Biochem/Physiology Pt 2 Flashcards
The kidneys regulate acid-base balance by the:
• secretion of bicarbonate ions (HC03-) into the renal tubules and the reabsorption of
hydrogen ions (H’)
• secretion of hydrogen ions (W) into the renal tubules and the reabsorption of
bicarbonate ions (HC03-)
• secretion of both hydrogen (W) and bicarbonate ions (HC03-) into the renal tubules
• reabsorption of both hydrogen (W) and bicarbonate ions (HC03-)
• secretion of hydrogen ions (H’) into the renal tubules and the
reabsorption of bicarbonate ions (HCo3·)
hydrogen ions secreted; derived from carbonic acid
HCO3- into blood
net reabsorption of HCO3 but not a net secretion of H+
\_\_\_ is the best overall index of kidney function. • CPR • TFR •APR • GFR
GFR
inulin and creatinine: neither absorb nor secrete; clearance = GFR
excessive constriction of afferent arteriole –> decrease RBF and GFR
The countercurrent mechanism is a system in the renal _ _ that facilitates
the __ of the urine. The system is responsible for the secretion of __
urine in response to __ plasma osmolarity.
• cortex/concentration/
hyperosmotic/elevated
• medulla/dilution/hypo-osmotic/depressed
• cortex/dilution/hypo-osmotic/
depressed
• medulla/concentration/
hyperosmotic/elevated
medulla, concentration, hyperosmotic, elevated
countercurrent - concentration of urine in medulla
Henle penetrates into medulla to create gradient
hyperosmotic interstitium –> water reabsorbed from urine
BUT asc loop is impermeable to water!
NaCl reabsorbed from asc loop of Henle and water is retained –> increases in medullary interstitium
Reabsorption of glomerular filtrate would be most affected if modifications
were made to the permeability of which section of the nephron?
• descending loop of Henle
• distal convoluted tubule
• proximal convoluted tubule
• ascending loop of Henle
proximal tubule
2/3 is reabsorbed (almost all of glucose)
also some in Henle, distal and collecting
Your afternoon patient complains that she has consumed “tons of liquids”
today. The patient asks ifthis will have an effect on her urine concentration.
What would you say in response to this question?
• Your plasma osmolarity is lower than normal, and you will likely excrete a large amount
of concentrated urine
• Your plasma osmolarity is lower than normal, and you will likely excrete a large amount
of dilute urine
• Your plasma osmolarity is higher than normal, and you will likely excrete a large amount
of concentrated urine
• Your plasma osmolarity is higher than normal, and you will likely excrete a large amount
of dilute urine
What are the normal values for daily glomerular filtrate amount and
excretion amount, respectively?
• 1 SO - 2SO L; 1 - 2 L
• 1 SO - 2SO L; 12 L
• 4S - 7S L; 1 - 2 L
• 4S - 7S L; 12 L
plasma lower, dilute urine
150-250 GFR, 1-2 urine/day
Ammonia is produced from the metabolism of a variety of compounds.
1. Which compound listed below is quantitatively the most important source
of ammonia?
2. Which compound is not a source of ammonia?
3. Which compound is converted to ammonia mainly in the kidney?
• glutamine
• amino acids
• a mines
• purines and pyrimidines
• triglycerides
AA
TGs
glutamine
sources of ammonia: AA in liver by aminotransferases (PLP cofactor)
glutamine in kidney
urea forms in liver
uric acid crystals –> gout
arginase catalyzes urea formation (cofactor Mn)
carbonic anhydrase cofactor
Zn
PLP is cofactor for
aminotransferases
arginase fx
urea formation in cell, cofactor = Mn
Mn is cofactor for what
arginase which makes urea in cell
- Which of the following processes is not involved in the formation of urine?
- Which two of the following processes in the formation of urine involve the
most similar amounts of fluid transport? - Which two processes supplement each other, working in the same
“direction”? - Which process is most affected by levels of ADH?
- Which process occurs in Bowman’s capsule?
• filtration
• reabsorption
• excretion
• secretion
excretion - not a part of formation
filtration and reabsorption - about 99% of filtrate is reabsorbed
filtration and secretion - both from blood to tubules
reabsorption
filtration
Cardiac muscle has a shortened action potential compared to skeletal
muscle.
