Human Coelomic Divisions

Coelom = body cavity within lateral plate mesoderm, lined by mesothelium and partitioned during development in all amniotes

Peritoneum = mesothelium & conn. tiss. that lines the abdominal coelomic cavity and the abdom. visceral organs

Retroperitoneal = Description of something that is “outside” the peritoneum (bladder, rectum, kidneys)

Coelomic Cavities

Transverse septum = separates pericardial & pleuroperitoneal cavities

Pericardial Cavity = coelomic cavity around the heart

Pleuroperitoneal cavity = coelomic cavity around all visceral organs except the heart

Peritoneal cavity = abdominopelvic cavity; lined by peritoneum

Coelomic Cavities

Coelomic Cavities

transverse septum

Pleural / Pulmonary Cavity = coelomic cavity around the lungs

evolved independently in reptiles and mammals

Pulmonary fold = (in reptiles) forms along the dorsal midline of the pleuroperitoneal cavity...

grows ventrolaterally around each lung. Each lung in separate pleural cavity.

Coelomic Cavities

Avian Cross Section

gut

lunglung

heart

pulmonaryfold

pleuralcavity

peritonealcavity

pericardialcavity

Unique to CrocodyliansPost Hepatic “Diaphragm”

Coelomic (pleuroperitoneal) fold = in mammals, forms transversely across the dorsal pleuroperitoneal cavity, behind the lungs and...

grows ventrally to meet the transverse septum.

Diaphragm = mucularized coelomic fold separating pleural and peritoneal cavities (anterior to the liver)

Mammal Coelomic Cavities

Mammal Longitudinal Section

lung

liver

pleuralcavity

peritonealcavity

pericardialcavity

coelomic fold

Developing Human Coelom

Coelomic fold component of diaphragm becomes muscularized.

Transverse septum component of diaphragm become the central tendon.

Mammalian Diaphragm

Human Coelomic Divisions

Amniota

monotre

mes

mar

supia

ls

euth

eria

ns

turtl

es

lizar

ds & s

nakes

croco

dilian

s

birds

prehepaticdiaphragm;1 pleural cavity 2 pleural cavities

* posthepatic “diaphragm”

*

Human Digestive System (and assoc. digestive organ) Development

General Digestive Terms

Human Digestive Tube Overview (Oral Cavity to Anus)

Human Associated Digestive Organ Development and Overview

Comparative Digestive Anatomy

Digestive System

Digestive tract = continuous tube; for extracting nutrients from food.

Endoderm surrounded by splanchnic mesoderm.

Digestive System

Endoderm = epithelial lining of most of digestive tract; usually simple epithelia.

Splanchnic mesoderm = surrounds endoderm, muscle and conn. tissues

Stomodeum = ectoderm; forms most of oral cavity & some salivary glands; stratified squamous epithelium.

Proctodeum = ectoderm; forms cloaca (posterior rectum); strat. squamous epithelium.

Digestive System Development

Human Endoderm Development

Human Endoderm Development

Pharyngeal Pouches = paired anterior pouches (mammals – 4, but the last one = 2

pouches; in non-mammalian gnathostomes = 6).

2nd pouch of tetrapods forms Eustacian tube between middle ear and pharynx

Thyroid Bud - between 1st and 2nd pouches

Other buds that form are respiratory (Osteichthyans), hepatic, dorsal pancreatic, ventral pancreatic, & allantoic

Endoderm Development

Human Endoderm Development

thyroid bud

respiratory bud

yolk sac

allantoicbud

liver budventralpancreaticbud

dorsalpancreaticbud

four pairspharyngealpouches

Liver = Largest coelomic organ; regulates chemical metabolism (detoxifies, glycogen storage, secretes serum albumin) & produces bile (emulsifies fats & contains RBC waste).

Develops from ventral hepatic bud from duodenum in ventral mesentary. Mostly endodermal; a little lateral plate mesoderm.

Bile released into duodenum via hepatic duct then common bile duct.

Gallbladder = Stores bile; connected to bile duct through cystic duct.

Human Liver

Vertebrate Embryo (section)

gut

coelom

Vertebrate Embryo (section)

gut

coelom

dorsalmesentery(splanchnic mesoderm)

hepatic bud

ventral mesentery(splanchnic mesoderm)

Vertebrate Embryo (section)

gut

coelom

dorsalmesentery(splanchnic mesoderm)

liver

falciform ligament(ventral mesentery)

Pancreas = A distinct gland located along the duodenum with endocrine (sugar metabolism regulation) and exocrine function (digestive enzyme secretion).

