Session 6: Epithelial Tissues And Exocrine Glands Flashcards
What are mucous membranes?
Membranes that line certain internal tubes which open to the exterior and bear mucus secreting cells
What layers do mucous membranes consist of?
- epithelium (lines the lumen)
- connective tissue “lamina propria”
- smooth muscle “muscularis mucosae”
Aggregates of lymphocytes, known as ____________ are present in which layer of the alimentary tract?
Peyer’s patches
Connective tissue layer “Lamina propria”
How do serous membranes differ from mucous membranes?
They are thin, two layered membranes which line certain CLOSED cavities rather than spaces that open to the exterior
Serous membranes envelope the _________
Viscera
Serous membrane and __________ can be used interchangeably
Serosae
Serous membranes line what?
The peritoneum (many abdominal organs)
The pleural sacs (lungs)
The pericardial sac (heart)
Serous membranes secrete _________, __________ fluid to promote friction-free movement of the structures they surround.
Watery
Lubricating
What two layers does the serous membrane consist of?
- Simple squamous epithelium “mesothelium”
- Connective tissue layer
The connective tissue layer of serous membranes connects to what?
Epithelium of adjacent tissues
The connective tissue layer of serous membranes carries what?
Blood vessels and nerves
True of false: Heart, lungs and gut develop and lie within the serious cavity.
False!! They invaginate the cavity during development so are surrounded by it, not contained within it.
(Balloon analogy)
The inner layer of the serous cavity is known as the what?
Visceral Serosa
The outer layer of the serous cavity is known as the what?
Parietal Serosa
What are epithelia?
Sheets of contiguous cells that cover the external surface of the body and line internal surfaces
Simple epithelia are ____ cell(s) thick
One
Stratified epithelia are __________ cell(s) thick
More than one
Simple epithelia can be what four types?
Squamous- thin and flat
Cuboidal- cuboid shaped
Columnar- taller than they are wide
Pseudostratisfied- look stratified (more than one layer) but all attach to BM so are classed as “simple”
Stratified epithelia can be subdivided into what four types?
Squamous- thin and flat
Cuboidal- cuboid shaped
Columnar- taller than they are wide
Transitional- Can look squamous or columnar depending on how they are stretched
What area of the body are transitional stratifies epithelia confined to?
Urinary Tract
What is the basement membrane?
The thin, flexible acellular layer which lies between epithelial cells and the subtending connective tissue
What is the function of the basement membrane?
provides a strong, flexible layer for cells to adhere to and serves as a cellular and molecular filter
The simple squamous epithelium lining all vascular elements is known as what?
Endothelium
What is mesothelium?
The simple squamous epithelium that lines the pleural sac, the pericardial sac and the peritoneum
Endothelium can exchange ______ and _______ and allow certain blood cells to enter the tissues
gasses
nutrients
Give 4 or some locations of simple squamous epithelium
Lining blood and lymph vessels (endothelium) Linking body cavities (mesothelium) Pulmonary alveoli Bowman's capsule Loop of Henle
Give 4 functions of simple squamous epithelium
Active transport by pinocytosis
Lubrication (mesothelium)
Barrier (Bowman’s capsule)
Gas exchange (Pulmonary alveoli)
Simple cuboidal epithelium are located where?
Thyroid follicles
Small ducts of many exocrine glands
Kidney tubules
Surface of the ovary
What are some functions of the simple cuboidal epithelium at the locations in which they are found?
Absorption and conduit (Exocrine glands)
Absorption and secretion (Kidney tubules)
Barrier/covering (Ovary surface)
Hormone synthesis, storage and metabolisation (Thyroid)
Simple columnar epithelium are found where?
Stomach lining and gastric glands Small intestines and colon Gallbladder Large ducts of the exocrine glands Oviducts Uterus
What are some of the functions of simple columnar epithelium at their specific locations
Absorption (Small intestine, colon and gallbladder)
Secretion (Stomach lining and gastric glands, small intestine, colon)
Lubrication (Small intestine and colon)
Transport (Oviduct)
Pseudostratified epithelia are found where?
Respiratory tract: Lining the nasal cavity, trachea and bronchi
Epididymis and ductus deferens
Auditory tube
Lacrimal sac
What are the functions of pseudostratified epithelia in their specific location?
