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Lungs, Kidneys, and Intestines
BMS300-Lungs, Kidneys, & Intestines
91
Physiology
Undergraduate 2
11/28/2009

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Term
Inspiration
Definition
inhalation of air into the intrapulmonary space, or the area inside the lungs
Term
Expiration is:
Definition
exhalation of air out of the intrapulmonary space, into the ambient air
Term
Pleura
Definition
lung lining
Term
Pleural effusion
Definition
fluid between pleural space
Term
Steps of air travel
Definition
trachea -> bronchi -> bronchioles -> alveoli
Term
Alveoli
Definition
  • functional units of respiration take up most of the area in interpulmonary space
  • air-filled sacs
  • 2 types
Term
Types of alveoli
Definition
  • Type I: Epithelial cells, provide structural support
  • Type II: Septal cell, produce surfactant
Term
Purpose of respiration
Definition
  • Carry O2 to tissues
  • Bring CO2 to lungs for excretion
Term
Ventilation
Definition
  • Process of inspiration/expiration
  • Amount of air inhaled/exhaled is determined by several Gas Laws
Term
Dalton's Law
Definition
  • sum of partial pressures adds to total pressure PT = (%N2 * PT) + (%O2 * PT) + (%CO2 * PT) + etc…
  • %O2 = 21%
Term
Boyle's Law
Definition
V1P1 = V2P2
Term
Henry's Law
Definition
Partial pressure of a gas in contact with a liquid determines the solubility of the gas in that liquid
Term
Fick's Law of Diffusion
Definition
diffusion of a gas is directly related to SA and indirectly related to membrane thickness
Term
Inhalation
Definition
Requires diaphragm and external intercostals
Term
Intrapulmonary pressure
Definition
  • pressure inside the lungs
  • Must be negative to allow inspiration
  • Boyle’s Law
Term
Intrapleural pressure
Definition
  • pressure inside the pleural cavity
  • Always negative
  • Keeps lungs inflated
Term
Expiration (discuss pressures)
Definition
  • PASSIVE PROCESS!!! No muscles necessary for normal quiet expiration
  • Intrapulmonary Pressure: Becomes positive to exhale air
  • Intrapleural Pressure: Remains negative to keep lungs inflated; Less negative than during inspiration
Term

Spirometry

[image]

Definition

Measurements of lung volumes

a. Inspiratory reserve volume
b. Vital capacity
c. Inspiratory capacity
d. Tidal volume
e. Expiratory reserve volume
f. Total lung capacity
g. Residual volume
h. Functional residual capacity

Term
Tidal Volume
Definition
avg. volume inhaled per breath
Term
Respiratory Rate
Definition
number of breaths per minute
Term
Dead space
Definition
  • air in the conducting zone
  • DS = TV - alveolar volume
Term
Minute ventilation rate
Definition
RR x TV
Term
Alveolar ventilation rate
Definition
RR x (TV - DS)
Term
Dead space ventilation rate
Definition
RR x DS
Term
External respiration
Definition
  • Occurs in alveoli at the respiratory membrane (alveolar-capillary)
  • Brings O2 in, CO2 out
Term
Respiratory membrane is composed of
Definition
  • Type I alveolar cells and associated basement membrane
  • Endothelial cells of pulmonary capillaries and associated basement membrane
Term
How is Oxygen carried?
Definition
  • 1.5% dissolved in plasma
  • 98.5% bound to hemoglobin
Term
How is Carbon Dioxide carried?
Definition
  • 7-10% dissolved in plasma
  • 20-30% bound to hemoglobin
  • 60-70% bicarbonate ion
Term
Bohr effect on Oxygen binding
Definition
  • Right shift of Curve due to increased H+ concentration
  • Corresponds to decrease in pH
  • Decreases O2 binding affinity
Term
Haldane effect on Oxygen binding
Definition
As O2 unloads from Hb, CO2 can load and be more readily carried
Term
Control of Respiration: Information is sent to the medulla to moderate respiration in the following manner:
Definition
  1. Higher brain centers
  2. Joint/muscle receptors
  3. Irritant/Stretch receptors
  4. Emotional stimuli
  5. Peripheral Chemoreceptors (carotid artery and aortic arch) Mostly CO2
  6. Central Chemoreceptors (Medulla) H+
Term
Diseases of the Respiratory System
Definition
  • Lung Cancer: 87% due to smoking
  • Emphysema: Disease of over-compliance
  • Pneumonia: Fluid in the lungs
Term