Endodermal.

Develops from dorsal and ventral pancreatic buds off of duodenum.

Human digestive enzymes enter intestine through vent. pancreatic duct connecting to common bile duct.

Human Pancreas

Pancreas Development

Human Digestive DevelopmentDevelop. Adult Human Epithelial Devel. Outpouchings

stomodeum anterior oral & nasal cavities

parotid salivary glands

pharynx (with openings)

oropharynx & nasopharynx(only Eustacean tube)

submandibular & sublingual salivary glands

thyroid from thyroid budtrachea & lungs from resp. bud

esophagus long -

stomach present -

intestine small intestine(duodenum, jejunoileum)

colon

liver + ducts from hepatic budpancreas from 2 pancreatic buds

cecum / appendixur. bladder in part from allantois

proctodeum rectum -

1. Epithelium – stratified squamous or simple columnar epith. around lumen.

2. Lamina Propria – loose conn. tissue.

3. Muscularis Mucosae – thin layer of smooth muscle.

4. Submucosa – loose connect. tissue.

5. Muscularis – 2-3 layers of skeletal or smooth muscle.

6. Serosa – thin layer of loose conn. tissue covered by a simple squamous epith. (coelomic mesothelium)

Digestive Tube Structure (Human)Esophagus to Rectum

endoderm

mesoderm

Esophagus Section

mesoderm

epithelium(strat. squamous)

muscularis mucosae(thin lamina propria between

muscularis muc. & epithelium)

submucosa

muscularis(2 layers, circular& longitudinal))

serosa

endoderm

Sphincter – ring of muscle that can close (or partially close) a point along the digestive tube.

Peristalsis – Rhythmic contraction of smooth muscle that pushes something along the digestive tract.

Ridges/folds in digestive tube that are perpendicular to the axis of the tube = slow movement

Ridges/folds parallel to the axis of the tube = speed movement

Digestive Tube Structure (Human)Esophagus to Rectum

Cleft Palate Cleft Palate = Secondary palate doesn’t fuse

along midline during development.

Salivary Glands = Oral cavity glands produce saliva; simple cuboidal epith. Parotid Glands - ectoderm

Submandibular Glands - endoderm

Sublingual Glands - endoderm

Human Salivary Glands

Human Pharynx

Human Oropharynx

Human Esophagus Section

mesoderm

epithelium(strat. squamous)

muscularis mucosae(thin lamina propria between

muscularis muc. & epithelium)

submucosa

muscularis(2 layers, circular& longitudinal))

serosa

endoderm

Human Abdominal Viscera

Human Stomach

lessercurvature

greatercurvature

Human Stomach SectionMuscularis has three layers, oblique, circular,

and longitudinal.

Human Small Intestine

Human Small Intestine

Plicae = folds of the intestinal epithelium. Villi = multicellular “finger-like” projections

of the intestinal epithelium. Columnar epith. cells have microvilli.

Human Small Intestine

Human Large Intestine

Rectum

Liver Ducts

cystic duct

common bile duct

pancreatic duct

hepatic duct

Human LiverTwo big lobes, left & right separated by

falciform ligament. Right lobe has subsidiary caudate and quadrate lobes.

ventral view(anterior view)

Human Bile & Pancreatic Ducts

Human Digestive System

Oral Cavity = mouth to pharynx, no separate nasal cavity in vertebrates without a secondary palate.

Mammals, crocodylians, & many turtles have a secondary palate, all other verts. lack this.

Salivary Glands = Present as multicellular, large glands only in Tetrapods, largest in amniotes.

Comparative Digestive Anatomy

Pharynx in non-amniotes also site or respiration (gills).

Esophagus is much longer in tetrapods than in non-tetrapods.

Crop = Distended region of the esophagus in birds for food storage

Pharynx- Esophagus

Stomach is ancestrally absent in vertebrates and its presence is a synapomorphy of gnathostomes.

Secondarily lost in lungfishes and a few groups of teleosts.

Gizzard = Highly muscularized stomach body of archosaurs, stratified squamous (keratinized) epithelium. (Gastroliths = “stomach stones”)

Stomach

Bird Digestive Tract

No lg. & sm. distinction, just intestine. Pyloric ceca = out-pocketings of ant.

intestine for digestion & absorption in some Actinopterygii.

