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Lina Le Period 6 Digestive and Urinary System - Coggle Diagram
Lina Le Period 6 Digestive and Urinary System
Major functions of the digestive system
Break it down into nutrient molecules
Absorb molecules into the bloodstream
Rid body of any indigestible remains
Take in Food
Major organs of the digestive system
Alimentary canal (gastrointestinal or GI tract or gut)
Absorbs fragments through lining into blood
Digests food: breaks down into smaller fragments
Organs
Pharynx
Food passes from mouth into oropharynx and then into laryngopharynx
Allows passage of food, fluids, and air
External muscle layers consists of two skeletal muscle layers
Esophagus
Flat muscular tube that runs from laryngopharynx to stomach
Is collapsed when not involved in food propulsion
Gastroesophageal (cardiac) sphincter surrounds cardial orifice
Keeps orifice closed when food is not being swallowed
Mucus cells on both sides of sphincter help protect esophagus from acid reflux
Mouth
Also called the oral (buccal) cavity
Walls of mouth lined with stratified squamous epithelium
Oral orifice is the anterior opening
Lips and Cheeks
Lips (labia): composed of fleshy orbicularis oris muscle
Cheeks: composed of buccinator muscles
Labial frenulum: median attachment of each lip to gum
Palate
Palate forms the roof of the mouth and has two distinct parts
Hard palate: formed by palatine bones and palatine processes of maxillae with a midline ridge called raphe
Soft palate: fold formed mostly of skeletal muscle
Closes off nasopharynx during swallowing
Uvula: fingerlike projection that faces downward from free edge of soft palate
Stomach
Gross Anatomy
Stomach is a temporary storage tank that starts chemical breakdown of protein digestion
Converts bolus of food to paste-like chyme
Empty stomach has ~50 ml volume but can expand to 4 L
When empty, stomach mucosa forms many folds called rugae
Major regions of the stomach
Cardial part (cardia): surrounds cardial orifice
Fundus: dome-shaped region beneath diaphragm
Body: midportion
Pyloric part: wider and more superior portion of pyloric region, antrum, narrows into pyloric canal that terminates in pylorus
Pylorus is continuous with duodenum through pyloric valve (sphincter controlling stomach emptying)
Greater curvature: convex lateral surface of stomach
Lesser curvature: concave medial surface of stomach
Mesenteries extend from curvatures and tether stomach to other digestive organs
Lesser omentum
Runs from lesser curvature to liver
Greater omentum: drapes inferiorly from greater curvature over intestine, spleen, and transverse colon
Blends with mesocolon, mesentery that anchors large intestine to abdominal wall
Contains fat deposits and lymph nodes
Microscopic Anatomy
Mucosa layer is also modified
Consists of simple columnar epithelium entirely composed of mucous cells
Secrete two-layer coat of alkaline mucus
Surface layer traps bicarbonate-rich fluid layer that is beneath it
Dotted with gastric pits, which lead into gastric glands
Gastric glands produce gastric juice
Mucosa Barrier
Harsh digestive conditions require stomach to be protected
Mucosal barrier protects stomach and is created by three factors
Thick layer of bicarbonate-rich mucus
Damaged epithelial cells are quickly replaced by division of stem cells
Surface cells replaced every 3-6 days
Muscularis externa has circular and longitudinal smooth muscle layers, as well as extra third layer, the oblique (diagonal) layer
Together, smooth muscles allow stomach not only to churn, mix, and move chyme, but also to pummel it, which increases physical breakdown and ram it into small intestine
Stomach wall contains regular four tunics; however, muscularis and mucosa are modified
Small Intestine
Gross Anatomy
2–4 m long (7–13 ft) from pyloric sphincter to ileocecal valve, point at which it joins large intestine
Small intestine is the major organ of digestion and absorption
Subdivisions
Jejunum: ~2.5 m (8 ft) long; attached posteriorly by mesentery
Duodenum: mostly retroperitoneal; ~25.0 cm (10.0 in) long; curves around head of pancreas
Hast most features
Ileum: ~3.6 m (12 ft) long; attached posteriorly by mesentery; joins large intestine at ileocecal valve
Microscopic Anatomy
Modifications of small intestine for absorption