Renal System

[image]

Definition
A: Paratubular Capillary
B: Distal Convoluted Tubule
C: Collecting Duct
D: Loop of Henle - ascending limb
E: Vasa Recta
F: Loop of Henle - descending limb
G: Afferent Arteriole
H: Glomerulus
I: Bowman's Capsule
J: Proximal Convoluted Tubule
Term
What are the processes of the Renal System?
Definition
Filtration, Resorption, and Excretion
Term
What is the process of filtration in the Renal System?
Definition
Materials from blood are transferred to nephron
Term
What is the process of resorption in the Renal System?
Definition
Necessary materials are transferred from the nephron to the blood
Term
What is the process of excretion in the Renal System?
Definition
Unnecessary materials exit the body via the urine
Term
Glomerulus
Definition
capillaries in contact with Bowman’s capsule
Term
Bowman's Capsule
Definition
1st part of nephron
Term
Materials entering Bowman’s capsule from glomerulus
Definition
Water, salt, urea, amino acids, glucose
Term
Filtration pressures
Definition
  • Pressures drive materials from the blood into Bowman’s capsule
  • Hydrostatic pressure: 55mmHg into Bowman’s capsule
  • Osmotic pressure: 30mmHg out of Bowman’s capsule (albumin concentration)
  • Capsular Hydrostatic Pressure: 15mmHg out of Bowman’s Capsule
  • Net Filtration Pressure: 10 mmHg into Bowman’s capsule
Term
Regulation of Net Filtration Pressure
Definition
  • Myogenic control: Smooth muscle cells tend to contract when under pressure, “Closes the valve”
  • Macula densa/Juxtaglomerular Apparatus:
  • Macula densa monitors salt concentration and releases adenosine in response to low salt
  • Juxtaglomerular cells detect adenosine and release renin
  • Renin initiates a cascade which results in constriction of efferent arteriole. Constriction leads to an increase in net filtration pressure
Term
Myogenic control
Definition
  • Smooth muscle cells tend to contract when under pressure
  • “Closes the valve”
Term
Macula densa/Juxtaglomerular Apparatus
Definition
  • Macula densa monitors salt concentration and releases adenosine in response to low salt
  • Juxtaglomerular cells detect adenosine and release renin
  • Renin initiates a cascade which results in constriction of efferent arteriole
  • Constriction leads to an increase in net filtration pressure
Term
Proximal Convoluted Tubule
Definition
  • 100% glucose and amino acid resorption
  • Cross apical side via Na+ driven cotransporters
  • Cross basilar side via passive channels 65% water and ion resorption Remember…resorption means the “reuptake” of materials into blood
  • Materials leave the nephron and enter the paratubular capillary
Term
Descending limb of the Loop of Henle
Definition
  • Important for water resorption
  • Water exits through specialized water channels called aquaporins
  • PASSIVE DIFFUSION occurs here
  • Allowed due to the corticomedullary gradient….more later
Term
Ascending limb of the Loop of Henle
Definition
  • Resorption of salts occurs here
  • Bottom of ascending limb = passive diffusion Top of ascending limb = active pumping
  • Also allowed due to corticomedullary gradient
Term
Distal Convoluted Tubule
Definition
  • More salt reabsorption -> hormonally controlled
  • Filtrate salt concentrations here are LOW!
  • Hormonal Regulation
    • Aldosterone: released from the adrenal cortex
    • Causes an increase in production and insertion of Na+ pumps and channels
    • High Aldosterone = more sodium resorption
Term
Collecting Duct
Definition
  • Incredibly low numbers of ion channels…no ion resorption
  • Aquaporins are found here
    • Hormonal control: ADH (Vasopressin)
    • ADH causes more aquaporins to be created and inserted in the membrane
    • More ADH = more water resorption
  • Also permeable to urea
Term
Corticomedullary Gradient
Definition
  • Within the kidney (but outside the nephron) ionic concentration increases with depth into the medulla
  • This gradient is highly dependent on urea concentration
  • Gradient is maintained by vasa recta
    • Vasa recta: blood vessel which has very low hydrostatic pressure
    • Ionic concentration in the blood in the vasa recta is equal to the ionic concentration in the kidney at all places!!!
Term
Vasa Recta
Definition
  • blood vessel which has very low hydrostatic pressure
  • Ionic concentration in the blood in the vasa recta is equal to the ionic concentration in the kidney at all places!!!
Term

