Physiology I & II Flashcards
________ refers to the maintenance of nearly constant conditions in the internal environment and is the condition in which the body’s internal environment remains relatively constant within limits
Homeostasis
What are the 3 primary characteristics of the internal environment of an organism in homeostasis?
Contains optimum concentration of gases, nutrients, ions, water
Has optimal temperature
Has optimal pressure for health of cells
_______ is any stimulus that creates an imbalance in the internal environment
Stress
What type of feedback loop is defined by a response that reverses the direction of the initial condition?
Negative feedback loop
What are the 2 primary characteristics of negative feedback loops?
- Diminishes original change
- Stabilizing
What are the 2 primary characteristics of positive feedback loops?
Enhances original change
Destabilizing (can lead to runaway effects)
The stretch of the cervix during delivery sends signals that increase the force of uterine contractions which then increase the stretch on the cervix. This is an example of what type of feedback loop?
Positive
Baroreceptors are stretch receptors associated with the carotid system. When these sense an increase in arterial pressure, they send inhibitory signals to vasomotor receptors in the medulla. Heart pumping capacity is reduced and blood vessels dilate, leading to a decrease in arterial pressure. This is an example of what type of feedback loop?
Negative
An increase in the production of TSH releasing factor results in an increase in the release of TSH, which results in the release of more thyroxine, which results in a decrease in the production of TSH releasing factor. This is an example of what type of feedback loop?
Negative
______ is the degree of effectiveness with which a control system maintains constant conditions
Gain
How is gain calculated?
Correction/error
Adding 2 L of blood to an uncontrolled system and to a controlled system:
Uncontrolled system: Pressure rises from 100 to 175
Controlled system: Pressure rises from 100 to 125
Calculate the gain in this case.
Gain = Correction/Error = -50/25
Answer: -2
Baroreceptors (pressure receptors) in the carotid system sense changes (increases) in the arterial pressure. These baroreceptors send signals to the brainstem where the cardiac centers are located. A feedback system then activates a number of responses that result in a lowering of arterial presure. Two dogs are used in a study to test the effects of a drug that causes hypertension as a possible side effect. In one of the dogs the baroreceptor feedback system has been inactivated. In the dog with the intact feedback system, the arterial pressure increases from 100 to 110. In the animal with the inactivated control system, the pressure increases from 100 to 150. What is the effectiveness with which the baroreceptor system controls increase in blood pressure?
A. -1
B. -2
C. -4
D. -5
C. -4
The Na+/K+ ATPase pump utilizes energy derived directly from the breakdown of ATP. What type of transport is this?
Primary active transport
The Na+-Glucose co-transporter utilizes energy derived secondarily from concentration differences of molecular ionic substances created originally by primary active transport. What type of transport is this?
Secondary active transport
What is the most common cation in the extracellular environment?
Sodium
What is the most common cation in the intracellular environment?
Potassium
How is speed of action potential transmission affected by axon diameter and myelination?
Small diameter axons transmit more slowly than large diameter
Myelinated axons transmit more rapidle than non-myelinated
What type of action potential conduction requires myelination and is characteristic of the axon but not the cell body or dendrites?
Saltatory conduction
During skeletal muscle contraction, what specific event directly follows the opening of ligand-gated sodium channels in response to Ach binding?
Influx of sodium leads to end-plate depolarization (EPP)
During skeletal muscle contraction, what specific event directly follows the opening of voltage-gated sodium channels?
Sarcolemma action potential
Which band of skeletal muscle is formed by actin filaments and becomes narrower in width during contraction?
I band
Which band of skeletal muscle is equivalent to the length of the myosin filaments and does not change width during contraction?
A band
Which band of skeletal muscle is the part of the A band that is not overlapped by actin filaments and becomes narrower during contraction?
H band
Compare skeletal muscle fibers to cardiac muscle fibers in terms of nucleation
Skeletal = multinucleated, peripheral nuclei
Cardiac = central, single nucleus
Compare skeletal muscle fibers to cardiac muscle fibers in terms of arrangement
Both have sarcomeric arrangement
Compare skeletal muscle fibers to cardiac muscle fibers in terms of locations of T tubules
Skeletal: T tubules are found at the ends of thick filaments
Cardiac: T tubules are found along the Z line
Compare skeletal muscle fibers to cardiac muscle fibers in terms of number of cisternae per T tubule
Skeletal: 2 cisternae/T tubule
Cardiac: 1 cisternae/T tubule
In skeletal muscle fibers, T tubules form ______ with the sarcoplasmic reticulum. In cardiac muscle fibers, T tubules form ______ with the sarcoplasmic reticulum.
Triads
Dyads
Do skeletal muscle fibers or cardiac muscle fibers have a more extensive sarcoplasmic reticulum?
Skeletal muscle fibers
Describe the arrangment of muscle fibers in skeletal muscle fibers vs. cardiac muscle fibers
Skeletal: motor unit arrangement (one nerve fiber synapses with multiple muscle fibers)
Cardiac: muscle cells form syncytium
Which of the following utilize DHP channels on T-tubules and Ryanodine receptors on the sarcoplasmic reticulum?
A. Skeletal muscle fibers
B. Cardiac muscle fibers
C. A and B are correct
D. None of the above
C. A and B are correct
Which phase (1-4) of a fast cardiac muscle action potential is considered the resting potential, and what is this resting potential?
Phase 4 is the resting potential = -85 mV
What are the 4 phases of fast cardiac action potentials?
Phase 4: Resting potential (-85 mV)
Phase 0: Rapid depolarization
Phase 1: Initial, incomplete repolarization
Phase 2: Plateau or slow decline of potential
Phase 3: Repolarization
Fast cardiac action potentials have:
________ AP amplitude
More _______ rate of rise of phase 0
_________ cell diameter
Greater
Rapid
Larger
Do slow cardiac muscle action potentials have fast sodium gates?
