Lecture 41: Principles of viscera Flashcards
What are the 4 listed functions of viscera?
SEAD - secretion, excretion, absorption, digestion
What are the two types of viscera
Hollow/tubular and solid
What part of the body do most organ systems NOT involve?
The back
What are the three layers of hollow viscus?
From interior to exterior:
(Lumen), Mucosa, Muscularis, Serosa
What is the role of the serosa?
Minimizes the friction
What are waves of smooth muscle called?
Peristalsis
What structural feature may the mucosa have to increase surface area?
Folds
What are the two structural parts of a hollow organ?
Constrictions and dilations
Give an example of how knowing where constrictions are in an organ is useful?
Estimate where a caculus could become lodged in the urethra, ie restrictions in size such as constrictions
Where is a calculus likely to be lodged?
The orific
What two ducts do gallstones have to pass through to get to the bowls?
Cystic ducts and common bile duct.
What are the two types of smooth muscle?
Longitudinal and circular
What 2 features of smooth muscle is important for bladder control?
- Smooth muscle can be stretched without loosing any tension (important for storage and excretion) and can contract to force urine out to the exterior
- Motility
What are the two subdivisions in a secretory solid viscus?
Outer cortex and inner medulla
What structural feature is typical of solid viscus?
Solid viscera tend to have impressions/marks from adjacent structures.
What are the two types of sphincters?
Anatomical and functional
What are the 2 main roles of a sphincter?
Prevents reflux of contents and control passage of contents.
What can happen to a sphincter if a drug causes it to lose tone?
Anything that alters tension/tone of smooth muscle can cause unchecked flow of contents
What is a functional sphincter?
A tube that enters the wall of a muscle obliquely so that when the muscle contracts it closes the tube and prevents back flow, eg the ureter entering the bladder or in the esophagus entering the stomach via the diaphragm
What is the key difference between an anatomical sphincter and a functional sphincter?
No localized muscle thickening around a functional sphincter.
Are autonomic sphincters under involuntary or voluntary control?
Autonomic sphincters are under involuntary control
Are voluntary sphincter made of skeletal or smooth muscle?
Skeletal
Which line of defense are the voluntary and involuntary sphincters? (Think ‘rectum’)
1st - involuntary
2nd - voluntary
What are the serous membranes of the thorax and abdomen?
Thorax - pleura
Abdomen - peritoneum
