PNEUMONIA

A. DESCRIPTION

– is an inflammatory process involving the respiratory bronchioles, alveolar space and walls, and lobes, caused primarily by chemical irritants or by specific bacterial, viral, fungal, mycoplasmal, or parasitic organisms

– “Pneumonitis” is a more general term that describes an inflammatory process in the lung tissue that may predispose or place the patient at risk for microbial invasion

B. ETIOLOGY

Classification:

1. Community-Acquired Pneumonia

Ø Occurs either in the community setting or within the first 48 hours after hospitalization or institutionalization

1. Pneumonia caused by Streptococcus pneumoniae

Ø Most common CAP in people younger than 60 years of age and above

Ø A gram-positive, capsulated, non-motile coccus that resides naturally in the respiratory tract

Ø May occur as a lobar or bronchopneumonic form in patients of any age and may follow a recent respiratory illness

b. Mycoplasma pneumonia

Ø Occurs most often in older children and young adults and is spread by infected respiratory droplets through

Ø person-to-person contact

Ø Spreads throughout the entire respiratory tract, including the bronchioles, and has the characteristics of a bronchopneumonia

c. Haemophilus influenzae (type B)

Ø Frequently affects elderly people and those with comorbid illnesses (eg. COPD, alcoholism,diabetes mellitus)

Ø The presentation is indistinguishable from that of other forms of bacterial CAP and may be subacute, with cough or low-grade fever for weeks before diagnosis

Ø Chest x-rays may reveal multilobar, patchy bronchopneumonia or areas of consolidation (tissue that solidifies as a result of collapsed alveoli or pneumonia)

d. Viruses

Ø The most common cause of pneumonia in infants and children but are relatively uncommon causes of CAP in adults

Ø In immunocompetent adults, the chief causes of viral pneumonia are influenza viruses types A and B, adenovirus, parainfluenza virus, coronavirus, and varicella-zoster virus

Ø In immunocompressed adults, cytomegalovirus is the most common viral pathogen, followed by herpes simplex virus, adenovirus, and respiratory synctial virus

Ø Acute stage of a viral respiratory infection occurs within the ciliated cells of the airways. This is followed by infiltration of the tracheobronchial tree

B.Hospital-Acquired Pneumonia

Ø Also known as nosocomial pneumonia

Ø Defined as the onset of pneumonia symptoms more than 48 hours after admission in patients with no evidence of infection at the time of admission

Occurs when at least one of three conditions exists:

Ø host defenses are impaired

Ø an inoculum of organisms reaches the lower respiratory tract and overwhelms the host’s defenses

Ø a highly virulent organism is present

Ø The common organisms responsible for HAP include the pathogens Enterobacter species, Escherichiacoli, H. influenzae, Klebsiella species, Proteus, Serratia marcescens,

P. aeruginosa, methicillin- sensitive or methicillin-resistant Staphylococcus aureus (MRSA), and S. pneumoniae

3. Pneumonia in the Immunocompromised Host

Ø Pneumocystis pneumonia (PCP), fungal pneumonias, and Mycobacterium tuberculosis

Ø Pneumocystis jiroveci causes PCP

Ø May be caused by the organisms also observed in CAP or HAP

Ø Rarely observed in immunocompetent hosts and is often an initial AIDS-defining complication

Ø Has a subtle onset, with progressive dyspnea, fever, and a non-productive cough

4. Aspiration Pneumonia

Ø Refers to the pulmonary consequences resulting from entry of endogenous or exogenous substances into the lower airway

Ø The most common form of aspiration pneumonia is bacterial infection from aspiration of bacteria that normally reside in the upper airways

Ø May occur in the community or hospital setting

Ø Common pathogens are S. pneumoniae, H. influenzae, and S. aureus

Ø Causes and contributing factors to pneumonia include:

a. Inability to move pulmonary secretions.

b. Aspiration pneumonia due to an abnormal swallowing mechanism or tube feedings

c. Immunosupressed clients

d. Frequent alcohol intoxication

e. Immobility

f. Cigarette smoking

D. INCUBATION PERIOD

• The incubation period for pneumonia varies, depending on the type of virus or bacteria causing the infection. Some common incubation periods are: respiratory syncytial virus, 4 to 6 days; influenza, 18 to 72 hours.

E. PERIOD OF COMMUNICABILITY

• Not known.

• It appears that transmission can occur as long as the organism remains in respiratory secretions.

