gastrointestinaltractgit-220817021937-805e8aa3.pdf

gastrointestinaltractgit-220817021937-805e8aa3.pdf

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  THE DIGESTIVE SYSTEM Representedby WASIM AKRAM BSc(N) ADWIKA INSTITUTE OF NURSING
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  CONTENTS  INTRODUCTION  FUCTIONSOF GI SYSTEM  ALIMENTARY CANAL 1. MOUTH 2. PHARYNX 3. OESOPHAGUS 4. STOMACH 5. SMALL INTESTINE 6. LARGE INTESTINE  COVERINGS OF ALIMENTARY CANAL
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  INTRODUCTION  The DigestiveSystem is also known as the Gastrointestinal System.  It is the route through which Nutritive substances , vitamins , minerals and fluids enter in the body .  The digestive system describes the Alimentary Canal , it’s accessory organs , glands and a variety of digestive processes that prepare food eaten in the diet for absorption.  The activities of the Digestive System can be grouped under five main headings : 1) INGESTION 4) ABSORPTION 2) PROPULSION 5) ELIMINATION. 3) DIGESTION
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  FUNCTIONS OF GISYSTEM 1) SECRETION OF DIGESTIVE JUICES 2) DIGESTION OF FOODS 3) ABSORPTION 4) MOVEMENTS OF FOODS 5) PROTECTION 6) ELIMINATION OF WASTE PRODUCTS.
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  PARTS OF GISYSTEM The digestive system is composed of A. ALIMENTARY CANAL B. DIGESTIVE GLANDS ∆ ALIMENTARY CANAL: •It is also known as the GASTROINTESTINAL TRACT (GIT) . •It is essentially a long tube through which food passes. •It commences at the mouth and terminates at the anus. •In adults, it is around 5 meters in length. •PARTS OF GIT: - Mouth. - Stomach - Pharynx. - Small Intestine - Oesophagus. - Large Intestine.
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  MOUTH • Mouth isthe beginning part of the Gastrointestinal System. • Mouth contains two parts : a) Vestibule b) Oral Cavity a) Vestibule: It is the cavity bounded by lips and cheeks , gums & teeth. b) Oral Cavity: > It is the cavity ( also known as Buccal Cavity ) bounded Laterally by maxillary bone & Teeth Superiorly by Palate Inferiorly by Tongue & soft tissues of floor of the mouth Posteriorly it is continuous with Oropharynx. > The oral cavity is lined with mucous membranes, consisting of stratified squamous epithelium containing small mucus secreting glands.
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  >PALATE: The palateforms the roof of the mouth and is divided into the ANTERIOR HARD PALATE and the POSTERIOR SOFT PALATE. ~ The hard palate is formed by the Maxilla and the Palatine bones . ~ The soft palate extends posteriorly and forms the UVULA. ~ During swallowing, uvula enclose the Nasopharynx to prevent the entry of food into the nasal cavity . >TONGUE: The tongue is composed of voluntary muscle. ~ It is a freely movable organ attached to HYOID BONE (posteriorly) and It is attached to the floor of the oral cavity by LINGUAL FRENULUM . ~ On the surface of the tongue , many small projections are present. These are called as PAPILLAE . ~ Tastes on the tongue : •Front – Sweet •Backside – Bitter •Besides – Sour •Middle - Salt
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  > TEETH: Humanteeth are embedded in the sockets of the mandible & maxilla ( Jaw). ~ Human teeth are # Thecodont- Teeth are embedded in the socket of jaw bone. # Diphyodont- Human teeth are diphyodont with respect to tweenty teeth. # Heterodont- Four different type of adult teeth: Incisors (I), Canine (C), Premolar (PM), Molar (M). ~ Milk Teeth / Deciduous Teeth: 20 in number : 2102/2102 ; it is the dentition of the child teeth upto 6 years . Adult teeth / Permanent teeth : 32 in number : I/I, C/C, PM/PM, M/M = 2/2, 1/1, 2/2, 3/3 . * The third molar ( wisdom teeth ) are the last to erupt . * Monophyodont teeth of human – Premolar teeth. ~ Origin of teeth is Ectomesodermal . Enamel ( Ectodermal)- secreted from Ameloblast Cells. Dentine (Mesodermal)- secreted from Odontoblast Cells. * Enamel is the hardest part of the body ( Calcium Salts ). ~ The main function of the teeth are Chewing and Mastication of Food .
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  ~ Blood supply:Branches of Maxillary Arteries & Bunch of veins empty into the Internal Jugular veins. ~ Nerve supply: Branches of Trigeminal Nerves.
