Exam 2 Flashcards
Renal and GI
Excretion rate of a substance
Excretion rate of substance:
Ux x UF
- concentration of substance in urine (Ux)
- Urinary flow rate
FIltration rate of a substance
Filtration Rate of a substance:
GFR x Px
-Px = plasma concentration of substance (x)
-GFR = rate of plasma filtered into Bowman’s space/time
Clearance is defined as the volume of plasma from which a substance has been completely removed and excreted into the urine per unit time (ml/min). What is the equation for clearance of a substance?
UF x Ux/Px
Urine flow = Urine Volume
The Clearance of Inulin is equal to the
GFR
GFR = UF x Uin/Pin
Clearance of PAH is equal to
RPF
RPF = UF x U(PAH)/P(PAH)
FIltration Fraction:
Fraction of plasma that goes to the kidney to get filtered
GFR/RPF
Components of Graph – PAH at top, Glucose at bottom
PAH:
- -100% cleared/excreted (filtered and secreted; not reabsorbed
- –highest clerance of all substances
- -filtered and secreted
- Inulin:
- freely filtered
- not reabsorbed; not secreted
- equal to GFR
- glomerular marker
- Chloride
- HCO3-
- Amino acids
Glucose:
–100% re-absorbed; no excretion (except in the case of diabetes)
= 0
–completely reabsorbed into the bloodstreatm
ADH/Vasopressin is secreted in response to
- high plasma osmolarity (high solutes in plasma) and decreased blood volume
- released from posterior pituitary
- Stimulates Na+ reabsorption in the TAL, DT and CCD & water reabsorption in the DT and CCD
When ADH is secreted: Water is _____ and urine is ______
When ADH is low, water is _____ and urine is _____
When ADH is released: Water is reabsorbed; urine is concentrated (less water)
When ADH is low: Water is cleared/excreted so urine is diluted with water
Aldosterone is secreted in response to
- secreted in response to low blood volume (via angiotensin II) OR increased plasma K+
- causes increased Na+ reabsorption
- Increases K+ secretion
Free water clearance:
UF x 1 - (Uosm/Posm)
Urine osm < Posm = positive clearance
Urine osm > Posm = negative clearance
- *High water in body = increase clearance = positive
- *Low water in body = decreased clearance = negative
Diabetes insipidus: Two types
Due to lack of ADH meaning you can’t concentrate urine
A. Central: doesn’t produce ADH or can’t release
–synthetic ADH increase plasma
B. Nephrogenic: ADH doesn’t bind B2 receptor
Polydipsia:
- -ingest too much water
- –lack of water will induce ADH and cause conc. urine
What is the normal physiological range for plasma osmolarity?
A. 50 – 100 mOsm/L B. 280 – 290 mOsm/L C. 0 – 50 mOsm/L D. 600 – 1200 mOsm/L E. 1200 – 5000 mOsm/L
Answer: 280-290
What is the normal physiological range for GFR?
A. 90 – 120 ml/min B. 0 – 50 ml/min C. 150 – 200 ml/min D. 200 – 250 ml/min E. 250 – 300 ml/min
90-120 ml/min
What is the normal fractional reabsorption of fluid in the proximal tubule?
A. Zero or 0% B. 0.5 or 50% C. 0.8 or 80% D. 0.67 or 67% E. 1.0 or 100%
67%
What is a normal physiological fractional excretion for sodium? A. Zero or 0% B. 0.5 or 50% C. 0.01 or 1% D. 0.8 or 80% E. 100%
0.01 or 1%
The clearance of which substance below best estimates GFR?
Sodium Potassium PAH Creatinine Urea
Creatinine
What are the two major stimuli for ADH secretion from the pituitary?
A. High plasma osmolarity and high plasma [Ca2+]
B. Low plasma [Na+] and high ECV volume
C. High plasma osmolarity and low ECV volume
D. High ECV volume and low plasma [K+]
High plasma osmolarity and low ECV volume
Fractional Excretion
amount excreted/amount filtered
fraction of filtered amount that gets excreted
Excretion/Filtration
Ux x UFR
GFR x Px
FE < 1
FE > 1 = net secretion
Know how afferent and efferent arteriolar resistance affects GFR and RBF
Changes in relative arterial resistance affect PGC, GFR and RBF
- -Constrict Afferent blood flow (slow the blood coming in) – no effect on efferent flow
- Decrease PGC, Decrease GFR, Decrease RBF
- -Decrease Efferent blood flow (slowed blood going out)–afferent blood flow gets backed up
- Increase GC, Increase GFR, Dec. RBF
Body Fluid Composition
TBW: 60%
ICF: 40% (2/3)
ECF: 20% (1/3)
ISF: 15%
PV (5%)Steps in Digestion
6 step process:
Ingestion
Propulsion
Peristalsis – alternate waves of muscular contraction and relaxation in the primary digestive organs. The end result is to squeeze food from one part of the system to the next
Mechanical Digestion
- physical preparation of food for digestion.