Loop of Henle

[image]

Definition
A: Cortex
B: Outer Medulla
C: Inner Medulla
D: Loop of Henle
E: H2O
F: NaCl
G: Active Transport
H: Passive Transport
Term
Organs involved in digestion
Definition
  • Major: Esophagus, Stomach, Small intestine, Large intestine, Pancreas, Liver
  • Accessory: Brain, Salivary glands
Term
Enteric Nervous System
Definition
  • One of the GI control systems
  • Local system
  • Has connections with the CNS
Term
Enteric Endocrine System
Definition
  • One of the GI control systems
  • Scattered epithelial cells throughout GI tract release hormones into blood
Term
GI Tract
Definition
  • 4 Major layers in each piece called “tunics”
  • From outside to lumen:
    • Serosa: thin outer layer
    • Muscularis: smooth muscle layers, funtion in motility
    • Submucosa: connective tissue, blood, lymphatics
    • Mucosa: epithelial cells including endocrine cells, contact with lumen
Term
Pregastric Digestion
Definition
  • Includes manual processing of food (i.e. chewing and swallowing)
  • Control of Food Intake
    • Hypothalamus: control of hunger drive
    • Fat cells release leptin
    • Leptin “turns off” hunger
    • Can only be used as a weight control agent in leptin deficient people
Term
Esophagus
Definition
  • Moves food to stomach
  • Uses peristalsis for motility
  • Food stays here 4-5 sec.
  • Secretion of mucus
  • No absorption
  • Type of epithelium = stratified squamous epithelium
Term
Stomach
Definition
  • Epithelial type: columnar epithelium
  • 2 types of motility:
    • Relaxation
    • “Gastric Grinder”
  • Secretion:
    • Pepsinogen: protease which auto-catalyzes its activation, begins protein digestion, secreted via Chief Cells
    • Acid: Sterilizes stomach contents, secreted via Parietal cells
    • Gastrin: hormone, meaning it is secreted into blood, necessary for the release of acid from parietal cell, from G cell
    • Mucus: epithelial cells
Term
Acid Secretion
Definition
  • 3 molecules need to bind parietal cells to stimulate acid secretion
    • Histamine (most common pharmaceutical target)
    • Gastrin
    • Acetylcholine
  • Acid created by dissociation of carbonic acid
    • Carbonic acid created by carbonic anhydrase
    • Hydrogen ions pumped into lumen via proton pump
Term
Three phases of digestion (gastric) in the stomach
Definition
  • Cephalic: low level secretion in response to the presence of food
  • Gastric: Stomach distended when food enters
  • Intestinal: Slow release of food into small intestine, distension of small intestine causes cessation of stomach secretion and motility (ENS)
Term
Entering the small intestine
Definition
  • Food entering small intestine stimulates endocrine activity
  • Fats and Proteins: Act on cells to initiate release of cholecystokinin (CCK)
  • Acid: acts on cells to initiate release of secretin Hormones released from these small intestine endocrine cells act on the pancreas and liver
Term
Pancreas
Definition
  • Has both endocrine and exocrine functions
  • Exocrine functions involved in digestion
    • Secretes 2 major substances into small intestine
      • Digestive enzymes
      • Bicarbonate
Term
Pancreatic digestive enzymes
Definition
  • Secretion is driven by CCK
  • 3 types of enzymes
    • Proteases
      • Trypsinogen
      • Chymotrypsinogen
    • Amylase
      • Carbohydrate digestion
    • Lipase
      • Lipid digestion
Term
Proteases
Definition
  • Trypsinogen and chymotrypsinogen are inactive forms
  • Enterokinase in the small intestine activates trypsin
  • Trypsin activates chymotrypsin
  • Trypsin and chymotrypsin work on protein digestion
Term
Bicarbonate Ion
Definition
  • Released in response to secretin
  • Acts as a base to neutralize acid released into the small intestine from the stomach
Term
Liver
Definition
  • Aids in digestion via lipid digestion
  • Receives 75% of its blood supply from the hepatic portal vein
    • Contains blood which has passed the GI tract (lots of nutrients here)
  • Also receives blood from the hepatic artery
  • Blood contacts liver cells (hepatocytes) via sinusoids
  • Hepatocytes secrete bile
  • Bile is transported through canaliculi between sheets of hepatocytes
  • Canaliculi converge into the common bile duct
