lecture exam 3 Flashcards
Trace the path of bile from its production by hepatocytes to its storage in the gallbladder
Bile is synthesized in hepatocytes and transported to bile canaliculi, which empty into bile ductules. The bile ductules merge to form the right and left hepatic ducts, which unite to form the common hepatic duct. The common hepatic duct merges with the cystic duct from the gallbladder to form the common bile duct.
- How does the presence of acidic chyme in the duodenum affect the pancreas?
Acidic chyme in the duodenum stimulates the mucosa of the small intestine to release secretin. Secretin triggers the pancreas to produce and release pancreatic juice filled with bicarbonate ions to neutralize the acidity of the chyme.
- Describe the modification of the mucosa of the small intestine.
Ridges of the mucosa form cirular folds from the duodenum to the ileum. Finger-like projections of the mucosa form villi. Each villus is covered with microvilli that form a brush border, giving the lining of the small intestine a velvet-like texture.
- Name the brush border enzymes and state their functions.
The principal brush border enzymes are maltase, sucrase, and lactase, which digest maltose, sucrose, and lactose, respectively, into glucose, fructose, and galactose. Other brush border enzymes are carboxypeptidase, aminopeptidase, and dipeptidase, which split small peptides into amino acids.
- What makes lipid absorption so complicated? EXPLAIN.
Lipids are not soluble in water, so they cannot be easily transported through the blood. Fatty acids and monoglycerides resulting from lipid digestion must be converted into micelles so they can enter into the absorptive cells. Absorptive cells recombine the fatty acids and monoglycerides and combine them with cholesterol and proteins to form chylomicrons. Chylomicrons enter the lacteals of the lymphatic system to be transported to the blood.
- How is flatus produced?
Flatus is produced by bacterial fermentation of any carbohydrates that remain in the large intestine.
- Explain the defecation reflex.
The presence of fecal matter in the rectum causes distension of the rectum. Stretch receptors send signals to the spinal cord. The spinal cord sends motor signals along parasympathetic nerves to increase peristalsis in the distal portions of the colon and to relax the internal anal sphincter. This action is conveyed to the cerebrum where a decision to voluntarily relax the external anal sphincter can be made.
- Trace the path that a molecule of oxygen would follow from the external naris to an alveolus.
External naris - nasal cavity - internal naris - nasopharynx - oropharynx - laryngopharynx - larynx (glottis) - trachea - primary (main) bronchus - secondary (lobar) bronchus - tertiary (segmental) bronchus - bronchiole - terminal bronchiole - respiratory bronchiole - alveolar duct - alveolus.
- Which piece of cartilage protects the opening to the larynx?
Epiglottis
- Why are male voices typically lower in pitch than female voices?
Higher levels of testosterone in the male make his vocal cords longer and thicker than the vocal cords of a female.
- What is the respiratory membrane?
A very thin barrier between an alveolus and a blood capillary, formed from the the wall of a type I alveolar cell and the wall of a blood capillary, plus the shared basement membranes.
- How would you increase the volume of your lungs?
Contract the diaphragm to increase the volume of the thoracic cavity from top to bottom. Contract the external intercostal muscles to raise the ribcage and increase the volume of the thoracic cavity from front to back. Because of the organization of the pleurae, this will expand the volume of the lungs.
- What is meant by low lung compliance?
Low compliance means that the lungs will resist expansion.
- What lung volume/lung capacity would a two-year old use to hold his/her breath during a temper tantrum?
Because s/he is holding his/her breath, inspiratory capacity would be used.
- Is it possible for your lungs to explode? EXPLAIN.
NO! The Hering-Breuer reflex would inhibit inspiratory neurons before they could cause overinflation of the lungs.
- What is the principal factor that determines the rate of alveolar gas exchange?
The difference in partial pressures of oxygen and carbon dioxide between the alveoli and the pulmonary capillaries.
- What effect would exercise have on systemic gas exchange? EXPLAIN.
Systemic gas exchange would increase. Cells will need more oxygen to carry out cellular respiration. This will generate more carbon dioxide. Thus, the partial pressures of oxygen and carbon dioxide will increase resulting in greater gas exchange.
- How is the bulk of carbon dioxide transported back to the lungs from the tissues? EXPLAIN.
In the form of bicarbonate ions. Carbon dioxide diffuses into a red blood cell where it combines with water to form carbonic acid. Carbonic acid dissociates into hydrogen ions and bicarbonate ions. Bicarbonate ions return to the plasma to be transported to the lungs.
