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Digestive & Urinary System Erika Castro Period: 1 - Coggle Diagram
Digestive & Urinary System
Erika Castro
Period: 1
Major functions
of the digestive system
Digestion
mechanical and chemical
breakdown of foods and
absorption of nutrients
Chemical digestion breaks down
large nutrient molecules into
smaller chemicals
Mechanical digestion breaks
down large pieces of food into
smaller ones
Mixing movements
Segmentation in the small intestine aids mixing by alternately
contracting and relaxing the smooth muscle in each area
Propelling movements
wavelike motion called peristalsis
• A ring of contraction in a portion of the tube occurs, while relaxation occurs ahead of the ring
• This allows a mass of food to be propelled to the next segment of the tube
Salivary Secretions
• Salivary glands contain serous cells that produce a watery fluid containing salivary amylase, and mucous cells that produce lubricating and binding mucus
• Amylase breaks down starch into disaccharides
Swallowing Mechanism
1st stage
• Voluntary stage
• Food is chewed and mixed with saliva, forming a bolus
• Bolus is forced into the oropharynx with the tongue
2nd stage
• Triggers swallowing reflex (involuntary)
• Epiglottis closes off the larynx
• Peristaltic wave begins in the pharynx, and proceeds toward the esophagus
• Breathing is inhibited briefly
3rd stage
• Peristalsis transports food from esophagus to stomach
stomach
• upper left abdominal quadrant
• Receives food from esophagus
• Mixes food with digestive juices
• Begins digestion of proteins
• Limited absorption of nutrients occurs in stomach
• Propels food to the small intestine
stomach absorbs small quantities of water, certain salts, alcohol, and some lipid-soluble drugs
mixture of food and gastric juice
made in the stomach is called chyme
passed toward the pyloric region using peristaltic waves
Chyme enters the duodenum in small amounts,
through the pyloric sphincter
Fats may be in the stomach for 3 to 6 hours
Proteins and carbohydrates pass through quickly
Gastric gland
Mucous cells produce mucus that protects the stomach lining
• Chief cells secrete pepsin (to hydrochloric acid protein) as inactive pepsinogen, which is activated when it comes in contact with hydrochloric acid
• Parietal cells secrete hydrochloric acid, which activates pepsinogen, and intrinsic factor, which is required for vitamin B12 absorption from the small intestine
gastric juice: products of mucous cells, chief cells, and parietal cells
Digestive organs
Alimentary Canal
Muscular tube that passes through thoracic and
abdominopelvic cavities
Food passageway between the mouth and anus
8 meters long
4 layers
Mucosa
inner layer of the wall
mucous membrane that surrounds the lumen of the tube
Consists of epithelium, underlying connective tissue, a little smooth muscle
Protects tissues of the canal
Carries on secretion and absorption of dietary nutrients
modified into folds or projections,
that increase surface area
Submucosa:
Lies under the mucosa
Consists of loose connective tissue, housing blood and lymphatic vessels, nerves, and glands
Nourishes the surrounding layers of the canal
transport absorbed nutrients away from digestive organs
Muscularis
2 layers of smooth muscle: inner circular layer and outer longitudinal layer
Propels food through the canal
Serosa
Outer serous layer, or visceral peritoneum
Protects underlying tissues, and secretes serous fluid to reduce friction between organs
The mouth/ 1st portion of alimentary canal
• First portion of the alimentary canal
• Functions: receives food, and begins mechanical digestion by mastication
• Surrounded by lips, cheeks, tongue, and palate
• Oral cavity is the chamber between the palate and tongue
• The narrow space between the teeth, cheeks, and lips is called the vestibule
cheeks
• form the lateral walls of the mouth
• Involved in chewing and expression
lips
• Highly mobile structures that surround the mouth opening
• Contain sensory receptors to detect the temperature and texture of food
tongue
• Thick, muscular organ, composed of skeletal muscle
• Covered by a mucous membrane
• Surface contains projections called papillae, which provide friction for moving food in the mouth
• Taste buds occur along the sides of the papillae
• Attached to the floor of the mouth by lingual frenulum
• Lingual tonsils are lymphatic tissues located at the root of the tongue
Palate
• Forms the roof of the oral cavity
• Consists of an anterior, bony, hard palate and posterior, muscular, soft palate
• Posterior projection of the soft palate, the uvula, closes off the nasal cavity during swallowing
