Internal Surfaces of the Body Flashcards
What kind of places do mucous membranes line?
Certain internal tubes which open to the exterior
Give 3 places where mucous membranes line
NAME?
What do mucusoe bear to a varying degree?
Mucus-secreting cells
What do mucous membranes consist of?
- Epithelium
- Adjacent later of connective tissue
What do mucus membranes in the alimentary tract have?
A third layer consisting of smooth muscle
What kind of epithelium is present in mucous membranes?
Depends on site
What does the epithelium of the mucous membrane line?
The lumen of the tube
What is the layer of connective tissue in mucus membranes often referred to?
Lamina propria
What is the layer of smooth muscle isn the alimentary tract called?
Muscularis mucosae
Are serous membranes thick or thin?
Thin
How many parts do serous membranes consist of?
2
What kind of places do serous membranes line?
Closed body cavities (spaces that don’t open to the exterior)
What do serous membranes envelope?
The viscera
What do serous membranes secrete?
Lubricating fluid
What is the purpose of the serous membranes secretions?
Promotes relatively friction free movement of the structures they surround
What do serous membranes consist of?
NAME?
What does the mesothelium in serous membranes do?
Secrete watery lubricating fluid
What is the purpose of the connective tissue in serous membranes?
NAME?
What happens, regarding the serous membrane, during embryological development?
The heart, lungs and gut develop next to a bag-like cavity in which they invaginate
What is the result of the invagination of the heart, lungs and gut?
They are surrounded by serous membrane. They don’t lie within a serous cavity, they are surrounded by it
What is the pericardial sac?
Membrane that surrounds the heart
Describe the structure of the pericardial sac
NAME?
What is the purpose of the pericardial sac?
Allows the heart to beat
Does everything in the abdomen have serosa around it?
No
Give two examples of something in the abdomen without serosa around it
- Kidneys
- Bladder
What organs are intraperitonial?
NAME?
What is the gut mesentery?
A thin strand of peritoneum going out, wrapping around and folding back in again, that leads to the ileum
What does the alimentary canal consist of?
- Oesophagus
- Stomach
- Small intestine (duodenum, jejenum and ileum)
- Colon
- Rectum
What feeds into the alimentary canal?
Accessory glands-
- Salivary glands
- Liver
- Gall bladder
- Pancreas
What are the 4 layers of the gut wall?
- Mucosa (innermost)
- Submucosa
- External muscle layer
- Serosa
What is the submucosa made up of?
Connective tissue
What is the external muscle layer of the gut wall known as?
Muscularis externae
When is the serosa present in the gut wall?
If an intraperitoneal portion of the gut
What does the mucosa of the gut wall line?
The lumen
What does the mucosa of the gut wall consist of?
- Muscularis mucosae
- Lamina propria
- Epithelium
What epithelium does most of the gut have?
Simple columnar
What is often present in the lamina propria?
Peyer’s patches
What are Peyer’s patches?
Aggregations of lymphocytes
Where in the lamina propria are Peyer’s patches found?
Near the lumen
Why are Peyer’s patches found near the lumen/
Because it’s where bacterial attack occurs
What do Peyer’s patches do?
Produce igA’s to combat bateria and their toxins
What happens as you get further down to gut, towards the colon?
There are more aggregations of lymphocytes
What is the purpose of mucosal glands in the lamina propria?
They feed mucus into the gut
What is present in the submucosa?
Glands, arteries and nerves
What is the purpose of the arteries in the submucosa?
They keep the tissue alive
What do the glands in the submucosa produce?
Secretory products that then go into the gut lumen
Why is the submucosa often quite a loose tissue?
Because it allows it to change shape as muscles squeeze
What does the muscularis externa consist of?
Two layers of smooth muscle-
- Outer longitudinal layer
- Inner circular layer
What shape do both layers of muscle in the muscularis externa form?
Spirals
- Inner one very tight
- Outer one very relaxed
What is produced in the muscularis externa?
Successive peristaltic waves
What is the purpose of the successive peristaltic waves in the muscularis externa?
Moves luminal contents along the cut
What kind of membrane is the serosa around the outermost layer of the gut wall?
Serous
What does the mesentery contain?
- Arteries
- Veins
- Nerves
- Lymphatic vessels
Are cells normally contiguous in connective tissue?
No
What does connective tissue product a lot of?
Extra cellular material
What is the most fundamental fibre producing cell?
A fibroblast
What does connective tissue contain a lot of?
Immune system cells
What does the oesophagus consist of?
NAME?
What kind of epithelium is present in the oesophagus?
Stratified squamous non-keratinized
What is the purpose of the epithelium in the oesophagus?