- How does your body respond to respiratory acidosis?
Hyperventilation. Increasing the rate of breathing allows the body to exhale carbon dioxide faster than it forms. Hydrogen ions will bind with bicarbonate ions to balance the loss of carbon dioxide, which removes hydrogen ions from the blood and brings pH back up to the normal range.
respiration
refers to gas exchange from atmosphere to the blood of the cells
ventilation
moving air into and out of lungs
alveolar gas exchange
lungs and blood
systemic gas exchange
blood and tissue cells
upper respiratory system consists of
nose, pharynx, larynx, and trachea
lower respiratory system consists of
bronchial tree, and lungs
conductive zone
passageways that warm, humidify, and cleanse incoming air before it reaches respiratory zone which is actual site of gas exchange
vestibule of nose
just inside the nostrils and is lined with stratified squamous epithelium and stiff vibrissa
nasal septum
divides nasal cavity into right and left chambers
turbinate bones are covered with
mucous membranes
internal nares link the
nasal cavity with the pharynx
internal structures of the nose have 3 functions
air is filtered and warmed, odors detected, speech sounds modified
what may indicate hypertension
spontaneous bleeding from capillaries in nasal epithelium
ciliated pseudostratified mucosa contains glands that secrete
up to one liter of mucus daily to trap particles and drive them towards the pharynx
pharynx extends from
internal nares to larynx
nasopharynx
two openings lead to auditory tubes that connect to ears
oropharynx
contains palatine and lingual tonsils, passageway for food
laryngopharynx
links the esophagus with larynx
larynx
nine pieces of cartilage, thyroid cartilage forms anterior wall, larger in males
epiglottis
cartilaginous flap that closes the glottis during swallowing preventing food and drinks from entering
cricoid cartilage
attatches the larynx to trachea
arytenoid, corniculate, and cuneiform cartilages function in
speech production
extrinsic ligaments
link thyroid cartilage to hyoid bone and cricoid cartilage to trachea
intrinsic ligaments
hold laryngeal cartilages together
superior fold or vestibular fold
false vocal cords and they close the glottis during swallowing
inferior vocal fold
true vocal cords and they produce sounds as air rushes past them
pitch is controlled by
tension on cords
taut vocal cords produce
high pitched sounds
relaxed vocal cords produce
lower sounds
sounds that are produced by the vocal cords get converted into speech by actions of
the pharynx, mouth, tongue, lips, and nasal cavity
inflamed vocal cords are caused by
infection, dry air, overuse. They swell and cause hoarseness
trachea carries air from
larynx to lungs
mucocilliary elevator
moves mucus and particles up to the pharynx so they can be swallowed
tracheostomy
incision is made below the cricoid cartilage to create emergency air passageway
intubation
a tube is inserted into the nose or mouth and passed through larynx and trachea to clear obstruction
right primary bronchus
short wide and more vertical than left
primary bronchus divides into
secondary(lobar) bronchus
lobar bronchus divides into
tertiary(segmental) bronchi
tertiary bronchus divide into
bronchioles which are surrounded by smooth muscle and innervated by autonomic nervous system to regulate diameter of bronchiole
bronchioles branch repeatedly to form
terminal bronchioles
terminal bronchioles subdivide into
microscopic respiratory bronchioles
each respiratory bronchiole divides into
several alveolar ducts
primary bronchi, blood vessels, lymphatic vessels, and nerves enter
via the hilum
each lung is covered by a
pleura which consists of two layers of serous membranes
outer parietal pleura is attacthed
to the wall of the thoracic cavity
inner visceral pleura covers
surface of each lung
pleural cavity
between the pleurae filled with serous fluid to reduce friction
pleurisy describes
inflammation of the pleurae caused by cancer, pneumonia, and tuberculosis. increases friction and causes stabbing pain, with shortness of breath
right lobe of lung
consists of three lobes and is larger
left lobe of lung
only has two lobes because of cardiac notch
a bronchopulmonary segment consists of
of lobules enclosed in elastic connective tissue. each is supplied with a lymphatic vessel, an arteriole, venule, and a terminal bronchiole
alveolar sacs consist of
of clusters of grape-like alveoli.
