QP Test 2 Flashcards
Name four things involved in excitation-contraction coupling in skeletal muscle
Generation of end plate potential, formation of cross-linkages between actin and myosin, depolarization
What is a feature common to skeletal, cardiac, and smooth muscle?
Increase in cytoplasmic free calcium concentration
How is skeletal muscle innervated?
Motor neurons exclusively
What is the result of a ryanodine receptor knockout?
no Ca release into cytosol from sarcoplasmic reticulum
Name four things that increase intracellular calcium in smooth muscle.
- activation of voltage gated calcium channels
- activation of gap junctions
- activation of IP3 receptor channel
- activation of ligand gated calcium channel
What is the purpose of gap junctions between smooth muscle cells?
electrical communication between neighboring cells
What happens in latch state (smooth muscle)?
(incomplete) dephosphorylation of myosin light chain
What is a pancreatic hormone with a strong hypoglycemic effect?
Insulin
What does a shift in the hormone response curve to the left of the control indicate?
An up-regulation and the receptors are more sensitive to hormone action.
Give an example of a hormone that acts mainly through a membrane receptor.
Growth hormone
Circadian rhythms fluctuate _________.
Daily
Give an example of a hormone released from the pituitary.
Adrenocorticotropic hormone (ACTH)
What pituitary peptide stimulates the thyroid gland?
Thyroid stimulating hormone (TSH)
What is the condition called when the hypothalmus hypersecretes a particular hormone.
Tertiary hypersecretion
In the negative feedback of complex neuroendocrine systems, what happens if negative feedback from the primary gland hormone decreases?
The secondary glad increases secretion of its tropic hormone
What is the pacemaker of the heart?
The sinoatrial node
In an EKG, what causes the P wave?
Atrial depolarization
Where is conduction of cardiac impulse the slowest?
AV nodal fibers
The plateau of cardiac action potential is maintained by what?
Both calcium and potassium channels
What is the most important factor in influencing the amount of blood pumped by the ventricles of the heart?
preload (venous return)
What is another name for the bicuspid valve?
The mitral valve
Beta Blockers are commonly used as what?
Anti-hypertensive drugs
According to starlings law, what happens if the interstitial osmotic pressure decreases?
Less filtration
What is the most important factor in determining vascular resistance?
Vascular diameter
If the diameter changes by a factor of 2, how will the flow change?
Flow will change by a factor of 16
During hemorrhage, activation of baroreceptor reflex causes what?
Increase in heart rate (look up baroreceptor reflex)
What is flow autoregulation?
Maintaining blood flow nearly constant in the face of pressure change
Gases inspired in the tidal volume are thoroughly and rapidly mixed in the alveolar space by ________.
simple diffusion
What disease causes the lungs to become more compliant?
Emphysema
“For a fixed amount of gas kept at a fixed temperature, pressure and volume are proportional” is what law?
Boyle’s law
Lungs are wrapped by two layers of pleura membranes. What is the relationship between the pressure in the space between the membranes and the alveolar pressure?
The space in between the membranes is always more negative than the alveolar pressure.
How is CO2 carried in the blood?
As bicarbonate in plasma
Which way would the oxyhemoglobin dissociation curve move with an increase in PCO?
It would move to the left (learn all of these)
Both peripheral and central chemoreceptors will contribute to increased ventilation as the result of _________.
Increased arterial partial pressure of carbon dioxide.
What is the function of ryanodine receptors?
The release Ca into the cytosol from sarcoplasmic reticulum in skeletal muscle cells
What happens in myosin/actin’s location during activation of skeletal muscle contraction?
Actin filaments slide past myosin filaments shortening the Z discs.
Tetanic skeletal muscle tension is resulted from the sustained elevation of which molecule’s concentration in myocytes?
Calcium
What does the pre-stimulation length of the muscle represent in terms of myosin-actin interaction?
Number of myosin cross-bridges interacting with actin.