Villi
Fingerlike projections of mucosa (~1 mm high) with a core that contains dense capillary bed and lymphatic capillary called a lacteal for absorption
Microvilli
Cytoplasmic extensions of mucosal cell that give fuzzy appearance called the brush border that contains membrane-bound enzymes brush border enzymes, used for final carbohydrate and protein digestion
Small intestine’s length and other structural modifications provide huge surface area for nutrient absorption
Large Intestine
Large intestine has three unique features not seen elsewhere:
Teniae coli: three bands of longitudinal smooth muscle in muscularis
Haustra: pocketlike sacs caused by tone of teniae coli
Epiploic appendages: fat-filled pouches of visceral peritoneum
Subdivisions of large intestine
Appendix: masses of lymphoid tissue
Bacterial storehouse capable of recolonizing gut when necessary
Twisted shape of appendix makes it susceptible to blockages
Colon: has several regions, most which are retroperitoneal (except for transverse and sigmoid regions)
Transverse colon: travels across abdominal cavity
Ends in another right-angle turn, left colic (splenic) flexure
Descending colon: travels down left side of abdominal cavity
Sigmoid colon: S-shaped portion that travels through pelvis
Ascending colon: travels up right side of abdominal cavity to level of right kidney
Ends in right-angle turn called right colic (hepatic) flexure
Cecum: first part of large intestine
Rectum: three rectal valves stop feces from being passed with gas (flatus)
Anal canal: last segment of large intestine that opens to body exterior at anus
Has two sphincters
Internal anal sphincter: smooth muscle
External anal sphincter: skeletal muscle
Anus
Continuous muscular tube that runs from the mouth to anus
Accessory digestive organs
Tongue
Functions
Gripping, repositioning, and mixing of food during chewing
Formation of bolus, mixture of food and saliva
Initiation of swallowing, speech, and taste
Tongue occupies floor of mouth
Lingual frenulum: attachment to floor of mouth
Gallbladder
Gallbladder is a thin-walled muscular sac on ventral surface of liver
Functions to store and concentrate bile by absorbing water and ions
Teeth
Tooth structure
Each tooth has two major regions
Crown: exposed part above gingiva (gum)
Covered by enamel, the hardest substance in body
Root: portion embedded in jawbone
Connected to crown by neck
Teeth are classified according to shape:
Incisors: chisel shaped for cutting
Canines: fanglike teeth that tear or pierce
Premolars (bicuspids): broad crowns with rounded cusps used to grind or crush
Molars: broad crowns, rounded cusps: best grinders
During chewing, upper and lower molars lock together, creating tremendous crushing force
Dentition and the dental formula
Mastication: process of chewing that tears and grinds food into smaller fragments
Teeth lie in sockets in gum-covered margins of mandible and maxilla
Digestive glands: produce secretions that help break down foodstuffs
Liver
Gross Anatomy of the liver
Largest gland in body; weighs ~3 lbs
Consists of four primary lobes: right, left, caudate, and quadrate
Bile ducts
Common hepatic duct leaves liver
Cystic duct connects to gallbladder
Bile duct formed by union of common hepatic and cystic ducts
Bile : Composition and enterohepatic circulation
Yellow-green, alkaline solution containing:
Bile salts: cholesterol derivatives that function in fat emulsification and absorption
Bilirubin: pigment formed from heme
Bacteria break down in intestine to stercobilin that gives brown color of feces
Cholesterol, triglycerides, phospholipids, and electrolytes
Pancreas
Endocrine function: secretion of insulin and glucagon by pancreatic islet cells
Composition of pancreatic juice
Watery, alkaline solution (pH 8) to neutralize acidic chyme coming from stomach
Digestive enzymes
Proteases (for proteins): secreted in inactive form to prevent self-digestion
Amylase (for carbohydrates)
Lipases (for lipids)
Nucleases (for nucleic acids)
Exocrine function: produce pancreatic juice
Salivary glands
Functions of saliva
Cleanses mouth
Dissolves food chemicals for taste
Moistens food; compacts into bolus
Begins breakdown of starch with enzyme amylase
Salivary glands are composed of two types of secretory cells