Withstand abrasion
Is the lamina propria in the oesophagus tight or loose?
Loose
What does the lamina propria in the oesophagus contain?
- Blood vessels
- Lymph vessels
- Some smooth muscle cells
- Many cells of the immune system
What is the muscularis mucosae of the oesophagus?
A thin layer of smooth muscle cells
What does the submucosa of the oesophagus contain?
Mucus secreting glands
What is the importance of the muscularis externae in the oesophagus?
It moves food by peristalsis
What is the adventita of the oesophagus?
A thin, outermost layer of connective tissue
Does the oesophagus have peritoneal enfolding?
No
What happens to the oesophagus when it’s not containing something?
The lumen is convoluted
What does the stomach consist of?
NAME?
What does the gastric mucosa do?
Secretes acid, digestive enzymes, and the hormone gastrin
How many layers of smooth muscle are there in the muscularis externa of the stomach?
3
What are the 3 layers of smooth muscle in the muscularis externa of the stomach?
NAME?
What are rugae?
Folds of gastic mucosa, forming longitudinal ridges in the empty stomach
What are the ridges of the rugae a feature of?
The submucosa being flexible
What is the function of the jejunum?
Does most of the absorbance of nutrients
What does the jejunum consist of?
- Jejunal mucosa
- Submucosa
- Muscularis externa
- Plicae ciculares
What does the jejunal mucosa consist of?
- Simple columnar epithelium
- Lamina propria
- Muscularis mucosae
What are plicae circulares?
Circular folds of mucosa and submucosa that project into the gut lumen
What does the large intestine contain?
- Numerous crypts of Lieberkühn
- Peyer’s patches
What are crypts of Lieberkühn?
Tubular glands with lots of simple goblet cells in each
What epithelium is found in the crypts of Lieberkühn?
Simple columnar
What do the crypts provide?
- Lots of mucus
- Cells to the surface
What do the surface epithelial cells absorb?
Water and electrolytes
What is the conducting portion of the respiratory tract?
The nasal cavity → bronchioles
What is the purpose of the conducting portion of the respiratory tract?
To get air down to respiratory portion
What is the respiratory portion of the tract?
Respiratory bronchioles → alveoli
What is the purpose of the respiratory portion?
Where gas exchange happens
What is the purpose of the tracheal wall?
To hold the trachea open
What kind of epithelium is found in the tracheal wall?
Pseudostratified ciliated columnar
What does the fibroelastic membrane of the tracheal wall contain?
The trachealis muscle
What does the wall of the trachea have lots of?
Mucus glands
How are the walls of the trachea connected to the mucus glands?
Ducts
What to primary bronchi have?
Complete rings of cartilage
What happens to the rings of cartilage as the bronchi get smaller?
They become crescents
What epithelium do bronchi have?
Pseudostratified ciliated
Do bronchioles have cartilage?
No
Why don’t bronchioles need cartilage?
The surrounding alveoli keep the lumen open
What epithelium is in the bronchioles?
Simple columnar → cuboidal as it gets narrower
What are the types of cells in the alveoli?
- Type I
- Type II
What epithelium is found in type I alveoli cells?
Squamous
How much of the alveolar surface area do type I cells cover?
90%
What is the purpose of the type I alveolar cells?
Permit gas exchange with the capillaries
What epithelium is found in the type II alveolar cells?
Cuboidal
What is the purpose of the type II alveolar cells?
Produce surfactant so alveoli stay open
What lines the alveolar surface?
Numerous macrophages
What is the purpose of the macrophages at the alveolar surface?
Phagocytose particles
What does gas exchange occur over?
Blood-air barrier
What must gas pass through to get from the alveolus to the blood?
2 squamous cells
What 2 squamous cells must gas pass through to get from the alveoli to the blood?
NAME?
What are the capillaries surrounded by?
A ‘basketwork’ of capillaries and elastic fibres
What does the urinary tract consist of?
- Kidneys
- Ureter
- Bladder
- Urethra
What is the function of the kidneys?
Main job is to filter blood, to get rid of toxins and put them into urine
What must the bladder be able to do?
Distend
What does the ureter consist of?
- Transitional epithelium
- Fibroelastic lamina propria
- Circular muscularis externia
What happens to the stellate urethral lumen as urine passes through?
It becomes ovoid
What does the bladder wall consist of?
- Epithelium
- Smooth muscle in lamina propria
- 3 interwoven layers of muscularis externae
What epithelium does the bladder wall have?
Transitional
How is the impermeability to urine of the bladder wall conferred?
By the thick plasma membrane and tight intercellular junctions
How does the bladder wall appear when relaxed?
Folded
What is the job of the bladder wall?
To protect underlying tissues from toxins and stretching