What are the differences between Type I (slow, red) human skeletal muscle fibers and Type II (fast, white) muscle fibers?
The type I have more mitochondrias, smaller fiber diameter, more myoglobins, harder to get tired, lower glycolytic enzyme activity than the type II.
What is the primary function of gap junctions between smooth muscle cells?
Allows them to communicate electronically.
What happens if the level of myosin light chain phosphorylation increases in smooth muscle?
The rate of the actin-myosin cross-bridge cycle increases. The maximum contraction force increases.
What is the “latch state” in smooth muscle?
The cross bridge cycle is slowed down due to the myosin light chain dephosphorylation but not completely stopped.
What are the similarities between smooth muscle and skeletal muscle contraction?
Both involve voltage dependent calcium channels, ATP consumption, myosin-actin interaction and Ca release from the SR
What four factors modulate smooth muscle contraction?
- autonomic nerves
- circulating hormones
- local signals from other cells
- electrical signals from other smooth muscle cells
Why does the force of smooth muscle in blood vessels continually increase after (longer than) the optimal length?
Because passive stress from other tissues continually increases
What are the 5 sequential events during smooth muscle cell contraction?
- rising intracellular Ca
- binding of Ca to calmodulin
- Activation of MLCK by Ca/calmodulin complex
- phosphorylation of myosin light chain
- activation of myosin ATPase
What 4 factors regulate intracellular calcium of skeletal muscle?
L-type Ca channel, calcium pump, ryanodine receptor, Na/Cl exchanger
What are the differences among skeletal, cardiac, and smooth muscle in terms of nucleus?
Skeletal muscle has many nuclei, smooth muscle is mononuclear, cardiac muscle is a mixture of the two
What are the differences among skeletal, cardiac, and smooth muscle in terms of performing autonomic phase contraction?
Only smooth muscle performs autonomic phase contraction
What are the differences among skeletal, cardiac, and smooth muscle in terms of fatigue?
Only white (fast twitch) muscle fibers get fatigued
Is skeletal muscle innervated by sympathetic nervous system?
No. Diaphram and facial muscles are exceptions though
What type of contraction is happens when myosin heads bind to the same F-actin monomer during cross-bridge cycling?
Isometric contraction
Why can airway allergies be treated with epinephrine?
Epinephrine activates Beta2 adrenergic receptors, which then activate the cAMP signaling pathway which causes smooth muscle cell relaxation
Can nerve stimulation induce smooth muscle relaxtion?
Yes, smooth muscle innervation regulates both contraction and relaxation.
In a single stimulated isotonic contraction, what 4 things change in the shortness-time relationship while load is increasing?
- latency of contraction increases
- total shortening duration decreases
- speed of contraction decreases
- maximal shortening distance decreases
Where is adrenocorticotropic hormone (ACTH) secteted from?
pituitary gland
Where is progesterone secreted from?
The ovaries
Which hormones regulate calcium absorption?
Vitamin D increases calcium absorption, parathyroid hormone (PTH) increases Vitamin D synthesis
Where is insulin secreted from?
Pacreatic Beta Cells
What class of receptors does testosterone belong to?
Nuclear receptors
Compare the endocrine and exocrine systems.
Both are essential communicating systems. The nervous system uses neurons to target specific cells and the endocrine system send hormones through the body affecting cells nonspecifically. Endocrine system’s action is much slower and longer compared to the nervous system.
What is the hormone secreted from the adipose tissue that controls food intake?
Leptin
What is the pituitary peptide that stimulates the thyroid gland?
Thyroid stimulating hormone
What is the largest class of hormones?
The proteins (peptide) hormones
How are steroid hormones made?
The enzymatic conversion from cholesterol
What type of chronotropic control observed within the endocrine system that occurs with a pulse every 24 hours?
Circadian rhythm
Name 2 types of hormones that come from amino acids
- Thyroid hormones are basically a double tyrosine with three or four iodine atoms.