F. MODE OF TRANSMISSION (Dependent on the infecting organism)

• Breathing in small droplets that contain the organisms that can cause pneumonia

• Sharing drinking glasses and eating utensils to the infected person

• Touching the used tissues or handkerchiefs of an infected person.

G. ASSESSMENT FINDINGS

a. Clinical Manifestations

• Dullness with consolidation on percussion of chest

• Bronchial breath sounds auscultated over consolidated lung fields; egophony “EE” to “AY”

• Sudden onset fever over 100 degrees Fahrenheit

• Shaking chills (with bacterial pneumonia)

• Chest pain aggravated by hacking cough

• Dyspnea, respiratory grunting, and nasal flaring

• Flushed cheeks; cyanotic lips and nail beds

• Purulent sputum

• Anxiety and confusion

• In the elderly, the only signs may be mental status' change and dehydration.

b. Laboratory Findings

• Sputum culture and sensitivity are positive for a specific causative organism.

• White blood cell (WBC) count is elevated in pneumonia of bacterial origin; WBC count is depressed in pneumonia of mycoplasmal or viral origin.

c. Diagnostic Findings

• Chest radiograph shows density changes, primarily in the lower lung fields.

• Cytologic findings - neutrophilic inflammation that may or may not be septic

• Bacterial culture - indicated to detect secondary infection

H. TREATMENT MODALITIES

• Bacterial pneumonia (caused by the streptococcus pneumonia bacteria) is often treated with penicillin, ampicillin-clavulanate (Augmentin) and erythromycin.

• Bacterial pneumonia (caused by the hemophilus influenza bacteria) is treated with antibiotics, such as cefuroxime (Ceftin), ampicillin-clavulanate (Augmentin), ofloxacin (Floxin), and trimethoprim-sulfanethoxazole (Bactrim and Septra).

• Bacterial pneumonia (caused by legionella pneumophilia and staphylococcus aureus bacteria) are treated with antibiotics, such as erythromycin.

• Mycoplasma pneumonia is often treated with antibiotics, such as erythromycin, clarithromycin (Biaxin), tetracycline or azithromycin (Zithromax).

• Bedrest

• Plenty of fluids

• Therapeutic coughing, breathing exercises

• Proper diet

• Cough suppressants

• Pain relievers and fever reducers, such as aspirin (not for children) or acetaminophen

• In severe cases, oxygen therapy and artificial ventilation may be required.

I. NURSING MANAGEMENT

• Administer prescribed medications, which may include antibiotics, mucolytics expectorants, or antitussive agents.

• Promote infection control measures, especially droplet precautions as indicated.

• Prevent aspiration pneumonia in a client receiving tube feedings. Keep the client in an upright position during feedings and for 30 minutes afterward. Check for residual gastric contents; if more than 100 mL, stop feeding and reevaluate.

• Pt will need to have breath sounds monitored q 4hr to determine if pneumonia is progressing.

• O2 saturation should be done regularly ( at least q4°during acute phase) to make sure that patient is getting adequate perfusion.

• Make sure to give all scheduled antibiotics on schedule so that therapeutic ranges are maintained.

• Any signs and symptoms of infection must be monitored and reported to the physician.

J. METHODS OF PREVENTION

• Practice good hygiene.

• Get a pneumonococcal vaccine.

• Practice good preventive measures by eating a proper diet, getting regular exercise and plenty of sleep.

• Stop smoking. Smoking makes it more likely you will get pneumonia.

• Avoid contact with people who have respiratory tract infections, such as colds and influenza (flu). Pneumonia may develop after these types of infections.

• If you have not had measles or chickenpox, avoid contact with people who have these infections. Pneumonia can be a complication of measles and chickenpox, so getting these infections can put you at risk for developing pneumonia.

LARYNGITIS

DEFINITION

Ø an inflammation of your voice box (larynx)

due to overuse, irritation or infection.

Ø The larynx is a framework of cartilage,

muscles and mucous membranes that forms

the entrance of the windpipe (trachea). Inside

the larynx are the vocal cords — two folds of

mucous membrane covering muscle and

cartilage.

Ø The vocal cords become inflamed or irritated.

They swell, causing distortion of the sounds

produced by air passing over them. As a

result, the voice sounds hoarse.

Ø In some cases of laryngitis, the voice can

become so faint as to be undetectable.

Ø The vocal cords become inflamed or irritated.

They swell, causing distortion of the sounds

produced by air passing over them. As a

result, the voice sounds hoarse.

Ø In some cases of laryngitis, the voice can

become so faint as to be undetectable.

