pseudostratified columnar: secretion, particularly of mucus o Can be ciliated! o Nuclei aren’t all lined up and cells are oblong in different orientations - Stratified: better protection o Callouses are just where layers of stratified skin get thicker (more layers o Stratified squamous: protect underlying tissues in areas subject to abrasion  Example: epidermis o Stratified cuboidal: protection o Stratified columnar: protection and secretion - Transitional epithelium: allows for stretch Downloaded by Connor Ward ([email protected])  lOMoARcPSD|43571669 12 o Think: bladder o Shape of cells can change depending on degree of stretch Glandular tissue: made of mostly epithelial tissue; secretes things… - Endocrine glands: into bloodstream o Hormones - Exocrine glands: into ducts (tubes) to be taken somewhere o Saliva, GI, mucous, sweat, oil Cell junction types found in epithelial tissues: - Desmosomes: anchor cells together o Found in places where you might have mechanical stress (like skin, heart) - Tight junctions: act as a barrier to prevent certain molecules to pass from one side of tissue to another o Found in blood-brain barrier, blood-testes barrier, etc. - Gap junctions: passageways from one cell to the next, allowing for “sharing” o Found in heart, for sharing of ions (allowing for electrical impulse to occur at once across entire chamber) Desmosome: Tight junction: Gap junction: Connective tissue: - Most diverse and abundant tissue o Connective tissue proper o Cartilage o Bone tissue o Blood - Cells are separated by a large amount of extracellular matrix Formation of connective tissue from the embryo: - Mesoderm -> mesenchyme -> cellular descendants (bold) -> class (underlined) -> subclasses (square bullets) o Fibroblast -> fibrocyte -> connective tissue proper  Loose connective tissue (areolar, adipose, or reticular)  Dense connective tissue (regular, irregular, elastic) o Chondroblast -> chondrocyte -> cartilage  Hyaline cartilage  Fibrocartilage  Elastic cartilage o Osteoblast -> osteocyte -> osseous (bone) Downloaded by Connor Ward ([email protected])  lOMoARcPSD|43571669 13  Compact bone  Spongy (cancellous) bone o Hematopoietic stem cell -> blood cells Areolar connective tissue – using this as a model, because it has most of the potential components of connective tissue: - Fibroblasts produce fibers in the ECM (these are NOT cells!) o Collagen fibers: resist tension (pulling apart) forces; even better at it than steel o Reticular fibers: have some give to them, allowing for stretch (think: blood vessels) o Elastic fibers: can stretch, followed by recoil o Proportions of these fibers kind of dictates how the tissue behaves - Defense cells: includes things like WBCs o Scattered throughout the tissue - Everything else between the cells and fibers is called either ground cells or matrix - o Note that the random fat cells don’t make this adipose tissue; areolar connective tissue contains lots of random cells Cartilage: provide structure and shape - We only find chondrocytes here! - 80% water - NO blood vessels or nerves (which is why it doesn’t heal very well) Bone: support, protection, nutrient storage (calcium/phosphate) - Cells are osteoblasts and osteoclasts - Does contain blood vessels, but no nerves Blood: transport of O2, CO2, waste, heat, etc. Exception: cartilage Downloaded by Connor Ward ([email protected])  lOMoARcPSD|43571669 14 Epithelial tissue requires a connective basement membrane underneath. Connective tissue IS the basement membrane. Muscle tissue: - Function: movement - Structure: elongated muscle fibers 3 subclasses: - Skeletal: controlled voluntarily - Cardiac: heart - Smooth: found in our hollow organs, involuntary Nervous tissue: - Function: regulation/control of body functions - Structure: neurons, and supporting (non-conducting) cells Downloaded by Connor Ward ([email protected])