In cardiac muscle, the action potential is caused by opening oftwo types of
channels.
• both statements are t rue
• both statements are fa lse
• the first statement is true, the second is fa lse
• the first statement is false, the second is true
first false, second true
cardiac mm has a plateau –> 15x longer potential
skel mm: fast Na channels
cardiac mm: fast Na + slow Ca (which actually make plateau)
strength of Ca directly proportional to intracellular Ca
refractory of atria much shorter than ventricles, can depol again faster
channels in cardiac mm
fast Na (also in skel) and slow Ca (make plateau)
The bicuspid or mitral valve is located between which two chambers of the
heart?
• the right and left ventricl es
• the right atrium and the left ventricle
• the right and left atri a
• the left atrium and the left ventri cle
Which valve is unique in having a different number of cusps than the others?
• mitral valve
• tri cuspid valve
• pulmonary semilunar valve
• aortic semilunar valve
LA and LV
mitral - 2
An electrocardiogram is a graphic illustration of the: • cardiac cycle • cardiac conduction system • cardiac output • systemic and pulmonary circuits heart
cardiac conduction system
Cardiac function is the volume of blood pumped each minute, and is expressed by which equation? • CO = SV- HR • CO = SV + HR • CO = SVx HR • CO = SV I HR
CO = SV x HR
5-6 L
SV = end diastolic - end systolic (70-80 ml)
BP = CO x TPR
equation for BP
CO x TPR
The Bainbridge Reflex is a positive feedback mechanism in which there is a
compensatory increase in heart rate, due to a rise in right atrial pressure.
It is commonly referred to as an Atrial Reflex.
• both statements are true
• both statements are false
• the f irst statement is t rue, the second is false
• the f irst statement is fa lse, the second is true
164
both true
Bainbridge reflex = atrial reflex
HR increases when RA pressure increases
stretch receptors through vagus to medulla
Use the same answer options for the following questions.
1. Your patient has a defective mitral valve, allowing backflow. Which of the
following cardiac phases will be least affected by this defect?
2. Normally, which phase would have the highest ventricular pressure?
• isovolumetric contraction
• fill ing phase
• isovolumetric relaxation
• ejection phase
filling (bc valve is open anyway)
ejection
each cardiac cycle ~0.8 seconds
The first heart sound ("Lub") is associated with the closure of the:
• aortic and mit ral valves
• mit ral and t ri cuspid valves
• aortic and pulmonary valves
• t ri cuspid and pulmonary valvesmitral and tricuspid (AV valves)
ventricular systole begins at S1, ventricular diastole ends with S1
second sound - closure of semilunars
ventricular diastole begins at S2
aortic valve closes before pulmonary valve –> splitting of S2
S2
semilunars close, aortic before pulmonary –> S2 splitting
S1
AV close
You have four patients with the following heart defects. For each patient,
choose which portion of the cardiac conduction system that is most likely
malfunctioning.
1. Craig has a higher than normal heart rate (tachycardia).
2. Gary’s ventricles contract nearly simultaneously with the atria.
3. Ashley’s right ventricle does not contract on the lateral side.
4. Jimmy’s entire left ventricle does not contract.
• sinoatrial node
• atrioventricular node
• internodal pathways
• atrioventricular bundle
• purkinje fibers
SA node
AV node (responsible for delaying)
purkinje
AV bundle
AV node located in lower interatrial septum; impulse is delayed to allow filling
purkinje fibers -> to lateral walls
Use the same answer options for the following questions.
1. The ventricles are completely depolarized during which isoelectric
portion of the ECG?
2. This portion of the ECG represents atrial depolarization.
3. This portion of the ECG represents the segment between depolarization of
the atria and depolarization of the ventricle.
• QRS complex
• Q-T interval
• S-T segment
• P wave
• P-R interval
QRS
P
PR
ST segment: period when ventricles depolarized (from full depol to beginning of repol; isoelectric)
QT - between depol and repol
also isoelectric bw T and P (resting)
Venous return (VR) is the flow of blood back to the heart. Under steady-state
conditions, venous return must equal _____ when averaged over time
because the cardiovascular system is essentially a closed loop .
• sv
·CO
• HR
• BP
CO
what is frank-starling relationship
SV increases in response to increased filling
Which of the following equations correctly defines blood flow through the
vasculature?