• Acid reflux, also known as gastroesophageal reflux disease, can cause chronic laryngitis.

• Persistent laryngitis in the absence of an infection or other cause could be a sign of cancer.

SIGNS AND SYMPTOMS

• hoarseness and loss of voice

• a raw throat, a dry cough, a tickling

sensation in the back of the throat, and a

constant need to clear the throat

ETIOLOGY

• Acute laryngitis is usually caused by an upper respiratory tract infection. The infection may be localized to the larynx (voice box), or it may be part of a wider respiratory tract infection such as a cold or flu.

• Most cases of laryngitis are caused by viral infections, but bacterial infections such as bronchitis and pneumonia can also result in inflammation of the vocal cords.

SIGNS and SYMPTOMS

• hoarseness and loss of voice

• a raw throat, a dry cough, a tickling sensation in the back of the throat, and a constant need to clear the throat

• symptoms may include pain, fever, difficulty swallowing, and general malaise

• The severity of inflammation determines the severity of symptoms. Severe swelling of the vocal cords may cause difficulty breathing.

PROGNOSIS

• Most cases of laryngitis resolve within a few days to a week. Acute laryngitis almost invariably resolves after the infection or other transient cause is cleared. Although chronic inflammation can lead to permanent changes in the vocal cords, most people with chronic laryngitis recover completely when the underlying cause is eliminated. Chronic laryngitis caused by nerve damage or cancer, however, usually does not fully resolve.

ASSESSMENT FINDINGS

Many times you can be thoroughly evaluated with only a complete history and physical exam.

• The doctor will pay particular attention to your ears, nose, throat, and neck.

• If symptoms are severe, particularly in children, the doctor may order an x-ray of your neck or chest.

• The doctor may also choose to look at your throat with a small, lighted scope.

This thin scope is inserted through your nose after numbing the nose and nostrils. The procedure only takes a few minutes and may yield valuable information.

• Sometimes in children, rarely in adults, the doctor may order blood work such as a complete blood cell count.

TREATMENT MODALITIES

• After a careful exam the doctor will decide on a course of treatment.

o Most of the time, the doctor will recommend the home care actions and may prescribe a steroid injection or prescription.

o If the doctor is concerned about a bacterial infection causing the laryngitis, then he or she will prescribe a course of antibiotics.

o Sometimes, the doctor may choose to observe in the office or the emergency department for a short period of time in order to be sure it is not getting worse quickly.

• If you have any signs of respiratory distress or think your airway could swell and close, then you will be admitted to the hospital.

o In some emergency situations, more commonly in children than adults, the danger of your throat swelling shut exists.

o It may be necessary to place a breathing tube into the throat in order to breathe.

o The patient will be placed on a machine to breathe called a ventilator.

o In this situation, he/she will receive IV antibiotics and likely steroids.

METHODS of PREVENTION

• Wash hands often especially before touching your face.

• For children, it is important that they receive the Haemophilus influenzae vaccine in order to protect them from this possibly life-threatening bacterial infection.

• Do not overuse your voice.

EPISTAXIS

DESCRIPTION

Ø The most common causes of which are

nose picking and injury

ETIOLOGY

Ø Epistaxis may be spontaneous or may

result from trauma (usually nose picking)

Ø It also may be be associated with chemical

irritation, acute or chronic infection (such as

rhinitis or sinusitis), purpura, leukemia and

other blood dyscrasias, hypertension,

anticoagulant therapy, or deviated septum.

PATHOPHYSIOLOGY

Ø In children, epistaxis usually originated in the

anterior nose and tends to be mild. In adults,

it tends to originate in the posterior nose and

be more severe.

Ø Slight to moderate epistaxis usually causes

no complications; however, severe bleeding

(persisting longer than 10 minutes after

pressure is applied) may cause blood up to

1 L/hr

ASSESSMENT FINDINGS

Ø Clinical manifestation may include:

1. Bleeding through the nares, blood tricking

into the oropharynx

2. Blood in the corner of eyes (through the

lacrimal ducts)

3. Blood in the auditory canal if the tympanic

membrane is perforated

Ø Diagnostic Findings:

1. Nasal inspection with a bright and speculum

may locate the source of bleeding.

2. Artery legation may be required for anterior

posterior packs fail to control epistaxis.

NURSING INTERVENTIONS

Ø Instruct client to minimize activity for

approximately 10 days, such as avoiding

strenuous exercises, not blowing the nose;

sneezing with the mouth open; and not

lifting; stooping, or straining.

