lab practical 1 (tissues/skin/bone histology)

epithelial tissue

refers to the sheets of cells that cover exterior and interior surfaces of the body, line internal cavities and passageways, and form certain glands, supports gas exchange, surface movement of substances and absorption; appears like thousands of cells squished into layers

• skin, lining of organs, sweat glands

apical surface

an upper free surface exposed to the body exterior or the cavity of an internal organ

basement membrane / basal surface

layer between epithelium and underlying connective tissue; where epithelial cells are attached

simple squamous epithelium

single layer of flattened cells

• allows easy passage of materials by diffusion and filtration; secretes lubricating substances

• located in kidney, glomeruli, air sacs of lungs, lining of heart, capillaries, and lymphatic vessels

simple cuboidal epithelium

single layer of cube shaped cells

• secretion and absorption

• located in ducts and secretory portions of small glands, kidney tubules, ovary surface

simple columnar epithelium

single layer of tall column shaped cells

• absorption, secretion of mucus, enzymes and other substances

• nonciliated types lines most of the digestive tract (stomach to anal canal), gallbladder and excretory ducts of some glands

• ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus

stratified squamous epithelium

multiple layers of flat cells

• protects underlying tissues in areas subject to abrasion

• nonkeratinized type forms the moist lining of the esophagus, mouth and vagina

• keratinized type forms the epidermis of the skin, a dry membrane

stratified cuboidal epithelium

two or more layers of cube shaped cells

• protection

• located largest ducts of sweat glands, mammary glands and salivary glands

stratified columnar epithelium

two or more layers of column like cells

• protection and secretion

• rare in the body; small amounts in male urethra and in large ducts of some glands (salivary esophageal)

pseudostratified columnar epithelium

single layer of cells that appears to be made up of multiple layers of cells; each cell may have different heights/nucleus positions

• secretes substances, particularly mucus; propulsion of mucus by ciliary action

• ciliated variety lines the trachea, most of the upper respiratory tract; males sperm carrying duct

transitional epithelium

Type of stratified epithelium that lines the urinary tract

• stretches readily and permits distension of urinary organ by contained urine

• only in the urinary system: lines the ureters, urinary bladder, and part of the urethra

connective tissue

binds the cells and organs of the body together and functions in the protection, support, and integration of all parts of the body

• made up of fibroblasts (connective tissue cells)

• bone, fat, cartilage, blood, padding tissue

areolar connective tissue (loose)

gel-like matrix with web like fibers

• fills the spaces between muscle fibers, surrounds blood and lymph vessels, and supports organs in the abdominal cavity

• underlies most epithelium

adipose connective tissue (loose)

closely packed adipocytes; acts as storage depts for fat with little cellular matrix

• rapid storage mobilization of lipid molecules

• cushion and protection

• found cushioning around the kidneys and back of the eye

reticular connective tissue (loose)

network of reticular fibers in a typical loose ground substance; mesh-like supportive framework

• form a framework for soft internal structures; creates network that supports attachment of other cell types like white blood cells, mast cells, and macrophages

• located in lymphoid organs, lymph nodes, bone marrow and spleen

• Looks kind of like a cherry blossom tree in most images — reticular fibers are the wood

dense regular connective tissue (dense)

fibers are parallel to each other, enhancing tensile strength and resistance to stretching in the direction of the fiber orientations

• attaches muscle to bones or to muscles; attaches bones to bones, withstands great tensile strength when pulling force is applied in ONE direction

• makes up / located in tendons, ligaments, and layer under the epidermis

• collagen fibers are densely packed and run parallel to each other, creating a "wavy-hair" like pattern.

dense irregular connective tissue (dense)

fibers are in randomized directions; increases strength when pulled in multiple directions, less in one direction

• able to withstand tension exerted in MANY directions; provides structural strength

• dermis of the skin, submucosa of digestive tract; fibrous capsules of organs and of joints

elastic connective tissue (Dense)

stretchy and squiggly appearance; densely packed fibers

• allows recoil of tissue following stretching; maintains pulsatile flow of blood through arteries; aids passive recoil of lungs

• located in walls of large arteries; within certain ligaments associated with vertebral column, within the walls of the bronchial tubes

cartilage

connective tissue made up of chondrocytes and empty spaces called lucana

hyaline cartilage

most abundant type of cartilage; short and dispersed collagen fibers

• forms moveable joints and embryonic skeleton

• found on the ends of long bones, ribs and nose

elastic cartilage

cartilage with abundant elastic fibers

• characterized by a matrix rich in elastic fibers, allowing it to bend and recoil without losing its original shape.