  • The common bile duct empties into the small intestine
Term
Liver receives blood from:
Definition
  • 75% from Hepatatic portal vein
  • Hepatatic artery
Term
Blood contacts liver cells called __________ via __________. These liver cells secrete __________.
Definition
  • Hepatocytes
  • Sinusoids
  • Bile
Term
Canaliculi
Definition
  • Transports bile
  • Converge into the common bile duct which empties into the small intestine
Term
Bile consists of
Definition
water, salts, bicarbonate, bile acids, cholesterol, bilirubin, and bicarbonate
Term
Bile acids are responsible for:
Definition
  • breaking up blobs of lipid into smaller water soluble blobs called micelles
  • Bile acids aid lipase in lipid digestion
Term
Bilirubin is created
Definition
when RBCs are destroyed. It must be conjugated to glucoronic acid in hepatocytes to be water soluble for excretion
Term
Small Intestine
Definition
  • Most nutrient absorption occurs here
  • Absorptive epithelial cells transport nutrients from the lumen to the blood stream
  • These cells reside on the tips of villi
  • Villi create folds in the small intestine
  • The bottoms of these folds are called crypts
    • Stem cells in the crypts divide to make more absorptive epithelial cells
Term
Villi
Definition
  • Folds in the small intestine
  • Dips are called crypts
  • Epithelial cells on tips
Term
Brush border
Definition
  • Apical region of mature absorptive epithelia
  • Contains membrane bound enzymes which finish digestion
    • Peptidases convert peptides to amino acids
    • Lactase converts lactose to glucose and galactose
Term
Glucose Absorption
Definition
  • Polysaccharides are broken down by amylase in the lumen
  • Brush border enzymes break disaccharides into monosaccharides
  • Sodium in the lumen binds hexose transporter
  • Glucose also binds transporter and both molecules are transported across the membrane
  • Glucose diffuses passively out the basilar side of the cell and into the blood stream
Term
Water Absorption
Definition
  • Osmotic gradient must be created to shuttle water into the blood stream
  • Sodium flows into epithelial cells creating this osmotic gradient
  • Water then passively flows through the cell and into the blood
Term
Amino Acid Apsorption
Definition
  • Process is nearly the same as that for glucose
    • Utilizes peptidases in the brush border
    • Utilizes a Na+ driven cotransporter for amino acids
Term
Lipid Absorption
Definition
  • Triglycerides are broken down in the lumen by lipase and bile acids
  • Monoglycerides and fatty acids freely diffuse through the membrane of the absorptive epithelium
  • MGs and FAs conglomerate into chylomicrons
  • Golgi apparatus packages chylomicrons for exocytosis
  • Chylomicrons then diffuse to the central lacteal
Term
Large Intestine
Definition
  • Final water and salt absorption
  • Creation of feces for defecation
  • Contains millions of microbes (lots of E. coli)
  • Fermentation:
    • microbes utilize carbohydrates.
    • Microbes contain cellulases which can break down cellulose (normal digestion does not break down any cellulose)
Term
Post-Absorptive Metabolism
Definition
  • Objective: Maintain blood glucose levels in a normal range
  • Controlled by endocrine hormones which trigger biochemical processes
  • Processes
    • Glycogenesis
    • Glycogenolysis
    • Gluconeogenesis
    • Glycolysis
    • Krebs cycle and Oxidative Phosphorylation
Term
Glycogenesis
Definition
creation of glycogen from glucose for storage
Term
Glycogenolysis
Definition
breakdown of glycogen to glucose
Term
Gluconeogenesis
Definition
Creation of glucose from different precursors (ex. Amino acids
Term
Glycolysis
Definition
creates some ATP from glucose
Term
Krebs cycle and Oxidative Phosphorylation
Definition
Creation of lots of ATP
Term
Insulin
Definition
Acts to decrease blood glucose by inserting new glucose channels in membrane; from pancreas
Term
Glucagon
Definition
Acts to increase blood glucose by triggering glycogen breakdown; from pancreas
Term
Epinephrine
Definition
Acts to increase blood glucose (conservation); from adrenal medulla
Term
Cortisol
Definition
Acts to increase blood glucose (gluconeogenesis); from adrenal cortex
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