- catecholamines including epinephrine, norepinephrine, dopamine
What is the receptor for catecholamine?
Adrenergic receptor that is a 7-trans-membrane spanning protein
What does a shift of the hormone dose response cure to the right from the control indicate?
An ED50 dose of hormone that is greater than before the shift occurred. The response of receptor (binding, activity, etc.) is reduced for the same concentration of hormonal stimulation.
What is the relationship between metabolic clearance of a hormone and its half-life?
The shorter the half life, the higher the metabolic clearance number
Give 4 examples of the way that the nervous system integrates its control with the classical endocrine system?
- hypothalamus secretion of releasing hormones
- hypothalamus secretion of posterior pituitary hormones
- adrenal medulla secretion of catecholamines
- autonomic nervous system control of endocrine secretion
In a complex control system with three hormones, where is the tertiary endocrine gland?
At the hypothalamus
In a negative feedback system of complex control, what happens if negative feedback from the primary glad hormone decreases for some reason?
The secondary glad increases secretion of its tropic hormone
There is a primary hyposecretion of a hormone. What will happen?
The tropic hormone will be high because there is no negative feedback by the primary gland hormone which is low.
Where is corticotropin releasing hormone secreted from?
Hypothalamus
What is the peptide hormone secreted by the pancreas alpha-cells that raises plasma glucose its action in the liver?
Glucagon
What is the relationship among insulin, glucagon, and somatostatin?
All inhibit each other except glucagon stimulates the other two
What is the critical step by which 25-OH-D is converted to the activated form 1,25-(OH) D?
In the kidney, the enzyme 1-alpha-hydraxalase converts 25-OH-D to the 1,25-(OH)D.
How many hormones are included in the class of steroids?
Intermediate (less than peptides)
What is the function of T3 thyroid hormone?
Decreases TSH from anterior pituitary, increases basal metabolism all over the body, plays a significant role in brain growth and development.
What indole hormone is secreted by the pineal gland?
Melatonin, which is a tryptamine derivative
Give 8 (or so) examples of hormones that act through a nuclear receptor.
T3, T4, testosterone, Vit D, estradiol, cotrisol, progesterone, aldosterone
What is ultradian rhythm?
like a circadian rhythm but it’s less than 24 hours and greater than 1
What is the steroid hormone secreted by the adrenal that regulates Na reabsorption by the kidney?
Aldosterone, which is secreted by Zona glomerulosa
Where are the receptors for protein hormones?
Cell membrane
What is the hormone that specifically inhibits the pituitary secretion of ACTH?
cortisol
In complex control, where is the primary endocrine gland located?
Periphery (away from the brain)
What is another name for vasopressin?
ADH (antidiuretic hormone)
What is Cushing syndrome?
Hypersecretion of cortisol
What is Addison’s disease?
Hyposecretion of cortisol
What is the effect of plasma thyroid hormone on TSH and TRH secretion?
inhibition
How many hormones are released from the pituitary? (anterior and posterior)
Anterior: FSH, LH, GH, TSH, Prolactin, ACTH
Posterior: Oxytocin, vasopressin
What hormones are released by the hypothalmus?
GnRH, GHRH, SS, TRH, DA, CRH
What are the common stimulators for the insulin release from human pancreatic beta-cells?
Glucagon, Potassium, Glucose, Amino acids, Fatty acids
What are the common inhibitors for insulin release from human pancreatic beta-cells?
Somatostatin, epinephrine, norepinephrine
What are the hormones secreted from the adrenal gland?
aldosterone, cortisol, androgen, epinephrine, norepinephrine
What are the major differences between diabetes I and II?
Type I is a defect in Beta cells.
Type II is a defect in non-beta-cells where the insulin receptor is damaged
Name three major functions of glucocorticoid
- anti-inflamitory
- suppress immune system
- increase blood glucose
Where is the bicuspid valve (mitral valve) located?
The bicuspid valve is located between the left atrium and left ventricle
What is the P wave of the EKG?