- Segmentation – mixing of food in the intestines with digestive juices.
Chemical Digestion
- Carbohydrates, Fat, and Proteins are broken down by enzymes.
Absorption
- transfer of the digested portion of food into the blood from the digestive canal.
Defecation
- removal/elimination of the waste products from the body.
Innervation to the gut
Regulated by autonomic nervous system
A) Parasympathetic nerves (Vagus and Pelvic nerves) and
B) Sympathetic NS (celiac, superior mesenteric, inferior mesenteric and hypogastric nerves)
C) Enteric division (Enteric NS) – Intrinsic
Myenteric plexus / plexus of Auerbach
Submucosal plexus / plexus of Meissner
1) Able to function independently from rest of nervous system
2) Linked to CNS by extrinsic sympathetic and parasympathetic nerves
Sympathetic nerves decrease GI secretions & motility
Parasympathetic nerves (Vagus and Pelvic nerves) increase GI
Lingual lipase
- mouth
- digestion of fat/lipids (triglycerides)
List the 3 salivary glands
- Parotid- serous saliva - Parasympathetic
- Submandibular (70%- Mixed)- Sympathetic
- Sublingual (5%- Mixed)- Sympathetic
(Autonomic nervous system)
*Sjogran’s syndrome
Which Immunoglobulin is found in saliva?
IgA
Salivary amylase
- starch
- Breaks down Polysaccharides to Disaccharides: via amylase
- further down in GI tract: broken down to monosaccharides
R-protein (salivary glands)
*R protein - from the salivary glands promotes the absorption of vitamin B12
Saliva is hypotonic and _____ (pH)
alkaline
The esophagus is a collapsible muscular tube through esophageal hiatus of diaphragm. It is involved in transporting food from the pharynx to the stomach via peristalsis.
There are two waves associated with movement., primary and secondary. Explain these.
1st third- Striated muscle
Miiddle third- Mixed
Last third- Smooth Muscle
- Primary – Wave continuation from pharynx
- Secondary– Due to distention/stretch of esophagus by food.
Upper and lower esophageal sphincter (anatomic sphincter)
There is an intrinsic gradient of decreasing cholinergic
and increasing nitrergic innervation (VIP or substance P) distally in the esophagus. VIP allows the propulsion of swallowed food into the stomach via ____
–receptive relaxation.
VIP: below
Ach: above
The stomach serves as a mixing chamber and storage area for ingested food. Mixing waves are caused by peristaltic movement. What are the features of the stomach?
- Acid kills bacteria entering the stomach
- Chyme released in process of gastric emptying
- Rugae allow for increased surface area
Pyloric stenosis
Hypertophy of muscles around pyloric sphincter and occlusion
The muscularis mucosa of the stomach contains what cells? What do these cells secrete?
-Gastric glands and pits - exocrine
- Parietal cells – HCL, intrinsic factor
- Chief cells – pepsinogen, lipase,
- G cells – gastrin
What are the three primary functions of the stomach?
**Intrinsic factor: most important action of the stomach
- ***Intrinsic factor: most important
- parietal cells
- VB12 absorption (ileum) - A reservoir which regulates how frequently boluses of food can enter the duodenum.
- Acid secretion which facilitates protein digestion.
The H+ is secreted into the lumen of the stomach in exchange for K+. This is achieved via primary active transport (i.e. requires ATP).
What are the stimulators of stomach secretions?
- Stretch or Vagus nerve: stimulates Ach release
- Ach stimulates gastrin releasing peptide
A. gastrin release – G cells
B. gastrin stimulates HCl secretion: parietal cells
C. secretion; stimulates chief cells to produce pepsinogen
-pepsin via HCL – degrades proteins
*Fundus, Antrum: mucous; HCO3- to neutralize
Describe the effect of drinking milk on ulcer formation
milk can stimulate gastrin — acid production
Cells of the stomach
- Parietal cells (body): HCl and intrinsic factor.
- Chief cells: Pepsinogen.
- cleaved into pepsin in the acidic environment of the stomach - Mucous cells (antrum): mucus
- protective barrier - G cells (antrum): gastrin
- stimulates the parietal cells to secrete acid - D cells (antrum): somatostatin.
- dec. stomach secretions
- also stimulated by pancreas - Enterochromaffin like cells: histamine
- stimlates parietal cells to produce histamine (which stimulates gastrin) - Stem cells (gastric pits): replenish the gastric epithelium.
