Tissues and Integumentary System

continue w skin and body membranes

Four primary types of tissue

Epithelial, Connective, Muscle, Nervous

Epithelial Tissue

avascular, regenerate easily if well nourished, tightly packed cells, lots of nerves

apical surface

exposed either to the external environment or to some internal body space, it may have either microvilli or cilia on its surface

basal surface

where the epithelium is attached to a basement membrane with underlying connective tissue

functions of epithelial tissue

physical protection, selective permeability, secretions, sensations

simple squamous

• lines body cavities, allows for diffusion, they form the thinnest possible barrier to allow rapid movement of molecules and ions across the epithelium membrane
  

• can be found in alveoli, the lining of lumen of the capillary walls, forms serous membranes that cover body organs and secret serous fluid

simple cuboidal

• absorption and secretion

• can be found in the walls of kidney tubules and forms the follicles of the thyroid gland and covers each ovary

simple columnar

• absorption and secretion

• digestive system and gallbladder

non-ciliated simple columnar

• often contains microvilli and a scattering of unicellular glands called goblet cells

• stomach to anal canal

microvili

appear as a ‘brush border’ and secretes ‘mucin’ that when hydrated (H2O) forms mucus.

ciliated simple columnar

• cilia project from the apical surface. Goblet cells are interspersed, so mucus covers the apical surface which is moved along by the cilia.

• larger bronchioles in the lungs, and luminal surface of the uterine tubes

ciliated pseudostratified columnar

• contains cilia on its apical surface which

  house the goblet cells that secrete ‘mucin’ (+ H2O = mucus)

• Found mostly in the upper respiratory tract (mostly the trachea)

non-ciliated pseudostratified columnar

• rare, lacks goblet cells

• found in part of the male urethra

keratinized stratified squamous

• filled with a protein called keratin which is a tough, protective protein that strengthens the tissue

• hair and nails

non-keratinized stratified squamous

• lack keratin so the cells remain alive.

• Forms the surface of the pharynx, part of the larynx, the esophagus, vagina, and anus

transitional

• stretching

• urinary tract

glands

• either individual cells or multi-cellular organs composed mainly of epithelial tissue.

• Secrete substances either for use elsewhere in the body or for elimination from the body

glandular secretion

mucin, ion, hormones, enzymes, urea

endocrine glands

• lack ducts

• secret hormones which are transported by blood to target organs or tissues

unicellular exocrine glands

do not contain a duct and are located close to the surface of the epithelium

multicellular exocrine glands

• contain numerous cells that work together to produce a secretion

• typically are surrounded by a fibrous capsule which is divided into lobes

merocrine glands

• package their secretions into secretory vesicles and release the secretions by exocytosis

• lacrimal glands, salivary glands, eccrine glands

apocrine glands

• secretion occurs when the cell’s apical portion pinches off, releasing cytoplasmic content. the cell then repairs itself to repeat

• mammary glands and ceruminous glands of the ear

holocrine glands

• formed from cells that accumulate product; the entire cell then disintegrates

• sebaceous glands

functions of connective tissue

support, protect and bind organs

three basic components of connective tissues

cells, protein fibers, and ground substance

dense regular connective tissue cell type

fibroblasts

adipose connective tissue cell type

adipocytes

cartilage connective tissue cell type

chondrocytes

resident cells (CT)

• stationary cells (fixed) which help to support, maintain, and repair extracellular matrix

  • fibroblasts, adipocytes, mesenchymal cells, fixed macrophages

Fibroblasts

flat cells with tapered ends. Most abundant and produce the fibers and ground substance components of the extracellular matrix

mesenchymal cells

embryonic stem cells and divide when tissue becomes damaged

fixed macrophages

type of WBC derived from monocytes which phagocytize damaged

cells or pathogens. Also, release chemicals that stimulate the immune system.

wandering cells (CT)

• continuously move through out the tissue

• Primarily leukocytes, mast cells, plasma cells, free macrophages

mast cells

small, mobile cells, found close to blood vessels. They secrete heparin to inhibit blood clotting and histamine to dilate blood vessels

plasma cells

formed when B-lymphocytes are activated. Produce antibodies

free macrophages

mobile phagocytic cells

protein fibers

• strengthen and support tissue

• collagen, reticular, elastic

collagen fibers

• strong, flexible, and resistant to stretching. Stronger than steel of the same diameter.

• comprises bout 25% of the body’s protein content. They appear white so referred to as ‘white fibers’ (tendons and ligaments)

reticular fibers

• similar to collagen but much thinner. Tough but flexible.

• Abundant in the framework of organs such as lymph nodes, spleen, and liver.

elastic fibers

• contain the protein ‘elastin’. Stretch and recoil. Appear yellow so referred to as ‘yellow fibers’.

• Abundant in the skin, arteries, and lungs

ground substance

• non-cellular material produced by the connective

  tissue cells

• can be viscous, semisolid or solid

• contains glycosaminoglycans which attract H2O (provides fluidity

• when a GAG is linked to a protein within this = proteoglycan

Mesenchyme embryonic connective tissue

• First kind of connective tissue in the developing embryo

• All connective tissue is ultimately derived from here.

Mucous connective tissue

• Located within the umbilical cord

three categories connective tissue is classified after birth

connective tissue proper, supporting connective tissue and fluid connective tissue

Loose connective tissue

• contains fewer cells and protein fibers

• Used for supporting and surrounding structures and organs

• Well vascularized

Areolar connective tissue

• collagen and some elastic fibers and well vascularized

• The predominant cell is the fibroblast and the ground substance is abundant and viscous

• Found in the skin as well as surrounding organs to protect them

Adipose connective tissue

• composed of adipocytes and well vascularized

• The number of adipocytes remains relatively stable. Weight gain or loss is due more because of enlarging or shrinking of the adipocytes.

Reticular connective tissue

• Houses abundant leukocytes and some fibroblasts within a network of reticular fibers

• Forms the ‘stroma’ (framework) of lymphatic organs such as the spleen, lymph nodes, and red bone marrow

dense regular connective tissue

• Abundant collagen fibers, few fibroblasts, limited ground substance

• Found in tendons and ligaments where stress typically is applied in a single direction

• very few blood vessels (long time to heal)

dense irregular connective tissue

• clumps of collagen fibers extending in all directions so resistant to stress in multiple directions

• found in dermis of the skin

elastic connective tissue

• Compose of numerous fibroblasts and densely packed elastic fibers to stretch and recoil

• Found in walls of large arteries, the trachea, and the vocal cords.

cartilage

• Firm, semisolid extracellular matrix containing collagen and elastic protein fiber

• avascular

hyaline cartilage

• The most common type and provides flexible support to structures

• respiratory tract, epiphyseal plates, and ends of long bones

fibrocartilage

• weight bearing cartilage

• Dense collagen fibers resists compression and tensile forces (good shock absorber)

• Found at pubic symphysis, intervertebral discs, and menisci of the knee joint

elastic cartilage

• Flexible cartilage containing numerous elastic fibers in its extracellular matrix

• External ears and epiglottis

compact bone

perforated by many neurovascular canals

spongy bone

• Located in the interior of bone, especially at the ends of long bones

• strong and light weight

blood

fluid connective tissue composed of ‘formed elements’ (RBCs, WBCs, Platelets) and liquid ground substance called plasma (proteins and solutes)

lymph

Derived from blood plasma but does not contain cellular components or fragments Ultimately returned to the bloodstream.

muscle tissue

• well vascularized

• produces movement

• skeletal, cardiac, smooth

nervous tissue

• Located within the brain, spinal cord, and nerve network

• made up of neurons and glial cells

body membranes

• formed from an epithelial layer that is bound to an

  underlying connective tissue\

• line body cavities, cover viscera, or cover the body’s external surface

mucous membrane

• Lines passageways that eventually open to the external environment

• Perform protective, absorptive, and secretory functions

• Often covered with layer of mucus derived from goblet cells

• GI tract, respiratory tract, urinary tract, reproductive tract

serous membrane

• Lines body cavities that do not open to the external environment and covering external surface

  of organs

• Composed of simple squamous epithelium and mesothelium and produce watery serous fluid

• pericardium of heart, peritoneum of abdomen and pleura of lungs

cutaneous membrane

• Composed of keratinized stratified squamous epithelium (epidermis)

• protects internal organs and prevents H2O loss

• skin

synovial membrane

• Cells within the membrane secrete synovial fluid that reduces friction among moving bone parts and distributes nutrients to the cartilage on the articular surfaces of bone

• Found in joints

ectoderm

epidermis of the skin, hair, nails, exocrine glands of the skin

mesoderm

muscle tissue, dermis of the skin, adrenal cortex, heart, spleen, kidneys, and ureters and internal reproductive organs

Endoderm

epithelial linings of the tympanic cavity, auditory tube, digestive, respiratory, reproductive and urinary tracts, thyroid gland, parathyroid glands, thymus, liver, gall bladder, and pancreas

hypertrophy

increase in size of the existing cells in a tissue while the

number remains the same.

Hyperplasia

increase in the number of cells in a tissue

Atrophy

is a decrease in cell size or number

skin

• houses sweat glands, hair follicles and sebaceous glands

Skin color

a combination of the colors of hemoglobin, melanin, and carotene.

Hemoglobin

• O2 binding protein present in blood cells, Exhibits bright red when binding to O2

• If the blood vessels in the superficial layers vasodilate (like in exercise), red tones are more visible

melanin

transferred in melanosomes in melanocytes to keratinocytes in the stratum basale.

Carotene

• yellow-orange pigment acquired from yellow-orange vegetables such as carrots, corn, and squash.

• accumulates inside keratinocytes of the stratum corneum and the sub-cutaneous fat

• converted into Vitamin A,

albinism

inherited recessive condition where the enzyme neede to produce

melanin is non-functional

UVC rays

absorbed by the upper atmosphere

UVA and UVB rays

both reach the earth’s surface and affect an individuals skin color and can cause burning and skin cancer

SPF

sun protection factor

nevus

harmless mole (overgrowth of melanocytes)

freckles

localized areas of increased melanocyte activity

Hemangioma

anomaly that results in skin discoloration due to blood vessels that

proliferate to form a benign tumor.

Friction ridges

• ridge patterns that follow the contours of the skin

• fingerprints, palm, soles, and toes

dermis

• deep to the epidermis and ranges in thickness from 0.5-3mm.

• Composed of connective tissue proper containing primarily collagen fibers and some reticular and elastic fibers

• contain motile WBCs called dendritic cells, blood vessels, sweat glands, sebaceous glands, hair follicles, nail roots, sensory nerve endings and smooth muscle tissue

• papillary layer superficial to the reticular layer

papillary layer

Composed of areolar connective tissue

dermal papillae

• contain the capillaries that supply nutrients to the cells of the epidermis.

• contains sensory nerve endings to monitor touch

reticular layer

• deeper of the two layers of the dermis

• consists primarily dense irregular connective tissue with large bundles of collagen fibers

collagen fibers

tensile strength (pulled apart)

elastic fibers

stretch and recoil

subcutaneous layer (hypodermis)

• consists of both areolar and adipose tissue

• functions to protect and pad the body, provide log term energy storage and thermal insulation

• drugs are injected here bc of its extensive vascularity

functions of the integument

• protection

• prevention of H2O loss or gain

• immune function

• metabolic regulation

• secretion and absorption

• temperature regulation

• sensory reception

integument protection

• Protects the entire body from injury and trauma against harmful chemicals, toxins, microbes, and excessive heat or cold

• protects deeper tissues from solar radiation

integument prevention of water loss or gain

epidermis is water resistant but not waterproof

how is water lost (integument)?

transpiration in which fluids slowly penetrate through the epidermis and evaporate into the air

immune function (integument)

presence of immune cells (epidermal dendritic cells) in the stratum spinosum

metabolic regulation (integument)

Vitamin D3 is then released into the blood and transported to the liver to be converted to ‘calcidiol; and then transported to the kidney and converted to ‘calcitriol’ which is the active form of Vitamin D3 considered to be a hormone.

function of vitamin d3 (metabolic reg)

increase absorption of Ca and PO4 from the small intestine to the blood. Ca, especially, is so important for bone mineralization, among many other uses.