anatomy tissues and skin test

histology

the study of tissues

tissue

a group of cells with similar structure working together to perform a similar job

the anatomy of a cell…

matches its physiology

muscle cell job

contract and relax

neuron

receive pass and impulses

red blood cell

carries oxygen through the bloodstream

4 types of tissues

muscle, nervous, epithelial, connective

connective tissue

blood, fat, cartilage, bone, tendons and ligaments

epithelial tissue

the lining tissue that forms the boundary between our body and the external environment

epithelial tissue functions

protection, absorption, filtration, secretion, temp regulation

top surface - epithelial tissue

apical or free, surface not attached to underlying tissue

bottom surface

basal, surface attached to underlying tissue, specifically connective tissue

what are epithelial tissues classified as

avascular (no blood vessels)

what are epithelial tissues classified by

the number of layers and the shape of the cells

apical vs basal

apical isn’t attached to underlying tissue, while basal surface is

basement membrane

forms a zipper between epithelial tissue and the underlying connective tissue, underneath the basa surface and made of collagen and other fibers

simple squamous

single, flat layer of cells that is thin and permeable

function: allows gases and molecules to pass by diffusion rapidly

• lines organs such as lungs and blood vessels

simple cuboidal

single layer of cube shaped cells

function: secretion and absorption of substances

• in the tissues of the kidney, which absorbs resources from blood, and glands that secrete things like saliva

simple columnar

a single layer of tall, closely packed cells

function: secretion of mucus for protection and absorption of substances

• may have cilia and goblet cells which secrete mucus

lining of digestive tract, instestines as they create a liter of mucus every day

stratified squamous

thick layers that provide protection for underlying layers

function: provides protection from abrasion and protects delicate places

• epidermal skin layer, mouth, esophagus, vagina

stratified cuboidal

more than one layer of cuboidal cells, rare in the body

• salivary and mammary glands

stratified columnar

apical surface lined with columnar cells, rare in the body

• pharynx, male urethra

psuedo-stratified epithelium

nuclei are found at different levels, so it appears stratified, but it is not (1 layer)

function: secretion and absorption, specifically mucus

• found in upper respiratory tract, trachea, fallopian tubes

transitional epithelium

apical surface vary in appearance based on the stretching of the tissue, changes shape with elasticity

function: changes between dome like cells and squamous cells depending on how full the urinary organ is

• in the lining of the urinary bladder

gland

made of a group of cells that secrete a fluid substance

how are glands classified

• complexity

• how substances are secreted (exocrine and endocrine)

exocrine glands

secrete substances outward through a duct, ex: sweat glands

endocrine glands

ductless glands that secrete hormones through the bloodstream

ex: thyroid gland

types of exocrine glands

merocrine, apocrine, holocrine

merocrine

cells excrete the products (substances) vis exocytosis

ex: sweat glands

apocrine

a portion of the cell pinches off with the secreted products

holocrine

cells rupture and spill products into the duct

characteristics of endocrine glands

• secrete hormones into the blood so they can be delivered over longer distances

• packed tightly together with capillaries running through the glandular tissue

• cells secrete products through exocytosis

ex: thyroid, thymus, adrenal glands, pancreas

smooth muscle tissue

• contracts involuntarily

• non-striated

• found in walls of stomach, uterus, intestines, bladder, arteries, veins and eyes

• moves food and fluids

cardiac muscle tissue

• contracts involuntarily

• striated

• found in the heart muscle

• activated by brain or hormones

• pumps blood through the body

skeletal muscle tissue

• contracts voluntarily

• striated

• connected to bones of skeleton

• controlled by somatic nervous system

neurons

• make up 10% of nerve cells

• convert stimuli into nerve impulses

• pass impulses to other neurons, myscle fibers, or glands

• unable to regenerate

neuroglia

• make up 90% of nerve cells

• support and protect neurons

• do not generate nerve impulses

• able to regenerate after injury

connective tissues

provide support and bind other tissues together

• insulation and protection for other tissues

• some can transport substances

what is mesenchyme

all connective tissues are formed from one type of stem cell (mesenchyme)

vascullarity

amount of blood vessels

what are connective tissues mostly composed of

extra cellular matrix

what is the extracellular matrix made of

ground substance and fibers

ground substance

watery or gel-like substance created by cells (empty areas)

fibers

collagen, elastic, reticular

loose connective tissue types

areolar, adipose, reticular

areolar

• mostly open space

• holds water and salts for surrounding tissues

• found under epithelium around organs

adipose

• tightly packed fat cells, little matrix (adipocytes)

• have large vacuoles that contain fat/oil

• insulates and warms the body

• cushions organs, energy reserves

• under skin, around kidneys and heart

reticular

contains reticular fibers, which create a stiff framework that supports other cells