Identify the parts of the renal tubule
Filtrate from the bowman’s capsule enters the inital portion of the renal tubule (proximal convoluted tubule). Empties into the loop of Henle.
- DTL: descending thin limb (inner medulla)
- ATL: ascending thin limb (inner to outer medulla)
- TAL: thick ascending limb (outer medulla to cortex)
- Fluid flows into the macula densa
- Distal convoluted tubule
- Connecting tubule (joins nephron with the collecting duct)
- CCD: cortical collecting duct (Cortex)
- OMCD: outer medullary collecting duct
- IMCD: inner medullary collecting duct
Describe the three phases of acid secretion in the stomach
(1) The cephalic phase
- vagus nerve
- taste, sight, smell, and thought of food.
(2) The gastric phase:
- food enters stomach
- gastrin and histamine
(3) The intestinal phase:
- protein in duodenum
- inhbitory: dec. contraction upstairs
N/B: The ileum and colon release peptide YY which acts on the enterochromaffin-like cells (ECLs) and inhibits the release of histamine.
Factors that protect the stomach from the acidic environment
- Highly vascularized epithelium
- allows blood to sweep away excess acid. - Mucous barrier
- prevents acid erosion - Bicarbonate secretion f
- neutralize acid - Prostaglandin E (PGE)
- facilitates bicarbonate and mucous production
- neutralize acid
- ibuprofen (non-steroidal drugs)- inhibits prostaglandins; inc. acid - ulcers
What are the cells of the small intestine?
- Absorptive
- Goblet
- Endocrine
- Paneth: lysozyme,
- Intestinal glands (crypts of Lieberkühn)
1. S cells: secretin
2. CCK cells: cholecystokinin
Basal electric rhythm
- migrating motor/migrating myenteric complex
- basal movement from secretion of motilin
Irritable bowel syndroms
-inc. bowel movement
– effect of excess migrating motor complex
Macrocytic anemia vs. Microcytic anemia
- Macrocytic anemia: B12, IF
- Microcytic anemia: Iron
- right quadrant pain: fat malabsorption
Glucose transport/absorption in GI and liver is _____ transport
- 2ndary active transport
- Fructose: GLUT 5 – no diffusion
- Glucose: Na/Gluc co-tranporter – GLUT 2, GLUT 4
_______ are readily absorbed in the duodenum
Micronutrients: divalent cations (iron, magnesium)
- Iron (Fe2+ in acidic; Fe3+ alkaline)
- acidic areas: absorption good
- alkaline area: absorption decreases
Fat and lipids stimulate ____ cells in the duodenum to release CCK and aid in fat digestion.
I cells
- emulsification (bile) and breakdown (pancreatic lipase)
- fat carried through lymphatics
NOTE:
1. Gallbladder contraction and sphincter Oddi relaxation → release of bile → emulsification of fat
2. Pancreatic secretions → pancreatic enzymes (pancreatic lipase) → breakdown of fat
D. Decreased gastric emptying (increased satiety)
From the cecum is the ______ COLON (5 inches). It is retroperitoneal.
The RIGHT COLIC FLEXURE leads to the _______ COLON (15 inches).
The LEFT COLIC FLEXURE leads to the _______COLON (10 inches) and it is also retroperitoneal
From the cecum: ASCENDING COLON
The RIGHT COLIC FLEXURE leads: TRANSVERSE COLON (15 inches).
The LEFT COLIC FLEXURE: DESCENDING COLON (10 inches)
The final sphincter in the anal canal is the
sphincter ani (involuntary)
-relaxes during peristalsis
Stages of Swallowing
Stages of swallowing
1. Voluntary
Mouth to oropharynx
- Pharyngeal
Deglutition center in medulla oblongata and pons
Closing of epiglottis
Involuntary- Afferent nerves- CN V, VII, IX and X. - Esophageal
Involuntary
Peristaltic contractions
Bacteria that live in the colon are responsible for:
- synthesis of Vit. B12 and K.
- Other bacteria are responsible for destroying the “bad” bacteria.
ex: E. coli
Peristalsis of the Small Intestine involves the movement of intestinal chyme. Which part of the small intestine sets the pace in the fed state? What happens in the fasting state?
Fed: Duodenum
Fasting: Migrating myoelectric complex (MMC)
– motilin
Parasympathetic: cholinergic Parasympathetic: cholinergic Vagus stimulates
Sympathetic: Adrenergic inhibits
Secretin in the duodenum of the small intestine is secreted by what cells? What is its function?
- S cells
- stimulated by acid and fat
Functions:
1. decrease acidity
→ improved function of pancreatic enzymes
- Stimulates Cl-/HCO3- antiporter in pancreas → increased HCO3- in intestinal lumen → increased luminal pH
Stimulates the liver to produce bile
GIP is produced by ____ cells in the duodenum and the jejunum. It is stimulated by fatty acids, amino acids and oral glucose. What is its purpose?
