Histology Practical Flashcards
Organ
Structures composed of 2 or more different types of tissue that work together to perform particular functions.
Tissue
Groups of cells that have the same structural characteristics and perform the same functions
Organ system
Composed of various organs
Fixation
Tissue is immersed in the preservative solution to maintain the tissue’s existing structure
Embedding
Water is removed with alcohol, and the tissue is impregnated with paraffin wax
Sectioning
Tissue is cut into extremely thin slices by a microtome. When the section runs the length of the tissue it is called a longitudinal section; when the section runs across the tissue it is called a cross section
Staining
The tissue is immersed in dyes that stain different structures
Simple
Only one layer of cells
Stratified
Cell layers are placed on top of each other
Pseudostratified
They only appear to be layered
Microvilli
Hair-like extensions called cilia
Basement membrane
Consist of glycoproteins and collagen fibers, joins and epithelium to underlying connective tissue
Epithelial tissue
Forms a continuous layer, or sheet, over the entire body surface and most of the body’s inner cavities. It protects the body from infection, injury, and drying out. Some epithelial tissues produce and release secretions. Others absorb nutrients. Epith. Tissues are attached to underlying tissues by a basement membrane composed of extracellular material containing protein fibers. Consist of four types: simple squamous, pseudostratified Ciliated columnar, simple cubital, simple columnar.
Simple squamous Epith.
Single layer of thin, flat, pancake-shaped, many sided cells, each with a central nucleus. Connected to basement membrane.
Lines internal cavities, the heart, walls of capillaries, all blood vessels, parts of the urinary, respiratory (air sacs of lungs), and male reproductive tracts.
Function : filtration, diffusion, osmosis. Protects.
Stratified squamous Epith.
Consists of many layers of cells. Innermost layer produces cells that are first cubital or columnar in shape, but as the cells push toward the surface, the epidermis, they become flattened, accumulating keratin, a protein, and eventually die. Outermost layer of cells surrounding the cavity is simple squamous epith. In these organs, this layer of cells remains soft, moist, and alive.
Composes outer region of the skin, the epidermis, the lining of the mouth, throat, anal canal, vagina.
Function: protection, repel water
Simple cuboidal Epith.
Single layer of cube-shaped cells, each with a central nucleus. Lines the tubules of the kidneys and various glands, where it has a protective function, also occurs in the secretory portions of some glands. Protects, absorbs, secretes.
Location: surface of ovieries, lining of ducts and glands, lining of kidney tubules
Simple columnar Epith.
Single layer of tall, cylindrical cells, each with a nucleus near the base. Lines the digestive tract from the stomach to the anus, including the linings of the small intestine, oviducts, and uterus . Protects, secretes, and allows absorption of nutrients. Goblet cells.
Goblet cells
Mucus secreting cells. In living animals, the mucus is discharged into the gut cavity and protects the lining from digestive and enzymes.
Pseudostratified Ciliated columnar Epith.
Appears to be layered. But actually all cells touch the basement membrane. Many cilia are located on the free end of each cell. In males/females the cilia move sex cells along tubes. Trachea: cilia move mucus, debris, impurities, up toward the throat so that it can’t enter the lungs. Smoking destroys cilia, but they will grow back if smoking is discontinued. Goblet cells.
Lines respiratory passages.
Function: protection, secretion, movement of mucus and sex cells
Connective tissue
Joins different parts of the body together.
4 general classes: connective tissue proper, bone, cartilage, and blood
All consists of cells surrounded by a matrix that usually contains fibers (elastin fibers, collagenous fibers)
Elastic fibers
composed of a protein called elastin
Collagenous fibers
Contain the protein collagen
Loose fibrous connective tissue
A.k.a. Areolar tissue. Supports Epith. & many internal organs: I.e. muscles, blood vessels, nerves.
Presence allows organs to expand
Characteristics: has space between components, occurs beneath skin and most Epith. layers. Fibers widely separated
Function: supports and binds organs together
Location: between muscles, beneath the skin, beneath most Epith. layers
Dense fibrous connective tissue
A.k.a. White fibrous tissue. Contains many collagenous fibers packed closely together: I.e. *Tendons - which connect to muscles, *ligaments - which connect to other bones at joints. Also in dermis of skin.
Functions in support, binds organs together, binds muscle to bone, binds bone to bone
Adipose tissue
Connective tissue. Cells have a large, central, fat-filled vacuole = causes nucleus and cytoplasm to be at perimeter of the cell.
Located: beneath the skin = insulates body, stores fat, around organs - kidneys, heart = cushions, helps protect, in breast.
Compact bone
Connective tissue. Found in bones of skeleton. Consists of: osteons (Haversian system) with a central canal, lacunae (concentric rings of spaces) connected by canaliculi (tiny crevices)
Central canal contains a nerve and blood vessels which service the bone.