TREATMENT MODALITIES

Important step to prevent nosebleed include:

Ø Avoiding picking the nose

Ø Bleeding usually can be controlled at home by

pinching the sides of the nose together for 5 to

10 minutes

Ø Icepacks to the nose

Ø Putting wads of tissue paper in the nostrils

Ø And placing the head in various position are not

effective

NURSING MANAGEMENT

Ø Interventions to control bleeding, as follow:

1. Instruct patient to sit upright, breathe through

the mouth, and refrain from talking.

2. Instruct patient to compress the soft outer

portion of the nares against the septum for 5

to 10 minutes.

3. Instruct patient to avoid nose blowing during

or after the episode.

METHODS OF PREVENTION

Ø If pressure does not control bleeding, insert

anterior packing or posterior pack as

appropriate. Keep scissors and hemostat on

hand to cut the string and remove the

packing in the event of airway obstruction.

Ø Monitor bleeding: inspect for blood trickling into the posterior pharynx; observe for hemoptysis, hematemesis.

Ø Frequent swallowing or belching; instruct the patient not to swallow but to spit out any blood.

Ø If indicated, provide information regarding electrocautery.

The Digestive System

DIGESTIVE ORGAN

Divided into two groups:

Alimentary tract (GI tract):

• Mouth

• Pharynx

• Esophagus

• Stomach

• Small intestine

• Large intestine

• Anus

Accessory digestive organs

• Teeth

• Tongue

• Salivary glands

• Liver

• Gallbladder

• Pancreas

SIX BASIC PROCESSES:

Ingestion – this process involves taking foods and liquids into the mouth (eating).

Secretion – production and release from a cell or a gland of a physiologically active substance

Mixing and propulsion – alternating contraction and relaxation of smooth muscle in the walls of the GI tract mixing food and secretions and propel them towards the anus.

Digestion – mechanical and chemical process

• Mechanical digestion: teeth and smooth muscles

• Chemical digestion: use of digestive enzymes produced by the salivary glands

Absorption – the passage of digested foods from the gastrointestinal tract into blood or lymph.

Defecation – wastes, indigestible substances, bacteria, and digested materials that are not absorbed leave the body through the anus in the process of defecation.

Layers of the GI tract

MUCOSA

Inner lining of the GI tract which is a mucous membrane

Epithelium

• Squamous epithelium:

serves as protective function

Found in the mouth, pharynx, esophagus, and anal canal

• Squamous columnar:

Secretion and absorption

Lines the stomach and the intestines

Contains two types of cells:

Exocrine cells are present - secretes mucus and fluid into the lumen of the tract

Enteroendocrine cells - secretes hormone into the bloodstream

• Simple columnar epithelial cells

Are firmly sealed to each other by tight junctions that restricts leakage between cells

Lamina propria

– Is an areolar connective tissue containing many blood and lymphatic vessels, which are the routes by which nutrients absorbed into the GI tract reach the other tissues of the body.

– It also contains MALT (mucosa – associated lymphatic tissue). MALT are lymphatic nodules that contains immune system cells that protects against diseases.

MALT is present a along the GI tract, especially in the tonsils, small intestine, appendix, and large intestine

Muscularis mucosae

– The one that form the folds of the mucous membrane of the stomach and small intestine. This folds increases the surface area for digestion and absorption.

– It ensures that a absorptive cells are fully exposed to the contents of the GI tract

SUBMUCOSA

Consists of areolar connective tissue that binds the mucosa to the muscularis

It has many blood vessels and lymphatic vessels that receive absorbed food molecules

Submucosal plexus or Plexus of Meissner (a network of neurons) . These neurons are part of the enteric nervous system. It contains sensory and motor enteric neurons, plus parasympathetic and sympathetic postganglionic neurons that innervate the mucosa and submucosa.

Also contains glands and lymphatic tissue

MUSCULARIS

Consists of:

– Skeletal muscles - produces voluntary swallowing and it is found in the mouth, pharynx, superior and middle parts of the esophagus

– Smooth muscles – found in two sheets. The 1. Inner sheet of muscular fiber and 2. Outer sheet of longitudinal fibers. It is found all throughout the rest of the tract.

Involuntary contractions of the smooth muscle help break down food physically, mix it with digestive secretions, and propel it along the tract.

Myenteric plexus

Contains enteric neurons, parasympathetic ganglia, parasympathetic postganglionic neurons, and sympathetic postganglionic neurons that innervates the muscularis.