each lung contains approximately
150 million alveoli creates 70 square meters of surface for gas exchange
type I alveolar cells are
thin-walled simple squamous cells that permit rapid gas exchange
type II alveolar cells produce
the lipoprotein surfactant lowers surface tension of alveolar fluid to prevent collapse of alveoli during expiration
alveolar macrophages
are wandering phagocytes that remove debris
respiratory membrane
thin barrier separating the alveoli from the blood capillaries across which gas exchange between the lungs and blood occurs
atmospheric air is a
gaseous mixture of approximately 78% nitrogen, 21% oxygen, and .04 CO2
partial pressure of O2 in atmospheric air is
160 mm Hg
partial pressure of CO2 is
.3 mm Hg
since pO2 is higher in alveolar air…
blood “loads” O2 in the lungs
since pCO2 is relatively higher in alveolar blood..
it unloads CO2 in lungs
pO2
is 140 mm Hg in alveolar air while in the blood entering capillaries is 40 mm Hg
pCO2
in blood entering capillaries is 46 mm Hg while in the air is 40 mm Hg
at high altitudes pO2 is
low and pressure gradient is smaller and less O2 diffuses into blood
under hyperbaric conditions pO2
is very high pressure gradient is great and more O2 diffuses into blood
most soluble of gases in blood plasma
CO2/ O2 is only 5% soluble
O2 doesnt dissolve easily in water so only
1.5% is carried in blood plasma
what percent of O2 is carried by oxyhemoglobin
98.5
at low pO2 in tissue capillaries hemoglobin is
only partially saturated/ in pulmonary capillaries it is fully
carbonic anhydrase catalyzes
reaction between CO2 and water to form carbonic acid
bicarbonate ions are pumped out of RBCs and replaced with
chloride ions during chloride shift to maintain balance of anions
hydrogen ions combine with hemoglobin to
prevent change in blood pH
what causes O2 to be released from oxyhemoglobin
increase in temp and drop in pH
BPG
metabolic byproduct produced when RBCs break down glucose by glycolysis and it promotes O2 unloading
carbon monoxide
colorless,odorless gas produced by incomplete combustion. reduces O2 carrying capacity of hemoglobin
bicarbonate ions act as
a crucial buffer in the blood and rarely give up CO2
breathing during rest is aimed at regulating
concentration of hydrogen ions in the brain
normal blood pH
7.35-7.45
respiratory acidosis
low blood pH, increase in pCO2 causes hypercapnia. increases rate and depth of breathing
respiratory alkalosis
high blood pH, decrease in pCO2, hypocapnia occurs rate and depth of breathing slows and shallows
hyperventilation
allows body to exhale CO2 faster than it forms
hypoventilation
allows body to accumulate CO2 faster than it can be exhaled
if arterial pO2 falls dramatically ventilation will
be affected
hypoxia
deficiency of O2 in tissues
hypoxemic hypoxia
low pO2 in arterial blood due to high altitude, airway obstruction, fluid in lungs, carbon monoxide poisoning
ischemic hypoxia
decreased blood circulation
anemic hypoxia
blood cant carry enough O2 cause of anemia, hemorrhage, insufficient hemoglobin
histotoxic hypoxia
tissues cant use O2 because of a toxic agent
cyanosis
principle cause of hypoxia causes blue skin
O2 toxicity
generates free radicals from breathing pure O2 too long can produce coma or death. scuba divers need nitrogen and O2 to avoid
COPD
any disorder characterized by chronic and recurrent obstruction of airflow
COPD is caused by
smoking, secondhand smoke, pollution, allergens
pink puffers
very thin and exhibit normal blood gases
blue bloaters
stocky and exhibit cyanosis because of hypoxia
chronic bronchitis
inflammation of bronchi. goblet cells enlarge and secrete mucus, cilia are immobilized, alveolar macrophages die. sputum provides growth for bacteria
emphysemia
permanent enlargement of alveoli. alveolar walls break down, alveoli remain inflated, right ventricle enlarges, barrel-chest develops
asthma
immune response triggered by allergens, infection, drugs, or cold dry air. airway inflammation
most common chronic illness of children
asthma. especially in young boys before 10
