a&p lecture chap 4

• Covering and Lining Epithelium
• - outter layers of skin, lines the cavities of cardiovascular, digestive, respiratiry systems and covers the walls and organs of the closed ventral body cavity

• Glandular Epithelium
• - fashions the glands of the body

• 1) Polarity
• -Apical Surface, basal surface, basal lamina
• 2) Specialized Contacts
• -tight junctions
• 3) Supported by Connective Tissue
• -deep to the basal lamina is the reticular lamina. both are the basement membrane
• 4) Avascular, but Innervated
• -nurished by substances diffusing from blood vessels in connective tissue
• 5) Regeneration
• -high regenerative capacity

Either by number of cell layers or by shape

Simple vs. stratified

Squamous vs. cuboidal vs. columnar

flat, sparse cytoplasm, filtration

Endothelium- provides slick, friction reducing lining in the lymphatic system. Also, in the hollow organs of the cardiovascular system (heart and blood vessels)

Mesothelium- found in the serous membranes lining the ventral cavity and its organs

cube-like

important functions: secretion and absorbtion

ex: kidney tubules

• Simple Columnar- tall,
• -function: secretion and absorbtion
• - dense microvilli on the apical surface of absorbative cells
• -goblet cells secrete mucus

• Pseudostratified Columnar- vary in height, all cells touch basment membrane but only tallest reach apical surface, have cilia
• -they absorb and secrete like simple
• -ex: lining of trachea

• -most widespread epithelium
• -apical surface is squamous, may be cuboidal or columnar deeper
• -top layer constantly rubbed off
• -skin is keratinized to make the surface harder
• -forms the external layer of sin and a short way into all orephaces directly attached to the skin

• -quite rare in the body
• -typically two layers

ex: ducts of sweat glands, mammery glands

• -also rare
• -found in small quantities in the pharymx, make urethra, and lining of some glandular ducts

• -forms the lining of hollow urinary organs, which stretch to fill with urin
• -basal layer is cuboidal and columnar
• -when bladder is filled, the apical layer thins out, allowing for more urine

• Endocrine: internally secreting
• -called ductless glands
• -producde hormones secreted by exocytosis
• -structurally diverse

• Exocrine: externally secreting
• -numerous
• -secrete products onto skin or into body cavities
• -ex: mucus, swear,oil, salviary gland, live, pancreas
• -unicellular:mucous or goblet cells

• 1. Tubular: secretory cells form tubes
• -simple: intestinal glands
• -branches: stomache glands
• -compound:glands of small intestine

• 2. Alveolar: secretory cells form small, flasklike sacs
• -simple: non in humans
• -branched: sebaceous glands
• -compund-mammery glands

• 3. Tubularalveolar-have both
• -salivary glands

• 1. Mesocrine: secrete by exocytosis and sectrory cells are not altered
• -ex: pancreas, salivary glands, most sweat glands

• 2. Holocrine: accumulate product within the secretory gland until they rupture. dead cell fragments are released as well
• -ex: oil glands

• 3. Aprocrine glands: might not exist in humans, possibly the mammery glands
• -glands accumulate product just below free surface, apex pinches cell off; released the product and small amounts of cytoplasm

• -Found everywhere in hte body
• -Most abundant and wifely distributed of all the primary tissues

• 1. Connective Tissue Proper
• 2. Cartilage
• 3. Bone Tissue
• 4. Blood

• Major Functions:
• 1. Binding and Support
• 2. Protection
• 3. Insulation
• 4. Transportation

1. Common Origin: all connective tissue arise from the embyronic mesenchyme

2. Degrees of Vascularity: cartilage is avascular, dense connective tissue is poorly vascularized, wile other have rich blood flow

3. Extracellular Matrix: large portions are matrix, which bears weight, endures abuse, and withstands great tension

• 3 Main Elements:
• -Ground Subtance
• -Fibers
• -Cels

• -unstructured material that fills the space between cells
• -contains the fibers
• -holds large amounts of fluid
• -acts as molecular sieve or medium through which nutrients nad other dissolved substances can diffuse between blood capillaries and cells

Provide Support

• Collagen fibers: white fibers
• -strongest and most abundant
• -constructed of collagen
• -provide high tensile strength

