Session 5.2b - Lecture 1 - Epithelial Tissues and Glands Flashcards
Slides 17 - 36
What is the basal lamina?
Often used interchangeably with basement membrane, but it forms a part of the basement membrane. (Won’t come across term much)
What is simple squamous epithelia?
A single layer of thin, squamous cells
What do we call a single layer of thin, squamous cells?
Simple squamous epithelia
Fig. 18
Caption this image
Simple squamous
Dashed line indicates if we took a cross-section
Draw simple squamous epithelia.
Now draw a dashed line indicating a cross-section.
See Fig. 18
Simple squamous
Fig. 19
Caption and label this image.
A glomerulus stained with PAS.
Simple squamous epithelium forms the parietal layer of Bowman’s capsule.
Draw a glomerulus on a histology slide.
See Fig. 19
A glomerulus stained with PAS.
Simple squamous epithelium forms the parietal layer of Bowman’s capsule.
What is the glomerulus?
A network of capillaries known as a tuft, at one end of the nephron (the functional unit of the kidney)
What is the function of the glomerulus?
Loops around around with blood going in and out - filtering the blood, which is what the kidney does
What’s the basic unit of a kidney?
The nephron
What is the Bowman’s capsule?
Bounding edge on the free space, that performs the first step in the filtration of blood (first filtrate being produced)
What epithelium lines the Bowman’s capsule?
Simple squamous epithelium.
Simple squamous epithelium on a histology slide appears how?
Dark blue nucleus
Cytoplasm barely visible bc it’s so thin, as is the basement membrane
How does the nucleus appear on a simple squamous epithelium histology slide?
Dark blue - big
How does the cytoplasm appear on a simple squamous epithelium histology slide?
Barely visible bc it’s so thin
How does the basement membrane appear on a simple squamous epithelium histology slide?
Barely visible bc it’s so thin
What is the tuft of blood capillaries called in the kidney?
The glomerulus
What filters blood in and out of the kidney?
The first step is blood filters from the glomerulus into the Bowman’s capsule.
What epithelium lines the arteriole?
Simple squamous epithelium
How does the endothelium of an arteriole appear on a histology slide?
Has much smaller nuclei than the bigger ones of smooth muscle that surround the arteriole
What surrounds an arteriole?
- Endothelium
- Basement membrane
- Smooth musclw
What epithelium lines the venules?
Simple squamous epithelium - appears flattened, thin, single layer of cells lining it
What epithelium lines the lymphatics?
Simple squamous epithelium
What do we call the simple squamous epithelium that lines the blood system/vascular elements?
Endothelium
What is endothelium?
The simple squamous epithelium that lines all vascular elements (arterial, venous, capillary and lymphatic) - i.e. the blood system
What epithelium lines the glandular duct in a neurovascular bundle?
Stratified cuboidal (slide) / columnar (voice) epithelium
Fig. 20
Label the image.
A L L D V
A neurovascular bundle.
Simple squamous epithelium lines the lumen of an arteriole (A), a venule (V), and two lymphatics (L).
(D = duct lined by stratified cuboidal epithelium)
Draw how a neurovascular bundle would appear on a histology slide. Identify the epithelia that would surround the structures.
See Fig. 20
A L L D V
A neurovascular bundle.
Simple squamous epithelium lines the lumen of an arteriole (A), a venule (V), and two lymphatics (L).
(D = duct lined by stratified cuboidal epithelium)
Fig. 20
What is surrounding the arteriole?
(Big circle)
A layer of simple squamous epithelia
Smooth muscle further around that
How can we identify simple squamous epithelia on a histology slide?
They have a flattened, thin, single layer of cells lining them
Fig. 21
What structure is this figure showing?
Something as small as a capillary, could call it a capillary
Fig. 21
What does the structure have inside of it?
RBCs coursing along it
Fig. 21
Describe the appearance of what is lining the ‘capillary’.
Flattened nuclei of simple squamous epithelium (endothelium).
Why is the capillary lined with simple squamous epithelium?
This endothelium is really important for immunological cells to get through that, to come in the blood and to migrate through that into diseased tissues and so on
How is the capillary specialised for immunological cells to migrate through the blood?
Capillaries are lined with endothelium, which are simple (one cell layer thick) squamous epithelia - meaning immunological cells can migrate into the blood and travel to diseased tissues.
What are the structures lined by endothelium in the vascular system?
- Arteries
- Veins
- Capillaries
- Lymphatics
What is the function of the endothelium?
- Exchange gases and nutrients
- Allows certain blood cells to enter the tissues
- Regulate platelet coagulation
How is the endothelium specialised for its function?
- THIN to allow gas/nutrient exchange
- Cells can DRAW APART to allow MIGRATORY CELLS to go through, including WBCs
What is the difference between endothelium and mesothelium?
Endothelium - simple squamous epithelium that lines vascular elements (e.g. arteries, veins, capillaries, lymphatics)
Mesothelium - simple squamous epithelium that lines serous membranes (e.g. pleural sac, pericardial sac, peritoneum)
Fig. 21
Label the image.
The simple squamous epithelium lining all vascular elements (arterial, venous, capillary and lymphatic) is termed ENDOTHELIUM.
- Endothelium can exchange gases and nutrients, allow certain blood cells to enter the tissues, and regulate platelet coagulation.
(When simple squamous epithelium lines the pleural sac, the pericardial sac, and the peritoneum, it is termed MESOTHELIUM).
Draw a capillary on the histology slide. Label the endothelium (drawn accurately).
See Fig. 21
The simple squamous epithelium lining all vascular elements (arterial, venous, capillary and lymphatic) is termed ENDOTHELIUM.