asthma has muscle spasms that trigger
bronchioconstriction and excess mucus clogs bronchioles
treatment of asthma
inhaling epinephrine
pneumonia
infection of alveoli caused by viruses, bacteria, or fungi. Alveoli fill with fluid and dead leukocytes
tuberculosis
infection from inhalation. lung tissue is destroyed and replaced with fibrous CT
lung cancer
develops primarily from smoking
squamous-cell carcinoma
develops in bronchial epithelium and spreads to bronchial walls where bleeding lesions occur
adenocarcinoma
develops in bronchial glands and alveolar cells
small-cell carcinoma
originates in primary bronchi but invades mediastinum
cystic fibrosis
characterized by salty sweat/genetic disease that reduces bodys ability to transport chloride ions across plasma membrane of epithelial cells
leading cause of death
is lung disease that develops by age 30
high altitude sickness
air pressure and pO2 decrease. less O2 reaches the blood and causes shortness of breath, severe headache, fatigue, nausea
nitrogen narcosis
affects underwater workers who breathe air under high pressure. allows nitrogen gases to dissolve easily and causes giddiness and disorientation
decompression sickness (bends)
divers who surface to quickly. nitrogen rapidly leaves body fluids and produces gas bubbles in joint, bones, muscle. causes pain, dyspnea, or loss of consciousness
peristalis
moves food through the alimentary canal by waves of muscle contraction
digestion
breakdown of food. chemical and mechanical
absorption
movement of digested food from gastrointestinal tract to blood or lymphatic system to cells
alimentary canal
tube extending from mouth to anus. consists of mouth, pharynx, esophagus, stomach, small and large intestines
accessory structures to canal
teeth, tongue, salivary glands, liver, pancreas, gallbladder. either prepare food for digestion or produce and store secretions that aid in it
mucosa
inner lining of canal
stratified squamous epithelium lines
canal from mouth to stomach and anal canal
lamina propria
areolar CT that contains blood and lymphatic vessels. protects gastrointestinal tract
muscularis mucosae
layer of smooth muscle. folds in stomach and small intestine increase surface are for digestion
submucosa
thick. contains blood and lymphatic vessels, submucosal nerve plexus (of meissner) which controls movements of muscularis
muscularis
skeletal muscle in mouth, pharynx, and esophagus to assist in swallowing. inner layer of smooth muscle contains circular fibers
muscularis contains
myenteric nerve plexus (of Auerbach) which controls motility through GI tract
serosa (visceral peritoneum)
areolar tissue and squamous epithelium that secretes serous fluid to keep membrane surfaces moist and reduce friction
parietal peritoneum
lines wall of abdominopelvic cavity
visceral peritoneum
covers organs in abdominopelvic cavity
peritonitis
occurs as a result of a stab wound, perforated ulcer, ruptured appendix
mesentery
binds intestines together and suspends them from abdominal wall
mesocolon
anchors large intestine to posterior abdominal wall
lesser omentum
extends from stomach to liver
greater omentum
covers small intestine
mouth
oral or buccal cavity. only location for ingestion.
cheeks
form lateral walls of mouth and consist of skin, fat, muscles, and stratified squamous
lips
attached to gum by labial frenulum
tongue
skeletal muscle and stratified squamous. covered with papillae which contain taste buds
palate
seperates oral cavity from nasal cavity
uvula
closes nasopharynx when swallowing
teeth
adults have 32. primary structures for mechanical digestion
8-4-8-12
incisors for biting, canines for tearing, pre-molars, broad molars for crushing
first set of 20 deciduous teeth erupt through gums when
between 6 months and two years. get replaced around 6-17
each tooth is embedded in
alveolus in mandible or one of the maxillae
periodontal ligament
lines each alveolus and anchors tooth
dentin
calcified CT. in crown and neck it is covered by enamel. covered by cementum in root.