· flow = (initia l pressure - fina l pressure) x resistance
• flow = (init ial pressu re - final pressure ) I resistance
• flow = resistance I (initial pressure - fina l pressure)
flow = CO = BP/TPR
BP = CO x TPR
flow inversely proportional to resistance and directly proportional to pressure gradient
resistance inversely proportional to radius^4
Changes in vessel __ are most important quantitatively for regulating
blood flow within an organ, as well as for regulating arterial pressure.
· thickness
•length
• diameter
• viscosity
diameter
Fill in the blanks so that each statement correctly describes a situation that
will increase venous return to the heart.
• the contraction of _____(skeletal I cardiac I smooth) muscle
• a(n) _____ (increase I decrease) in intrathoracic pressure
• the presence of venous _____ (valves I peristalsis)
• a(n) ______ (increase I decrease) in venous compliance
contraction of skeletal
decrease in intrathoracic pressure
presence of valves
decrease in compliance (increases central venous pressure)
Which ofthe following parameters is decreased during exercise? • heart rate • cardiac output • total peripheral resistance • stroke volume • arteria l pressure
TPR
vasodilator metabolites (lactate, K, adenosine), bc increased metabolism, to increase blood flow to mm – and constriction elsewhere, in veins too
in exercise, CO increases more than TPR decreases; mean pressure is higher
Parasympathetic fibers innervate the heart by way of the vagus nerves.
The right vagus nerve goes to the AV node while the left vagus nerve goes to
the SA node.
• both statements are true
• both statements are false
• the f irst statement is t rue, the second is false
• the f irst statement is fa lse, the second is true
first true, second false
symp also increases ICF Ca –> stronger contractions
right vagus –> SA node, left vagus –> AV node
velocity of conduction: fastest in Purkinje, slowest in AV (Av responsible for delay)
automaticity: SA > AV > Purkinje
If a patient’s SA and AV nodes fail, what is the most likely situation the patient
will be in?
• dead; the patient’s heart will fail immediately
• both the atria and ventricl es will continue to contract on the pace of the bundle
of His (30-40 impulses per minute)
• the ventricles will contract and passively fil l, keeping the patient alive for a short
period
• the atri a will take over and contract; the ventricles will allow the blood to flow
through and out to the periphery of t he body
[
His will take over (proximal interventricular septum). 30-40
The isoelectric point (pi):
• is the pH at which the number of positive and negative charges on a molecule equal
each other
• is the pH at which the number of posit ive and negative charges in a solution equal
each other
• can be determined using the Henderson-Hasselbalch equation
• is the pKa of a solution at which it is neither basic nor acidic
• two of the above
+ and - on molecule equal each other
pK - dissociation constant
Which of the following represents the pH of a solution that has a 10-4 M concentration of OH- ion? • 5 ·8 ·7 ·10
10
Carbonic acid/bicarbonate is the most important physiological buffer
system in the body.
Proteins also participate in pH buffering, mainly through their histidine side
chains.
• both statements are t rue
• both statements are false
• the fi rst statement is true, the second is false
• the fi rst statement is fa lse, the second is t rue
178
both true
histidine side chain not far from from blood pH
Hb - major intracellular buffer
buffers commonly consist of weak acid and salt (or conjugate base)
reduce effect of abrupt change in H+ ion concentration - release ions when pH rises and accept ions when pH drops
The famous relationship stated in the Henderson-Hasselbalch equation can
be used to:
• predict the pH that acid buffers work best at
• predict the pKa that acid buffers work best at
• predict the dissociation constant of a weak acid only
• predict the dissociation constant of a strong acid only
• predict the dissociation constant of any acid
179
predict optimal pH of buffer
CANNOT predict dissociation constants
pH = pK when acid half-neutralized
HH equation:
pH = pKa + log A-/HA
All of the following are mechanisms the body uses to control the blood’s
acid-base balance EXCEPT one. Which one is the EXCEPTION?
• excess acid is excreted by the kidneys
• pH buffers are found in the blood
• excretion of carbon dioxide
• filtering blood by the spleen
filtering blood by spleen
kidneys excrete H+ in acidosis and HCO3- in alkalosis
Respiratory acidosis results from hyperventilation.
Metabolic acidosis results from excessive vomiting.