No
The upstroke of SLOW cardiac action potentials is due to _________, so it proceeds slowly. The resting phase potential 4 is close to ______ mV rather than -90 mV characteristic of fast APs. The overall change in potential (amplitude) is _______ compared to fast action potentials. SA and AV nodal tissue will spontaneously depolarize to reach phase ____
Calcium
-60
Less
4 (resting)
The force of contraction and stroke volume are related to the _______, which is the amount of blood left in the ventricle just before it contracts at the end of diastole
End diastolic volume (EDV)
The force of contraction is related to ______ which is the actual amount of blood that is ejected from the heart.
Stroke volume (SV)
How is stroke volume calculated?
EDV - ESV
Force of contraction and stroke volume are related to ____ which is the amount of blood left after contraction
End systolic volume (ESV)
What is ejection fraction and how is it calculated?
EF is the amount of blood capable of being ejected
EF = SV/EDV [will need to calculate on exam - on slide the answer is 70/110=64%]
Stroke volume can be increased to more than double by increasing _______ and/or decreasing _______
EDV
ESV
On a normal ECG, depolarization is represented by which waves?
P and QRS
Of the depolarization waves on the ECG, what wave refers to atrial depolarization?
P wave
Of the depolarization waves on an ECG, what wave refers to ventricular depolarization?
QRS
What represents the repolarization wave on a normal ECG?
T wave - ventricular repolarization
On ECG vectors, where are the 2 electrodes placed for the axis for bipolar lead I? What is the direction of the lead?
2 electrodes on 2 arms
R=negative
L=positive
Direction of the lead = 0 degrees
On ECG vectors, where are the 2 electrodes placed for the axis for bipolar lead II? What is the direction of the lead?
Electrodes on R arm and L leg
R Arm = negative
L Leg = positive
Direction of the lead = 60 degrees
On ECG vectors, where are the 2 electrodes placed for the axis for bipolar lead III? What is the direction of the lead?
Electrodes on L arm and L leg
L arm = negative
L leg = positive
Direction of the lead = 120 degrees
What is the primary characteristic on an ECG representing a sinoatrial nodal block?
P wave is absent
Blood pressure varies in different parts of the circulatory system. The pressure begins at ______ mm Hg in the aorta and decreases to ____ mm Hg once it reaches the venous system
120
0
[so a total loss of 120 mm Hg from the heart to the venous sytem]
In terms of blood distribution, the majority of blood volume overall is in systemic circulation (84%). The majority of the blood in systemic circulation at 64% is in which of the following?
A. Veins
B. Arteries
C. Arterioles
D. Capillaries
A. Veins
A systemic vein is about 8x as distensible as its corresponding artery and has a volume of about 3x as great. How would its compliance compare to that of a corresponding artery?
The systemic vein is 24x more compliant than the artery
What is another term for vascular compliance?
Capacitance
Vascular compliance/capacitance tells us the total quantity of blood that can be stored in a given portion of the circulation for each mm Hg rise in pressure. How is compliance calculated?
Increase in volume/increase in pressure
[note direct relationship to volume and indirect relationship to pressure]
Factors that affect venous return to the heart from the systemic circulation involve the degree of filling of systemic circulation. When heart pumping stops, all blood flow ceases. Pressures in everywhere in the body become equal, this is known as what type of pressure?
Mean circulatory filling pressure
When the blood volume is 4 L, what is the mean circulatory filling pressure?
0 mm Hg
When the blood volume is 5 L, what is the mean circulatory filling pressure?
7 mm Hg
The mean circulatory filling pressure is almost equal to what pressure?
The mean systemic filling pressure
Resistance to blood flow affects venous return to the heart from systemic circulation. When the venous return is 5 L/min, mean systemic filling pressure is 7 mm Hg, and the right atrial pressure is 0 mm Hg, what is the resistance to venous return?
1.4 mm Hg per L/min of blood flow
[these are the normal parameters]
The kidneys receive about what percentage of total cardiac output?
22%
What is the main driving force for filtration in the kidneys?
Hydrostatic pressure
This is high in glomerular capillaries (rapid filtration) and low in peritubular capillaries (rapid reabsorption)
Glomerular filtration rate is determined by what 2 forces acting across the capillary membrane?
Hydrostatic forces
Colloid osmotic forces
[the capillary filtration coefficient is the product of permeability and filtering surface area of capillaries]
What is the average glomerular filtration rate (GFR) in ml/min and in L/day?
125 ml/min
180 L/day
Which of the following has the greatest effect on increasing GFR?
A. Bowman’s capsule hydrostatic pressure
B. Glomerular capillary colloid osmotic pressure
C. Glomerular hydrostatic pressure
D. Colloid osmotic pressure of Bowman’s capsule
C. Glomerular hydrostatic pressure
Which kidney tubule is responsible for reabsorption of 65% of filtered sodium, chloride, bicarbonate, and potassium?
PCT
The proximal tubule of the kidney reabsorbs all filtered glucose and amino acids using WHAT type of transport via WHAT transporter?
Secondary active transport
Sodium/glucose cotransporter
What is the source of Aldosterone?
Adrenal cortex
What is the major site of action of Aldosterone? What type of transporter is used?
Principle cells of cortical collecting ducts using Na+/K+ ATPase pump
Aldosterone increases _______ reabsorption and stimulates ______ secretion
Na+
K+
The late distal tubule/cortical collecting tubule of the kidney utilizes __________ cells to reabsorb ____ from the tubular lumen and secrete _____ into tubular lumen
Intercalated
K+
H+
What buffer system plays a major role in buffering renal tubular fluid and intracellular fluids?
Phosphate buffer system