Controls GI tract motility (frequency and strength of the muscularis)

SEROSA

A superficial layer of those portion of the GI tract that are suspended in the abdominopelvic cavity

A serous membrane composed of areolar connective tissue and simple squamous epithelium.

PERITONEUM

It is the largest serous membrane of the body.

It consist of a layer of simple squamous epithelium with an underlying supporting layer of connective tissue.

Two divisions:

Parietal peritoneum – lines the wall of the abdominopelvic cavity

Visceral peritoneum – covers some of the organs in the cavity

Peritoneal cavity – the slim space found between the parietal and viscera cavity.

Contains large folds that weave between the viscera.

PERITONEAL FOLDS

GREATER OMENTUM

Omentum (fat skin)

The largest peritoneal fold.

Drapes over the transverse colon and coils of the small intestine

It is a double sheet that folds back upon itself

Contains considerable amount of adipose tissue

It has many lymph nodes (contributes macrophages and antibody – producing plasma cells that help combat and contain infections of the GI tract).

LESSER OMENTUM

Arises as two folds in the serosa of the stomach and duodenum

It suspends the duodenum and the stomach from the liver.

MESENTERY

Is fan – shaped.

Binds the small intestine to the posterior abdominal wall.

It extends from the posterior abdominal wall to wrap around the small intestine and then return to its origin, forming a double layer.

MESOCOLON

Binds the large intestine to the posterior wall

It carries blood and lymphatic vessels to the intestines

Together the mesentery and mesocolon holds the intestine loosely in place, allowing for a great amount of movement as muscular contractions mix and moved the contents along the GI tract.

ALIMENTARY CANAL

1. MOUTH
2. PHARYNX
3. ESOPHAGUS
4. STOMACH
5. SMALL INTESTINE
6. LARGE INTESTINE
7. ANUS

I.MOUTH/ ORAL/ BUCCAL CAVITY

• It is a cavity bounded externally by the lips and cheeks and leading into the pharynx.

• The roof is formed by the hard and soft palates

• And the anterior two thirds of the tongue fills the floor of the mouth.

• Lips

– are fleshy folds that surrounds the opening of the mouth.

– It is covered externally by skin and internally by a mucous membrane

– There is a transition zone where the 2 kinds of covering tissue meet. This portion of the lips is non-keratinized, and the color of the blood in the underlying blood vessels is visible through the transparent surface layer

• Hard Palate

– The anterior portion of the roof of the mouth

– Is formed by the maxillae and palatine bones

– It forms a bony partition between the ora and nasal cavity

• Soft Palate

– Posterior portion of the roof of the mouth

– An arch-shaped muscular partition between the oropharynx and nasopharynx that is lined by mucous membrane

• Uvula

– a conical muscular process that hangs from the border of the soft palate

– Uvula and soft palate closes off the nasopharynx and oropharynx during swallowing. This prevents swallowed food and liquids from entering the nasal cavity.

– Lateral to the base of the uvula are two muscular folds that run down the lateral sides of the soft palate:

• Palatoglossal arch – anteriorly, extends to the sides of the base of the tongue

• Palatopharyngeal arch – posteriorly, extends to the sides of the pharynx

• Palatine tonsils

– Located between the arches

• Soft Palate

w Posterior portion of the roof of the mouth

w An arch-shaped muscular partition between the oropharynx and nasopharynx that is lined by mucous membrane

• Uvula

w a conical muscular process that hangs from the border of the soft palate

w Uvula and soft palate closes off the nasopharynx and oropharynx during swallowing. This prevents swallowed food and liquids from entering the nasal cavity.

w Lateral to the base of the uvula are two muscular folds that run down the lateral sides of the soft palate:

s Palatoglossal arch – anteriorly, extends to the sides of the base of the tongue

s Palatopharyngeal arch – posteriorly, extends to the sides of the pharynx

• Palatine tonsils

w Located between the arches

II. PHARYNX (throat)

It is a funnel-shaped tube that extends from the internal nares to the esophagus posteriorly and to the larynx anteriorly.

It is composed of skeletal muscle and lined by mucous membrane.

Deglutition – or the movement of food from the mouth into the stomach is achieved by the act of swallowing. It is facilitated by saliva and involves the mouth, pharynx, and esophagus.

