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Flashcards in Week 2 Content Deck (23):

What does endoderm form?

The lining of the digestive tract which covers the entire length of the body. It buds off the liver, gall bladder, pancreas and lungs. The cranial part becomes the pharynx with budding of the thyroid, thymus and parathyroid.


During body folding, there is the formation of an endodermal tube. What does the tube form?

The gut tube.


The mesodermal layer of the gut tube consists of what type of mesoderm?

Splanchnic mesoderm.


What type of mesoderm lines the body cavity?

Somatic mesoderm.


What does the septum transversum do?

It separates the coelom into thoracic and abdominal cavities and develops into part of the diaphragm and ventral mesentery of the stomach and duodenum.


What does the allantois help with?

Gas exchange and excretion.


What does the allantois become?

The urachus (connects fetal bladder to yolk sac).


Which artery supplies the foregut?

The celiac artery.


Which artery supplies the midgut?

The superior mesenteric artery.


Which artery supplies the hindgut?

The inferior mesenteric artery.


Which part of the stomach grows the fastest?

The dorsal part.


While growing, the stomach undergoes what degree of rotation?

90 degree clockwise rotation.


A smaller/lesser curvature is found on which side of the stomach?

The right side. (Ventral border).


A greater curvature is found of which side of the stomach?

The left side. (Dorsal border).


As well as 90 degree rotation, the stomach undergoes what type of rotation?

Superior (upwards) rotation to form characteristic 'c' shape.


List the three general steps of development for other endodermal organs.

1. Endodermal thickening.
2. Cells proliferate to form bud.
3. Continuous lengthening and bifurcation/branching.


Briefly outline lung development.

1. Budding of endoderm (will form trachea).
2. Ventro-caudal growth. Bifurcates to form left and right trachael buds (will form bronchi).
3. Next bifurcation forms bronchial buds (3 on right, 2 on left).
4. Third bifurcation gives tertiary bronchial buds.
5. There are 14 more branchings to give terminal bronchioles.


The four pharangeal arches have an outer covering of ectoderm, a core of mesenchymal cells and an inside lining of endoderm. They also have a cartilage (skeletal), muscle and nerve element. What do they give rise to?

Skeletal, muscle and nerve elements in the head of the embryo.


Where do the primordial germ cells migrate?

Along the hindgut, through the dorsal mesentery to left and right genital ridges (to gonads).


When are the various structures of the embryo most susceptible to birth defects upon exposure to harmful agents?

The first 2 to 3 months.


Classify a human.

Kingdom: Animalia
Superphylum: Coelomate
Phylum: Chordata
Subphylum: Vertebrate
Class: Mammalia
Order: Primate
Family: Hominidae
Genus: Homo
Species: Homo sapiens


What is a coelom?

A coelom is a body cavity which is
completely lined with mesoderm.


Where is a human's gut tube suspended?

In their coelom.