Spiral valve = Spiral flap in intestine, increases surface area. In all craniates except teleosts & tetrapods. Spiral valve ntestines with spiral valves usually shorter and wider.

Rectal gland = out-pocketing of posterior intestine; secretes excess salts in Chondrichthys.

Non-Tetrapod (Fish) Intestine

Shark Digestive Tract

Tetrapods have small & large intestines separated by the Ileocolic / Ileocecal valve.

Cecum = out-pocketing of anterior large intestine for fermentation of plant matter or other digestion. Synapomorphy of amniotes (ancestrally 1, birds have 2)

Tetrapod Small & Large Intestine

Cloaca = (sewer in Latin) ectodermal; intestine, reproductive system, & urinary system all empty into the cloaca.

Vent = external cloacal opening Cloaca lost in therian mammals and

Actinopterygiians.

Separate, external anal and urogenital openings.

Cloaca

Liver usually large in chondrichthyans because it stores fats for buoyancy.

Gallbladder in gnathostomes but lost in many groups.

Pancreas distinct in gnathostomes (may be incorporated into liver in some teleosts & lungfishes as a hepatopancreas).

Pancreas may be single (as in humans and most verts.) or double when the two buds do not fuse.

Associated Organs/Glands

salivaryglands; spiral valve lost; lg. & sm. intest. (illeocecal sphincter)

Craniates

Myx

ini (

hagfis

hes)

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

true teeth; stomach

stom.lost

intestinal spiral valve; cloaca

rect

al g

land

cloa

ca lo

st

cecum

sturg

eons

&

paddle

fishes

gars bowfin

(Am

ia c

alva

)

TELEOSTS

reed

fishes

Class Actinopterygii

Intestinalspiralvalvelost

cloaca lost (separate openings)

Amniota

monotre

mes

mar

supia

ls

euth

eria

ns

turtl

es

lizar

ds & s

nakes

croco

dilian

s

birds

crop;2 large

intestinalceca

gizzardcloacalost

large intestinal cecum

Subphylum Vertebrata

Myx

ini (

hagfis

hes)

lam

preys

Chondrichth

ys

Actin

optery

gii

coel

acan

ths

lungfis

hes

amphib

ians

Mam

mal

ia

Reptil

ia

liver; pancreatic cells (diffuse in hagfishes & lampreys)

gallbladder; distinct pancreas (from two developmental buds)

Vertebrate Digestive TubeMyxini & lampreys

Chondrichthys Non-TeleostActinopterygii

oral cavity oral cavity oral cavity oral cavity

pharynx gill openings gill openings gill openings

esophagus short short short

stomach absent present present

intestine simple with spiral valve

simple with spiral valve

simple with spiral valve

cloaca present present absent

Vertebrate Digestive TubeTeleosts Lungfishes Amphibians

oral cavity oral cavity oral cavity oral cavity

pharynx gill openings gill openings gill openings when larval

esophagus short short long

stomach present absent present

intestine simple, NO spiral valve

simple with spiral valve

NO spiral valve, small intestinelarge intestine

cloaca absent present present

Vertebrate Digestive TubeMontremes Therians Turtles

oral cavity 2ary palate - oral & nasal

2ary palate -oral & nasal

small 2ary palate- oral & nasal

pharynx no openings(only Eustacean tube)

no openings(only Eustacean tube)

no openings (only Eustacean tube)

esophagus long long long

stomach present present present

intestine NO spiral valve, small intestinelarge intestine (with 1 cecum)

NO spiral valve, small intestinelarge intestine (with 1 cecum)

NO spiral valve, small intestinelarge intestine (with 1 cecum)

cloaca present absent present

Vertebrate Digestive Tubeliz. & snakes crocodilians birds

oral cavity oral cavity large 2ary palate- oral & nasal

oral cavity

pharynx no openings (only Eustacean tube)

no openings (only Eustacean tube)

no openings (only Eustacean tube)

esophagus long long long with crop

stomach present present with gizzard

present with gizzard

intestine NO spiral valve, small intestinelarge intestine (with 1 cecum)

NO spiral valve, small intestinelarge intestine

NO spiral valve, small intestinelarge intestine (with 2 ceca)

cloaca present present present

Cow Digestive System

Horse Digestive System

Human Digestive System