Swallowing occurs in three stages:

Voluntary stage: the bolus is forced to the back of the oral cavity and into the oropharynx by the movement of the tongue upward and backward against the palate

Pharyngeal stage:

when the bolus is going into the oropharynx, the involuntary pharyngeal stage begins The respiratory passage closes, and breathing is temporarily interrupted

The bolus stimulates receptors in the oropharynx, which sends impulses into the deglutition center in the brain stem particularly the lower pons and medulla oblongata

The returning impulses causes the soft palate and uvula to move upward to close off the nasopharynx, and the larynx is pulled forward and upward under the tongue. The movement of the larynx pulls the vocal chords together further sealing off the respiratory tract. The bolus passes through the laryngopharynx and esophagus in 1 – 2 seconds

Pharyngeal stage:

when the bolus is going into the oropharynx, the involuntary pharyngeal stage begins The respiratory passage closes, and breathing is temporarily interrupted

The bolus stimulates receptors in the oropharynx, which sends impulses into the deglutition center in the brain stem particularly the lower pons and medulla oblongata

The returning impulses causes the soft palate and uvula to move upward to close off the nasopharynx, and the larynx is pulled forward and upward under the tongue. The movement of the larynx pulls the vocal chords together further sealing off the respiratory tract. The bolus passes through the laryngopharynx and esophagus in 1 – 2 seconds

Esophageal stage

the passage of food from the laryngopharynx into the esophagus is regulated at the entrance to the esophagus by a sphincter called the UES (upper esophageal sphincter).

The elevation of the larynx during the pharyngeal stage of swallowing causes the sphincter to relax, making the bolus enter the esophagus.

During this stage, because of peristalsis (a progression of coordinated contractions and relaxations of the circular muscles and longitudinal layers of the muscularis, wavelike motion) the bolus is push onward and towards the stomach. The passage of solid and semi solid from the mouth to the stomach takes about 4 – 8 seconds; while very soft foods and liquids pass through in about 1 second.

The LES (lower esophageal sphincter), relaxes during swallowing and thus allowing the bolus to pass from the esophagus to the stomach.

III. Esophagus

It is a collapsible tube that lies posterior to the trachea

It is about 25 cm (10 inches) long

It begins at the level of the sixth cervical vertebra and descends through the mediastinum in front of the vertebral column and behind the trachea.

It passes through the diaphragm at the level of the 10^th thoracic vertebrae and ends at the cardiac orifice of the stomach at the level of the eleventh thoracic vertebrae

The esophagus has four layers:

Fibrous outer layer: consists of areolar tissue containing many elastic fibers

Muscular layer: comprised of two layers, the outer with fibers running longitudinally and the inner layer consisting of circular fibers

Areolar or muscular layer:connects the mucous and muscular coats and contains the larger blood vessels and nerves, as well as the mucous glands.

mucous membrane

IV. STOMACH

Location:

Inferior to the diaphragm in the epigastric, umbilical, and left hypochondriac region.

J - shaped

Anatomy:

It has four main regions:

• Cardia: superior opening of the stomach

• Fundus: rounded portion

• Body: large central portion

• Pylorus: the region of the stomach that connects to the duodenum

Four layers of the stomach wall:

Outer serous layer

Muscular layer – this consists of three layers of smooth muscle fibers, the outer being longitudinal, the middle circular and the inner oblique

Submucous layer – this is composed of loose areolar tissue

The lining of the mucous membrane – it has numerous folds(rugae), which run longitudinally and flattens out once stomach is full

Functions of the stomach:

Mixes saliva, food, and gastric juice to chyme.

Reservoir for holding food before release into small intestine.

Secretes gastric juice (2000 – 300ml per day), which contains:

• HCl: kills bacteria and denatures proteins in food and stimulates secretion of hormones that promote the flow of bile and pancreatic juice

• Pepsin: protein-digesting enzyme

• Intrinsic factor: aids in absorption of Vitamin B₁₂

• Gastric lipase: aids digestion of triglycerides

Mixes gastrin (a type of hormone that is secreted by the G cell which is located in the pyloric antrum) in the blood

Regulation of Secretion and Motility

Cephalic Phase:

The cephalic phase of gastric digestion consists of reflexes initiated by sensory receptors in the head.

Sight, smell, thought of food

the cerebral cortex and the feeding center in the hypothalamus send nerve impulses to the medulla oblongata

Stimulate the gastric glands to secrete pepsinogen, hydrochloric acid, and mucus into stomach chyme and gastrin into the blood; and increase gastric motility

Gastric Phase

Once food reaches the stomach

The stomach walls distends and a peristaltic movement called mixing waves pass over the stomach every 15 – 25 seconds.