• Lymph nodes, spleen, bone marrow

• Gel-like ground substance

regular

• collagen fibers arranged in 1 direction

• provides “tensile strength” like a rope

• found in tendons and ligaments

connects muscles to bones or bones to bones

types of dense connective tissue

regular, irregular, elastic

irregular

• collagen fibers arranged in many random directions

• provides strength in numerous directions

• found in capsules around organs

Dermis, fibrous coverings around organs and joints

elastic

• provides flexible cushioning

• found between vertebrae and arteries

Walls of arteries, ligaments connecting vertebrae, lungs

many elastic fibers

types of cartilage

hyaline, fibro-cartilage, elastic

hyaline

• glassy looking, few collagen fibers

• found in larynx, bridge if nose, ribs

• firm around substance with lacuna (spaces for cells(

fibro-cartilage

• contains lots of collagen, mostly running parallel

• found in intervertebral spaces

elastic cartilage

• highly flexible

• more elastic fibers

• found in outer ear and tip of nose

osteocytes (bone) and ground substances

osteocytes secret ground substances, fibers, collagen, and fluids, and the ground substance eventually becomes calcified and hard

• 2 types: spongy and compact

types of vascular tissue

ground substance = plasma (fluid)

“fibers” = platelets which clot the blood

mast cells

• detect foreign substances

• contain granule that secrete inflammatory chemicals

macro-phages

• blob-like cells that engulf invading substances of organisms

blood cells

• red blood cells (erythrocytes) carry oxygen

• white blood cells (leukocytes) provide immune response

functions of the epidermis

• protection from water, air infection, chemicals, uv radiation

• sensations such as pressure, heat, cold and pain

• temperature regulation - body can be heated or cooled by sweat and blood flow near surface

• excretion of waste through sweat

• production of vitamin d

epidermis

the top layer of skin, composed of stratified squamous epithelial tissue

stratum corneum

layer of dead cells 20-30 thick

• thick keratinized cells protect the deeper layers

• regularly shed the from the body

stratum lucidum

(clear layer) a thin layer of translucent cells

• only found in thick skin of palms and soles of feet

stratum granulosum

cells here begin to flatten and disintegrate

• accumulate keratin granules, responsible for waterproofing skin

stratum spinosum

named for irregular shape of cells, severak cells thick, contains prekeratin filaments

stratum basale

constantly dividing and pushing cells up to the next layer, mitotic, constantly shedding

acronym for epidermis layer order

come lets get sunburnt

melanocytes

epithelial cells found in bottom 2 layers of epidermis, produce melanin that is absorbed by nearby epithelial cells

melanin

darkskins have same number of melanocytes, difference is amount produced

• protects skin from harmful uv rays

skin canceri

uv radiation mutates skin cells dna and cells divide uncontrollably

skin cancer types

melanoma - uncontrolled division of melanocytes

basal cell carcinoma - uncontrolled division of cells in the basale layer

squamous cell carcinoma - uncontrolled division of cells in the spinosum layer

dermis

composed of dense irregular connective tissue, contains nerves, blood vessels, sweat glands, hair follicles

dermal papillae

boundary between the epidermis and the dermis, wavy layer, cause of fingerprints

2 layers of dermis and epidermis

papillary layer made of loose connective

reticular layer made of bundles of collagen fibers

cleavage

arrangement of collagen fibers, cuts should be made parallel to lines of cleavage

blood flow in dermis

during exercise, blood vessels swell allowing heat to dissipate and cooling the body

bedsores

when blood supply is restricted for a prolonged time

hypodermis or subcutaneous layer

not actually a part of the skin

• composed of loose fatty connective tissue that connects skin to muscle or bone

• also insulates and stores nutrients

2 types of sudoriferous sweat glands

eccrine and apocrine

eccrine

merocrine sweat

• glands that are abundant and often on palms, soles of feet, forehead

• tubes that open into pores on surface of skin

sweat

99% water with some salt, vitamins, wastes, anti microbial peptide called dermicidin, acidic

apocrine

contains fatty substances and proteins that are originally odorless, but bacteria breaks down causing odor

sebaceous (oil) glands

produce sebum, holocrine, lubricate skin and hair, kills bacteria

• amount of oil is based on inheritance but increases during puberty

what are hair and nails made of

hard keratin

hair functions

• head hair: keeps in heat and protects us from sun

• body hair: alerts us to insects

• eyelashes: protects the eyes

• nose hair: prevents entry of foreign objects

hair shaft

part of hair that sticks out the skin, protected by outermost layer called dermis

where is hair follicle located

within dermis

apocrine glands location

found in armpit or genital areas

hair bulb

where hair cells divide within the follicle,

cells filled with keratin and pigments

arrector pili muscles

attach to hair shaft and make hair stand up

what are nails for

theyre protective and useful as tools, protected on 3 sides by nail fold

4 parts of nail

free edge, body, root, nail bed

nail matrix

produces heavily keratinized cells which become the nail body

lunula

little moon on nail bed, whiter due to thickness of nail

function of eponychium (cuticle)

provides a protective seal for nail matrix

muscle tissue types

muscle tissue types