Lecture 6: Epithelial cells & specialised surfaces Flashcards
What is a mucous membrane?
3 layers of epithelium, connective and smooth muscle tissue that line internal tubes that open to exterior.
Where can you find mucous membranes?
GI tract
Respiratory tract
Urinary tract
What is a serous membrane?
2 thin layers of mesothelium and connective tissue that lines closed body cavities; exude lubricants and envelop viscera (internal organs)
Where can you find serous membranes?
Peritoneum of abdominal organs
Pleural sacs of lungs
Pericardial sac of heart
Compare and contrast serous and mucous membranes.
S= lines closed body cavities M= lines open-to-exterior cavities
S= 2 thin layers of tissue M= 3 layers of tissue
Both carry blood, lymph vessels and nerves
Describe and explain the analogy of serous membranes.
Balloon analogy: outer balloon wall is parietal serosa & inner balloon wall is visceral serosa. Air inside balloon is cavity and (balloon surrounded) hand is an organ.
Where is the parietal serosal membrane in relation to the cavity?
It lines the outer edges of the cavity.
Where is the visceral serosal membrane in relation to the cavity?
It is closest to the organs surrounded by the membrane.
What is the definition of epithelium?
Adjacent cell sheets that cover external surfaces of the body and line internal surfaces; derived from embryological germ layers.
What are the names of the embryological germ layers and what do they become?
Ectoderm: epidermis
Mesoderm: inner & outer GI tract lining
Endoderm: inner linings of body cavities
Give some surfaces (exterior, interior to exterior and closed interior) with epithelial linings.
Exterior: skin
Interior to exterior: GI tract; respire. tract; genitourinary
tract.
Closed interior: pericardial sac; pleural sacs; blood vessels, lymphatic vessels
How can you classify epithelial tissue? (8 points)
- simple squamous
- simple cuboidal
- simple columnar
- stratified squamous (non and keratinised)
- stratified cuboidal
- stratified columnar
- pseudostratified columnar
- transitional
How can you tell the difference between stratified columnar and pseudostratified columnar?
Stratified columnar has more than 1 cell thick whereas pseudo. columnar is 1 cell thick but the nuclei are at different levels: hence looks stratified.
What is the basement membrane?
Basal lamina and reticular layer found at the basal (bottom) part of cells and this anchors epithelium and underlying connective tissue.
Give the functions of simple squamous epithelia.
Fast material exchange
Barrier to fluids (lymphatics and vasculature)
Barrier in the brain and CNS (prevent fluid leaking out)
What are some examples of simple squamous epithelium?
Bowman’s capsule barrier
Lungs, heart, viscera serosa
Mesenchymal cells of cavities
What are 3 functions of epithelia?
Secretion Protection Reproduction Reabsorption Lubrication
Name the 2 opposing surfaces of an epithelial cell and describe what you find at these surfaces.
Apical: microvilli, cilia, keratin(skin)
Basal membrane: basal & reticular lamina
Give the functions of simple cuboidal.
Absorption
Absorption & secretion
Barrier/ covering
Hormone syn. storage and mobilisation
What are some examples of simple cuboidal?
Lining of exocrine glands
Follicle cells of thyroid
Lining of ovaries
epithelial lining kidney tubules
Give the functions of simple columnar.
Absorption
Secretion
Lubrication
What are some examples of simple columnar?
Small intestine
Colon
gallbladder
gastric glands
Give the functions of pseudostratified columnar.
Secretion
Mucus secretion
Particle trapping and removal