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Rectum

• Rectum
• In pelvis(сальник)
• No teniae
• Strong longitudinal muscle layer
• Has valves
• Anal canal
• Pectinate (гребенчатые линии)line*
• Inferior to it: sensitive to pain
• Hemorrhoids (enlarged veins)
• Superior to pectinate line: internal
• Inferior to pectinate line: external
• Sphincters (close opening)
• Internal*
• smooth muscle
• involuntary
• External*
• skeletal muscle
• voluntary

• *

• *

• *

Defecation

• Defecation
• Triggered by stretching of wall, mediated by spinal cord parasympathetic reflex
• Stimulates contraction of smooth muscle in wall and relaxation of internal anal sphincter
• If convenient to defecate voluntary motor neurons stimulate relaxation of external anal sphincter
• (aided by diaphragm and abdominal wall muscles)

Histology – large intestine

• No villi
• Fewer nutrients absorbed
• “Columnar cells” in pic = absorptive cells
• Take in water and electrolytes
• A lot of goblet cells for mucus
• Lubricates stool
• More lymphoid tissue
• A lot of bacteria in stool

4. Histology of auxillary organs

• Supply secretions contributing to the breakdown of food
• Teeth & tongue
• Salivary glands
• Gallbladder
• Liver
• Pancreas

The Liver

• Largest gland in the body (about 3 pounds)
• Over 500 functions
• Inferior to diaphragm and epigastric area protected by ribs
• R and L lobes
• Plus 2 smaller lobes
• Falciform ligament
• Mesentery binding liver to anterior abdominal wall
• 2 surfaces
• Diaphragmatic
• Visceral
• Covered by peritoneum
• Except “bare area” fused to diaphragm

• anterior

• posterior

• Fissure (углубление) on visceral surface
• Porta hepatis: major vessels and nerves
• enter and leave - see pics
• Ligamentum teres(круглая связка): remnant of umbilical vein in fetus, attaches to navel(пупок)