• Elastic Fibers: yellow fibers
• -long, thin and form a network
• -elastin allows them to stretch like rubber bands

• Reticular Fibers:
• -short, fine, collagenous fibers
• -branch extensively to form networks
• -netlike

• Blasts: miotically active and secretory cells
• - fibroblast
• -osteoblast
• -chondroblast
• *hematopoietic stem cells in bone marrow produce blood cells

• Cytes: matures blasts
• -fibrocytes, osteocytes, chondrocytes

• White Blood Cells
• Fats
• Mast cells- detect foreign microorganisms
• Macrophage- eat up foreign and dead materials

All connective tissues arise from mesenchyme

• 1. Areolar Connective Tissue
• 2. Adipose
• 3. Reticular Connective Tissue
• 4. Dense Connective Tissue Proper
• - Dense Regular
• -Dense Irregular
• - Elastic

• Function:
• 1. supporting and binding other tissues
• 2. holds body fluids
• 3. defends against infection
• 4. storing nutrients as fats

• Description
• Gel-like matrix with..
• -all 3 fibers
• -cells
• -fibroblasts
• -mascrophages
• -mast cells
• -some white blood cells (when effected area becomes puffy its called edema)

• Location:
• -widely distributed under the epithelia of the body
• ex: surrounds capillaries, packages organs, forms lamina propria of mucous membranes

• Function:
• -provides reserve food fuel
• -insulates against heat loss
• -supports and protects (cushions) organs

• Description:
• -Very closely packed
• -signet ring look because the nuclei are pushed to the sides due to oil droplet

• Location:
• -genetically dispositioned areas
• -behind eyes
• -around kidneys
• -underskin in hypodermis

• Function:
• -fibers form a soft internal skelton that supports other cell types including white blood cells, mast cells, and macrophages

• Description:
• -network of reticular fibers
• -reticular cells lie on network

• Location:
• lympoid organs
• -lymphg nodes
• -spleens
• -bone marrow

• Function:
• -attaches muscles to bone or bone to muscles
• -withstands great tensile stress when pulling force is applied in one direction

• Description:
• -primarily collagen fibers
• -a few elastic fibers
• -major cell type is the fibroblast
• -run in the same direction

• Location:
• -tendons
• -most ligament
• -aponueroses

• Function:
• -provides structural strength
• -able to withstand tension exerted in many directions

• Description:
• -primarily irregularly arranged colagen fibers
• -some elastic fibers
• -major cell type is the fibroblast

• Location:
• -dermis of the skin
• -fibrous capsules of organs and of joints
• -submucosa of digestive tract

• Function:
• -allows recoil of tissue after its been stretched
• -maintains pulsatile flow of blood trhough arteries
• -aids in passive recoils of lungs following respirtation

• Description
• -contains a high proportion of elastic fibers

• Location:
• -walls of large arteries
• -within walls of bronchial tubes
• -within certain ligament associated with the vertebral column

• -tough but flexible
• -avascular
• -lacks nerve fibers
• -up to 80% water
• -recieves nurtients by diffusion of connected tissue
• -chondroblasts and chondrocytes are primary cells

• Function:
• -supports and reinforces
• -resists compressive stress
• -has resilient cushioning properties

• Description:
• -amorphous but firm cartilage
• -collagen fibers form iomperceptible network
• -chondroblasts produce matrix
• -when chondorblasts mature, chondrocytes are found in lacunae

• Location:
• -nose, trachea, larynx
• -costal cartilage
• -covers the ends of longbones in joint cavities
• -forms most of the embryonic skeleton

• Function:
• -maintains shape while allowing flexibility

• Description:
• -similar to hyaline, but more elastic fibers in matrix

• Location:
• -supports the external ear
• -epiglottis

• Function:
• -tensile strength with the ability to absorb compressive shock

• Description:
• -matrix similar to less firm than hyaline cartilage
• -thick collagen fibers predominate

• Location:
• -intervertebral discs
• -discs of knee joint
• -pubic symphisis

* osteoblasts and osteocytes main cells

• Function:
• -bone supports and protects
• -provides levers for muscles to act on
• -stores calcium and other minerals and fat
• -marrow inside spongy bone in where blood cells are made

