TISSUES, MEMBRANES AND INTEGUMENTARY SYSTEM

Lecture Notes

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I. Tissue junctions a. Tight junctions, for fluid tight seals in tissues that form hollow fluid-holding organs (e.g., urinary bladder) - cells sealed together with fused membrane linker proteins.

b. Anchoring junction, for "looser" junctions between cells to form tissues that stretch or allow fluids to pass (e.g., GI tract) -held together with adherens, desmosomes and hemidesmosome linker membrane proteins.

c. Communication junctions (also known as gap junctions), for allowing permanent ion transport between cells to allows rapid spread of nervous impulses (e.g., heart, smooth muscle layers in hollow organs)-held together with ion channel membrane proteins.

List the structure and function of the different junctions. Identify location..

II. Epithelial Tissues
structurally categorized by shape of cells and number of layer of cells.
cells glued together with a basement membrane secreted by cells of tissue.

A. Simple -one cell thick layer1. Squamous (scale or flat) cells-
makes up capillary blood vessel walls, alveoli of lungs, glomeruli of kidney
allows filtration and diffusion

2. Cuboidal (cube) -
lines inside of ducts and tubes (sweat and oil glands, digestive enzyme glands, endocrine glands)
for secretion and absorption

3. Columnar (columnar)-
lines inside of digestive and respiratory tubes
some cells in this category are specialized with: microvilli (cell membrane extensions for absorption ), goblet cells (mucus production) and cilia (movement of fluids outside of the cell)
for secretion/absorption, production of mucus, movement of ova and mucus

B. Stratified (two or more cells thick in layer)

1. Squamous (layers of flat)
keratinized (scaly protein filled-cells ) in skin, nonkeratinized in mouth/ vagina
protection against abrasion and damage

2. Transitional (top flat, bottom cube/column)
found ureters and urinary bladder
allows expansion of hollow organs

Compare and contrast epithelial tissue type, structure, location and function. Use drawings.

III. Glandular Epithelia and membranes

A. Glandular epithelium - cells that form glands to secrete products

1. Exocrine glands
open to outside of body or into digestive canal via ducts
produce sweat, oil, wax or digestive enzymes

2. Endocrine glands
secrete directly into blood supply
produce hormones (protein and lipid based messenger chemicals)
B. Epithelial membranes (epithelium layer sealed to a connective tissue layer) 1. Serous membrane secrete lubricating serous fluid around moving organs (lungs heart, digestive and urinary organs)

2. Mucus membrane secretes mucus to cover respiratory, digestive, urinary and reproductive inner surfaces as disease resistance layer

3. Skin or cutaneous membrane secretes acids, oils, sweat, wax to thermoregulate and protect against disease

4. Synovial membrane secrete lubricating fluid for moving joints
Compare and contrast membrane type, structure, location and function.

IV. Connective tissues
structurally categorized by type of matrix secreted by cells forming tissues. Typically have blood vessels passing within tissue layer.

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A.. Connective tissue proper
matrix is protein fibers -elastin protein (thin and elastic) and collagen protein (thick and strong)- secreted by fibroblast cells

1. Loose (areolar) connective tissue
found between many tissues. e.g., dermis to epidermis and dermis to lower muscle layer
-connects different tissues together

2. Adipose connective tissue -
found around most visceral organs, in bone, under skin fat cells
-used for storing energy in form of triglyceride oils

3. Collagenous (dense) connective tissue

a. regular dense (collagenous) tissue
found in tendons (bone to muscle) and ligaments (bone to bone
- resistant to tearing because abundant collagen fibers orient one way

b. irregular dense (collagenous) tissue-
found in dermis
-resistance to penetration/damage because abundant collagen fibers orient in all dimensions

4. Elastic connective tissue -
found in artery and arteriole blood vessel walls, bronchiole walls and around lung air sacs, and vocal cords.
-for stretch and recover as elastic fibers dominate

Compare and contrast epithelial tissue type, structure, location and function.

B. Cartilage -
matrix is semi-solid gel, initially secreted by chondroblasts, some tissues have protein fibers, always avascular
chondrocytes (mature chondroblasts) maintain cartilage matrix and found in open spaces (lacunae) of matrix 1. Hyaline cartilage -no obvious fibers in matrix, commonest type, remnant of fetal skeleton
articulating ends of long bones, growth zones of immature long bones, bronchii, larynx, nose, ribs
-form articulation sites and growth zones of bones, structual element of respiratory system

2. Elastic cartilage - elastic fibers in matrix, very flexible
pinna of ear and epiglottis
-uncommon structural element

3. Fibrocartilage - collagen fibers in matrix, very tough
pubic symphysis and intervertebral discs
-joint fomation structure resisting greater pressure
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D. Blood -
matrix is viscous fluid with red, white blood cells and platelets secreted by hematocytoblasts
Blood cells promote gas transport (red blood cells), vessel tear sealing (platelets) and disease resistance (white blood cells)
-mostly water responsible for transport of water, gases and most dissolved substances to/from body cells.