Depolarization of the atrial muscle fibers
In the EKG, when does repolarization occur?
The T wave
Can EKG be useful for determining a patient’s cardiac output?
No. EKG is useful for heart rate
What is responsible for the plateau of cardiac action potential?
Both Ca and Na channels
Which cells have the pacemaker potential?
The SA node
What determines cardiac output?
Stroke volume x heart rate
What is the ratio of stroke volume and end-diastolic volume?
Ejection fraction
What is the most important factor determining how much blood is pumped by the ventricle?
Venous return
Which two great vessels bring deoxygenated blood back to the heart?
The superior and inferior venae cavae
When does the first heart sound occur?
isovolumetric contraction
What is the sequence for the propagation of cardiac impulse? (4)
- SA node
- AV node
- bundle of His
- Purkinje fibers
Where are the bundle of His and its branches located?
In the intraventricular septum
What are most responsible for phase 0 of a cardiac action potential?
Na channels
What causes cardiomyocyte repolarization?
Ca channels begin to close while more K channels open. K leaves the cell
What relationship is defined by the Frank-Starling Lab?
End-diastolic volume and stroke volume
The opening of which channel in the autorhythmic cell (pace maker cells) is responsible for huge positive spike in membrane potential?
L-type calcium channel
What is the typical stroke volume of an adult at rest?
70mL
When does atrial systole occur?
Towards the end of ventricular diastole
Due to what even does the second heart sound occur?
Closing of the semilunar valves
What does heart rate depend on?
Rate of pacemaker potential
Which structure has the slowest conduction velocity of the cardiac impulse?
AV nodal fibers
What is the correct sequence for blood flow in the heart?
right atria, tricuspid, right ventricle, pulmonic, left atria, mitral, left ventricle, aortic, aorta
Why does the electrical activation from the atria to the ventricles need to delay?
The delay allows atrial contraction to push and additional amount of blood into the ventricle before it contracts
Which heart valves open or close during diastole and systole of the heart cycle?
In diastole, AV valves (bicuspid, tricuspid) poen and semilunar valves close. In systole, opposite occurs
What changes in the ventricular pressure occur during the isovolumetric contraction phase?
The beginning of ventricular contraction causes leaflets of the mitral valve to close, continuation of ventricular muscle contraction will increase ventricular pressure very rapidly until it exceeds aortic pressure
What is the Beta adrenergic effect on ventricular myocyte function?
It increases cAMP/PKA signal pathway which activates L-type calcium channels. It also causes release of free calcium from SR. Results in more muscle contractility.
What is the effect of activation of baroreceptor reflex during hemorrhage?
Increase heart rate due to activation of sympathetic tone on the vasculature.
What is the effect of NO on smooth muscle?
NO causes arteriolar vasodilation.
What is active hyperemia?
Increasing blood flow of an organ when its metabolic activity increases.
Where does the slowest blood flow occur?
In the capillaries
What happens to the capillary hydrostatic pressure during arteriolar constriction?
Decreases
Where does the highest vascular resistance occur?
Arterioles, there is a large decrease in pressure
What is the effect of the heart when parasympathetic stimulation decreases?
Heart rate increases
How do lipid soluble substances (CO2 O2) cross the capillary membrane?
Diffusion
What will cause decreases hematocrit in the microcirculation?
Velocity profiles in higher vessels, few RBCs near the walls
Where is NO released?
Arteriolar endothelial cells
What does Starling’s law of filtration predict?
Write this the fuck down and know it.
What percentage of blood is RBCs?
45% of blood volume.
WBCs are less than 1%
What are the myogenic and metabolic vasodilator hypotheses of autoregulation?
Myogenic autoregulation depends of the stretch activated channels in VSM that, when stretched allow Ca2+ ions to enter and induce contraction. Metabolic is thought to be due to substances produced in the tissue
What is the Fahraeus effect?