Macerates, mixes the food with gastric juice and reduce the food into a soupy liquid (chyme).

chyme (10 –15 ml) will got to the duodenum passing the pyloric sphincter making the stomach wall less distended

The negative feedback cycle suppresses secretion of gastric juice

Intestinal Phase

This phase is an inhibitory phase wherein it prevents chyme from totally leaving the stomach and overloading the duodenum.

Two hormones are release into the blood that affects the stomach:

• Secretin – decreases gastric secretion

• Cholecystokinin – inhibits stomach emptying

Small Intestine

It is where the major event of digestion and absorption occurs

Length: 3 meters (10 feet)

Divided into three regions:

• Duodenum – the shortest region

Only about 10 inches

Starts at the pyloric sphincter and merges with the jejunum

• Jejunum – about 1 m (3 feet)

• Ileum – measures about 2 m (6 feet)

Muscles of the Small Intestine

Mucosa and submucosa facilitates the process of digestion and absorption

Mucosa – forms a series of fingerlike villi

- each villi has a connective tissue which contains a venule, arteriole and a blood capillary network and a lymphatic capillary

- microvilli

- lined with epithelium that formed intestinal glands which secretes intestinal juice;

- epithelial cells in the mucosa are also goblet cells which secretes mucus

Submucusa – contains duodenal glands that secretes an alkaline mucus that helps neutralize gastric acid in the chyme.

Mechanical digestion in the Small Intestine

Two types of movement in the small intestine

A. Segmentation

B. Are localized, mixing contractions that occur in portions of intestine distended by a large portion of chyme. Chyme is mix with the digestive juices and bring the particles of food into contact with the mucosa for absorption.

C. Segmentation is usually faster in the duodenum at is slower at the ileum.

• Migrating motility complex (MMC)

• Begins when all the food is absorbed and segmentations stops and peristalsis begins.

• Starts at the lower portion of the stomach and pushes chyme forward a long stretch of small intestine before it dries up.

• It takes about 90 – 120 minutes to reach the ileum, so chyme stays in the smal intestine for about 3 – 5hours

Chemical digestion in the Small intestine

The chyme that enters the small intestine contains partially digested carbohydrates, proteins, and lipids

Digestion of carbohydrates:

Starches that are not broken by the salivary amylase re acted on by pancreatic amylase (an enzyme in pancreatic juice) except for cellulose.

Digestion of Proteins:

Protein starts its digestion in the stomach. The following enzymes that act on protein are the following: trypsin, cymotrypsin, carboxypeptidase, and elastase

Digestion of Lipids:

Triglycerides are emulsified by the the bile salts

Absorption

Carbohydrates:

It is absorbed as monosaccharides via a facilitated diffusion.

Proteins:

Is absorbed as amino acids via active transport

Lipids

Absorbed via simple diffusion

Electrolytes

Via an active transport

Vitamins

ADEK (fat soluble): absorbed via simple diffusion

Most B vitamins and Vitamin C: simple diffusion

Vitamin B12: combines with intrinsic factor

Water

Absorb through osmosis

Large Intestine

- It is the terminal portion of the GI tract

Length: 1.5 m (5 feet)

Diameter: 6.5 cm (2.5 in.)

From the anus to the ileum

Parts:

Ileocecal sphincter (valve)

Cecum – a blind pouch

Appendix – a coiled tube attached to the cecum

Colon : ascending, transverse, and descending

Rectum

Anal canal

Mechanical Digestion

The passage of chyme from the ileum into the cecum is regulated by the action of the Ileocecal sphincter.

Presence of food

Gastroileal reflex

Intensifies ileal peristalsis

Pushes chyme in the ileum into the cecum making the cecum distended and contractions t the ileocecal sphincter intensifies

Absorption and Feces formationAbsorption and Feces formationAbsorption and Feces formation

Chyme becomes solid or semi solid because of water absorption and it will becomes as feces.

Approximately 100 – 200 ml of water is reabsorb back.

The large intestine also absorbs ions, sodium and potassium, and some vitamins.

Defecation

Distention of the recital wall stimulates stretch receptors which in return will initiate the defecation reflex.

Send impulses to the sacral spinal chord which will initiate contraction of the rectal muscles thereby increasing the pressure within.

Internal anal sphincter is open.

