Lecture 13: Digestion And Diet Flashcards
What is the evidence of autralopithicines being omnivorous incorporating fibrous or gritty plant foods?
Dentition
What is the evidence for A. Robustus and Africanus having a herbivorous diet with fruit?
Tooth microwear
What is the evidence for the diet of hominins including meat or animal products?
Cut marks, fractures or animal bones and association of stone tools and animal bones
What evidence is provided for the modern human diet including dependence on animal foods and rich, less bulky foods such as meat?
Poor synthesis of taurine and some fatty acids.
Relatively short gut and rapid passage of food
What are the dietary adaptations for fruit eaters?
Broad incisors
Low rounded molar cusps
Long small intestine
What are the dietary adaptations for gum eaters?
Stout incisors
Claws for clinging
Long cecum
What are the dietary adaptations for leaf eaters?
Well-developed molar shearing crests Small incisors Large cecum Complex stomach Enlarged long intestine
What are the dietary adaptations of insect eaters?
Sharp cusps
Short, simple gut
What is Kay’s threshold?
Body weight (~500 g) that separates primarily insectivorous from noninsectivorous primates
What is the peritoneum and what are its layers?
A serous membrane
- Parietal layer: lines the body wall and has abundant pain fibers via nerves form the body wall
- Visceral layer (serosa): covers viscera and lacks pain fibers
What is characteristic of intraperitoneal organs?
- covered on most sides by visceral peritoneum
- Suspended by mesentery from the body wall
What is characteristic of retroperitoneal organs?
- Lie deep to the parietal peritoneum
- covered by parietal peritoneum on one side only
What organs are considered intraperitoneal organs and have a mesentery and are completely covered by the peritoneum?
- Stomach
- Small intestine
- Spleen
- Liver
- Gall bladder
- Cecum with vermiform appendix
- Large intestine
- *The ones listed above are all “abdominal”**
- Uterus
- Ovaries
- Uterine tubes
- *there are all considered pelvic**
What organs are considered extraperitoneal organs which have either no mesentery or lost it during development?
- Kidneys
- Suprarenal glands
- Uterine cervix
- *above are primarily retroperitoneal
- Duodenum
- Pancreas
- Ascending and descending colon
- Rectum
- *above are secondarily retroperitoneal
- Urinary bladder
- Distal ureters
- Prostate
- seminal vesicle
- Uterine cervix
- Vagina
- Rectum
- *above are all infraperitoneal
What supplies blood to the foregut?
Celiac trunk
What does the foregut consist of?
- Esophagus
- Stomach
- Duodenum
- Liver
- Gallbladder
- Spleen
- Pancreas
What supplies blood to the midgut?
Superior mesenteric artery
What makes up the midgut?
- Duodenum
- Jejunum
- Ileum
- Cecum and appendix
- Ascending colon
- 2/3 of transverse colon
What supplies blood to the hindgut?
Inferior mesenteric artery
What makes up the hindgut?
- 1/3 transverse
- Descending and sigmoid colon
- rectum and anal canal
At what level does the thoracic esophagus pierce the diaphragm? What is this called?
T10
The esophageal hiatus
**slightly left of midline
What happens once the thoracic esophagus pierces the diaphragm and where does this occur?
It turns sharply left to enter the stomach at the cardiac orifice
~T11
About how long is the abdominal esophagus?
2.5 cm
What is characteristic of the esophageal sphincter?
It’s physiologic, not well defined anatomically
What are openings in the diaphragm called?
Hiatuses
What structure passes through the diaphragm at T8
Inferior vena cava
What structure passes through the diaphragm at T 12?
Aorta
What is a sliding hiatal hernia?
- Esophageal hiatus of diaphragm enlarges or weakens
- Abdominal esophagus and parts of the stomach (cardia and sometimes fundus) herniate into the thorax
What is a paraesophageal hiatal hernia?
- Defect in diaphragm next to the esophageal hiatus
- Permits fundus of stomach to herniated (not usually the esophagus)
Why do humans typically ingest less food than predict for their body size?
Because we are really good at storing fat and good an taking in food with a very nutrient rich high caloric value
Where is the stomach located? Where is the left end fixed at? Right end?
Left hypochondriac and epigastric regions
- Left end fixed at T10-11
- Right end fixed at L1-2
What are the parts of the stomach?
- Fundus (cranial part of stomach)
- Cardiac part, cardiac orifice (attached to esophagus)
- body
- Pylorus (pyloric antrum is entrance to pylorus)
What is the rugae of the stomach?
Longitudinal folds in the stomach
What is the pylorus/pyloric sphincter/pyloric orifice?
Lowest part of stomach. Pyloric sphincter determines passage of food to duodenum.
Pyloric orifice lines the sphincter and is the entrance to the duodenum
Which curvature (lesser or greater) is found on the side of the stomach closes to the esophagus?
Lesser curvature
Which curvature (lesser or greater) of the stomach is found opposite the esophagus?
greater curvature
What are the 3 parts of the small intestine?
Duodenum
Jejunum
Ileum
How is the duodenum shaped? How long is it?
C-shaped
10 inches long
Where is the duodenum located approximately at? Where does it start and end at?
L1-L4
Starts at pylorus of the stomach and ends at the duodenal-jejunal junction
What are the 4 parts of the duodenum?
- Superior
- Descending
- Horizontal
- Ascending
What “type” of organ is the duodenum considered? What is it covered by?
Secondarily retroperitoneal (except for some of the 1st and 4th parts)
- Covered anteriorly by peritoneum except where the mesocolon of the transverse colon crosses the 2nd part.
- The first part is surrounded by the hepatoduodenal ligament
Where does the root of the mesentery begin at?
The duodeno-jejunal flexure
Where does the superior duodenum start at? How long is it and what holds it in place?
Starts at the pyloric sphincter
~2 inches lone
Held in place by the hepatoduodenal ligament
What is the widened area of the superior duodenum referred to as?
Duodenum bulb
About how long is the descending duodenum and what “type” of organ is this considered?
~3 inches long
All secondarily retroperitoneal
Where do the bile and pancreatic ducts enter into he duodenum?
Second part of duodenum (descending portion) at the major duodenal papilla