Test 3-Lecture Flashcards
What are the functions of the kidneys?
Removal of toxins, metabolic wastes, and excess ions from the blood; Regulate H20 volume, body osmolity, and extracellular ion concentrations; ensure long-term acid-base balance; produce erythropoietin and renin for RBC production and BP control; convert Vit. D into its active form; carry out gluconeogenesis during fasting
What are the specialized cells in the juxtaglomerular apparatus?
macula densa cells, granular cells, and extraglomerular mesangial cells
What is the function of the macula densa cell?
they are the chemoreceptors that moniter NaCl content of entering filtrate
What is the functional unit of the kidneys?
the nephron
What is the normal osmolality of our body fluids?
between 280-300
What is osmolality?
The # of solute particles dissolved in 1 kilogram(1000gr) of water-it reflects the solution’s ability to cause osmosis.
What is the function of the granular cells?
They act as mechanoreceptors that sense blood pressure-granular cells that release renin
What is the function of the extraglomerular mesangial cells?
They are between the arteriole and tubule cells, interconnected by gap junctions. May pass signals between macula densa and granular cells.
What is GFR?
Glomerular filtration rate-Volume of filtrate formed each minute by all 2 million glomeruli. 120-125ml/min
What are the intrinsic controls of the GFR?
renal autoregulation-acts locally within the kidneys. Two ways-myogenic mechanism and Tubuloglomerular feedback mechanism. Maintains constant GFR when MAP is 80-180mm Hg
What are the extrinsic controls of the GFR?
nervous and endocrine mechanisms that maintain blood pressure, but affect kidney function. They are external controls that take over if MAP is >180 or <80 mm Hg
What is released among the extrinsic controls of GRF and by what?
Norepiephrine is released by the sympathatic system; epinephrine is released by the adrenal medulla-both causing cinstriction of afferent arterioles. When renin is released, it triggers the Renin-Angiotensin Mechanism
What is the function of renin?
It activates angiotensinogen into angiotensin I and then angiotensin I is converted into angiotensin II by ACE.
What are the effects of Angiotensin II?
It constricts arteriolar smooth muscle, causing MAP to rise; stimulates the reabsorption of Na by acting directly on the kidney tubules and triggering the adrenal cortex to release aldosterone; stimulates the hypothalamus to release ADH and activates the thirst center.
What is the difference between glomerular filtrate and plasma?
glomerular filtrate is just like plasma minus the RBCs and proteins
Why is it important that proteins to not get through and into the filtrate?
Because proteins are important for maintaining osmotic pressure
What do the kidneys reabsorb in the distal convoluted tubules?
re-absorption occurs in the distal portion with the assistance of hormones. Na (sodium) by aldosterone; Cl- follows Na; Ca2+ by parathyroid hormone
What is reabsorbed at the proximal distal convoluted tubules?
Almost everything! Na+; virtually all nutrients-glucose, amino acids, vit.,some ions; HCO3; water; lipid-soluble solutes; urea
What is the reason for high glomerular pressure?
To continue hydrostatic pressure which is the chief force in pushing water and solutes out of the blood and across filtration membrane-it 55mm Hg. the glomeruli are drained by a high resistance efferent arteriole whose diameter is smaller than the feeding afferent arteriole-allowing filtration across membrane
How much urine do we produce each day?
1.5L (<1%)
In renal auto-regulation, what do the intrinsic and extrinsic regulation maintain?
Intrinsic maintains the GFR; extrinsic helps maintain systemic blood pressure when things get beyond the intrinsic control?
What force influences glomerular filtration?/
Hydrostatic Pressure
How do the kidneys respond to a low blood PH?
renal tubule cells secrete more H+ into the filtrate and retain more HCO3
What is inulin?
a plant polysaccaride that flows freely and is neither reabsorbed or secreted by the kidneys. It is the standard used to determine GFR because it has a renal clearance equal to the GFR
What is renal clearance?
It is the volume of plasma which the body clears a particular substance in a given time (usually 1 min). C=UV/P
What does renal clearance tell us?
Can detect glomerular damage and follow the progression of renal failure
What is reabsorbed in the Loop of Henle?
Descending Limb-Water; Ascending limb-Na, K+, Cl-
What is the action of the muscles involved in micturition/voiding?
Contraction of the detrusor muscle by ANS; Opening of internal urethral sphincter by ANS (Contraction); Oopening of the ecternal urethral sphincter by ANS (relaxation)
How is CO2 carried in the blood and in what amounts?
7-10% dissolved in plasma; ~20% bound to the globin part of hemoglobin; ~70% as bicarbonate (HCO3-) ions in plasma
Where does CO2 get converted into bicarbonate?
At the RBC membrane. Dissolved CO2 diffuses into the RBC and the reaction occurs quickly
How is CO2 converted into bicarbonate?
CO2—–>into RBC—–>combines with H2O to make carbonic acid—->carbonic acid is unstable and dissociates into hydrogen ions and bicarbonate ions
What are the 6 essential digestive processes?
Ingestion Propulsion Mechanical Digestion Chemical Digestion Absorption Defecation
What is the function of a mesentery?