Serous cells: produce watery secretion, enzymes, ions, bit of mucin
Mucous cells: produce mucus
Digestive enzymes (including names and functions)
Types of Gland cels
Glands in fundus and body produce most gastric juice
Glands include secretory cells
Mucous neck cells
Secrete thin, acidic mucus of unknown function
Parietal cells
Secretions include:
Hydrochloric acid (HCl)
pH 1.5–3.5; denatures protein, activates pepsin, breaks down
plant cell walls, and kills many bacteria
Intrinsic factor
Glycoprotein required for absorption of vitamin B12 in small
Chief cells
Secretions include:
Pepsinogen: inactive enzyme that is activated to pepsin by HCl and by pepsin itself (a positive feedback mechanism)
Lipases
Digest ~ 15% of lipids
Enteroendocrine cells
Secrete chemical messengers into lamina propria
Act as paracrines
Serotonin and histamine
Hormones
Somatostatin (also acts as paracrine) and gastrin
Layers of the GI tract (including stomach)
Muscularis externa
Muscle layer responsible for segmentation and peristalsis
Contains inner circular muscle layer and outer longitudinal layers
Circular layer thickens in some areas to form sphincters
Serosa
Outermost layer, which is made up of the visceral peritoneum
Submucosa
Consists of areolar connective tissue
Contains blood and lymphatic vessels, lymphoid follicles, and submucosal nerve plexus that supply surrounding GI tract tissues
Has abundant amount of elastic tissues that help organs to regain shape after storing large meal
Mucosa
Tunic layer that lines lumen
Functions: different layers perform one or all three
Secretes mucus, digestive enzymes, and hormones
Absorbs end products of digestion
Protects against infectious disease
Nephron anatomy and physiology
Nephrons are the structural and functional units that forms urine in the Kidneys
1 million per kidney
Two main parts
Renal corpuscle
Glomerus
Tuft of capillaries composed of fenestrated endothelium
Highly porous capillaries
Allows for efficient filtrate formation
Filtrate: plasma-derived fluid that renal tubules process to form urine
Glomerular capsule
Also called Bowman’s capsule: cup-shaped, hollow structure surrounding glomerulus
Consists of two layers
Parietal layer: simple squamous epithelium
Visceral layer : clings to glomerular capillaries; branching epithelial podocytes
Extensions terminate in foot processes that cling to basement
membrane
Filtration slits between foot processes allow filtrate to pass into
capsular space
Renal tubule
Consists of single layer of epithelial cells, but each region has its own unique histology and function
Renal tubule is about 3 cm (1.2 in.) long
Three major parts
Proximal convoluted tubule
Proximal, closest to renal corpuscle
Cuboidal cells with dense microvilli that form brush border
Increase surface area
Also have large mitochondria
Functions in reabsorption and secretion
Confined to cortex
Nephron loop
U-shaped structure consisting of two limbs
Descending limb
Proximal part of descending limb is continuous with proximal tubule
Distal portion also called descending thin limb; simple squamous
epithelium
Ascending limb
Thick ascending limb
Thin in some nephrons
Cuboidal or columnar cells
Formerly called loop of Henle
Distal convoluted tubule
Distal, farthest from renal corpuscle
Cuboidal cells with very few microvilli
Function more in secretion than reabsorption
Confined to cortex
Major functions of the urinary system
Maintaining the body's internal environment by:
Regulating total water volume and total solute concentration in water
Regulating ion concentrations in extracellular fluid (ECF)
Ensuring long-term acid-base balance
Excreting metabolic wastes, toxins, drugs
Producing erythropoietin (regulates blood pressure and renin (regulates RBC production)
Activating vitamin D
Carrying out gluconeogenesis, if needed
Location of digestion and absorption of each macromolecule
Digestion
Carbohydrate digestion
Foodstuff
Starch and disaccharides
Oliogosaccharides and disaccharides
Lactose
Galactose
Glucose
Maltose
Glucose
Sucrose
Fructose
Glucose
Enzymes and source
Salivary amylase
Pancreatic amylase
Brush border enzymes in small intestine (dextrinase, gluco-amylase, lactase, maltase, and sucrase)
Site of Action
Mouth
Small intestine
Path of absorption