Lacunae contain osteocytes (bone cells), whose processes extend into the canaliculi.
Separating the lacunae is a matrix - that is hard bc it contains minerals (calcium salts), also contains collagenous fibers
Function: support, protect
Structure: concentric rings
Hyaline cartilage
Connective tissue. Contains cells = chondrocytes, found in twos or threes in lacunae. Lacunae separated by flexible matrix containing weak collagenous fibers
Location: nose, rings in walls of respiratory passages, ends of bones, between ribs and sternum
Function: support and protection
Blood
Connective tissue in which the matrix is an intracellular fluid = plasma.
R.B.C., W.B.C., Platelets.
Location: blood vessels
Structure: red and white cells floating in plasma
Red blood cells
Erythrocytes. More numerous than w.b.c. Look biconcave, lack a nucleus. Cells carry oxygen combined with hemoglobin (respiratory pigment) for respiration. Located in blood vessels.
White blood cells
Leukocytes. Can be separated into 5 distinctive grps: Neutrophil, Lymphocyte, Eosinophil, Basophil, Monocyte.
Contain a nucleus, typically large than r.b.c. Fight infection.
Located in blood vessels.
Neutrophil
W.b.c. Multi lobed nucleus
Lymphocyte
Smallest of all w.b.c., with a spherical or slighty indented nucleus
Muscular tissue
Composed of muscle fibers, has the ability to contract, contraction = movement.
Body contains: skeletal, cardiac, and smooth muscle
Skeletal muscle
Occurs in the muscles attached to the bones of the skeleton. Voluntary contraction. Striated, contains light and dark bands - caused by the arrangement of contractile filaments (actin & myosin filaments) in muscle fibers. Each fiber contains peripherally located nuclei.
Striated cells with multiple nuclei.
Cardiac muscle
Found only in the wall of the heart. Involuntary. Striated cells with single nuclei. Fibers are branched and bound together at intercalated disks, where their folded plasma membranes touch. This arrangement aids communication between fibers. Functions in pumping blood.
Smooth muscle
A.k.a. Visceral muscle bc it makes up the walls of the internal organs, I.e. intestines, blood vessels. Involuntary. Spindle-shaped cells with a single nucleus. NO striations.
Function in movement of substances in lumens of body.
Found in blood vessel walls and walls of the digestive tract.
Nervous tissue
Found in Brain, spinal cord, nerves. Receives and integrates incoming stimuli before conducting nerve impulses, which control the glands and muscles of the body. Composed of two types of cells: neurons & neuroglia.
Neurons
Transmit messages
Neuroglia
Support and nourish the neurons
Motor neurons
Take messages from the spinal cord to the muscles, are often used to exemplify typical neurons. Contains several dentrites.
Dentrites
Process that takes signals to the cell body.
Cell body
Where the nucleus is located
Axon
Takes nerve impulses away from the cell body. Long axons are called nerve fibers.
Intestine
Part of the digestive system. Processes food and absorbs nutrient molecules.
Mucosa
(mucous membrane layer) Lines central lumen (cavity), is made up of columnar epith. overlaying a layer of connective tissue. The epith. is grandular -that is it secretes mucus from goblet cells and digestive enzymes from the rest of the epith. The membrane is arranged in deep folds (fingerlike projections) called villi, which increase the small intestine’s absorptive surface.
Submucosa
(Submucosal layer) Connective tissue layer containing nerve fibers, blood vessels, and lymphatic vessels. The products of digestion are absorbed into these blood and lymphatic vessels.
Muscularis
(Smooth muscle layer ): contains circular muscular tissue and then longitudinal muscular tissue. Rhythmic contraction of these muscles causes peristalsis, a wavelike motion that moves food along the intestine.
Serosa
(Serous membrane layer): in this layer, a thin sheet of connective tissue underlies a thin, outermost sheet of squamous epith. This membrane is part of the peritoneum, which lines the entire abdominal cavity.
Skin
Covers the entire exterior of the human body. Functions include protection, water retention, sensory reception, body temp regulation, and vitamin D synthesis
Epidermis
Composed of stratified squamous epithelial cells. Epidermis outer cells are nonliving and create a waterproof covering that prevents excessive water off. These cells are always being replaced because an inner layer of the epidermis is composed of living cells that constantly produce new cells.
Dermis
Composed of connective tissue containing blood vessels, nerves, sense organs, and the expanded portions of oil (sebaceous) inflict glands and hair follicles.
Subcutaneous layer
Layer of loose connective tissue and adipose tissue that lies beneath the skin proper and serves to insulate and protect inner body parts. This layer is NOT part of the skin.
Platelets
Thrombocytes. Tiny cell fragments which are involved in blood clotting.
