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Digestive and Urinary System: Katy Colindres - P.6 - Coggle Diagram
Digestive and Urinary System: Katy Colindres - P.6
Major Functions of the Digestive System
take in food
break food down into nutrient molecules
absorb molecules into the bloodstream
rid body of any indigestible remains
Major Functions of the Urinary System
kidneys maintain body's internal environment by:
regulating total water volume and total solute concentration in water
regulating ion concentrations in extracellular fluid
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 glycogenesis (when needed)
kidneys cleanse blood and adjust its composition
Major Organs of the Digestive System
alimentary canal (gastrointestinal or GI tract or gut)
continuous muscular tube that runs from the mouth to anus
digests food: breaks down into smaller fragments
digestive process:
1: ingestion: eating
2: propulsion: movement of food through the alimentary canal
swallowing
peristalsis: involves alternating waves of contraction and relaxation
3: mechanical breakdown: chewing, mixing food with saliva, churning food in stomach, and segmentation
segmentation: local constriction of intestine that mixes food with digestive juices
4: digestion: series of catabolic steps that involves enzymes that break down complex food molecules into chemical building blocks
5: absorption: passage of digested fragments from lumen of GI tract into blood or lymph
6: defecation: elimination of indigestible substances via anus in form of feces
absorbs fragments through lining into blood
organs the GI tract consists of:
mouth
where food is chewed and mixed with enzyme-containing saliva that begins process of digestion, and swallowing process is initiated
associated organs:
tongue
salivary glands
teeth
also called the oral (buccal) cavity
oral orifice: anterior opening
walls of mouth: stratified squamous epithelium
lips and cheeks
lips (labia) composed of fleshly orbicularis oris muscle
cheeks composed of buccinator muscles
labial frenulum: median attachment of each lip to gum
palate
forms roof of the mouth and has two distinct parts
hard palate: formed by palatine bones and palatine processes of maxillae with a mid-line ridge called raphe
soft palate: fold formed mostly of skeletal muscle
closes off nasopharynx during swallowing
uvula: fingerlike projection that faces downward from the free edge of soft palate
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
conduit to pass food from mouth to stomach along with esophagus
major function: propulsion, along with the esophagus, that starts with deglutition (swallowing)
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
conduit to pass food from mouth to stomach along with pharynx
major function: propulsion, along with the pharynx, that starts with deglutition (swallowing)
stomach
temporary storage tank that starts chemical breakdown of protein digestion
converts bolus of food to paste-like chyme
empty stomach has about 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 in continuous with duodenum through pyloric valve (sphincter controlling stomach emptying)
gross anatomy:
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:
stomach wall contains regular four tunics; however, muscularis and mucosa are modified
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
mucosa layer 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
types of gland cells:
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:
2 more items...
chief cells
secretions include:
2 more items...
enteroendocrine cells
secrete chemical messengers into lamina propria
2 more items...
mucosal barrier
harsh digestive conditions require stomach to be protected
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
digestive process in the stomach:
1: carries out breakdown of food
2: serves as holding area for food
3: delivers chyme to small intestine
4: denatures proteins by HCl
5: pepsin carries out enzymatic digestion of proteins
milk protein (casein) is broken down by rennin in infants
results in curdy substance
6: lipid-soluble alcohol and aspirin are absorbed into blood
7: only stomach function essential to life is secretion of intrinsic factor for vitamin B12 absorption
B12 needed for red blood cells to mature
lack of intrinsic factor causes pernicious anemia
treated with B12 injections
small intestine
gross anatomy
7-13 ft long from pyloric sphincter to ileocecal valve, point at which it joins large intestine
subdivisions
duodenum: mostly retroperitoneal; about 10 inches long; curves around head of pancreas
has most features
jejunum: about 8 ft long; attached posteriorly by mesentery
ileum: about 12 feet long; attached posteriorly by mesentery; joins large intestine at ileocecal valve
major organ of digestion and absorption
microscopic anatomy:
modifications of small intestine for absorption
small intestine's length and other structural modifications provide huge surface area for nutrient absorption
surface area is increased to about the size of a tennis court
villi: fingerlike projections of mucosa 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
digestive processes
chyme from stomach contains partially digested carbohydrates and proteins and undigested fats
takes 3-6 hours in small intestine to absorb all nutrients and most water
motility of the small intestine
after a meal
segmentation is most common motion of small intestine
initiated by intrinsic pacemaker cells
mixes/moves contents toward ileocecal valve
intensity is altered by long and short reflexes and hormones
1 more item...