blood, lymphatic vessels and nerves enter
root canal through apical foramen
salivary gland
any cell or organ that releases saliva into oral cavity
extrinsic salivary glands
byond oral mucosa and empty into ducts
parotid glands
near ears. open into oral cavity by ducts near upper molars
submandibular glands
along mandible. open into oral cavity via ducts near lower incisors
sublingual glands
floor of mouth. open into oral cavity by ducts beneath tongue
extrinsic salivary glands secrete
1-1.5 liters of saliva each day
what controls salivation
autonomic nervous system
parasympathetic signals in response to
aroma or taste of food to produce saliva rich in enzymes
sympathetic signals in response to
stress. cause saliva with more mucus resulting in a dry mouth
saliva
mostly water and solutes. digests some starch and lipids, inhibits bacterial growth, dissolves chemicals, binds food particles together
salivary amylase
digestive enzyme present in saliva. digests starch at neutral pH. breaks starch into maltose
lingual lipase
digestive enzyme present in saliva. digests fats after it is activated by stomach acids. break triglycerides into fatty acids and monoglycerides
lysozyme
kills bacteria
immunoglobin A
inhibits bacterial growth
electrolytes
buffer acidic foods
masseter and temporalis muscles activate
jaws to start mastication
mastication
grinds food into pieces and mixes it with saliva to form a soft flexible bolus initiating swallowing
pharynx
extends from internal nares to esophagus. composed of skeletal muscle lined with mucus membranes
swallowing center in medulla oblongata and pons requires
22 sepearte muscle groups to work together
voluntary buccal phase
tongue pushes bolus of food into oropharynx which triggers pharyngeal phase
soft palate and uvula close off nasopharynx and epiglottis closes
off the glottis so bolus of food can enter esophagus
esophagus
collapsible tube that lies posterior to trachea
esophagus mucosa contains
non-keratinized stratified squamous to protect against abrasion
submucosa of esophagus
contains esophogeal glands that secrete mucus
superior end of muscularis in esophagus
is skeletal muscle and inferior end is smooth muscle
adventitia attaches
esophagus to surrounding structures
bolus of food enters esophagus through
upper esophageal sphincter
lower esophageal sphincter
how food enters stomach. if fails to close, stomach contents can enter and cause heartburn
stomach
hollow located beneath diaphragm
cardia
small area of stomach near lower esophageal sphincter
fundus
dome-shaped region of stomach
empty volume of stomach
50 mL. but can hold 1-1.5 L with a max capacity at 4 L
pyloric region
below body of stomach. divided into antrum and pyloric canal
pyloric sphincter
seperates stomach from small intestine
gastric mucosa
simple columnar contains goblet cells that produce surface layer of alkaline mucus above bicarbonate rich fluid. contains many gastric pits which lead to tubular gastric glands that secrete gastric juice
parietal cells
secrete hydrochloric acid and intrinsic factor
chief cells
secrete pepsinogen and gastric lipase
enteroendocrine G cells
secrete hormones and paracrines
gastric rugae
in gastric submucosa composed of areolar CT and combines with mucosa when stomach is empty
gastric muscularis
3 layers of smooth muscle. third layer is oblique allows stomach to mix and propel food through tract
gastric serosa
part of visceral peritoneum and forms omenta
chyme
churning of food mixed with gastric juice. gets released from stomach by gastric emptying
gastric juice
pH of .8. contains hydrochloric acid which kills microbes in food and breaks down collagen in meat and plant cell walls, removes amino acids from pepsinogen to convert to pepsin
pepsin
breaks complex dietary proteins into shorter peptide chains. catalyzes conversion of pepsingen into more pepsin
intrinsic factor from parietal cells is needed by
small intestine to absorb vitamin B12 which is needed to make hemoglobin
what can be absorbed by the stomach wall
aspirin, alcohol, and some lipid-soluble drugs
neural mechanisms
involve parasympathetic actions of vagus nerve and sympathetic actions of other nerves that decrease stomach activity
hormonal mechanisms
involve gastrin to regulate gastric function
cephalic phase
initiated by sight, smell, taste, or thoughts of food. parasympathetic signals increase stomach motility and stimulate gastric glands to secrete gastric juice
gastric phase
initiated by food in stomach. stretch receptors are activated and parasympathetic signals trigger peristalsis..
during gastric phase chief cells secrete pepsinogen which relax
sphincters that regulate movement of chyme out of stomach.
gastrin secretion is inhibited when
pH of gastric juice falls below 2.
histamine
acts with acetylcholine and gastrin to stimulate parietal cells to release more HCl
gastric emptying takes about
4 hours. takes less if meal is liquid or high in carbs. takes more time if high in fat
intestinal phase
presence of fatty acids and partially digested proteins in duodenum triggers enterogastric neural reflex which inhibits gastric emptying/
presence of chyme in duodenum stimulates enteroendocrine cells to release
hormones that affect stomach.
secretin decreases
gastric juices
cholecytokinin CCK
inhibits gastric emptying
gastric inhibitory peptide GIP
suppresses gastric secretion and motility
vomiting (emesis)
forcible expulsion of stomach contents. preceded by nausea cause lower esophageal sphincter relaxes and stomach and duodenum contract
vomiting is triggered by
distension of stomach or irritation from bacterial toxins alcohol or drugs.