• Description:
• -hard, calcified matrix
• -collagen fibers
• -very well vascuarlized
• -osteocytes lie in lacunae

• Location:
• -Bones

*does not "connect" but develops from mesenchyme

• Function:
• -transport respiratory gases, nutrients, waste, and other substances

• Description:
• -red and white blood cells in a fluid (plasma) matrix

• Location:
• -Inside blood vessels

• 1. Neurons: highly specialized nerve cells that generate and conduct nerve impulses
• -respond to stimuli
• -transmit electric impulses over long distances in the body
• -dendrites recieve message
• 2. Axon: distributes potential message
• -Schwann Cells around Axon (cell membrane insulates)

*fatty sheath around neuron

• Function:
• -transmit electrical signals from sensory receptors and to effectors which control their activity

• Description:
• -neurons are braching cells
• -cell processes that may be quite long extend from the nucleus-containing the cell body

• Location:
• -brain, spinal cord, and nerves

• -highly cellular
• -well vascularlized
• -responsible for most types of body movement
• -possesses Myofilaments

• Function:
• -locomotion and voluntary movement
• -manipulation of the enviornment
• -facial expression
• -voluntary control

• Description:
• -long and cylindrical
• -multinucleate cells (muscle fibers)
• -obvious striations

• Location:
• -skeletal muscles attached to the bone
• -occassionally skeletal muscles attached to the skin

• Function:
• -as it contracts, it propels blood into circulation
• -involuntary control

• Description:
• -branching and striated
• -generally uninucleate cells
• -joined at intercalated discs

• Location:
• -walls of the heart

• Function:
• -propels substances and objects (food, baby) along internal passageways
• -involuntary control

• Description:
• -spindle shaped
• -central nuclei
• -cells arranged closely to form sheets

• Location:
• -mostly in walls of hollow organs

• Continuous, multicellular sheets compose of at least 2 types of tissue:
• 1. An epithelium bound to..
• 2. an underlying layer of connective tissue

• -skin
• -exposed to air = dry membrane
• - protectoin
• -keratinized simple squamous epithelium
• -attached to a thick layer of irregular connective tissue (dermis)

• -line the open body cavities
• -"wet" or moist membrance
• -protection and lubrication
• -often adapted for secretion and absorbtion
• -most mucosae contain either: stratified squamous or simple columnar
• -epithelial sheet directly underlain by loose connective tissue (lamina propria)

• -moist membrane
• -found in closed ventral cavities
• -simple squamous on top of a thin layer of loose connective tissue (Areolar)
• -serous fluid lubricates the face visceral and paietal layers so they glide against each other
• -parietal covers cavity, visceral covers organ

non-specific to injurt, while immune response is very specific but takes longer to kick in

• 1. Inflammation sets the stage
• 2. Organization restores blood supply
• 3.Regeneration and Fibroblasts effect permenant repair

-capillaries dialate and become permeable, allowing white blood cells, antibodies, platelet rich plasma, and other substances to site of injury

• -leaked clotting protiens create clot
• -stops bleeding
• -holds wound together
• -protection

-clot exposed to dry air creates a scab

• -Granulation tissue replaces clot
• ->contains capillaries which grow from other areas, restoring the blood supply to the site of the injury

-fibroblasts and granulation tissue produce collagen fibers that fill the gap

-macrophages digest debris and the original clot

-epithelium regenrates

-scab detaches

-fibrosed area matures and contracts

-epithelium thickens

-underlying scar tissue

3 primary germ layers in embryonic development:

• 1. Ectoderm
• 2. Mesoderm
• 3. Endoderm

• Ectoderm --> nervous tissue
• Mesoderm --> muscle and connective tissue
• All 3 --> Epithelium

-at 2 mo after conception, primary tissues have appeared and all major organs are in place

-division of nerve cells stops or nearly stops during fetal period

-In adults, only epithelial and blood tissue are highly miotic

• -In old age...
• - epithlia thins
• -bone, muscle, and nervous tissue begin to astrophy
• -these things often result from a deteriorating diet or decreased circulatory effiency
• -higher risk of DNA mutations and cancer