between meals
peristalsis increases, initiated by rise in hormone motilin in late intestinal phase (every 90-120 minutes)
meal remnants, bacteria, and debris are moved toward large intestine
complete trip from duodenum to ileum takes about 2 hours
ileocecal valve control
ileocecal sphincter relaxes and admits chyme into large intestine when:
gastroileal reflex enhances force of segmentation in ileum
gastrin increases motility of ileum
ileocecal valve flaps close when chyme exerts backward pressure
prevents regurgitation into ileum
large intestine
gross anatomy
three unique features:
haustra: pocketlike sacs caused by tone of teniae coli
epiploic appendages: fat-filled pouches of visceral peritoneum
teniae coli: three bands of longitudinal smooth muscle in muscularis
subdivisions:
1: cecum: first part of large intestine
2: appendix: masses of lymphoid tissue
bacterial storehouse capable of recolonizing gut when necessary
twisted shape of appendix makes it susceptible to blockages
3: colon: has several regions, most which are retroperitoneal (except for transverse and sigmoid regions)
ascending colon: travels up right side of abdominal cavity to level of right kidney
ends in right-angle turn called right colic (hepatic) flexure
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
4: rectum: three rectal valves stop feces from being passed with gas (flatus)
5: 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
bacterial flora
consists of more than 1000 different types of bacteria
outnumber our own cells 10 to 1
metabolic functions
fermentation
ferment indigestible carbohydrates and mucin
release irritating acids and gases (about 500 mL per day)
vitamin synthesis
synthesize B complex and some vitamin K needed by liver to produce clotting factors
gut bacteria and health
proportions of gut bacteria can influence:
body weight
susceptibility to various diseases (including diabetes, atherosclerosis, fatty liver disease)
our moods
digestive processes
residue remains in large intestine 12-24 hours
no food breakdown occurs except what enteric bacteria digest
major functions of large intestine
propulsion of feces to anus and defecation
reabsorption of vitamins (made by bacterial flora), water, and electrolytes (especially Na+ and Cl-)
defecation
mass movements force feces toward rectum
muscles of rectum contract to expel feces
anus
accessory digestive organs
tongue
lingual frenulum: attachment to floor of mouth
occupies floor of mouth
functions:
initiation of swallowing, speech, and taste
gripping, repositioning, and mixing of food during chewing
formation of bolus (mixture of food and saliva)
gallbladder
associated with the small intestine
chief function is storage of bile
thin-walled muscular sac on ventral surface of liver
functions to store and concentrate bile by absorbing water and ions
digestive glands: produce secretions that help break down food
salivary glands
functions of saliva:
cleanses mouth
dissolves food chemicals for taste
moistens food; compacts into bolus
begins breakdown of starch with enzyme amylase
composed of two types of secretory cells
serous cells: produce watery secretion, enzymes, ions, but of mucin
mucous cells: produce mucus
liver
associated with the small intestine
digestive function is production of bile
bile: fat emulsifier
gross anatomy:
largest gland in body; weight around 3 pounds
consists of four primary lobes: right, left, caudate, and quadrate
bile ducts
common hepatic duct leaves liver
cystic duct connect 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
associated with the small intestine
supplies most of enzymes needed to digest chyme, as well as bicarbonate to neutralize stomach acid
exocrine function: produce pancreatic juice
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
teeth
lie in sockets in gum-covered margins of mandible and maxilla
mastication: process of chewing that tears and grinds food into smaller fragments
dentition and the dental formula
primary dentition consists of 20 deciduous teeth (milk/baby teeth) that erupt between 6 and 24 months of age
32 deep-lying permanent teeth enlarge and develop while roots of milk teeth are resorbed from below, causing them to loosen and fall out (around 6 to 12 years of age)
teeth classified according to shape
incisors: chisel shaped for cutting
canines: fang-like 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
tooth structure