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  PHARYNX • It isthe common passage for food and air. • The pharynx is divided into three parts : i) The Nasopharynx is important for respiration . ii) The Oropharynx continuous with oesophagus . iii) The Laryngopharynx continuous with trachea . * Epiglottis is a thin , elastic , cartilaginous flap whuich prevent the entry of food into the glottis . • Tonsils – These are lymphoid organ present in both side of the Uvula . ~ They are 4 in number and form a ring like structure known as the waldeyer’s ring . Pharyngeal, Tubeal, Palatine & Lingual tonsil . ~ Tonsils helps in 'First Line of Defence’ by secreting IgA . ~ Tonsillitis ~ Tonsillectomy
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  • Blood Supply: ~Arterial Supply : Several branches of the Facial Arteries . ~ Venous Drainage : The facial veins & the Internal Jugular veins . • Nerve Supply: The pharynx is controlled by the ANS. ~ Parasympathetic supply is mainly by the Glossopharyngeal & Vagus nerves . ~ Sympathetic supply is from the Cervical Ganglia .
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  OESOPHAGUS • It isa thin , long tube which extends posteriorly passing through the neck , thorax , and diaphragm and it leads to the stomach . • It is about 25cm long and about 2cm in diameter. • It lies in the median plane in the thorax in front of the vertibral column and behind the trachea and the heart. • It passes between muscles fibres of the diaphragm behind the central tendon at the level of the 10th Thoracic Vertibra. • It’s opening into the the stomach is regulated by Cardiac Sphincter / Gastro-oeso phageal Sphincter. • During transport of food – Peristalsis ( Successive waves of muscular contraction ). • During vomitting – Reverse Peristalsis .
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  STOMACH • THE STOMACHIS A J-SHAPED BAG-LIKE DIALATED PORTION OF THE ALIMENTARY CANAL. • IT IS LOCATED IN THE UPPER LEFT PORTION ( EPIGASTRIC , UMBILICAL & LEFT HYPOCHON- DRIAC REGION ) OF THE ABDOMINAL CAVITY. • ORGANS ASSOCOATED WITH THE STOMACH: >ANTERIORLY- Left lobe of liver & anterior abdominal wall. >POSTERIORLY- Abdominal aorta, Pancreas, Spleen, left kidney & adrenal gland. >SUPERIORLY- Diaphragm, Oesophagus & left lobe of liver. >INFERIORLY- Transverse colon and small intestine. >TO THE LEFT- Diaphragm and Spleen. >TO THE RIGHT- Liver and Duodenum.
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  • PARTS OFSTOMACH: The stomach is divided into four regions – i) Cardiac region: Oesophagus open into cardiac region and it is guarded by cardiac sphincter . ii) Fundic region: Secretory cells are present at this region . iii) Body/ corpus region : It is the largest section of our stomach . This region contracts and begins to mix food . iv) Pyloric region : Last part of stomach which opens into the first part of small intestine ( duodenum ) . Sphincter between pyloric portion and duodenum is known as Pyloric Sphincter .  Gastric Rugae : Some irregular folds or Rugae on the innerline of stomach .
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  SMALL INTESTINE  Smallintestine is distinguishable into three regions – 1. DUODENUM :  Smallest part of small intestine ( 25 – 30 cm ) .  C shaped .  No villi are present .  Brunner’s glands releases mucus .  Maximum digestion takes place here .  Fe absorption take place here . 2. JEJUNUM :  A long coiled middle portion ( 2 – 3 m ) .  Fold of kerkring or plicae circularis => circular folds on mucosal layer .  Villi present here => site of absorption . 3. ILEUM :  Highly coiled and largest part of small intestine ( 3 – 4 m ) .  LYMPHOID organ – Payer’s patch (secondary lymphoid organ) :- defence .  Ileum opens into large intestine and guarded by Ileo-caecal valve .  Villi : These are small finger like foldings ; site of absorption .
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  LARGE INTESTINE  Itconsists four parts – 1. CAECUM :  A small blind sac which hosts some symbiotic bacteria ( micro-organisms ) . Eg : Escherichia coli - helps in Vitamin B12 synthesis .  A narrow finger like tubular projection called Vermiformed Appendix ( vestigial organ ) arises from CAECUM . 2. COLON :  Caecum opens into colon .  Colon divided into four parts – Ascending colon , Transverse colon , Descending colon and Sygmoid/Pelvic colon . 3. RECTUM :  Storage of caecum . 4. ANAL CANAL :  Blood capillaries are present around anal canal .  Swelling of piles – Haemorrhoids .  Anal opening is Anus and controlled by voluntary anal sphincter .
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  COVERING OF ALIMENTARYCANAL The wall of alimentary canal from oesophagus to rectum possesses four layers: 1. SEROSA :  Outermost layer .  Made up of a thin mesothelium with some connective tissues .  Nerves and blood vessels are present in it . 2. MUSCULARIS :  Formed by smooth muscles .  Usually arranged into Inner circular layer and outer longitudinal layer . 3. SUB-MUCOSA:  Formed of loose connective tissues containing nerves, blood and lymph vessels .  In duodenum , glands ( Brunner’s glands ) are also present in sub-mucosa layer . 4. MUCOSA :  The innermost layer lining the lumen of the alimentary canal .  In stomach : Rugae ; in small intestine : Villi .  Cells lining the villi – produce numerous microscopic projections called Microvilli giving a Brush Border appearance .  Lacteals : a network of capillaries and a large lymph vessel . Helps in Fat Absorption .