Glucose and galactose are absorbed via cotransport with Na
Fructose passes via facillitated diffusion
All monosaccharides leave the epithelial cells via facilitated diffusion enter the capillary blood in the villi and are transported to the liver via the hepatic portal vein
Protein digestion
Enzymes and source
Pancreatic enzymes (trypsin, chymotrypsin, carboxypeptidase)
Brush border enzymes (aminopepridase, carboxypeptidase, and dipeptidase)
Pepsin (stomach glands) in presence of HCl
Site of action
Stomach
Small Intestine
Foodstuff
Proteins
Large polypeptides
Small polypeptides, small peptides
Amino acids (some dipeptides and tripeptides)
Path of absorption
Some dipeptides and tripeptides are absorbed via cotransport with H and hydrolyzed to amino acids within the cells
Infrequently, transcytosis of small peptides occurs
Amino acids leave the epithelial cells by facilitated diffusion, enter the capillary blood in the vili, and are transported to the liver via the hepatic portal vein
Amino acids are absorbed via cotransport with Na
Fat digestion
Foodstuff
Unemulsified triglycerides
Monoglycerides and fatty acids
Enzymes and source
Lingual lipase (minor importance)
Gastric lipase (minor importance)
Emulsification by the detergent action of bile salts ducted in from the liver
Pancreatic lipases
Site of action
Mouth
Stomach
Small intestine
Path of absorption
Fatty acids and monoglycerides enter the intestinal cells via diffusion
Fatty acids and monoglycerides are recombined to form triglycerides and then combined with other lipids and proteins within the cells. The resulting chylomicrons are extruded by exocytosis
The chylomicrons enter the lacteals of the villi and are transported to the systemic circulation via the lymph in the thoracic duct
Some short-chain fatty acids are absorbed, move into the capillary blood in the villi by diffusion, and are transported to the liver via the hepatic portal vein
Nucleic Acid digestion
Enzymes and source
Pancreatic ribo-nuclease and deoxyribonuclease
Brush border enzymes (nuclerosidases and phosphatases)
Site of action
Small intestine
Path of absorption
Units enter intestinal cells by active transport via membrane carriers
Units are absorbed into capillary blood in the villi and transported to the liver via the hepatic portal vein
Foodstuff
Nucleic acids
Pentose sugars, N-containing bases, phosphate ions
Absorption
Vitamin absorption
In small intestine
Fat-soluble vitamins (A, D, E, and K) are carried by micelles; diffuse into absorptive cells
Water-soluble vitamins (C and B) are absorbed by diffusion or by passive or active transporters
Vitamin B12 (large, charged molecule) binds with intrinsic factor and is absorbed by endocytosis
In large intestine: vitamin K and B vitamins from bacterial metabolism are absorbed
Absorption of electrolytes
Most ions are transported actively along length of small intestine
Iron and calcium are absorbed in duodenum
𝑁𝑎+ absorption is coupled with active absorption of glucose and amino acids
𝐶𝑙− is transported actively
𝐾+ diffuses in response to osmotic gradients; lost if water absorption is poor
Usually amount in intestine is amount absorbed
Iron and calcium absorption is related to need
Ionic iron is stored in mucosal cells with ferritin
When needed, transported in blood by transferrin
𝐶𝑎2+ absorption is regulated by vitamin D and parathyroid hormone (PTH)
Absorption of water
Net osmosis occurs if concentration gradient is established by active transport of solutes
Water uptake is coupled with solute uptake
9 L water, most from GI tract secretions, enter small intestine
95% is absorbed in the small intestine by osmosis
Most of rest is absorbed in large intestine
Major organs of the urinary systems
Ureters
Ureters: slender tubes that convey urine from kidneys to bladder
Enter base of bladder through posterior wall
As bladder pressure increases, distal ends of ureters close, preventing backflow of urine
Urinary bladder
Urinary bladder anatomy
Retroperitoneal, on pelvic floor posterior to pubic symphysis
Males: prostate inferior to bladder neck
Females: anterior to vagina and uterus
Muscular sac for temporary storage of urine
Urine storage capacity
Collapses when empty
Rugae appear
Expands and rises superiorly during filling without significant rise in internal pressure
