ANAT20006 Lecture Notes - Lecture 21: Serous Membrane, Peristalsis, Mesentery
12 Jun 2018
School
Department
Course
Professor
LECTURE 21
VISCERA & VISCERAL SYSTEMS
VISCERA
•(1) organs regulating internal environment. Tend to be located in cavities including thorax,
abdomen, pelvis (not all; Eg. Testes).
•Involved in excretion, digestion, absorption.
VISCERAL SYSTEMS
•(2)
Lecture 21 - Friday 8 September 2017
ANAT20006 - HUMAN STRUCTURE & FUNCTION
HOLLOW VISCERA
•(3) typically tubular, cylindrical wall with lumen in the middle lined by
mucosa (internal layer) which may have folds that increase surface area
for absorption.
•Muscularis (middle layer) contains smooth muscle that may produce
waves of contraction – ‘peristalsis’, which help with propulsion. Can
also be involved in things like expansion and mixing (Eg. Stomach).
•Serosa (external layer) minimises friction via fluid production.
SEROSA
•(4) membrane lining viscus is serosa.
•Covers external surface of hollow viscera: minimizes friction
•Usually derived from lining of body cavities
•Can be continuous with a mesentery attaching
viscera to body wall (Eg. small intestines)
MUSCLE COATS
•(5) smooth muscle wall can be either circular or longitudinal.
•Provides for motility (eg peristalsis) & expansion (eg smooth
muscle may be stretched without changing force of contraction
to allow for storage of large volumes of liquids (eg. bladder)
or solids (eg. rectum)).
•At critical point of storage (stretch) reflexes are initiated to
cause micturition or defecation.
•Smooth muscle has the important property to help to
produce contraction even when stretched to allow
movement of things our of reservoirs.
LUMEN OF TUBULAR (HOLLOW) VISCUS
•(6) main feature: presence of dilations and
constrictions.
•Constrictions:
•usually at beginning & end
•also at specific sites along its course
•(Eg. where male urethra pierces pelvic floor)
•A duct tends to narrow where it approaches the wall of
a hollow viscus – its orifice (opening)
•Calculus (stone) likely
to lodge at orifice.
CALCULI
•(7) stones can be 2cm in
diameter.
SPHINCTERS
•Tubular viscera have a sphincter.
ANATOMICAL SPHINCTER
•(8) Localised muscle thickening around wall of tubular viscus
– controls passage & prevents reflux of contents. Also at distal
ends of ducts, near an external orifice.
•Top of urethra leaving bladder, and bile and pancreatic ducts.
Lecture 21 - Friday 8 September 2017
ANAT20006 - HUMAN STRUCTURE & FUNCTION
Document Summary
Tend to be located in cavities including thorax, abdomen, pelvis (not all; eg. Can also be involved in things like expansion and mixing (eg. Stomach): serosa (external layer) minimises friction via fluid production. Serosa: (4) membrane lining viscus is serosa, covers external surface of hollow viscera: minimizes friction, usually derived from lining of body cavities, can be continuous with a mesentery attaching viscera to body wall (eg. small intestines) Calculi: (7) stones can be 2cm in diameter. Anatomical sphincter: ( ) localised muscle thickening around wall of tubular viscus. Controls passage & prevents reflux of contents. Also at distal ends of ducts, near an external orifice: top of urethra leaving bladder, and bile and pancreatic ducts. Occur due to relationship between viscus and surrounding structures. Solid viscus: (11) glands are clusters of secretory (or excretory) cells. Eg. pancreas, liver, thyroid gland: external capsule (protection) lined by serosa (reduces friction).