liver
heaviest gland weighs 1.4 kg. covered by peritoneum and dense irregular CT. divided into large right lobe and left lobe by falciform ligament
lobules
hexagonal functional units liver lobes are composed of
hepatocytes
arranged radially around a central vein and produce bile
sinusoids
surrond hepatocytes. contain hepatic macrophages (kupffers cells) that remove worn out blood cells, bacteria and toxins
sinusoids receive blood from
hepatic(portal) triad. blood from stomach and small intestine are filtered by sinusoids
bile is secreted by
bile canaliculi which empty into bile ductules which merge to from left and right hepatic ducts which unite and exit liver as common hepatic duct
bile is a mixture of
water, bile acids, bile salts, cholesterol, lecithin, and bile pigments
bile salts
emulsify and absorb fats
principal bile pigment
billirubin derived from breakdown of hemoglobin. gives fecal matter its color
liver functions
carb,lipid, and protein metabolism/ removal of drugs and hormones from blood/ synthesis of bile and excretion of billirubin/ storage of glycogen, vitamins, and minerals/ phagocytosis of worn out blood cells
gallbladder
small sac attached to ventral surface of the liver
cystic duct from gallbladder joins with the
common hepatic duct to form common bile duct
the gallbladder stores and concentrates
BILE/
bile travels through
hepatopancreatic ampulla into small intestine.
between meals hepatopancreatic sphincter (of Oddi) remains
closed so bile accumulates in gallbladder
pancreas
oblong, spongy, gland located posterior and inferior to stomach
pancreatic islets (of Langerhans) form
endocrine portion of pancreas and they secrete the hormones glucagen and insulin
acini form the the exocrine portion of the pancreas and they secrete
between 1200 and 1500 mL of pancreatic juice daily
pancreatic juice is an alkaline mixture of
water, salts, sodium bicarbonate, and variety of digestive enzymes released in inactive form.
pancreatic amylase splits
starch molecules into molecules of disaccharide maltose
pancreatic lipase splits
emulsified fats into fatty acids and monoglycerides
trypsinogen is converted into
trypsin to split proteins into smaller peptides
chymotrypsinogen is converted into
chymotrypsin to split proteins into smaller peptides
procarboxypeptidase is converted into
carboxypeptidase to break peptides into individual amino acids
secretion of pancreatic juice is regulated by
nervous and hormonal mechanisms/ stimulated by parasympathetic impulses
acidic chyme in duodenum stimulates the intestinal mucosa to release
secretin which triggers release of pancreatic juice rich in bicarbonate ions
fatty chyme in duodenum stimulates intestinal mucosa to release cholescystokinin which causes the gallbladder to releases
bile, stimulates secretion of pancreatic enzymes and relaxes hepatopancreatic sphincter
small intestine
2-3 meters long and 2.5 diameters wide. extends from pyloric sphincter to large intestine
duodenum
shortest segment. receives chyme from stomach, bile from liver, and pancreatic juice from pancreas
jejunum
middle segment. where most digestion and absorption takes place
ileum
longest segment joins large intestine at ileoceal sphincter
circular folds
ridges in intestinal mucosa from duodenum to ileum. increase surface area and cause chyme yo move in a spiral path along small intestine to enhance absorption
intestinal mucosa
form villi which are covered with mucus-secreting goblet cells and columnar absorptive cells
each villus has a core of lamina propria that contains
an arteriole, capillary network, venule, and lymphatic lacteal that absorbs fat
each absorptive cell is covered with microvilli to form
brush border near the lumen of small intestine
one enzyme released by brush border activates
pancreatic enzymes. other enzymes are involved in contact digestion
intestinal crypts
secrete intestinal juice which is a watery mixture containing lots of mucus.
