4 - Laws Flashcards
Blood supply to the LV is directly dependent on the difference between the aortic diastolic pressure and LV end-diastolic pressure (coronary perfusion pressure) and inversely related to the vascular resistance to flow, which varies to the fourth power of the vessel radius.
Poiseuille law
Resting coronary blood flow in the adult is?
250 mL/min (1mL/min/g; 5% of normal cardiac output)
Primary regulator of coronary blood flow is the?
Coronary vascular resistance
Coronary blood flow to perfusion pressure
Are the primary physiologic determinants of coronary vascular tone and myocardial perfusion.
Metabolic factors
The heart normally extracts between _ -_% of arterial oxygen content.
75% to 80%
Primary determinant of myocardial oxygen consumption.
Heart rate
True or false?
Cardiac oxygen extraction is near maximal under resting conditions and cannot substantially increase during exercise.
True
Most important determinant of coronary blood flow
Myocardial oxygen consumption
True or false?
Coronary vascular resistance is greater in the resting, perfumed heart than in the contracting heart.
True
Is the external membrane of the cardiac muscle cell which contains ions, ion channels, pumps and exchangers and transport enzymes.
Sarcolemma
Deep invaginations of the sarcolemma penetrate the internal structure of the myocyte at regular intervals. It assures rapid, simultaneous transmission of depolarizing impulses that initiate myocyte contraction.
Transverse (T) tubules
Is the fundamental contractile unit of the cardiac muscle.
Sarcomere
This area is the area of overlap of thick and thin fibers. This band lengthens as the sarcomere shortens.
A band
This area represents the region of the sarcomere that contains the thin filaments alone and this band is reduced in width as the cell contracts.
I band
Each I band is bisected by what line which delineates the border between 2 adjacent sarcomeres.
Z band
Is at the center of the A band which is composed of thick filaments.
M band
These structure is packed with ryanodine receptors that function as the primary Ca release channel for the SR.
Cisternae
Components of the major contractile apparatus of the muscle (6).
- Actin
- Myosin
- Tropomyosin
- 3 tropomins
Contains 2 interwoven chain helices with two globular heads that bind to actin and two additional pairs of light chains.
Myosin
Functions as the main structural support of the myosin.
Tail (light meromyosin)
The light chain of the myosin complex serve 2 roles.
- Regulatory
2. Essential
A long elastic protein that attaches myosin to the Z lines. It is thought to be a length sensor that establishes progressively greater passive restoring forces as sarcomere length approaches its maximum or minimum.
Titin
Two types of actin
- G
2. F
Is a major component of the thin filament. It functions as the activator of myosin ATPase through its reversible binding with myosin.
Actin
Is one of the two major inhibitors of actin-myosin interaction. It serves to stiffen the thin filament through its position within the longitudinal cleft between intertwined F-actin polymers. Its primary action is its Ca-dependent interaction with troponin complex proteins.
Tropomyosin
Different troponins (3)
Troponin C, I, T
This troponin binds to calcium capable of binding divalent cations. Two of the four (I &II) acid-cation binding sequences are Ca specific.
Troponin C
Describes the factors that determine left ventricular wall stress, which is a major determinant of myocardial oxygen demand. Tension development in each myocyte increases LV wall stress that is transformed into pressure when applied to a fluid.
LV wall stress = pr/2h
h = thickness
Law of Laplace
This law is an approximation that states that the extension of a spring is directly proportional to the load applied to it.
Hooke’s law
This reflex relates to the characteristic but paradoxical slowing of the heart seen with spinal anesthesia. Blockade of the SNS levels T1-T4 ablates the efferent limb of cardiac accelerator nerves.
Bainbridge reflex
This law describes the surface tension at an air-fluid interface produces forces that tend to reduce the area of interface. For a bubble to remain inflated, the gas pressure within the bubble is contained by surface tension and must be higher than the surrounding gas pressure.
What is the formula?
Laplace law
2T/R
Surface tension during inspiration
40 mN/m
Surface tension during expiration
19 mN/m
What is the term for the difference between the intrapleural and alveolar pressure?
Transmural pressure gradient or transpulmonary pressure
Physiologic work of breathing includes 2 factors
- Elastic work (inspiratory work to overcome the elastic recoil)
- Resistive work (work to overcome resistance to gas flow in the airway)
Laminar and turbulent flow?
