Spectrum Biology - September 2016

 There are three pairs of salivary glands, which pour their

secretions into the mouth. They are

 two parotid,  two submandibular and

 two sublingual.

Pharynx

It is divisible into three parts:

(i) Nasopharynx,

(ii) Oropharynx and

(iii) Laryngopharynx.

Only oropharynx and laryngopharynx are associated with

the alimentary tract.

Oesophagus

The oesophagus is the first part of the alimentary tract. It

is about 25 cm long and about 2 cm in diameter. It lies in

the median plane in the thorax in front of the vertebral

column behind the trachea and the heart.

Stomach

The stomach is continuous with the oesophagus at the

cardiac orifice and the duodenum at the pyloric

sphincter.

Small Intestine

The small intestine is continuous with the stomach at the

pyloric sphincter and leads into the large intestine at the

ileocaecal valve.

Cardiac orifice

Fundus

Oesophagus

Le

sser

curvat

ure Body

Rugae

Gre

ater

curvatu

re

Duodenum

Pyloric

sphincter

Pyloric antrum

Longitudinal section of the stomach

Oesophagus

Trachea

Aorta

L. bronchus

Diaphragm

End of

oesophagus

and beginning

of stomach

Aorta

R. bronchus

Inferior

vena

cava

T8

T10

T12

Oesophagus and some associated structures

Parotid gland and its duct

Muscles of

the cheek

Tongue

Opening of

submandibular duct

Sublingual gland

Ductules

Sternocleidomastoid muscle

B

A

A. The position of the salivary glands,

B. Enlargment of part of a gland

L. adrenal gland

Spleen

Splenic artery

Tail of pancreas

Body of

pancreas

L. kidney

Inferior

mesenteric artery

Descending colon

L. ureter

Aorta

Sup. mesenteric

artery and vein

Inf. vena

cava

R. ureter

Ascending

colon

Duodenum

Head of

pancreas

R. kidney

Common

bile duct

R. adrenal gland

Portal vein

Inferior

vena

cava

Common

hepatic

artery

The duodenum and its associated structures

Greenland sharks (Somniosus microcephalus) The

Greenland shark, an iconic species of the Arctic

Seas, can found from surface waters in shallow

estuaries and bays to depths of at least 4,000 feet

(1,200 m) in continental shelf and slope waters. The

species is one of the larger sharks and by far the

largest of Atlantic-Arctic and Antarctic fishes. The

life period of this shark is at least as long as

400 years.