paneth cells secrete
bactericidal enzyme lysozyme
peyers patches
in lamina propria abundant in ileum and prevent bacteria from entering blood
duodenal Brunners glands
in submucosa of duodenum that secrete alkaline mucus to neutralize stomach acid
segmentations
localized contractions that mix chyme with digestive secretions to enhance contact digestion and absorption
migrating motor complex
type of peristalis begging in duodenum to push chyme through small intestine
place that does most digestion and absorption
small intestine
fifty percent of starch digestion is completed
before it reaches small intestine
salivary amylase gets denatured by
gastric juice. any starch left gets broken down by pancreatic amylase
maltase
brush border enzyme that splits maltose into glucose
sucrase
brush border enzyme that splits sucrose into glucose and fructose
lactase
brush border enzyme that splits lactose into glucose and galactose
carbs are absorbed as monosaccharides/ glucose and galactose are transported into
intestinal epithelium by sodium-glucose protein
fructose is absorbed into intestinal epithelium by
facilitated diffusion
monosaccharides enter capillaries of a villus by
facilitated diffusion
amino acids are absorbed by
sodium dependent active transport molecules and transported to the liver by hepatic portal system
fatty acids and monoglycerides are coated with bile acids to form
micells which release these components so they can diffuse into absorptive cells
absorptive cells synthesize triglycerides and combine them with
cholesterol and proteins to form chylomicrons which then enter lacteal
nucleic acid digestion gets completed in the
small intestine by pancreatic nucleases
vitamins D,E,K,A must be absorbed with
fat-containing food
sodium ions are transported with
monosaccharides and amino acids
chloride ions are exchanged for
bicarbonate ions and transported in ileum
potassium ions are absorbed
by simple diffusion
iron ions and calcium ions are absorbed in accordance with
bodys needs
large intestine
1.5 meters long and 6.5 centimeters wide. extends from ileum to anus. ileocecal sphincter passes materials from ileum to large intestine
cecum
blind pouch that hangs below ileocecal sphincter . appendix attaches here
colon
ascending, transverse, descending, and sigmoid regions
rectum
contains 3 rectal valves that allow gas to be passed without releasing feces
anal canal
lies in peritoneum outside of abdominopelvic cavity. mucus membrane is in longitudinal folds called anal columns
anus
controlled by anal sphincter(smooth muscle) and external anal sphincter (skeletal)
materials move through large intestine two ways when haustra fill
they become distended and contract to produce haustral churning and peristaolic mass movements triggered by gastrocolic reflex
chemical digestion occurs mainly through
bacterial action
bacteria ferment any remaing carbs and produce
flatus which is mostly air but contains other gases.
bacteria cleave remaing proteins into
amino acids.
large intestine absorbs
water minerals and vitamins and leaves behind a solid mass of feces that takes 12-24 hours to form
fecal is
75% water and 25% solid matter. 1/3 bacteria, 1/3 fiber, 1/3 salts and dead cells
diarrhea
frquent defecation of liquids because chyme passes too quickly for absorption. can produce dehydration or electrolyte imbalances. caused by stress or microbial irritation
constipation
difficult defecation cause feces in colon is too long and too much water is absorbed. caused by bad bowel habits, insufficient bulk in diet, stress, lack of exercise
dental caries
tooth decay/ occurs when bacteria produce acids that demineralize the enamel and the dentin and produce cavities
periodontal disease
variety of conditions characterized by inflammation and degeneration of gums, alveolar bone, periodontal ligament and cementum/ symptoms include gingivitis and bleeding gums
mumps
caused by a viral infection of the parotid salivary glands that produces inflammation fever and throat pain. in males testes may become inflamed and raise risk of sterility
gastroesophageal reflux disease
if lower esophageal sphincter fails to close and stomach contents reflux into esophagus. caused by alcohol, smoking, fatty and acidic foods, and caffeine. treated with antacids or pepcid ac or eating less
peptic ulcers
open sores in GI tract where the mucosa has been digested by gastric juice. causes excessive production of gastric juice with little food, stress, smoking, alcohol, caffeine
hiatal hernia
when part of stomach protrudes into thoracic cavity
hepatitis
inflammation of liver linked to several different viruses
hepatitis A
1/3 of all cases. spread by fecal contamination of food water toys
hepatitis B
40% of all cases/ spread by transfusions contaminated needles body secretion sexual contact. can cause cirrhosis and lead to liver cancer
hepatitis C
most common blood-borne infection. 50% of all cases of chronic liver disease
cirrhosis of liver
destroys hepatocytes and replaces them with scar tissue. caused by hepatitis, alcoholism, liver parasites
gallstones
crystallization of cholesterol in bile. treatment includes gallstone dissolving drugs, lithotripsy, surgery
if gallbladder is removed the bile duct will
enlarge to store bile
acute pancreatitis
inflammation of pancreas cause pancreatic cells to releases enzymes that digest pancreatic tissue. caused by trauma or alcoholism
appendicitis
preceded by obstruction of the lumen of the appendix by chyme or foreign bodies. ruptured it releases toxins that can cause peritonitis or gangrene
ulcerative colitis
inflammation of the mucosa of large intestine and rectum that reduces water absorption. causes cramps and bloody diarrhea and dehydration. hereditary or auto-immune disease
diverticulitis
inflammation of the colon. causes pain nausea vomiting and constipation because of insufficient fiber
crohn disease
inflammatory bowel disease produces lesions in the intestines that cause pain and diarrhea
colorectal cancer
second leading cause of cancer in males and third in females. caused by heredity, alcoholism, diet high in animal fat and protein. symptoms include abdominal pain, cramping, rectal bleeding
hemorrhoids
permanently distended veins that protrude into the anal canal and cause itching pain and bleeding
airflow
governed by principles of flow, pressure and resistance.