- Endothelium can exchange gases and nutrients, allow certain blood cells to enter the tissues, and regulate platelet coagulation.
(When simple squamous epithelium lines the pleural sac, the pericardial sac, and the peritoneum, it is termed MESOTHELIUM).
What blood cells does the endothelium allow to enter the tissues?
Migratory cells and WBCs.
What are the functions of the simple squamous epithelium?
- Lubrication
- Gas exchange
- Barrier
- Active transport by pinocytosis
Simple squamous epithelium plays an important function in lubrication. Where is this a major function?
Pericardium
Pleura
Peritoneum/viscera
What is the problem with lubrication from simple squamous epithelium?
Secretion of fluid can be excessive.
Give 2 examples of how secretion of fluid from serous membranes can be excessive.
Fluid from serous membranes is normally very little/thin. However, it can accumulate in:
- Hydrocoele around testis
- Excessive fluid in pleural space
What is a hydrocoele?
An accumulation of serous fluid in a body cavity. It is often used to describe the accumulation of fluids around a testicle (hydrocoele testis).
It is often caused by fluid secreted from a remnant piece of peritoneum wrapped around the testicle, called the tunica vaginalis
What is the hydrocoele around the testis?
An accumulation of the clear serous fluid, which is normally present in just a thin amount.
What is the tunica vaginalis?
A pouch of serous membrane that covers the testis, derived from the peritoneum.
What is a hydrocoele around testis?
Accumulation of clear serous fluid between visceral and parietal layers of tunica vaginalis.
What can excess serous fluid in the tunica vaginalis lead to?
Hydrocoele around the testis (accumulation of clear serous fluid between visceral and parietal layers of tunica vaginalis)
What is excessive fluid in the pleural space around the lungs called?
Pleural effusion
What is a pleural effusion?
When there is excess fluid in the pleural space around the lungs
How is a pleural effusion normally treated?
Chest drain via a needle to drain fluid off, allowing lung to expand fully
What do you need to be careful about in pleural effusion drainage?
- How it’s drained
- Where the needle’s placed
- Where to put that needle to drain the fluid off
Where are simple squamous epithelium found in the alveoli?
- They line the capillaries coursing through the alveoli
- They line the Type 1 pneumocytes which are the major cells forming the walls of the capillary
What are Type 1 pneumocytes?
Major cells forming the walls of the pulmonary alveoli (cover approx. 90-95% of its surface and are involved in gas exchange).
They are simple squamous cells.
Give an example where simple squamous epithelium is important for gas exchange.
Type 1 pneumocytes of pulmonary alveoli.
Explain how simple squamous epithelium is important for type 1 pneumocytes of pulmonary alveoli.
Gas exchange -
SSE is very thin so gas has only to travel across something just a fraction of a micron to move from the air into the RBCs of the capillaries
Explain how the simple squamous epithelium of the alveoli is related to its function.
SSE is very thin so gas has only to travel across something just a fraction of a micron to move from the air into the RBCs of the capillaries, therefore aids the function of gas exchange.
Give an example of where the simple squamous epithelium acts as a barrier.
In the Bowman’s capsule (barrier for filtration).
What is the function of the simple squamous epithelium in the Bowman’s capsule?
To act as a barrier - it is a filtration barrier from the glomerulus to the Bowman’s capsule in the nephron.
Where is the simple squamous epithelium capable of active transport by pinocytosis?
Mesothelium & endothelium
What is pinocytosis?
- The ingestion of liquid into a cell by the budding of small vesicles from the cell membrane.
- Pinocytosis (fluid endocytosis) is a mode of endocytosis in which small particles suspended in extracellular fluid are brought into the cell through an invagination of the cell membrane, resulting in a suspension of the particles within a small vesicle inside the cell.
The ingestion of liquid into a cell by budding of the cell membrane into vesicles is know as what process?
Pinocytosis
What is the relationship between pinocytosis and simple squamous epithelium?
Simple squamous epithelium has a function of active transport by pinocytosis in the mesothelium and endothelium.
What is simple cuboidal epithelium?
A single layer of polygonal cells, whose height and width are approximately equal.
A single layer of polygonal cells, whose height and width are approximately equal is which type of epithelium?
Simple cuboidal epithelium
What shape are simple cuboidal epithelium?
Polygonal from the top, but approximately equal height and width (i.e. cuboidal)
How many layers of cells is a simple cuboidal epithelium?
One (simple = 1 cell layer)
Fig. 23
Caption and label this image.
Simple cuboidal: a single layer of polygonal cells, whose height and width are approximately equal.
Draw an image of simple cuboidal cells from the top, with a basement membrane underneath.
See Fig. 23
Simple cuboidal: a single layer of polygonal cells, whose height and width are approximately equal.
How do simple cuboidal epithelium look in cross-section?
Cuboidal
A ‘cuboidal’ looking single layer of cells is seen in cross-section. What type of epithelium does this represent?
Simple cuboidal epithelium
What is a neurovascular bundle?
The combination of nerves, arteries, veins, and lymphatics in the body that travel together.
The combination of nerves, arteries, veins, and lymphatics in the body that travel together is known as what?
A neurovascular bundle
Give examples of where you would find simple squamous epithelium.
MESOTHELIUM - serous membranes surrounding the:
- – pericardium (heart)
- – pleural sac (lungs)
- – peritoneum (abdominal cavity)
ENDOTHELIUM - the vascular system
- arteries
- veins
- capillaries
- lymphatics
Miscellaneous:
Bowman’s capsule (kidney)
Alveoli (lungs)
Tunica vaginalis (testis) (NB: derived from peritoneum)