Secretion and conduit (Respiratory tract)
Absorption (Epididymis)
Mucus secretion (Respiratory tract)
Particle trapping and removal (Respiratory tract)
What type of epithelia are found at moist locations in the body?
Stratified squamous NON-KERATINIZED epithelia
What locations can stratified squamous NON-KERATINIZED epithelia be found?
Oral cavity Oesophagus Larynx Vagina Part of the anal canal Surface of the cornea Inner surface of the eyelid
What are the 2 main functions of stratified squamous NON-KERATINIZED epithelia?
Protection against abrasion
Reduction of water loss whilst remaining moist
What type of epithelia make up the EPIDERMIS?
Stratified squamous KERATINIZED epithelium
Where are the keratinized cells of the epidermis found and how do they differ from living epidermal cells?
Outer most layers
They lose their nuclei, die and become ‘keratinized’
The epidermis sits on a basement membrane, below which is the _________
dermis
The outer most layer of the epidermis is made up of what? Followed by what? Then what?
dead keratinized epidermal cells
living epidermal cells
dermis of connective tissue
The epidermis is mainly made up of which cells and their products?
Keratinocytes
What are the four layers of the epidermis?
Give their latin names also
Horny layer (Stratum corneum) Granular layer (Stratum granulosum) Prickle cell layer Basal Layer (Stratum Basale)
In which layer does keratinocyte mitosis mainly occur?
Basal Layer
Keratinocytes move up through the layers from which layer?
They undergo terminal differentiation at which layer?
Basal Layer
Prickle Cell Layer
Keratinocytes synthesise what?
Keratins
Keratins contribute to what?
Strength of the epidermis
Keratins are the main constituents of what parts of the body?
Hair and Nails
Abrupt changes to keratinocytes occurs at which which layer of the epidermis?
The Granular layer
The Stratum Corneum (Horny layer) is mainly made up of layers of what cells?
Flattened corneocytes
What changes occur at the granular layer of the epidermis?
The keratinocytes lose their plasma membrane
The keratinocytes begin differentiating into corneocytes
The granular layer of the epidermis contains keratohyalin granules, which are aggregations of what three things?
keratins
fibrous proteins
enzymes
Besides keratinocytes and corneocytes, what other cells are present in the epidermis?
Melanocytes
Langerhans cells
Both melanocytes and Langerhans cells are what kind of cells?
Dendritic cells
Melanocytes are confined to which layer of the epidermis?
Basal cell layer
Langerhans cells are a type of specialised immune cell known as?
Professional Antigen Presenting cells
Melanocytes are dendritic cells that originate from where?
Neural Crest
Melanocytes produce what?
Melanin
Langerhans cells originate from where?
Bone marrow
Langerhans cells are found scattered through which of the epidermal cell layers?
Prickle cell layer
The Langerhans cells have highly specialised capacity to do what?
Present antigen to T lymphocytes
Where can stratified squamous keratinized epithelium be found?
The surface of the skin
(Limited) In the oral cavity
What are the functions of stratified squamous keratinized epithelium?
Protection against abrasion and physical trauma
Prevent water loss
Prevents microbes entering the body
Shields against UV light damage
Transitional epithelium are confined to where in the body?
The urinary tract
renal calyces, ureters, bladder, urethra
What are the functions of the transitional epithelium?
Distensibilty
Protection of underlying tissues from toxic chemicals
What is a gland?
An epithelial cell of collection of cells specialised for secretion
Glands can be classified by what four things?
Destination of secretion
Structure of the gland
Nature of the secretion
Method of the discharge
When glands are classified by the destination of secretion what two categories do they come under?
Exocrine - glands with ducts
Endocrine - ductless glands that secrete into the bloodstream
When glands are classified by structure in what 6 ways can they be classified?
Unicellular or multicellular
Acinar or tubular
Coiled or branched
When classified by method of secretion, glands can be separated into what three categories?
Merocrine- exocytosis
Apocrine- secreted droplets covered in plasma membrane
Holocrine- whole cell breads down
What are the three major salivary glands known as
Parotid
Submandibular
Sublingual
Is the pancreas an exocrine or an endocrine gland?
The pancreas is BOTH an exocrine and an endocrine gland
What are the 5 signs of inflammation?
Tubor (Firmness) Rubor (Redness) "Erythema" Calor (Warmth) Dolor (Pain) Loss of Function "Functio laesa"
Pruitis is what?
Itchy skin