atmospheric pressure
drives respiration
intrapulmonary pressure
pressure within alveoli referred to as alveolar pressure
direction that air flows depends on
gradient between atomospheric pressure and intrapulmonary
boyles law
pressure of a gas in a closed container is inversely proportional to the volume of its container at a constant temp
charles law
volume of a gas in a closed container is directly proportional to is absolute temp and a constant pressure
daltons law
each gas in a mixture exerts a partial pressure independent of the partial pressure of other gases
henrys law
amount of gas that dissolves in a liquid is directly proportional to its solubility in that liquid and its partial pressure
for air to flow into the lungs intrapulmonary pressure must be
lower than atmospheric
when diaphragm and intercostal muscles contract
volume of thoracic cavity increases
contraction of external intercostal muscles pulls the
ribs upward and outward
increasing the volume of the lungs causes a drop in
intrapulmonary pressure (boyle)
normal inspiration is an active process and can be increased by
contracting additional chest muscles which enlarges thoracic cavity and decrease intrapulmonary pressure
for air to flow out of the lungs intrapulmonary pressure must be higher than
atmospheric air pressure
normal expiration during quiet breathing is a passive process that can be made active by contracting
abdominal and internal intercostal muscles
pulmonary compliance
ease with which the lungs expand to a change in pressure gradient between atmosphere and lungs
high compliance
lungs will expand easily. degenerative lung disease decreases this
diameter of the bronchioles control
resistance
surfactant
mixture of phospholipids and lipoproteins that lower surface tension to reduce collapsing of alveoli and to adhere to each other during expirtation
surfactant deficiency in premature babies
leads to respiratory distress syndrome. alveoli collapse after each expiration
healthy adult averages ___ quiet breathing cycles per minute
12/ eupnea-normal breathing
spirometry
used to measure pulmonary function
restrictive lung disorders
reduce pulmonary compliance. limits inflation of lungs causing reduction in vital capacity
obstructive lung disorders
interfere with airflow. makes it harder to exhale
tidal volume*
volume of air exchanged during one breathing cycle (500mL)
inspiratory reserve volume
volume of air that can be inhaled in excess of TV with max effort (3000mL0
expiratory reserve volume
volume of air that can be exhaled in excess of TV with max effort (1200mL)
residual volume
volume of air that remains in lungs after max exhalation and keeps alveoli open (1300mL)
vital capacity
max volume of air that can be moved into and out of lungs during one forced breathing cycle. only measurement in lab (4700mL)
inspiratory capacity
max volume of air that can be inhaled after a normal expiration (3500mL)
functional residual capacity
resting lung volume (2500mL)
total lung capacity*
sum of all pulmonary volumes (6000mL)
basic rhythm of breathing is controlled by
medulla oblongata and pons
medullary rhythmicity area
has ventral and dorsal respiratory groups
inspiratory neurons from VRG send
impulses to stimulate muscles needed for inspiration. relax after 2 seconds
pontine respiratory group
in pons to modify rate and depth of breathing
input from limbic system and hypothalmus allow
pain/emotion to affect breathing
input from chemorecepters
adjust breathing to maintain homeostasis
stretch receptors in bronchial tree and visceral pleura monitor
lung inflation
hering-breur reflex
protective me3chanism that inhibits inspiratory neurons to prevent over-inflation of lungs
voluntary control over ventilation originates in
frontal lobe
ondines curse
brainstem damage that disables automatic respiratory functions and individual must constantly remember to breathe
