Anatomy and Physiology Saladin Chapter 5

Primary tissue categories

Connective; Muscle; Epithelium; Nervous

3 embryonic tissues and adult tissues that develop from them

-endoderm

-mucous membranes of the digestive and respiratory tracts and to the digestive glands

-ectoderm

-epidermis and nervous systems

-mesoderm

-mesenchyme

-muscle

-bone

-blood

-other tissues

Properties that distinguish epithelium from other tissue(s)

- more cells than matrix

-protects the body and its organs and tissues

-classified into two broad categories, simple and stratified, with an additional outlier category of Pseudostratified columnar

-simple squamous

single layer of flat cells enables quick movement of substances through diffusion and transport activities

simple columnar

space for unicellular glands and absorbtion of substances, as well as enabling movement of sperm or egg cells

simple cuboidal

cube shape makes space for production of substances as well as secretion or transport of mucous materials

stratified squamous

density protects and inhibits penetration or abrasion, also against water loss

stratified cuboidal

contributes to secretions and secretion production

pseudostratified columnar

secretion is enabled by large cellular space and accompanying cilia aids in movement of the secreted substance

transitional epithelial

multilayer formable cells enable tissue to stretch and move when the organ needs to contain more or less substance

Epithelium: what and where?

-simple squamous

*lungs, blood vessels, heart and kidneys

-simple columnar

* stomach

* uterus and uterine wall

-simple cuboidal

*kidney and ducts of small glands

*bronchioles

* liver

*thyroid

-stratified squamous

* integumentary system

*tongue

* oral mucosa

* esophagus

* anal canal

*vagina

-stratified cuboidal

* gland ducts

-pseudostratified columnar

* trachea

* windpipe

-transitional epithelium

* urinary tract

* allantoic duct in umbilical cord

Structural and resulting functional differences of epithelia

- simple squamous: single layer of flat cells enables quick movement of substances through diffusion and transport activities

-simple cuboidal: cube shape makes space for production of substances as well as secretion or transport of mucous materials

-simple columnar: space for unicellular glands and absorbtion of substances, as well as enabling movement of sperm or egg cells

-stratified squamous: density protects and inhibits penetration or abrasion, also against water loss

-stratified cuboidal: contributes to secretions and secretion production

-pseudostratified columnar: secretion is enabled by large cellular space and accompanying cilia aids in movement of the secreted substance

-transitional epithelial: multilayer formable cells enable tissue to stretch and move when the organ needs to contain more or less substance

Properties connective tissues have in common

- more matrix than cells

-cells not commonly in direct contact with each other

- highly vascular

- most abundant and histologically variable

Matrix of connective tissue and its components

extracellular fluid in connective tissue, often appears as empty space on slides, and contains:

ground substance, fibers, cells

Types of connective tissue

-areolar tissue

-reticular tissue

-dense regular connective tissue

-dense irregular connective tissue

-adipose tissue

-hyaline cartilage

-elastic cartilage

-fibrocartilage

-bone

-blood

Areolar tissue components

-ground substance

-elastic fibers

-collagenous fibers

-fibroblasts

Reticular tissue components

-leukocytes

- reticular fibers

-fibroblasts

Dense regular connective tissue

-collagen fibers

-fibroblasts

-scarcity of blood vessels

Dense irregular connective tissue

-collagen

-scanty ground substance

-few visible cells

-scanty blood vessels

Adipose tissue

-adipocytes (fat cells)

-blood cells

-plasma

Hyaline cartilage

-clear matrix

-collagen fibers

-chondrocytes

-perichondrium

-lacunae

Elastic cartilage

-elastic fibers

-lacunae

-perichondrium

-chondrocytes

Fibrocartilage

-collagen fibers

-chondrocytes

Bone

-lacunae

-canaliculi

-calcified matrix arraged in concentric lamellae of osteon

-osteon

Blood

-platelets

-neutrophils

-lymphocytes

-leukocytes

-erythocytes

-monocytes

-plasma ground substance not visible on slides

Distinguish excitable tissue from other tissue

excitability exists in every tissue but is developed to its highest point in muscular and nervous tissues. Electrical charge difference called the membrane potential occurs across the plasma membranes of all cells. Nervous and muscular tissue respond quickly to outside stimuli by means of changes in membrane potential.