Give the formula
Poiseuille law
R= (8 x length x viscosity) / (pi x radius)
= (pB - pA) / flow
Airway pressure rather than volume distention, appears to be the primary stimulation of pulmonary stretch reflex. This reflex is prominent in lower order mammal, that even 5 cmH2O CPAP will induce apnea.
Humans will continue to breathe spontaneously with CPAP in excess of 40 cmH2O
The neural ouput from the carotid body reaches the central respiratory centers via what nerve?
Aortic bodies?
Both these nerves are stimulated by what condition?
Glossopharyngeal
Vagus
PaO2 less than 100
But not until these pao2 range that neural activity increases sufficiently to substantially augment minute ventilation.
60-65 mmHg
Is called ultimum moriens(last to die)
Carotid bodies
The chemosensitive areas of the brain are located in the?
Inferolateral medulla
This area of the medulla is sensitive to the extracellular fluid H concentration.
Ventral medulla
Central chemoreceptors are primarily sensitive to what factor?
Changes in H concentration
How fast does the ventilatory response to changes peak after and acute change in paco2?
1-2 minutes
After breathholding for 1 minute the breakpoint at which people are compelled to breathe is at ___ mmHg
50 mmHg
If the patient is able to breathe 100% oxygen prior to breath-holding she would be able to hold her breath for how many minutes?
2 to 3 minutes or until paco2 rises to 60 mmHg
Hyperventilation with 100% oxygen can extend the apneic period to how long?
6 to 10 minutes
Refers to the fact that each gas in a mixture will exert its own partial pressure, and in sum will equal the total pressure.
Dalton’s law
Describes the relationship between pH, paco2 and hco3
Henderson-hasselbach equation
The sum of the partial pressures of each gas in a mixture of gases equals the total pressure of the entire mixture.
Dalton’s Law
This law expresses the relationship of concentration of a gas in solution to the partial pressure of the gas with which the solution is in equilibrium.
Henry’s law
states that at constant temperature(T)the volume(V) of a given mass of a gas is inversely proportional to the absolute pressure(P)
Boyle’s Law
V α 1/p
States that at constant pressure, volume of a gas is directly proportional to the temperature.
Charle’s Law
States that at constant volume pressure is directly proportional to the temperature
Gay Lussac’s law
States that equal volume of gases contain equal number of molecules at standard temperature and pressure(STP).
Avagadro’s hypothesis
Concept of the gas laws(Boyle’s law, Charle’s law and Gay Lussac’s law) can be combined with that of Avagadro’s hypothesis
Universal gas constant
states that in a mixture of gases the pressure exerted by
each gas is same as the pressure exerted as if it alone occupied the container.
It can also be defined as “in a mixture of gases the total pressure exerted by the mixture is equal to the sum of pressures exerted by the individual gases.
Dalton’s law of partial pressures
is applied for laminar flow. It states that the flow through the tube is directly proportional to the pressure gradient and 4th power of radius and inversely proportional to the length of the tube and viscosity of the gas.
Hegan- Poissuilles’ law
It is directly proportional to the velocity, density and diameter and inversely proportional to the viscosity.
Reynolds number
States that the Flow rate is directly proportional to square root of pressure gradient on either side of the tube and inversely proportional to square root of density of the fluid.
Graham’s law for turbulent flow
When a gas flowing through a tube encounters a constriction, at that point the pressure drops and the velocity increases i.e. kinetic energy increases and the potential energy decreases. This is called as Bernoulli’s principle.
Bernoulli’s principle
Is the tendency of the fluid jet to be attached to a nearby surface. This phenomenon is also called as wall attachment.
Coanda effect
This is the temperature above which the gas cannot be compressed to its liquid state with any amount of pressure.
Critical Temperature
When two gases, one of high and another of low critical temperature are mixed in a container,the critical temperature of the gas with a high critical temperature will decrease to a lower level(pseudo critical temperature)and the mixture will remain as a gas above this pseudo critical temperature.
Poynting effect
The three gas laws describe the behaviour of the gas when one of the three variables, pressure, temperature or volume is constant.
Adiabatic Changes
States that the reduction of vapour pressure of a solvent is proportional to the molar concentration of the solute.
Raoult’s law
