quiz 5 (E2)

tissues

Connective Tissue General Features

most abundant tissue in body

major functions: strength and support, protection, insulation, transport substances around body

Substantial Matrix: basis for classification

predominant type of matrix, composition of each type of matrix

Substantial Matrix: protein fibers

collagen, elastin (elastic fibers), reticular fibers

Collagen

most common protein in body, “rope” of three fibers wound around each other, flexible and strong, but not elastic

Elastin (elastic fibers)

long, thin proteins that form branching networks, elastic

Reticular Fibers

thin, short collagen fibers, generally continuous with collagen, form “nets”

Blasts

cells that create the matrix

Cytes

cells that maintain the matrix

Mesenchyme

embryonic connective tissue: all connective tissue arises from mesenchyme, some remains as source of stem cells in adult

structure: star-shaped mesenchymal cells, fluid ground substance

Areolar Tissue (loose connective tissue)

structure: gel like matrix, loosely-arranged protein fibers, hyaluronic acid

Areolar Tissue (loose connective tissue): cells

has fibroblasts

other cells: macrophages, mast cells, fat cells

Areolar Tissue (loose connective tissue): function

“universal packing material”, allows diffusion for nutrition and wastes, reservoir for water and salts

Areolar Tissue (loose connective tissue): location

most widely distributed connective tissue, surrounds organs and capillaries, attaches skin to underlying tissues

Adipose Tissue: structure

closely packed cells (adipocytes), each cell contains so much lipid that nucleus & cytoplasm pushed to side of cell, just under plasma membrane, low levels of mitosis

Adipose Tissue: function

energy storage, insulation, supports and protects organs (padding)

Adipose Tissue: location

subcutaneous, around kidneys, mammary glands

Reticular Connective Tissue (reticular tissue): structure

reticular cells, reticular fibers

Reticular Connective Tissue (reticular tissue): function

support soft tissue of organs and small blood vessels

Reticular Connective Tissue (reticular tissue): location

lymph nodes, spleen, bone marrow

Dense Regular Connective Tissue: structure

matrix of parallel fibers, cell type is primarily fibroblast

Dense Regular Connective Tissue: function

tensile strength and stretch resistance in ONE directio

Dense Regular Connective Tissue: location

ligaments, tendons

Dense Irregular Connective Tissue: appearance

interwoven fibers, cell type is primarily fibroblast

Dense Irregular Connective Tissue: function

tensile strength and stretch resistance in MULTIPLE directions

Dense Irregular Connective Tissue: location

dermis of skin, fibrous joint capsule

Elastic Connective Tissue: appearance

coiled appearance of elastin, elastin fibers parallel

Elastic Connective Tissue: function

elastic: returns to original shape, recoil of tissue following stretching

Elastic Connective Tissue: location

walls of large arteries, walls of bronchial tubes

Cartilage: general characteristics

• avascular: used in compression areas, slow healing

• chondrocytes widely dispersed in lacuna

• matrix: firm; fairly solid but not completely rigid, primarily collagen

• fibers associated with bone

Hyaline Cartilage: structure

matrix appears transparent, chondrocytes found in spaces (lacunae) within the matrix

Hyaline Cartilage: function

forms the embryonic skeleton, allows growth of long bones, rigid and smooth, yet slightly flexible

Hyaline Cartilage: location

articular cartilage, epiphyseal plate, costal cartilage of ribs, nose, trachea

Elastic cartilage: structure

elastin fibers, lacuna

Elastic Cartilage: function

flexibility, shape retention

Elastic Cartilage: location

external ear, epiglottis

Fibrocartilage: structure

bundles of collagen fibers, lacuna

Fibrocartilage: function

absorbs compression, tensile strength

Fibrocartilage: location

intervertebral disks, articular disks, pubic symphysis

Bone: general characteristics

most of skeleton, solid matrix, excellent blood supply, osteocytes found in lacunae in the matrix

Blood: structure

40-45% of volume is cells, primarily fluid: plasma, fibrous proteins in the plasma help with clotting

Blood: function

transportation of gasses, nutrients, wastes, hormones

Blood: location

cardiovascular system

Serous Membrane characteristics

made of thin layers of epithelial and connective tissues, “fist pushed into balloon”

Serous Membrane parts

Visceral Serous Membrane, Parietal Serous Membrane, Serous Fluid

Serosal membranes associated with ventral cavities

pleura - lungs, pericardium - heart, peritoneum - organs in abdominal cavityFunctions of Skin

Functions of Skin

Protection, body temperature regulation, cutaneous sensation, Vitamin D synthesis, blood reservoir, excretion

Skin Protection

physical barrier, chemical barrier, biological barrier

physical barrier of the skin

hard and thick, oil and glycolipid secretion (from glands waterproofs skin), melanin, hair

Chemical barrier of the skin

pH, RNAse

biological barrier of the skin

Langerhans cells within epidermis, macrophages within dermis

body temperature regulation of the skin

autonomic nervous system: heat loss required, sweating, vasodilation and greater opening of skin capillary beds

heat retention required: decreased sweating, vasoconstriction and decreased opening of skin capillary beds

Cutaneous sensation of the skin

touch in epidermis and dermis, temperature, pressure, pain receptors in dermis, hair follicles well innervated