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E. Bone -
matrix is highly vascularized solid, secreted by osteoblasts
osteoocytes (mature osteoblasts) maintain bony matrix and found in open spaces (lacunae) of matrix
Two types (spongy and compact)
-functions as support of body structures , protection of inner organs, calcium/phosphate storage,
blood cell formation, fat storage, movement of body.
Compare and contrast connective tissue type, structure, location and function.
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V. Muscular tissue
structurally categorized by presence of striations, size, shape and number of nuclei , vascular
- excitable (can carry an electrochemical signal "impulse" and be stimulated electrochemically) to contraction.

A. Skeletal
striated, multinucleate, linear, long
individually stimulated cells undergo strong, sometimes frequent contractions voluntarily controlled from cerebrum (somatic nervous system)
-moves skeleton

B. Cardiac
striated, branched and overlapping, uninucleate with communicating junctions
collectively stimulated cells undergo strong, rhythmic contractions involuntarily controlled from medulla oblongata (autonomic nervous system)
-moves blood though heart

C. Smooth
not-striated, spindle shaped, short, small with communicating junctions
collectively stimulated cells undergo weak, rhythmic contractions involuntarily controlled from lower brain (autonomic nervous system)
-regulates flow of material through hollow organs (bladder, intestines, blood vessels, bronchiole, reproductive tubes)

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Compare and contrast muscular tissue type, structure, location and function.

VI. Nervous tissue
structurally categorized by number and type of membrane extensions off cell body. However, primarily distinguished by function.


A. Neurons
variety of cells with different number of membrane extensions (axons and dendrites),
-excitable to conduct electrochemical messages along cell membrane

B. Neuroglia -
variety of cells without membrane extensions ,
-not excitable. surround and protect neurons , produce CSF, promotes increased conduction rate by neuron

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Compare and contrast nerous tissue type, structure, location and function.

Identify the two tissue types that can carry a signal (excitable tissues)

VII Functions of Integumentary System
A. Temperature regulation -sweat evaporation, hair and hypodemis fat insulation
B. Protection from injury (abrasion and injury by epidermis and dermis)
C. Disease resistance (protection from infection by epidermal conveyor belt, prevention of disease by antibiotics in oil and sweat.)
D. Reception of stimuli (sensory receptors of touch, pain, pressure and temperature)
E. Water balance-loss of water as sweat, retention by oil and epidermis
F. Produces vitamin D ( the hormone Calcitriol), which stimulates intestinal cells to increase Ca++ absorption from food in intestines thereby increasing blood Ca++ levels.

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Describe the functions of the integumentary system, listing involved structures.

VIII. Skin structure-a layered organ

A. Skin Layers/tissues 1. Epidermis layer -superficial
keratinized stratified squamous epithelium tissue
abrasion-resistant covering to prevent damage and infection
tissue is actively being replaced by mitosis to remove adhering pathogens and promote healing.

2. Dermis layer-deep
dense (collagen) irregular connective tissue
protect against damage

3. Hypodermis layer -deepest
adipose connective tissue
reduce heat loss
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B. Sensory organs 1. Touch (Meissner's corpuscle and hair root)

2. Pressure (Pacinian corpuscle)

3. Pain (naked nerve endings)

4. Temperature (thermoreceptor)
   

C. Exocrine glands (cuboidal glandular epithelium) 1. Oil (sebaceous) glands produce oil covering epidermis to reduce evaporation and prohibit bacterial growth

2. Sweat (sudodoriferous) glands produce sweat primarily to decrease body temperature and prohibit bacterial growth

D. Hair - reduce heat loss, some protection against injury and sensation

E. Nails-protection against injury

Describe the layers of the skin identifying the tissues that form those layers. Give the structure and function of structures embedded in skin.
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IX. Wound healing
A. Epidermal wound healing 1. Deepest layer of epithelial cells continuously produces squamous cells via mitosis

2. As cells move towards surface they fill with keratin, die and spread out and fill in wound.
 

B. Deep (dermal) wound healing 1. Inflammation a. Increased blood flow forms blood clot (solid protein fibers and cells) over wound

b. Increased number of white blood cells that phagocytize dead cells and invading pathogens to remove dying tissues

c. Increased nutrient and oxygen to promote healing

2. Migration a. epithelium cells migrate under clot to replace epidermis and fill wound

b. Fibroblasts migrate into deeper wound site

c. Blood vessels invade

3. Growth and maturation a. Epithelial cells extensively increase in size and number (mitosis) to remake epidermis

b. Fibroblasts deposit abundant collagen fibers, irregularly, to remake dermis.
Describe the processes of epidermal and dermal wound healing. 

X. Thermoregulation
example of nervous system negative feedback loop (response is opposite of stimulus)

A. Skin too hot (stimulus)1. thermoreceptors in skin send nervous signal via sensory neuron to control center in brain (hypothalamus) which makes decision and sends that information via motor neuron to effectors (sweat glands) whcih increase sweat production to increase evaporative cooling. Additionally, smooth muscle (effectors) in skin blood vessels are also allowed to dilate so blood can transport heat to surface.

2. Response is cooler body temperature

B. Skin too cold (stimulus) 1. receptors inform brain (hypothalamus) which orders skeletal muscle effectors to increase muscle tone (shiver) which increases heat production.

2. Response is is warmer body temperature
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Identify the stimulus, receptors, control center, effectors and responses in thermoregulation.


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Professor Thomas M. Lancraft
Human Anatomy and Physiology Courses
at St. Petersburg College
St. Petersburg/Gibbs Campus

2/2007