Moderately full bladder is ~12 cm long (5 in.) and can hold ~ 500 ml (1 pint)
Can hold twice that amount if necessary but can burst if overdistended
Kidneys
Kidneys, a major excretory organ, maintain the body’s internal environment by:
Regulating total water volume and total solute concentration in water
Regulating ion concentrations in extracellular fluid (ECF)
Ensuring long-term acid-base balance
Excreting metabolic wastes, toxins, drugs
Producing erythropoietin (regulates blood pressure and renin (regulates RBC production)
Activating vitamin D
Carrying out gluconeogenesis, if needed
Internal Gross Anatomy
Renal pelvis
Minor calyces
Cup-shaped areas that collect urine draining from pyramidal papillae
Funnel-shaped tube continuous with ureter
Major calyces
Empty urine into renal pelvis
Areas that collect urine from minor calyces
Renal medulla: deep to cortex, composed of cone-shaped medullary (renal) pyramids
Broad base of pyramid faces cortex
▪ Papilla, tip of pyramid, points internally
▪ Renal pyramids are separated by renal columns, inward extensions of cortical tissue
▪ Lobe: medullary pyramid and its surrounding cortical tissue; about eight lobes per kidney
Renal cortex: granular-appearing superficial region
Physiology of Kidney
180 L of fluid processed daily, but only 1.5 L of urine is formed
Kidneys filter body’s entire plasma volume 60 times each day
Consume 20–25% of oxygen used by body at rest
Filtrate (produced by glomerular filtration) is basically blood plasma minus proteins
Urine is produced from filtrate
Urethra
Muscular tube that drains urinary bladder
Disorders of the digestive and urinary systems
Peptic Ulcers
Symptoms
heart burn
severe chest pain
nausea
Treatment Options
lifestyle changes
medication
endoscopic surgery
Causes or Risk Factors
bacterial infection
smoking
imbalance of gastric juices
Description
Sores that develop in the lining of the stomach or the duodenum
Polyps
Description
growth
Causes or Risk Factors
hereditary
diet
age
Symptoms
asymptomatic
change in bowel movements
bloody stool
Treatment Options
surgical removal
diet adjustment
none
Inflammatory Bowel Disease (IBD)
Description
A chronic complex intestinal condition that causes inflammation in the digestive tract. Includes crohn's disease and ulcerative colitis
Causes or Risk Factors
possibly environmental
possibly immune
possibly genetics
Symptoms
abdominal pain
cramping
diarrhea
Treatment Options
medication
antibiotics
fluid replacement
Spastic Colon (IBS)
Causes or Risk Factors
lifestyle
stress
diet
Symptoms
abdominal pain
cramping
bloating and gas
Treatment Options
medication
diet
lifestyle change
Description
abnormal abdominal conditions
Gastroesophageal Reflux Disease (GERD)
Causes or Risk Factors
weakened esophageal sphincter
obesity
frequent acid reflux
Symptoms
chest pain
heart burn
dusphagia (difficulty swallowing)
Treatment Options
over the counter medication
prescription medication
surgery
Description
A chronic disease that occurs when the esophageal sphincter relaes, allowing the contents of the stomach to move back into the esophagus
Bladder Cancer
Causes or Risk Factors
caner drugs
radiation to pelvis
smoking
Symptoms
hematuria
pain when urinating
pain in lower abdomen
Treatment Options
chemotherapy
radiation
surgery
Description
when cells of the bladder grow abnormally
Cholecystitis
Causes or Risk Factors
primarily caused by blockage of the gall duct by gall stones
digestive tumors
blockage of the bile duct
Symptoms
tender abdomen
sweating
nausea
Description
an inflammation of the gall bladder
Treatment Options
medication
fasting
antibiotics
Urinary Tract Infection (UTI)
Causes or Risk Factors
sexually active women
pregnant women
menopausal women
Symptoms
burning when urinating
frequent urges to urinate
pain or pressure in lower abdomen
Description
an abnormal growth of bacteria along the urinary tract combined with symptoms
Treatment Options
oral antibiotic pills
Kidney Stones
Causes or Risk Factors
too much calcium in urine
overweight
diabetes
Symptoms
intense need to urinate
burning sensation when urinating
sharp cramping pain
Description
urine has high levels of minerals and salts so hard stones form
Treatment Options
medication
surgery
wait for stone to pass on its own