• both statements are t rue
• both statements are fa lse
• the first statement is t rue, the second is fa lse
• the first statement is fa lse, the second is true
pH
both wrong
respiratory acidosis - when don’t dispose of CO2; respiratory alkalosis in hyperventilation
metabolic acidosis: when kidney can’t excrete excess; metabolic alkalosis - excessive vomiting (bc loss of acids)
in respiratory acidosis: total CO2 in blood is elevated bc retained and is the cause of this acidosis
in metabolic acidosis, pt hyperventilates in attempt to compensate for kidney –> CO2 decreased
The cell (plasma) membrane is a fluid mosaic of: • lipids and carbohydrates • proteins and carbohydrates • lipids and proteins • carbohydrates membranes
lipids and proteins
Proteins account for about one quarter of the total mass in most membranes.
Membrane proteins are globular proteins.
• both statements are true
• both statements are false
• the f irst statement is t rue, the second is false
• the f irst statement is fa lse, the second is true
183
first wrong, second true
proteins ~1/2, globular
also carbs on exterior of membrane
held together by non-covalent interactions
lipid distribution is asymmetrical
Molecules that can easily penetrate a biologic membrane are usually: • large and nonpolar • small and polar • large and polar • small and nonpolar
small and nonpolar
water and gases
The organic matrix of enamel is made from noncollagenous proteins only
and contains several enamel proteins and enzymes.
Of the enamel proteins, 90% are a heterogenous group of low-molecularweight
proteins known as amelogenins.
• both statements are true
• both statements are false
• the fi rst statement is true, the second is false
• the fi rst statement is fa lse, the second is true
both true
All of the following statements concerning enamel hypoplasia are true
EXCEPT one. Which one is the EXCEPTION?
• it is a defect in the mineralization of the formed enamel matrix
• the enamel of primary and permanent teeth appear pitted
• radiographically, the enamel is either absent or very thin over tips of cusps and
interproximal areas
• it can be caused by nutritional deficiencies
• it is a defect in the mineralization of the formed enamel matrix
this is false
hypoplasia is defect in formation of enamel matrix
enamel hypoplasia refers to defects of thickness (quantitative defect)
hypocalcification - qualitative defect
enamel is hard but thin
Caries activity is directly proportional to all of the following EXCEPT one.
Which one is the EXCEPTION?
• the consistency of fermentable carbohydrates ingested
• the quantity of fermentable carbohydrates ingested
• the frequency of ingesting fermentable carbohydrates
• the oral retention of fermentable carbohydrates ingested
• the quantity of fe rmentable carbohydrates ingeste d
Strep mutans dextran sucrose (glucosyltransferase)
S. sanguis most common in oral cavity
others are s salivarius and lactobacillus
glucans –> dental plaque, holds lactic acid which dissolves HA crystals
most common oral bact
s sanguis
what makes dental plaque
glucans, holds lactic acid –> dissolves HA crystals
The primary physiologic control of the salivary glands is by the sympathetic
nervous system.
Control of salivary secretion is exclusively neural.
• both statements are true
• both statements are false
• the f irst statement is t rue, the second is false
• the f irst statement is fa lse, the second is t rue
first false, second true
exclusively neural (not hormonal) primary control is parasymps (VIP + ACh), symps also present
atropine blocks ACh –> decreased salivation
All of the following characterize saliva EXCEPT one. Which one is the
EXCEPTION?
• low K+ concentration
• low osmolarity
• the inorganic composition is entirely dependent on the stimulus and the rate of
salivary flow
• it is always hypotonic
• low K• concentration
low osmolarity, high K+, always hypotonic bc NaCl reabsorbed in ducts
inorganics depend on rate of flow and stimulation
The nonessential amino acids are synthesized either from common
metabolic intermediates or from other amino acids.
Only three amino acids: leucine, lysine and histidine, are exclusively
ketogenic.
• both statements are true
• both statements are false
• the f irst statement is t rue, the second is false
• the f irst statement is fa lse, the second is true
191
first true, second false
only leucine and lysine are purely ketogenic
purely ketogenic acids
lysine and leucine
In eukaryotes, DNA does not exist free; it is complexed with an approximately
equal mass of basic proteins called histones. These histones contain a large
portion of:
• cysteine and lysine
• arginine and lysine
•lysine and glutamine
• glutamine and arginine
arg and lys
(also histidine)
all +