- Glucose-dependent insulinotropic peptide (GIP)
- K cells
- fat and aa digestion
- glucose absorption
- insulin release (pancreas)
*Decreases H+ secretion by the G cells→ improved function of pancreatic enzymes
Motilin is released in the small intestine during the fasting state. It aids to clear small intestines in preparation for the next meal by:
- inc. movement
- migrating motor complexes
Vasoactive Intestinal Peptide (VIP) is released from parasympathetic ganglia (parasympathetic stimulus)
to increase fluid and flow in intestines. How?
- Relaxes intestinal smooth muscle → increased electrolytes (e.g. K+, Cl-, and Na+) and H2O enter lumen
- Relaxes sphincter of Oddi (assists CCK) → increased bile flow
External anal sphincter is voluntary and is composed of __ muscle
- skeletal muscle
- Part of defecation reflex: controlled by the sigmoid flexure and peristaltic activity.
How are macromolecules metabolized in the GI system?:
Carbs: luminal amylase and amylopectin
- -breakdown disaccharides to mono
- enterocytes
Proteins:
- absorbed in jejunum
- proteases (aminopeptidase)
- enteropeptidase (cleaves trypsinogen to trypsin – cleaves proteins)
- Na ion, H ion or transcytosis
Lipid:
- -Digested in duodenum: pancreatic enzymes (cholesterol esterase, lipase, and phospholipase A2)
- -Emulsified by Bile salts - micelles
- -Metabolized by Pancreatic lipase
- -Become chylomicrons in enterocytes
- Main lipid absorption site: jejunum**
Pancreas
Hormones: glucagon, insulin, somatostatin
Enzymes:
- Pancreatic amylase
- Trypsin
- Entereokinase
- Chymotrypsin
- Carboxypeptidase
- Elastase
- Pancreatic lipase
- Ribonuclease and deoxyribonuclease
Pancreatitis: lower right quadrant pain radiates to back
–Upper right quadrant: liver, gallbladder
- Bile flows through the _____ ducts to gallbladder
- Bile from gallbladder to _____ duct
Diseases:
- _____ occurs when there is a blockade at cystic duct; no fat malabsorption
- -bile from liver can still go directly to help in digestion/absorption - ____ occurs when there is a blockade of the common bile duct
hepatic ducts: gallbladder
-gallbladder to cystic duct
Cholecystitis: blockade at cystic duct
–no fat malabsorption
Choledocytitis: common bile duct
Gallstones are formed by
excess cholesterl or bilirubin
The liver is the largest gland in the GI tract. Its blood supply comes from two sources. The hepatic artery which carries ____ blood to the liver and the portal vein which carries _______ from the gut to the liver
Artery: oxygenated blood to liver
Vein: nutrients from gut to liver
Micronutrient absorption in the small intestine
Duodenum:
- Iron: as Fe2+ (acidic state)
- Copper: absorbed in stomach and duodenum – binds albumin in blood
- Ceruloplasmin: blood or bile; excreted with stool
Jejunum:
- HCO3: indirect active transport in the jejunum
- Ca: active transport in duodenum and jejunum
Ileum:
- Fat soluble vitamins- K, A, D, E are absorbed in the distal ileum
- Bile salts and Vit. B12 are reabsorbed in the distal ileum
Hydrostatic pressure vs. oncotic pressure
- Hydrostatic pressure of the glomerular capillaries:
(favors filtration) - Oncotic pressure of Bowman’s space
- favors filtration - . Hydrostatic pressure of Bowman’s capsule
(opposes filtration) - Oncotic pressure of the glomerular capillaries:
- opposes filtration
Describe what happens to GFR, RBF and Hydrostatic pressure (GC) when you constrict either the afferent or efferent arteries of the renal corpuscle
- Constrict afferent
- -dec. RBF, dec. GFR, dec. hydrostatic - Dilate afferent
- inc. RBF, inc. GFR, inc. hydrostatic - Constrict efferent
- dec. RBF, inc. GFR, inc. hydrostatic - Dilate efferent
- inc. RBF, dec. GFR, dec. hydrostatic
Fractional excretion is the fraction of a filtered substane that gets excreted. What is the formula for fractional excretion?
Ux x UF/GFR x Px
TBW indicators
TBW: Tritiated Water, Antipyrine, Deuterium Oxide (TriAD)
ECF: Inulin (*good indicator), Mannitol, Thiosulfate, Na, Sucrose (I Make Tacos Not Salty)
PV: Evans Blue, Radioidodinated Serum Ablumin (RISA)
