Lecture 3: Tissues and Epithelial Membranes Flashcards
Meaning of histology
Study of the structure, composition and function of tissues
What are the four major classes of tissues?
Epithelial
Connective
Nervous
Muscle
What are the two main types of epithelial tissue and their functions?
Covering and Lining Epithelia (Cover the outer body surface and surface of internal organs)
Glandular Epithelia (Forms secretory tissues in glands)
What is polarity (epithelial tissue)?
Consists of apical and basal surfaces which are connected to a basement membrane.
What are the five characteristics of epithelial tissue?
- Polarity
- Cells fitted tightly together
- Supported by connective tissue
- Avascular (no blood vessels) but innervated (nerves present)
- High capacity of regeneration
What are the three shapes of epithelial tissue?
Squamous
Cuboidal
Columnar
What are the number of layers for epithelial tissue?
Single layer = Simple
Multiple layer = Stratified
What are the functions of simple and stratified epithelia?
- Diffusion and Filtration: Separation of substances by their ability to pass through epithelial cells.
- Absorption: Passage of fluids or products of digestion from intestines to blood.
- Secretion: Release of substances such as enzymes, mucus hormones etc.
Stratified Epithelia: Protect underlying tissues where there is lot of wear and tear.
What are the five types of epithelial tissue?
- Simple squamous epithelium
- Simple cuboidal epithelium
- Simple columnar epithelium
- Ciliated pseudostratified columnar epithelium
- Stratified squamous epithelium
Describe, location and function of simple squamous epithelium
Describe: Single layer flattened cells with disc shaped central nuclei
Function: Allows passage of materials by diffusion and filtration in sites where protection is not important.
Location: alveoli, lining of heart, blood vessels, lymphatic vessels, lining of ventral body cavity
Describe, location and function of simple cuboidal epithelium
Describe: Single layer of cubelike cells with large spherical nuclei
Function: Secretion and absorption
Location: Kidney tubules, thyroid and salivary glands
Describe, location and function of simple columnar epithelium
Describe: Single layer of tall cells with round to oval nuclei (some cells may bear cilia and mucus secreting glands
Function: Specialized in absorption
Location: digestive tract, gallbladder and excretory ducts of small glands
Describe, location and function of Ciliated Pseudostratified Columnar Epithelium
Describe: Single layer of cells of differing heights, some not reaching the free surface and may contain mucus secreting cells/bear cilia.
Function: Secrete substances, mainly mucus, propulsion of mucus by ciliary action.
Location: Human trachea
Describe, location and function of stratified squamous epithelium
Describe: Thick epithelium membrane composed of basal cells (cuboidal or columnar) and surface cells (squamous). Surface cells are full of keratin and dead. Basal surface is active in mitosis.
Function: Protect underlying tissues from abrasion.
Location: Moist linings of esophagus, mouth and vagina; epidermis of the skin.
What is the difference between endocrine and exocrine glands?
Endocrine: Ductless glands which secretes chemical messages called hormones into the bloodstream. Ex. thyroid, adrenal, pituitary, pancreas
Exocrine: Cells which secrete products into ducts which are then transported to cavities and body surfaces. Ex. mucus, sweat, salivary gland
What are the functions of connective tissue?
- Binding and support
- Protection
- Insulation
- Transportation
What are the three types of fiber components of extracellular matrix?
- Collagen (Provides tensible strength)
- Elastic (Ability to stretch and recoil)
- Reticular (Forms the internal skeleton of soft organs)
What are the five types of connective tissue?
- areolar connective tissue (fibroblasts)
- Adipose tissue (adipocytes)
- Hyaline cartilage (chondroblasts and chondrocytes)
- Bone (Osteoblasts and osteocytes)
- Blood (erythrocytes and leukocytes)
Provide the description, function and location of areolar connective tissue
Describe: Gel like substance containing microphages, fibroblasts and mast cells.
Function: Wraps and cushions the organ with helping inflammation.
Location: Under epithelia of body surrounds capillaries
Provide the description, function and location of adipose tissue
Describe: Closely packed adipocytes or fat cells which push nucleus to side.
Function: Provides energy and insulates against heat loss.
Location: kidneys, eyeballs, hypodermis, breasts
Provide the description, function and location of hyaline cartilage
Describe: Made up of collagen fibers; chondroblasts produce the matrix until maturity (chondrocytes).
Function: Absorbs shocks in the joints; provides flexibility and resilience
Location: Ends of long bones; costal cartilages of ribs, nose, trachea and larynx
Provide the description, function and location of bone
Description: Contains many collagen fibers (lacunae) and very well vascularized.
Function: Stores minerals, fat, marrow; provides levers for the muscle
Location: Bone
Provide the description, function and location of blood
Description: Red and white blood cells in a fluid matrix.
Function: Transport of respiratory gases, nutrients, wastes and other substances.
Location: Blood vessel
What are the two major types of nervous tissue?
- Neurons: Generate and send electric impulses.
- Neuroglial cells: Support, protect and insulate neurons
Provide the description, function and location of nervous tissue?
Description: Made up of neurons and supporting glial cells.
Function: Transmit electrical signals from receptors and to effectors.
Location: Brain, spinal cord and nerves
What are the three types of muscular tissue?
- Skeletal muscle
- Cardiac muscle
- Smooth Muscle
Provide the description, function and location of skeletal muscle.
Description: Long striped fibers attached to bones.
Function: Voluntary movements of the body
Location: Attached to bones throughout the body.
Provide the description, function and location of cardiac muscle
Description: Branching, striated and intercalated disks.
Function: Propels blood into circulation (involuntary control)
Location: Walls of the heart
Provide the description, function and location of smooth membrane
Description: Small spindle shaped cells with no striations.
Function: Propels substances or objects in internal passageways (involuntary)
Location: Walls of hollow organs
What are three main types of epithelial membranes?
- Cutaneous
- Mucous
- Serous
What is cutaneous membrane?
It is the skin which covers our body. Outer epidermis is made up of stratified squamous epithelium.
What is mucous membrane?
Line body cavities which open to the exterior (such as respiratory and digestive tracts). Underlying connective tissue provides with nutrients/oxygen and removes waste.
Example: Trachea (Ciliated Pseudostratified columnar epithelium)
What is serous membrane?
Not open to exterior and cover organs in cavities. Consists of an outer parietal layer (line) and visceral layer (cover the organs). Serous fluid permits organs to slide without damage from abrasion.
