Alimentary canal and mouth BSc Nursing 1st Semester 2025 (2024-2025) Previous Year's Question Papers/Notes Download - HK Technical PGIMS

Notes of alimentary canal 

Mouth 

Alimentary canal
It is a continuous tube like st starting at mouth and ends at anus
Propulsion
Digestion
Absorption
Elimination
Ingestion
Activities involved in digestion
The alimentary canal begins at mouth, passes through thorax, abdomen and pelvis and
ends at anus● Ingestion: taking of food
● Propulsion:mixes and moves the contents
● Digestion:by mechanical breakdown and chemical breakdown of food
● Absorption: substances from digested food are absorbed
● Excretion:the undigested, unabsorbed food is excreted out
Activities of digestion
Organs of alimentary tract
Mouth
Pharynx
Oesophagus
Small intestine
Large intestine
Rectum and Anal canal
Accessory organs
3pairs of salivary gland, pancreas,liver and biliary ductBasic structure of alimentary canal
● There are four layers of tissue in walls of alimentary canal
● Adventitia or serosa
● Muscle layer
● Sub mucosa
● Mucosa
Adventitia or Serosa
Outermost layer
Thorax lose fibres tissue
At abdomen covered by serous
membrane called peritoneumMucosa
Serosa
Sub mucosa
Circular muscle
LongitudinalFunctions of serosa layer
● Reduces friction between the digestive tract and surrounding structures
● Provide a lubricating fluid to facilitate movement
● Helps to protect digestive tract
Peritoneum
● Type of serous membrane
● Lines th abdominal cavity
● Types of peritoneum
● Parietal Peritoneum
Visceral peritoneum
Parietal peritoneum lines the abdominal organs
Visceral peritoneum covers the abdominal organs like pelvic organs and abdominal
organs
It covers the stomach from posterior side ,it hangs like an apron in front of abdominal
organsMuscle layer
composed of smooth muscle and primarily responsible for moving food
along the digestive tract via peristalsis and other contractions.
It consists of 2 layers:an inner layer of circular muscle and inner layer of longitudinal muscle
Circular Layer:
Located inside the longitudinal layer, it contracts to constrict the digestive tract, preventing
food from moving backward and aiding in mixing.
Longitudinal Layer:
This outer layer contracts to shorten the digestive tract, pushing food forward and
contributing to peristalsis.
Between these two' layers of muscles are blood vessels,lymph vessels, plexus of sympathetic and
parasympathetic nerves called mysenteric or Auerbach’s plexus
Function of muscle layer
Propelling the food through digestive tract via peristalsis an mixing food with digestive juicesMucosa layer
The innermost layer of alimentary canal
Responsible for absorption and secretion
Made up of three layers
● The epithelium
● Lamina propria
● Muscularis mucosa
Epithelium:
This is the innermost layer facing the lumen of the digestive tract. It's a single layer of cells and is
responsible for most digestive, absorptive, and secretory processes.
Lamina Propria:
This layer of loose connective tissue lies beneath the epithelium. It contains blood and lymphatic vessels
and also houses immune cells and lymph nodes.
Muscularis Mucosae:
This is a thin layer of smooth muscle located at the base of the lamina propria. It helps to create folds in
the mucosa, which increases surface area for absorption and helps with the movement of material
through the digestive tract.Absorption:
The mucosa, particularly the epithelium, absorbs nutrients and water from the digested food.
In the small intestine, finger-like projections called villi and microvilli increase the surface area for efficient nutrient
absorption.
The epithelium is composed of specialized cells, like enterocytes, that facilitate this absorption process.
2. Secretion:
The mucosa produces mucus, which protects the lining and lubricates the passage of food.
Goblet cells in the mucosa secrete mucus, helping to keep the digestive tract moist and protecting it from damage, says the
Cleveland Clinic and the National Institutes of Health (NIH).
The mucosa also secretes digestive enzymes, hormones, and other substances involved in the digestion process.
3. Protection:
The mucosa acts as a barrier, protecting the underlying layers of the alimentary canal from pathogens and irritants.
The epithelium's cells can respond to ingested toxins, and the lining also contains immune cells that defend against infection.
In areas like the mouth and anus, the mucosa may be more resistant to abrasion due to the presence of stratified squamous
epithelium.
Function of mucosa layerSecretions of mucus membrane
● Saliva from salivary glands
● Gastric juice form gastric glands
● Intestinal juice form the intestinal glands
● Pancreatic juice from pancreas
● Bile from liver
Sub mucosa
● a loose connective tissue layer found beneath the mucosa. It's primarily composed of connective
tissue and contains blood vessels, nerves (including the submucosal plexus), and lymphatic
vessels.
● Donald plux is called meissner’s plexus
Function of sub mucosa
Protection and secretionsNerve supply
Parasymphatic nerve supply one pair of cranial Vagus now elementary canal and accessory organs
Supply the distal part of tract
Effects Of parasymphatetic stimulation are
● Increased muscular activity especially peristalsis through increased activity of myentric plexus
● Increased glandular secretion through increased activity of submucosal plexus
Sympathetic nerve supply numerous nerves emerge from spinal cord in thoracic
and lumber region
These form plexus in thorax abdomen and pelvis from which nerves pass to the
organs of elementary tract
● Decrease muscular activity especially peristalsis because there is less
stimulation of the myentric plexus
● Decrease glandular secretion as the stimulation of submucosal plexus is
reducedMouth
❖ Bounded by muscles and bones
❖ Anteriorly by lips, posteriorly it continues with oropharynx,
laterally by the muscles of cheeks, superiorly by Bony hard palate
and muscular soft palate, inferiorly by muscular tongue and the
soft tissues of the floor of the mouth
❖ The part of mouth between the gums and the cheeks is the vestibule
and remainder of the cavity is oral cavity
❖ The palate forms the roof of mouth and divided into anterior hard
palate and so posterior soft palate
❖ The hard palate is formed by maxilla and palatine bones
❖ Soft palette is muscular couch downward from posterior and of
hard palateThe uvula is curved fold of muscle covered with mucus membrane hanging down from mid line of free
border of soft palate
blood supply primarily
from the external carotid
artery and its branches,
including the facial,
lingual, and maxillary
arteries.