each tooth has two major regions
crown: exposed part above gingiva (gum)
covered by enamel, the hardest substance in the body
root: portion embedded in jawbone
connected to crown by neck
Major Organs of the Urinary System
kidneys
1: renal cortex
granular-appearing superficial region
2: 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
3: renal pelvis
funnel-shaped tube continuous with ureter
minor calyces
cup-shaped areas that collect urine draining from pyramidal papillae
major calyces
areas that collect urine from minor calyces
empty urine into renal pelvis
urine flow
renal pyramid
minor calyx
major calyx
renal pelvis
ureter
major excretory organ
physiology
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); basically blood plasma without proteins
urine: produced from filtrate
<1% of original filtrate
contains metabolic wastes and unneeded substances
three major renal processes:
1: glomerular filtration: a passive process
hydrostatic pressure forces fluids and solutes through filtration membrane into glomerular capsule
no reabsorption into capillaries of glomerulus occurs
no metabolic energy required
2: tubular reabsorption: quickly reclaims most of tubular contents and returns them to blood
selective transepithelial process
almost all organic nutrients are reabsorbed
water and ion reabsorption is hormonally regulated and adjusted
includes active and passive tubular reabsorption
substances can follow two routes:
1: transcellular
2: paracellular
3: tubular secretion: reabsorption in reverse
occurs almost completely in PCT
selected substances are moved from peritublar capillaries through tubule cells out into filtrate
K+, H+, NH4+, creatinine, organic acids and bases
substances synthesized in tubule cells also are secreted
tubular secretion is important for:
disposing of substances, such as drugs or metabolites, that are bound to plasma proteins
eliminating undesirable substances that were passively reabsorbed like urea and uric acid
ridding body of excess K+
controlling blood pH by altering amounts of H+ or HCO3- in urine
ureters: transport urine from kidneys to urinary bladder
slender tubes
enter base of bladder through posterior wall
as bladder pressure increases, distal ends of ureters close, preventing backflow of urine
urinary bladder: temporary storage reservoir for urine
anatomy
muscular sac for temporary storage of urine
retroperitoneal, on pelvic floor posterior to pubic symphysis
males: prostate inferior to bladder neck
females: anterior to vagina and uterus
capacity
collapses when empty
rugae appear
expands and rises superiorly during filling without significant rise in internal pressure
moderately full bladder is about 5 inches long and can hold around one pint
can hold twice that amount if necessary but can burst if overdistended
urethra: transports urine out of body
muscular tube that drains urinary bladder
Digestive Enzymes
proteases (for proteins): secreted in inactive form to prevent self-digestion
amylase (for carbohydrates)
lipases (for lipids)
nucleases (for nucleic acids)
Location of Digestion and Absorption of Each Macromolecule
carbohydrates
digestion
mouth
salivary amylase
small intestine
pancreatic amylase
brush border enzymes in small intestine (dextrinase, glucoamylase, lactase, maltase, and sucrase)
path of absorption
glucose and galactose are absorbed via cotransport with Na+
fructose passes via facilitated diffusion
all monosaccharides leave the epithelial cells via facilitated diffusion, enter capillary blood in villi, and are transported to liver via hepatic portal vein
proteins
digestion
stomach
pepsin (stomach glands) in presence of HCl
small intestine
pancreatic enzymes (trypsin, chymotrypsin, carboxypeptidase)
brush border enzymes (aminopeptidase, carboxypeptidase, and dipeptidase)
path of absorption
amino acids absorbed via cotransport with Na+
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 capillary blood in the villi, and are transported to the liver via the hepatic portal vein
fats
digestion
mouth
lingual lipase
stomach
gastric lipase
small intestine
emulsification by the detergent action of bile salts ducted in from the liver
pancreatic lipases
path of absorption
fatty acids and monoglycerides enter the intestinal cells via diffusion
fatty acids and monoglycerides are recombined to form triglycerides, 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 acids
digestion
small intestine
