Mesenteries

mesentery

structure consisting of a double layer of peritoneum

mesentery funcitons

anchors organs in place so they dont move when moving through the digestive system

produces a route for BV and nerves

stores fat- especially greater momentum

intraperitoneal organ defintion

conencted by mesenteries

intraperitoneal organs

liver, gall bladder

stomach, spleen

jejunum, ileum

transverse, sigmoid colon

retropeitoneal def

located behind the parietal peritoneum rather than being compeltely surrounded by the visceral peritoneum

retropertineal organs

dudoenum

cecum

ascedning, descending colon

pancreas

kidneys, ureters

IVC, abdominal aorta

primary retroperitaoneal organs def

developed behind the peritoneum to begin with

primary retriperitoneal organs (KAUAI)

kindeys

adrenal gland

ureters

abdominal aorta

IVC

secondary retroperitoneal organs def

started out intraperitoneal but later became attatched to the posterior abdominal wall

secondary retroperitoneal organs steps

1. organ initially has a

mesenetery and is intraperitioneal

secondary retroperitoneal organs steps

2. as development occurs, the organ

moves/rotates toward the psoterior abdominal wall

secondary retroperitoneal organs steps

3. mesentery becomes pressed

against the posterior abdominal wall

secondary retroperitoneal organs steps

4. mesentery fuses w/

posterior parietal peritoneum

secondary retroperitoneal organs steps

5. organ becomes

secondarly retroperitoneal

secondary retroperitoneal organs (DPAD)

dudoenum

pancreas

ascending colon

descening colon

falciform ligament (ventral)

anchors liver to the ventral body wall

divides liver inot left and right lobes

lesser omentum (ventral)

liver to lesser curvature of stomach

greater omentum (dorsal)

greater curvature of stomach to dorsal body wall

mesentery proper (dorsal)

jejunum and ileum to dorsal body wall

transverse mesocolon (dorsal)

trasnverse colon to dorsal body wall

sigmoid mesocolon (dorsal)

sigmoid colon to dorsal body wall

stomach is an enlargement of

the foregut

the liver devlops as a ventral outgorwith of the

foregut into the ventral mesentery

as the organs devleop they rotate, ex of stomach and liver

stomach goes left and liver goes right

the stomachs uneven and rotational growth pulls the dorsal mesentery

to the left

the mesentery continues to grow inferiorly, forming a double layered apron over

the tranverse colon (greater omentum)

two types of abdominal organs

segmental/somite derived

non-segmental

segmental/somite derived (kidneys, gonads)

supplied by PAIRED arteries from abdominal aorta

venous blood drians directly inot the IVC

non-segmental (gut tube and derivatives- unpaired)

supplied by UNPAIRED arteries form the abdominal aorta

venous blood passes through the liver first via the hepatic portal system

left gonadal vein goes to the

left renal vein and

right gonadal vein goes

staright to the IVC

3 unpaired arteries

celciac trunk —> foregut

SMA —> midgut

IMA —> handout

splenic a. supplies

spleen and pancreas

proper hepatic a. supplies

liver

branches into L and R hepatic artery

gastroduodenal a. supplies

stoamch and duodneum

branch off of common hepatic artery

L and R gastric a. supply

blood to lesser curvature of stomach

gastro-omental a. supply

blood to greater curvature of stomach

anastomosis

connection between two arteries, bypassing blockages

example of anastomosis

stomach (r and l gastro-omental)

these two arteries anastomose (connect) along the greater curvature of the stomach

blood can reach the stoamch in both directions

if BF through one vessel is reduces, blood may be able to reach the area through the other connected vessel

arterial arcade

serious of branching and reconnecting artieries that create a network of arches

what doeas rterial arcade ensure

consistent BF to organs in case of blockage

venous blood return - abdominla veins (segmental)

1. arteries branch off abdonimal aorta , enter organ and branch off into capillaries

2. capillaries merge giving rise to veins

3. veins empty inot IVC

portal veins

veins that begin and end in capillaries beofre entreing the heart

normal BF

artery—> capillary —> vein —> heart

portal system BF

artery —> capillaries —> vein —> second capillary bed —> vein —> heart

easy way to think of portal veins

a venous bridge between two capillary networks

venous blood return- abdominla veins (non-segmental)

1. arteries branch off abdominal aorta, enter organs and branch into capillaries

2. capillaries merge giving rise to veins (ex: superior mesenteric vein)

3. these enter into a signle heaptic portal vein whcih enters into the liver and branches off into capillaries

4. capillaries merge giving rise to multiple hepatic veins

5. hepatic veins empty into the IVC

hepatic portal vein take blood

TO the liver

hepatic vein take blood

AWAY from the liver

liver processes

blood from the digestive tract before sending it into genral curculation (quality control)

the liver: stores…, clears…, destroys…

stores excess glucose as glycogen

celars blood of drugs, alcohol, toxins, ammonia

destroys pathogens (bacteria, viruses, ect.)

hepatic portal veins is formed by

spelnic vein and SMV

autonomic innervation

nerve supply to organs that control involuntary functions

Foregut (arterial supply, sympathetic, parasympathetic)

arterial supply: celiac trunk

sympathetic: origin: T5-T9, celiac ganglion

parasympathetic: vagus nerve

Midgut (arterial supply, sympathetic, parasympathetic)

arterial supply: SMA

sympathetic: origin: T10-12, superior mesenteric ganglion

parasympathetic: vagus nerve

Hindgut (arterial supply, sympathetic, parasympathetic)

arterial supply: IMA

sympathetic: origin: L1-L3, inferior mesenteric ganglion

parasympathetic: S2-S4

sympathetic motor pathways

originate in thoracic and lumbar spinal cord

pre and postganglionic neruons synapse in preverterbal ganglia

parasympathetic motor pathways

origiante from gray matter of brain or sacral spinal cord

neurons synapse in terminal ganglia in the wall of the target organ

stomach, intestines (sympathetic, parasympathetic)

sympathetic: decrease motility

parasympathetic: increase motility

Pancreas (sympathetic, parasympathetic)

sympathetic: inhibit enzyme secretion

parasympathetic: promote enzyme secretion

Liver (sympathetic, parasympathetic)

sympathetic: inhibit bile secretion, promote glycogen breakdown into glucose

parasympathetic: promote bile secretion, glucose storage as glycogen

sympathetic responses

reduce digestive system activity to prioritze BF to/energy use by skeletal muscles

breakdown glycogen into glucose (fuel for ATP production in msucles)

parasympathetic responses

inhibit motlitiy (movement of food throughout gut)

increase availibility of enzymes, bile for digestion/absorbtion