Medical Physiology PHSL 1010: Exam 2

T-tubules (triads)

Depolarizing currents pass to the sarcoplasmic reticulum via:

Troponin

The muscle protein that binds to Ca++ during excitation-contraction coupling is:

One muscle cell only

A skeletal muscle fiber comprises:

Slow-twitch fibers have more myoglobin than fast-twitch AND Slow-twitch fibers are more fatigue-resistant than fast-twitch

Fast-twitch muscle fibers differ from slow-twitch fibers in which way(s)?

Smooth muscle cells have only one nucleus AND Smooth muscle contracts more slowly than skeletal muscle

Smooth muscle differs from skeletal muscle in which way(s)?

Z lines (from striated [cardiac & skeletal] muscles)

Smooth muscle dense bodies perform a similar function to:

Inside sheets of smooth muscle

Parasympathetic ganglia that aid in control of smooth muscle contraction are located:

Ca++ enters the cell, Ca++ binds to calmodulin, myosin heads are phosphorylated, myosin binds to actin

The correct sequence of events in smooth muscle contraction is:

Cardiac muscle cells have only one nucleus and are branched

Cardiac muscle differs from skeletal muscle in which way(s)?

Both serve as the insertion point for cardiac muscle cells and contain numerous gap junctions and desmosomes

Intercalated disks:

Is both limited by parasympathetic activity and is similar to that seen in skeletal muscle

Excitation-contraction coupling in cardiac muscle:

Are characterized by a broad plateau as Ca++ enters the cell

Action potentials in cardiac muscle cells:

Gap junctions

Depolarizing signals pass through the atrial musculature via:

Closure of the mitral valve AND Closure of the tricuspid valve

The first "heart sound" is made by:

Atrial diastole

The greatest blood pressure is achieved at:

Anchor the leaflets of the A-V valves AND Are inserted into the ventricular musculature

Papillary muscles:

Varies with heart rate (and stroke volume)

Cardiac output:

Achieves maximum force when muscle fibers are stretched AND Achieves maximum force when end diastolic volume is greatest

The Frank-Starling Law of the Heart shows that cardiac muscle:

Can be enhanced by catecholamines

Contractility of the heart:

Arteries have more elastic fibers in the tunica media than veins

Arteries differ from veins in which way?

Cardiac output and arterial resistance

Mean arterial pressure is directly proportional to:

Is affected by stress, emotion, epinephrine, and by sympathetic stimulation

Arterial resistance:

Affects blood pressure by altering blood volume AND Is initiated by sensors in the macula densa of the kidney.

does NOT stimulate aldosterone release, which promotes water loss

The renin-angiotensin system:

Paracrines, or local hormones, including NO

In addition to neural and hormonal factors, MAP may be controlled by:

Is classified as an arrhythmia AND Shows that there is a disruption in the cardiac conduction system

A third-degree heart block:

• Stroke volume -

x Heart rate

x Cardiac output

x Mean arterial pressure (MAP)

x Rate of P wave initiation

During exercise, all of these cardiac parameters show steady increase EXCEPT:

Macrophage infiltration, LDL accumulation, calcification, platelet adherence

Which sequence of atherosclerotic plaque formation is correct?

Disruption of the cardiac conduction cycle, Myocardial infarction has probably taken place, and Some cardiac conduction cells have begun firing on their own

Autorhythmic anomalies indicate:

Alveolar ducts, alveolar sacs

Respiratory passages include the following:

Alveolar type I cells, alveolar type II cells

Cells that make up the alveolar epithelium include:

x Diaphragm x

x Sternocleidomastoid x

• Abdominal muscles -

x Intercostal muscles x

x Anterior scalenes x

Active inspiration is supported by all of the following muscles EXCEPT:

• Alveolar pressure increases -

x Diaphragm contracts x

x Intrapleural pressure decreases

x Thoracic volumes increases x

x Rib cage flares out x

Upon inspiration, all of the following occur EXCEPT:

Relies on input from peripheral chemoreceptors AND Involves both dorsal and ventral nuclei in the medulla

Central (neural) control of breathing:

Is a sum of tidal volume and respiratory rate AND May be similar for different patterns of breathing

Pulmonary ventilation (VE):

Can be identified by receptors on the medullary surface

A change in the partial pressure of CO2 (PCO2):

More frequent firing of the phrenic nerve AND Decreased blood flow in capillaries in the most distal portions of the lung

A decrease in the amount of pulmonary surfactant secreted by type II alveolar cells would result in:

The amounts of the gas may not be the same in the two compartments AND If one compartment is a fluid, the amounts depend on gas solubility

If partial pressures of a gas are the same in two compartments:

In the atmosphere, In the alveolus, & In the arterial blood.

NOT In the capillaries

The partial pressure of O2 (PO2) is highest:

Changes affinity for O2 if pH decreases

Hemoglobin:

As part of a buffer system in the blood

Most CO2 is transported to the alveolus:

Resistance increases and flow decreases

As blood vessel length increases:

Preventing tetanus

The importance of the plateau phase of the actin potential of myocardial cells is:

Carbon dioxide

The most important chemical regulator of respiration is: