A and P Lecture Exam #3

Epithelial tissue

Sheet of closely adhering cells, apical surface is exposed to an environment, basal layer sits on basement membrane, avascular, covers most surfaces and lines cavities

Connective tissue

Cells and fibers in extracellular material (matrix), vascular, binds organs to each other, supports and protects organs, immune protection, transport

Muscular tissue

Elongated cells, contract in response to stimulation, creates movements

Nervous tissue

Communication by electrical and chemical signals, consists of neurons

What makes epithelium different from other tissues classes?

Very thin, cells are packed tightly together, have an apical surface that is exposed to the environment and a basal surface that sits on a basement membrane,

Simple squamous epithelium

Single layer, thin cells, rapid diffusion/transport, ex: alveoli

Simple cuboidal epithelium

Single layer, square/round cells, secretion and absorption, ex: kidney tubules

Simple columnar epithelium

Single layer, tall/narrow cells, absorption, ex: GI tract

Pseudostratified epithelium

Looks multilayered, secretion, ex: trachea

Keratinized stratified squamous epithelium

Layer of dead scaly cells at the surface, resists abrasion, ex: palms and soles

Non-keratinized stratified squamous epithelium

No keratinized layer, resists abrasion, ex: tongue

Stratified cuboidal epithelium

2+ cell layers, square/round, secretion, ex: sweat gland ducts

Transitional epithelium

Multilayered, surface cells change when stretched, ex: bladder

What properties do most connective tissues have in common?

Extracellular matrix, vascular, collagen/elastic/reticular fibers

What type of cells are found in connective tissue?

Fibroblasts- make up matrix

Adipocytes- energy storage

Plasma cells- immune defense

Leukocytes- immune defense

Mast cells- immune

Macrophages- immune

Collagen fibers

Most abundant, tough, flexible, resists stretching

Reticular fibers

Thin collagen fibers, framework for organs

Elastic fibers

Thinner than collagen fibers, made of elastin, stretch and recoil

Areolar connective tissue

Loosely arranged fibers, binds epithelial to deeper tissues

Reticular connective tissue

Mesh of reticular fibers and fibroblasts, framework for organs

Dense regular connective tissue

Densely packed, parallel collagen fibers, bind bones, attach muscle to bone

Dense irregular connective tissue

Densely packed, randomly arranged, withstands stresses

Adipose tissue

Made of adipocytes, energy reservoir

Hyaline cartilage

Clear/glassy, strongest, ex: trachea

Elastic cartilage

Elastic fibers, ex: external ear

Fibrocartilage

Bundles of collagen fibers, ex: intervertebralB discs

Bone

Solid matrix, calcified

Blood

Fluid CT

What cell types make up nervous tissue?

Neurons- main cells

Neuroglia- protect and assist neurons

Neurosoma- cell body

Dendrites- receive signals

Axons- send signals

Skeletal muscle

Long cells, unbranched, attach to bone, striations, multinucleate, voluntary

Cardiac muscle

Only in heart, branched, uninucleate, intercalated discs, striated, involuntary

Smooth muscle

Short cells, uninucleate, involuntary, digestive/respiratory/urinary tracts

Tight junctions

Waterproof barrier

Desmosomes

Strong anchors that keep cells in place

Gap junctions

Communication

Characteristics of a gland

Produce secretions, epithelial

Endocrine glands

Secretions go directly into the blood, no ducts, high density of blood capillaries, ex: thyroid, adrenal, pituitary

Exocrine glands

Release material by way of duct, may be released to the body surface or into the cavity of another organ, ex: sweat, mammary, tear

Serous glands

Thin, watery secretions, ex: sweat, milk, tears, digestive juices

Mucous glands

Produce mucin that absorbs water to form sticky substance called mucus, ex: oral and nasal cavities

Mixed glands

Both serous and mucous, ex: salivary

Cytogenic glands

Release whole cells, ex: testes and ovaries

Eccrine glands

Secrete by exocytosis, ex: tear, pancreas, gastric, mammary

Apocrine glands

Blebs with material come off cell, ex: axillary sweat glands

Holocrine glands

Cells accumulate product then entire cell disintegrates, ex: oil glands of scalp

Cutaneous membrane

Skin

Synovial membrane

Joint cavities

Mucous membranes

Line passages that open to exterior environment

Serous membranes

Line walls of body cavities

Hyperplasia

Growth through cell multiplication

Hypertrophy

Enlargement of preexisting cells

Neoplasia

Development of tumor

Differentiation

Unspecialized embryonic tissues become specialized mature types

Metaplasia

Changing from 1 type of mature tissue to another

Totipotent

Embryonic stem cells become undifferentiated cells

Pluripotent

Cells of embryo develop into any human cell but not accessory organs

Multipotent

Adult stem cells that can develop into more than 1 cell line

Atrophy

Shrinkage of tissue through loss in cell size or number

Apoptosis

Programmed cell death

Necrosis

Premature, pathological cell death of tissue due to trauma, toxins, or infection

Gangrene

Tissue necrosis due to insufficient blood supply

Major functions of the skin:

Barrier to infection/trauma/water loss, Vitamin D synthesis, sensation, thermoregulation, nonverbal communication

Epidermis

Keratinized stratified squamous epithelium, dead cells on the surface packed with protein keratin

Function of epidermis:

Protective barrier against injury, bacteria, viruses, and chemicals

Dermis

Connective tissue layer deep to the epidermis, major protein is collagen

Function of dermis:

Provides strength and elasticity, houses blood vessels/sweat glands/sebaceous glands/nerve endings

Hypodermis

Subcutaneous tissue made of mostly adipose and areolar tissue

Function of hypodermis:

Pads body, binds skin to underlying tissues, energy reservoir, thermal insulation

5 cells of the epidermis:

Stem cells- mitosis, deepest layer of the epidermis

Keratinoyctes- synthesize keratin

Melanocytes- synthesize melanin, shields DNA from UV radiation

Dendritic (Langerhans) cells- immune cells

Tactile cells- receptors for touch (sensation)

5 layers of the epidermis:

Stratum Basale- deepest; stem cell division; creates keratinocytes

Stratum Spinosum- multilayered; keratinocytes flattening

Stratum Granulosum- 3-5 layers; keratinocytes produce vesicles and release glycolipid to waterproof skin

Stratum Lucidum- thick skin only; keratinocytes densely packed

Stratum Corneum- 30 layers; dead, scaly keratinized flake off

What is the connection between stretch marks (striae) and the dermis layer of the skin?

They are caused by the tearing of collagen and elastic fibers in the dermis due to rapid stretching of the skin; happen during pregnancy, growth spurts, or significant weight gain

What are the two main structures of skin and the differences between them?

Thick skin- only on palms and soles, has stratum lucidum for extra protection against friction and pressure

Thin skin- covers most of the body, no stratum lucidum

Albinism

Lack of melanin

Cyanosis

Blueness from deficiency of oxygen in blood; caused by COPD, drowning, choking

Erythema

Redness of the skin from dilated cutaneous vessels; caused by anger, sunburn, embarrassment

Jaundice

Yellowing of skin from excess of bilirubin in blood; caused by liver disease

Bronzing

Golden-brown color of Addison disease; deficiency of glucocorticoid hormone

Pallor

Pale color from lack of blood flow; caused by fear, low BP

Hematoma

A bruise (mass of visible clot)

Freckle

Tan/black clump of melanocytes; flat, melanized patch

Mole

Tan/black clump of melanocytes; elevated, melanized patch

Hemangiomas (birthmarks)

Patches of discolored skin; benign tumors of dermal blood capillaries; strawberry disappear in childhood, port wine last for life

Flexion creases

Form after birth from repeated closing of hand

Flexion lines

Form in wrist and elbow areas (site where the skin folds during flexion of the joints)

3 kinds of hair:

Lanugo- fine, downy, unpigmented hair on fetus in last 3 months of development

Vellus- fine, pale hair that replaces lanugo by birth

Terminal- longer, coarser hair and usually more heavily pigmented

Hair

Mostly dead, keratinized cells; made of hard keratin

Bulb

Swelling at base where hair originates, only living hair cells

Root

Remainder of hair in follicle

Shaft

Portion above the skin surface

Follicle

Diagonal tube that digs deeply into the dermis, even hypodermis

Dermal papilla

Bud of vascular CT encased by hair bulb; provides hair with nutrition

Hair matrix

Region of mitotically active cells immediately above papilla; hair’s growth center

Cross section of hair:

Medulla- core of loosely arranged cells and air space

Cortex- bulk of hair; consists of dense cells with hard keratin

Cuticle- thin, scaly cells that overlap each other; outer covering

Nail fold

Surrounding skin rising above nail

Nail groove

Separates fold from plate

Nail bed

Skin underlying nail plate

Cuticle

Narrow zone of dead skin

Nail matrix

Growth zone of stratum basale at proximal end of nail

Apocrine glands

In groin, anal, and axillary regions; produce thicker, milky sweat with fatty acids

Bromhidrosis

Body odor produced by bacterial action on fatty acids