External anal sphincter is relaxed

Defecation occurs

Major Salivary glands

Where most saliva is secreted

Lies beyond the oral mucosa but has ducts that lead to the oral cavity

3 pairs of major salivary glands:

1. Parotid glands

• Are located inferior and anterior to the ears (between the skin and the masseter muscle)

• Secretes saliva into the oral cavity via a parotid duct

• Contains cells that secrete a watery (serous) liquid containing salivary amylase

2. Submandibular glands

• Found beneath the base of the tongue in the posterior aspect of the floor of the mouth

• Submandibular ducts – run under the mucosa on either side of the floor of the mouth

• Contains cells similar to those found in the parotid glands, plus some mucous cells

Sublingual glands

1. Are superior to the submandibular glands

2. The lesser sublingual ducts, open into the floor of the mouth in the oral cavity

3. It contains mostly mucous cells, so they secrete a much thicker fluid that contributes only a small amylase to the saliva

TONGUE

An accessory digestive organ that is composed of skeletal muscle covered with mucous membrane

Extrinsic muscles:

located on the side of the mouth

moves the tongue from side to side, in and out to maneuver food for for chewing, shape the food into a rounded mass, and force the food to the back of the mouth for swallowing.

Holds the tongue in position

Intrinsic muscles:

alter the shape of the tongue for speech and swallowing

Lingual frenulum:

A fold in the midline of the undersurface of the tongue and is attached to the floor

Limits the movement of the tongue posteriorly

TONGUE

3 MAJOR REGIONS:

CROWN – VISIBLE PORTION ABOVE THE LEVEL OF THE GUM

ROOT - SOCKET

NECK – CONSTRICTIVE JUNCTION OF THE CROWN AND ROOT NEAR THE GUM LINE

COMPOSITION:

Dentin – a calcified connective tissue that gives the teeth its basic shape and rigidity

Pulp cavity – lies within the crown and is filled with pulp

Enamel – the one that covers the dentin

Function:

Cut, tear, and pulverize food to reduce solids to smaller particles for swallowing

LiveR

The heaviest gland in the body

Weighs about 3 bs

And it is the 2^nd largest organ of the body

Divisions:

Right lobe

Left lobe – the smaller of the two

Falciform ligament – the one that divides the two lobes

STRUCTURE:

FUNCTIONAL UNIT: LOBULES

Lobules: made up of epithelial cells called hepatocytes

BLOOD SUPPLY:

It receives blood from two sources:

Hepatic artery – receives the oxygenated blood

Hepatic portal vein – receives the deoxygenated blood containing newly absorbed nutrients, drugs, and possibly microbes and toxins from the GIT.

FUNCTION

1. Metabolic function:

Desaturation – wherein is breaks down stored fats

Breaks down excess amino acids and converts to urea

Converts excess carbohydrates into fat for storage

Detoxifies drugs and poisons

Synthesizes Vit. A, plasma protein, and prothrombin and fibrinogen

It is the main heat producing organ in the body

Manufactures antibodies, antitoxins, and heparin

2. Storage function

Vitamins A and D

Anti anemic factor

Iron from the diet and worn out blood cells

3. Secretory function:

Secretes bile

GALBLADDER

It is a pear – shaped organ situated on the undersurface of the right lobe of the liver.

It has a cystic duct that passes backwards and downwards to form the common hepatic duct and together they form the bile duct.

It stores bile

When fatty foods enters the duodenum the sphincter at the entrance to the bile duct relaxes and bile that is stored goes to the intestine

PANCREAS

Location: lies posterior to the greater curvature of the stomach

Parts:

Head - attaches to the duodenum

Body

Tail

Ducts: 2 major ducts found

Pancreatic duct (duct of Wirsung) – larger of the two

• It joins the common bile duct and forms the hepatopancreatic ampulla (ampulla of Vater)

Accessory duct (duct of Santorini)

• Empties directly to the duodenum

Pancreas is made up of small clusters of glandular epithelial cells.

Acini – 99 percent of the pancreas

- exocrine portion of the organ

- Secretes pancreatic juice (a mixture of fluid and digestive enzymes)

- approx 1200-1500/day.

- clear, colorless liquid made up mostly of water, some salts, sodium bicarbonate and some enzymes

enzymes:

s pancreatic amylase – digests CHO

s trypsin, chymotrypsin, carboxypeptidase, and elastase – digests CHON

s Pancreatic lipase – digests triglycerides

Islet of Langerhans – 1% of the pancreas

s endocrine portion of the of the pancreas

s Secretes the following hormones: glucagon, insulin, somatostatin, and pancreatic polypeptide