Cell types that contain nervous tissue

-neurons

-neuroglia

-glial cells

Major parts of the nerve cell

-neurosoma (cell body)

-axon (sends signals)

-dendrites (receives signals)

Skeletal muscle

-striated

-voluntary

-most attach to bone

-multiple nuclei in cells

Cardiac muscle

-striated

-involuntary

-one nucleus (centrally located in cell)

-intercalated disks join cardiocytes end to end

-contains myocytes, or cardiocytes

Smooth muscle

-not striated

-involuntary

-short, fusiform cells

-one centrally located nucleus

Cell junctions

-tight junction

-gap junction

-desmosomes

Tight junction

-adjacent cells are bound together by fusion of outer phospholipid layer of plasma membranes

-nearly impossible for substances to pass between cells

-ensures digested nutrients pass through cells, not between them

Gap junction

-formed by ringlike connexon (6 membrane protiens arranged like the segments of an orange surrounding water filled pore)

-small solutes can pass directly from the cytoplasm of one cell to another

-found in intercalated discs of cardiac muscle, and between cells of most smooth muscle

Desmosomes

-patch like, holds cells together like a snap

-not continuous

-common in epidermis, epithelium of uterine cervix, other epithelia and cardiac muscle

-resists mechanical stress

Types of glands

-endocrine

-exocrine

-unicellular

Endocrine glands

-secrete directly into bloodstream

-secretions are called hormones

-has no contact with the surface of the body (such as epidermis/dermis)

Exocrine glands

-secretes into ducts

-secretions usually released to the skin surface

-often released into the cavity of another organ

Unicellular glands

-secretory cells found in epithelium that is predominantly nonsecretory

-can be endocrine or exocrine

Typical anatomy of a gland

round base of secretory cells channeling up to a neck of cells called the duct and then further to the surface or ending area. (Exocrine gland)

Modes of glandular secretion

Merocrine/Eccrine glands- contain vesicles that release their secretion by exocytosis

Holocrine glands- cells accumulate a product then the entire cell disintegrates so the secretion mixed with cell fragments is "secreted"

Apocrine glands- primarily merocrine in mode of secretion but different in that they are functionally and histologically different

Cutaneous membrane

- largest membrane in the body; stratified squamous epithelium; relatively dry; resists dehydration of the body; inhibits growth of infectious organisms

Types of membranes

Cutaneous membrane

- largest membrane in the body; stratified squamous epithelium; relatively dry; resists dehydration of the body; inhibits growth of infectious organisms

Mucous membrane

-consists of 2-3 of the following layers:

-epithelium

-lamina propria

-muscularis mucosae (sometimes this one)

-lines passageways that open to the exterior environment

-have absorptive, secretory and protective functions

-often covered with mucus secreted by goblet cells, multicellular mucous glands or both

-mucus traps bacteria and foreign particles, keeping them from invading tissue and aids in removal from the body.

-epithelium layer of membrane may also include, absorptive, ciliated and other types of cells

Serous membrane

-composed of a simple squamous epithelium resting on a thin layer of areolar connective tissue

-produces watery serous fluid which arises from the blood

-lines the insides of some body cavities

-forms smooth outer surface on some of the viscera, i.e. digestive tract

-includes, pericardium, peritoneum, and pleura

Synovial membrane

-lines some joints

-made only of connective tissue

-span the gap from one bone to the next

-secretes slippery synovial fluid into the joint

Modes of tissue growth

Hyperplasia

-common in embryonic and childhood tissues

-cell multiplication

Hypertrophy

-how exercised muscles grow

-enlargement of preexisting cells

Neoplasia

-development of a tumor (whether benign or malignant)

-composed of abnormal, nonfunctional tissue

Stem cells

Adult

-occur in small numbers in mature organes and tissues

-divide mitotically (one daughter cell remains a stem cell and the other develops into specialized cell)

-some are multipotent (able to develop into two or more different cell lines but not just any type of body cell)

-can be unipotent (only produces one type of mature specialized cell)

-generally limited developmental plasticity

Embryonic

-compose early human embryo

-in early stages of development these are totipotent stem cells (potential to develop into any kind of tissue)

-cells of the inner cell mass (developing fetus) are pluripotent stem cells

-great developmental plasticity

Ways tissues change

Differentiation- when tissue develops a more specialized form and function

Metaplasia- change from one type of mature tissue to another

Modes and causes of tissue shrinkage and death

Atrophy

-shrinkage of tissue through a loss in cell size or number

-results from both normal and aging

-results from lack of use of an organ

-muscles display atrophy (shrinkage) from not being used and cells become smaller

Necrosis

-premature, pathological death of tissue due to trauma, infection, toxins, etc.

Infarction

-sudden death of tissue (i.e. cardiac muscle or brain tissue)

-occurs when blood supply is cut off

Gangrene

- tissue necrosis resulting from an insufficient blood supply

-usually involves infection

-often occurs in diabetics

-often necessitates amputation of limbs and extremities

Apoptosis

-programmed cell death

-normal death of cells that have completed their function and best serve the body by dying and getting out of the way

-cells undergoing apoptosis shrink and are quickly phagocytized by macrophages and other cells

Ways body repairs tissue damage

Regeneration

-replacement of dead or damaged cells by the same type of cells as before

-restores normal function to the organ

-heals most skin injuries

-liver also regenerates remarkably well

Fibrosis

-replacement of damaged tissue with scar tissue

-composed mainly of collagen produced by fibroblasts

-scar tissue holds an organ together but does not restore normal function

-heals severe cuts, burns, muscle injuries, and scarring of the lungs following tuberculosis