It is made up of a double layer of peritoneum. It includes routes for blood vessels, lymphatics, and nerves; It holds organs in place; stores fat
What are the functions of salvia?
Cleanses the mouth, moistens and dissolves food chemicals; aids in bolus formation; contains enzymes that begin the breakdown of starch
What is the content of saliva?
97-99% Water, slightly acidic solution containing electrolytes, enzymes and defensins
Where do we start digesting starches/carbs?
In the mouth by salivary amalyse
What is amylase?
A digestion enzyme that breaks down starchs and carbs-found in the mouth and pancreas
What chemicals influence the release of Hydrochloric acid?
Stimulation of the parietal cells through second-messenger systems-ACh, histamine (H2), and gastrin
What inhibits the secretion of hydrochloric acid?
Antihistamines which block the H2 receptors and decrease its release
What is the role of HCl in food digestion?
to activate pepsinogen to become pepsin by creating an acidic environment for digestion to occur
What cells are found in the gastric gland?
Parietal cell, Chief cell, and enteroendocrine cells
What does the parietal cell secrete?
Hydrochloric acid
What does the chief cell secrete?
pepsinogen
What are the three phases of gastric secretion/salivation?
- Cephalic (reflex) phase-few minutes prior to food entry
- Gastric phase- 3-4 hours after food enters the stomach
- Intestinal phase-brief stimulatory effect as partially digested food enters the duodenum, followed by inhibitory effects
What is the role of bicarbonate (HCO3-) in the digestive tract?
neutralize the acidic gastric juice as it enters the small intestines
What cell produces HCO3- in the duodenum?
Brunner’s (duodenal) glands
What is the role of bile in fat digestion?
Bile contains bile salts emuslify (breakdown) large fat molecules into amino acids
What enzyme further breaks down micelles?
Pancreatic Lipase
What is the major absorptive organ of the digestive tract?
Small intestine-95% of everything is absorbed
What organs are retroperitoneal?
pancreas, duodenum of the small intestine, colon of the large intestine, liver, and kidneys
What organs of inta-peritoneal?
stomach, jejunum, ileum, ascending, transverse, and sigmoid parts of large intestine
Which muscles contract and which muscles relax during defecation?
rectal walls contract, external anal sphincter relaxes, and internal anal sphincter relaxes
What is the total body water content of infants? Men? Women? Elderly?
73%
60%
50%
45%
What are the major cations and anions of intercellular fluid?
Cation-Potassium; Anion-Phosphate
What are the major cations and anions of Extracellular fluid?
Cation-Sodium; Anion-Chloride
What is the distribution of fluids in Extracellular and Intracellular fluids?
ICF-2/3 of the volume—25L of the 40L of total body water; ECF-remaining 1/3—15L
What is the role of ANP in blood pressure regulation?
ANP-atrial natriuretic peptide—–>triggers the release of ADH (antidiuretic hormone) which causes the collecting tubules to decrease the amount of Na+ (Sodium) and H2O reabsorbed which lowers blood volume and lowers BP
What is the role of the kidney in acid-base regulation?
conserving (reabsorbing) or generating new bicarbonate ions or excreting bicarbonate ions.
What is alkalosis or alkalemia?
arterial PH above 7.45
What is acidosis or acidemia?
arterial PH lower than 7.35
What three ways are hydrogen ion regulated?
- Chemical buffer systems-act within seconds
- Respiratory center-within 1-3 min.
- Renal Mechanisms-most potent acid-base regulatory system-requires hours to days.
What are the three main chemical buffer systems?
- Bicarbonate buffer system-function of CO2
- Phosphate buffer system-kidneys use
- Protein buffer system
What should we remember about hydrogen and bicarbonate gaining and losing?
Losing a bicarbonate ion is the same as gaining a hydrogen ion; reabsorbing a bicarbonate ion is the same as losing a hydrogen ion
What is normal PH, HCO3-, and PaCO2?
PH-7.35-7.45; HCO3–22-26; PaCO2-35-45
When is it metabolic acidosis? how does the body compensate?
Low PH and Low HCO3-; from diarrhea, renal disease, startvation
Excess of H, Decrease HCO3-; Increase Respiratory Rate
When is it Respiratory acidosis? How does the body compensate?
Impaired lung function; PaCO2 high and PH low
Increase of PaCO2, Increase of H; Kidneys-Increase of H elimination and retain HCO3-
When is it Metabolic alkalosis? How does the body compensate?
Vomiting; High HCO3- and High PH
–Increase of BCO3-; decrease Resp. rate
When is it Respiratory alkalosis? How does the body compensate?
Hyperventilation; Low PaCO2 and High PH
Decrease PaCO2, Decrease H+; Decrease H+ elimination and Increase HCO3- Elimination
What distinguishes compensated versus uncompensated?
compensated-PH level normal
What is evidence of compensated metabolic alkalosis?
PH normal with elevated HCO3- and PaCO2 levels
What is evidence of renal compensation of of respiratory alkalosis?
Low PaCo2 levels