pancreatic ribonuclease and deoxyribonuclease
brush border enzymes (nucleosidases and phosphatases)
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
Nephron Anatomy and Physiology
the structural and functional units that form urine in the kidneys
over 1 million per kidney
two main parts:
renal corpuscle
glomerulus
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
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
about 1.2 inches long
consists of single layer of epithelial cells
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
distal convoluted tubule
distal, farthest from renal corpuscle
drains into collecting duct
cuboidal cells with very few microvilli
function more in secretion than reabsorption
confined to cortex
collecting duct
two types of cells
principal cells
sparse with short microvilli
maintain water and Na+ balance
intercalated cells
cuboidal cells with abundant microvilli
two types of intercalated cells
A and B: both help maintain acid-base balance of blood
collecting ducts receive filtrate from many nephrons
run through medullary pyramids
give pyramids their striped appearance
ducts fuse together to deliver urine through papillae into minor calyces
Disorders of the Digestive and Urinary Systems
cholecystitis:
causes/risk factors:
blockage of gall duct by gallstones
symptoms:
tender abdomen
sweating
nausea
treatment:
probiotics
medication
inflammation of the gallbladder
gastroesophageal reflux disease (GERD):
causes/risk factors:
obesity
diabetes
smoking
symptoms:
chest pain
dry cough
sour taste
treatment:
surgery
prescription medication
over the counter medication
a chronic disease that occurs when the esophageal sphincter relaxes, allowing the contents of the stomach to move back into the esophagus
inflammatory bowel disease (IBD):
causes/risk factors:
causes unknown, possibly: genetics, environmental or immune
symptoms:
loss of appetite
weight loss
bowel obstruction
treatment:
medication
fluid replacement
surgery
a chronic complex intestinal condition that causes inflammation in the digestive track; includes Crohn's disease and ulcerative colitis
peptic ulcers:
sores that develop in the lining of the stomach or the duodenum
causes/risk factors:
alcohol abuse
imbalance in gastric juices
bacterial infection
symptoms:
diarrhea
abdominal pain
cramping
treatment:
medication
antibiotics
fluid
hemorrhoids
inflamed veins in the rectum or anus
causes/risk factors:
obesity
pregnancy
anal intercourse
symptoms:
rectal bleeding
feces leakage
anal itching
treatment:
medication
surgical removal
injections
spastic colon or IBS:
abnormal abdominal conditions
causes/risk factors:
diet
stress
hormonal
symptoms:
cramping
bloating and gas
diarrhea
treatment:
medication
diet
lifestyle change
bladder cancer:
one or more tumors in the bladder, most start in the inside lining of the bladder
causes/risk factors:
smoking or inhaling tobacco smoke
cancer drugs
radiation to the pelvis
symptoms:
hematuria (blood in urine)
pain when you pass urine
pain in lower abdomen
treatment:
surgery
chemotherapy
urinary tract infection:
the abnormal growth of bacteria anywhere along the urinary tract combined with symptoms; most commonly in bladder
causes/risk factors:
sexually active
using diaphragm or spermicide
recent pelvic surgery or used a catheter
symptoms:
burning with urination
frequent or urgent need to urinate
cloudy urine
treatment:
oral antibiotic pills
kidney stones
urine contains dissolved minerals and salts; when having high levels, hard stones form. can be silent or very painful
causes/risk factors:
too much calcium in urine
acidic urine
chronic UTI's
symptoms:
an intense need to urinate or urinating more often
a burning feeling while urinating
sharp, cramping pain in the back and side
treatment:
wait for stone to pass
medication
surgery
Layers of the GI Tract
1: mucosa
tunic layer that lines lumen
functions (different layers perform one or three):
secretes mucus, digestive enzymes, and hormones
absorbs end products of digestion
protects against infectious disease
2: submucosa
consists of areolar connective tissue
contains blood and lymphatic vessels, lymphoid follicles, and submucosal nerve plexus supplying surrounding GI tract tissues
has abundant amount of elastic tissues that help organs to regain shape after storing large meal
3: 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
4: serosa
outermost layers made up of visceral peritoneum