• Palatine tonsils: masses of lymphatic tissue associated with the palate in the back of the mouth; help protect the body against infection
• Pharyngeal tonsils (adenoids): lymphatic tissue masses, located on the posterior wall of the pharynx, above the border of the soft palate
Teeth
Two sets of teeth develop in sockets within the alveolar processes of the maxillary and mandibular bones
The 20 primary (deciduous) teeth are shed in the order they appeared, and then replaced by 32 secondary (permanent) teeth
mechanical digestion: actions of chewing, teeth break food into smaller pieces,
Different teeth are adapted to handle food with incisors, cuspids, bicuspids, and molars
Teeth start the process of mechanical digestion by breaking down larger pieces of food into smaller pieces
Mechanical digestion makes chemical digestion easier, by increasing surface area for enzyme access to food particles
Salivary Glands
The salivary glands (Parotid, Submandibular, Sublingual glands) secrete saliva, which moistens and dissolves food particles, binds them together, aids in tasting, helps to cleanse the mouth and teeth, and begins carbohydrate digestion
Pharynx
cavity lying posterior to the mouth
3 sections of the pharynx
Nasopharynx: top portion, air passage behind nasal cavity
• Oropharynx: middle portion, passageway for food and air
• Laryngopharynx: bottom portion, passageway to esophagus
Esophagus
muscular tube leading from pharynx to stomach
• Straight, collapsible food passageway leading to the stomach
• Extends downward through an opening in the diaphragm
• Mucous glands scattered throughout submucosa produce mucus to moisten and lubricate the inner lining of the tube
• Lower esophageal (cardiac, cardioesophageal) sphincter helps to prevent regurgitation of the stomach contents into the esophagus
stomach
Cardia(c), a small region near opening to the esophagus
• Fundus, a small, rounded region superior to the cardia
• Body region, main portion of the stomach, between fundus and pylorus
• Pylorus, distal portion, near small intestine
• Pyloric canal is a narrowed area close to small intestine
• Pyloric sphincter, at end of pyloric canal, is a muscular ring that controls release of food from stomach into small intestine
accessory organs
the pancreas
liver
gallbladder
pancreas
• Pancreas is both endocrine and exocrine gland
• Exocrine function is to produce pancreatic juice that aids digestion
liver
located in the upper right quadrant of the
abdominal cavity
largest internal organ
Divided into large right and left lobes
gallbladder
pear-shaped sac on the inferior surface of the liver
Stores bile
cholesterol may precipitate in the gallbladder to
form gallstones
Small intestine
long tubular organ, which runs from the
stomach to the beginning of the large intestine
consists of the duodenum, jejunum, and ileum
Duodenum: the shortest and most fixed portion of the small intestine; the stomach empties chyme directly into the duodenum
Jejunum: makes up the proximal two-fifths of the small intestine, has a slightly larger diameter than the ileum, and is more active in the digestion process
Ileum: most distal portion
jejunum & ileum are suspended from the posterior abdominal wall by a double-layered fold of peritoneum called mesentery
mesentery contains blood vessels, nerves, and lymphatic vessels that serve the intestinal wall
Greater omentum drapes over the intestine, made of double fold peritoneal membrane
vomiting can be caused by
being emotionally upset, pain, stretching of the stomach,
irritants, sensory overload
pancreatic juices
Pancreatic amylase breaks down starch into disaccharides
• Pancreatic lipase breaks down triglycerides to glycerol and fatty acids
nucleases break down nucleic acids to nucleotides
Proteolytic enzymes, trypsin, chymotrypsin, and carboxypeptidase split certain bonds in amino acids, to break down proteins to dipeptides
contains bicarbonate ions, which create an
alkaline environment in the duodenum which allow enzymes to function.
liver
metabolism of
carbohydrates, lipids, and proteins
Maintains proper blood concentrations of glucose and other nutrients
Stores glycogen, vitamins A, D, and B12, and iron
Synthesizes lipoproteins, phospholipids, and cholesterol
secrete bile
Filters the blood
bile
Composed of water, bile salts, bile pigments, cholesterol, and electrolytes
Bile pigments are breakdown products
of hemoglobin
bile salts breaking down large fat globules into smaller droplets which increases their solubility in water
small intestine
• Receives chyme from stomach
• Receives pancreatic juice from pancreas and bile from liver and gallbladder
• Finishes digestion of nutrients that arrive in the chyme
• Absorbs digestive end products
• Transports the remaining residue to the large intestine