More RBCs in arterioles than capillaries
What percent of blood is in capillaries?
At any given time, only 5%
What is the relationship between the arteriolar vasodilators production and local oxygen level?
The production of vasodilators is inversely proportional to local oxygen levels
What causes ECs to produce more NO?
Shear stress
What is the effect of sympathetic stimulation of hydrostatic pressure?
Decrease
What factors determine the changes in mean arterial pressure?
Cardiac output and peripheral resistance
Does parasympathetic stimulation control arteriolar resistance?
No
What is flow autoregulation?
Maintaining blood flow constant in the face of pressure changes
What vascular region has the least amount of smooth muscle?
Capillaries
What is the most important factor in determining vascular resistance?
Diameter
Where is the most blood in the cardiovascular system?
Veins
How does a vasodilator relate to oxygen level?
Reversely proportional toit
Are enodthelial cells involved in the myogenic response?
Nope
What is the vital capacity?
The maximum volume that can be inspired after a maximum expiration
In which form is most CO2 in arterial blood carried?
Bicarbonate in plasma
What is normal aterial oxygen carrying capacity?
1.34 mL O2/gHb
What happens to the O2 binding on hemoglobin when blood temperature increases?
Less oxygen is chemically bound to hemoglobin at the same PO2
When the respiratory muscles are relaxed in a normal person with open airways, what is the volume of the lungs?
Functional residual capacity
How is lung movement controlled?
Not by muscle. Lungs are wrapped by two layers of pleura membranes and the pressure in the space between the membranes is always more negative than the alveolar pressure
During normal inspiration, what will happ to the intrapleural pressure?
It will become even more negative
How are inspired gases mixed in the alveolar space?
Simple diffusion
What is the relationship between body weight and conducting dead space?
1 mL/pound
What is the effect of pH on the oxyhemoglobin dissociation curve?
Increasing pH (becoming more basic) moves it to the left
As mixed venous blood enters and travels through capillaries in well ventilated areas of the lung, what happens to pH?
The pH increase (becomes more basic)
What is the effect of an increase in aterial CO2 on ventilation?
It will stimulate both peripheral and central chemoreceptors and increase ventilation
What do you expect on the CO2 response curve with an acclimation to altitude?
Shift to the left (that is, increase the respiratory response to a given arterial PCO2)
What is the effect of hydrogen ion concentration on perhipheral chemoreceptor activity?
The activity increases linearly with hydrogen ion in the range 40-45 mEq/L
What is the vital capactity?
Maximum volume that can be inspired after a maximal expiration
Do the terminal bronchioles belong to the respiratory zone?
Nope. The respiratory zone consists of respiratory bronchioles, alveolar ducts, and alveoar sacs
What type of flow is movement into the airways?
Bulk flow
In the absence of surfactant, what pressures would you see in two different sized alveoli?
Psmall»Plarge
What is the percentage of total volume that can be expired in the first second of exhalation?
80%
According to Fick’s law, how is membrane thickness related to diffusion?
Flow is inversely proportional to thickness
How is COPD different from Asthma?
In COPD patients, the inflammation is not triggered by allergies and cannot be treated with anti-inflamitory medications
What change in diphosphoglycerate (DPG) will shift the oxygen saturation curve to the left?
A decrease
What is the effect of CO on the oxygen saturation curve?
Shift to the left
How is most O2 transported in the blood?
Bound to hemoglobin
What enzyme is used in CO2 transportation?
Carbonic anhydrase
How do different pathologies affect lung compliance?
Emphysema increases compliance, decreases with fibrosis, no change or decrease with asthma
What is tidal volume?
The lung volume change during normal breathing
How is CO2 carried in the blood?
60% is bicarbonate
30% HbCO2
10% dissolved in plasma
What is the effect of PO2 on the oxygen saturation of hemoglobin?
O2 binding increases with pressure to a point and then there is no significant change
What does carbonic anhydrase do?
Converts back and forth between CO2 and bicarbonate