Vitamin D synthesis of the skin

produced in skin with UV light exposure, required for absorption of calcium from gut

blood reservoir of the skin

highly vascularized, when blood needed elsewhere, skin capillary beds close

excretion of the skin

nitrogen wastes, water and NaCl loss

Skin General Structure

Epidermis, Dermis, Hypodermis

Epidermis

thick stratified squamous keratinized epithelium

Epidermis: Keratinocytes

produce keratin (soft form), Desmosomes, developmental progression, turnover time ≈ 52-75 days

Epidermis: Melanocytes

produce melanin: pigment, provides protection from UV light

number of melanocytes is similar for people with different skin tones

people with darker skin have more active melanocytes that produce more pigment

how melanocytes create skin tone

melanin stored in membrane granules (packages), granules move to tips of processes, uptake by keratinocytes by phagocytosis

in response to UV light, melanin production increases

Epidermis: Langerhans cells

phagocytic scavengers, immune protection

Epidermis: Merkel Cells

detect touch, located at the junction between the epidermis and dermis

Epidermis: Strata

epidermis has several megalayers of cells

bottom layer contains

1) stem cells for keratinocytes

2) melanocytes

3) a few Merkel cells

as cells mature, they move to the surface

1) fill with keratin

2) die

surface strata contains multiple layers of dead cells

1) 20-30 cell layers

a) in thick skin can be up to 50 layers

b) completely keratinized cells: “cornified”

2) dead cells can “flake” of

Dermis

connective tissue; fibers primarily collagen, but also elastin and reticular fibers, cells primarily fibroblasts, ground substance is gel-like

Dermis: structural support for skin

the “hide” of animals, rich supply of blood and nerves, relationship to accessory structures

Dermis: Papillary Layer

areolar connective tissue, papillae project into epidermal layer: capillary loops, nerve endings

Dermis: dermal ridges

large mounds, force overlying epidermal layer to form ridges assist with grip, friction

Dermis: Reticular Layer

dense, irregular connective tissue, thick bundles of collagen

Hypodermis (subcutaneous tissue)

Loose connective tissue, Adipose tissue

Dermis: Thick Skin

in palms, fingertips, soles of feet

more layers of strata than thin skin

more papilla of dermal papillary layer than thin skin

has epidermal ridges

can have calluses

Dermis: Thin Skin

everywhere else that thick skin isnt

less strata than thick skin

less papilla of dermal papillary layer than thick skin

hair follicles found here

Hair characteristics

shaft formed by dead, keratinized cells, shaft is visible hair, cells added at base of hair root, “hard” keratin, rather than “soft” keratin of skin

Hair texture

determined by shape of shaft in cross section: flat/ribbon-like  tight curls oval  wavy round  straight, usually coarse

Hair Genetics

straight hair: KSKS

curly hair: KCKC

wavy hair: KSKC

Hair bulb

epidermal growth zone, epithelial tissue, single cell layer, actively dividing, producing hair cells, melanocytes add pigment to hair cells

Vellus Hair

short, fine hair; usually unpigmented, puberty over most of body

Terminal hair

coarse, longer and pigmented, tends to be localized in body

Hair growth cycle

1) hair growth

2) resting phase

3) hair shed, new growth begins

male pattern baldness

hair follicles lost, remaining follicles revert to producing vellus hair

Nails

modified epithtelial tissue

Nail components

nail root, nail body, free edge of nail

Nail matrix

by nail root, part of nail bed, responsible for most of nail growth

Nail bed

underneath nail body and root, contributes to nail thickness

Sebaceous Gland: produce sebum

oily, rich in lipids, released in holocrine manner, testosterone can increase release

Sebaceous Gland: actions

waterproofs, softens and lubricates skin, antibacterial

ducts usually terminate in hair follicles

Sebaceous Glands: distribution

cover body, except palms and soles, large on face, neck, upper chest

Eccrine Sweat Gland

most common, watery secretion, secretory portion located in dermis, duct opens to surface, not associated with hair follicles

Eccrine Sweat Glands: watery secretion

99% water, salts, trace metabolic wastes, released in a merocrine fashion, temperature regulation

Eccrine Glands: distribution

over the entire body surface, highest concentration in palms, soles, forehead

Apocrine Sweat Gland

merocrine secretion of sweat, proteins and lipids, larger than eccrine sweat glands, ducts terminate in hair follicles

~ ceruminous gland

~ mammary gland

Apocrine Sweat Gland: merocrine secretion of sweat, proteins and lipids

released in a merocrine fashion, protection from bacteria, odor results from bacterial degradation

Apocrine Sweat Gland: distribution

axillae, anogenital region

Skin Cancer

the most common type of cancer, correlates with sun damage

Basal Cell Carinoma

most common, originates in stratum basale, least malignant, 99% cure rate

Squamous Cell Carcinoma

stratum spinosum keratinocytes, rapid growth, spread, good cure rate if caught early

Melanoma (malignant melanoma)

5% of skin cancers

2) develops from melanocytes, usually pre-existing mole

3) unless caught early, generally fatal

4) ABCDE Rule

ABCDE Rule Melanoma

Asymmetry

Border irregularity

Color

Diameter

Evolving

Burns: process

denaturing of cell proteins, cell death, causes

Burns: 1st Degree

epidermal damage, redness, swelling and pain, generally heal in a few days

Bunrs: 2nd Degree

epidermis and upper dermis/all of dermis, results in blisters (in addition to previous symptoms), healing time depends on depth of damage in dermis