• gives rigid support as well as flexibility

• found in external construction of the ear

fibrocartilage

tough due to its thick bundles of collagen fibers dispersed through its matrix

• act as a cushion within joints

• found in menisci in the knee joint and intervertebral discs

bone

dense, mineralized, hard connective tissue composing the skeleton

• two main types: compact (cortical) and spongy (cancellous) bone

blood connective tissue

fluid extracellular matrix used to transport substances throughout the body filled with blood cells

muscle tissue

excitable, responding to stimulation and contracting / lengthening to provide movement

• skeletal, smooth, cardiac

skeletal muscle

muscle that is attached to the bones of the skeleton and provides the force that moves the bones; each cell

• voluntary

• striated

smooth muscle

muscle found inside many internal organs of the body that causes their movement (ex: stomach muscle)

• involuntary

• smooth

cardiac muscle

muscle tissue found only in the heart

• involuntary

• striated

• intercalated disc

intercalated discs

attachment sites between the transverse lines between cardiac muscle cells (CARDIAC ONLY)

nervous tissue

excitable, allowing the propagation of electrochemical signals in the form of nerve impulses that communicate between different regions of the body

• brain

thin skin

covers most of the body

• four layers of keratinocytes

• contains hair follicles

thick skin

covers palms of hands and soles of feet

• has five layers of keratinocytes

• no hair follicles

layers of skin

epidermis, dermis, hypodermis (subcutaneous)

epidermis

composed of keratinized, stratified squamous epithelium; outermost / top layer of the skin

• keratin is an intracellular fibrous protein that gives hair, nails, and skin their hardness and water-resistant properties

• keratinocytes is a cell that manufactures and stores the protein keratin

layers of epidermis (superficial to deep)

• stratum corneum

• stratum lucidum (not in thin skin)

• stratum granulosum

• stratum spinosum

• stratum basale

dermis

middle layer of skin; contains blood and lymph vessels, nerves and other structures, such as hair follicles and sweat glands

• papillary layer (superficial)

• reticular layer (deep)

hair follicle histology

surrounded by sebaceous glands

sweat gland histology

• apocrine sweat gland (larger than eccrine, like in armpits)

  • also has more “white” in circle in histology

• eccrine sweat gland (sweat)

sebaceous glands

exocrine glands in the skin that produce and secrete sebum, an oily substance that lubricates and waterproofs the skin and hair

arrector pili muscle

small muscle in the skin attached to hair follicles. When it contracts, it causes the hair to stand on end, a phenomenon known as "goosebumps".

Pacinian corupscle

pressure receptors

Meissner corpuscle

receptor in the skin that responds to light touch

parts of the skin (helpful overall diagram)

epidermis, dermis, hypodermis

parts of the bone

fossa

shallow, basin like and elongated depression in a bone, often serving as an articular surface

fovea

small pit in the bone

bone histology

matrix is dense and contains calcium, salts and collagen

bone histology image overview

osteon histology

whole thing essentially

osteocytes histology

bone cells

black dots within the osteon

lacunae histology

small spaces or cavities within the bone matrix that house osteocytes

lamellae histology

lamellae form concentric rings around a central canal

canaliculi histology

microscopic channels found within bone tissue that connect lacunae, which house osteocytes, to each other and to the Haversian canals

motor nerve ending

found at neuromuscular junction

neuron smear

found in central nervous system

Purkinje cells

cerebellum

nerve cross section

found in peripheral nerves