KINE 433 final exam complete

What is the pulmonary circuit?

Low-pressure circuit that carries blood to the lungs for gas exchange.

What is the systemic circuit?

High-pressure circuit that carries blood to body tissues.

What is macrocirculation?

Arteries and veins that transport blood to and from tissues.

What is microcirculation?

Arterioles, capillaries, and venules that regulate blood flow, blood pressure, and exchange.

What are the 3 main cardiovascular adjustments during exercise?

Increase cardiac output, redistribute blood flow to active muscle, and increase venous return.

What is the primary function of the heart?

Act as a pump.

What is the SA node?

The pacemaker of the heart.

What is the AV node?

The delay station of the heart.

What do gap junctions do in cardiac muscle?

Electrically connect cardiac myocytes.

What is intrinsic heart rate?

About 100 bpm.

What does the parasympathetic nervous system release at the heart?

Acetylcholine.

What does the sympathetic nervous system release at the heart?

Norepinephrine.

What does parasympathetic activity do to heart rate?

Decreases heart rate.

What does sympathetic activity do to the heart?

Increases heart rate and stroke volume.

What is the intima of a blood vessel?

Single layer of endothelial cells.

What is the media of a blood vessel?

Mostly smooth muscle.

What is the adventitia of a blood vessel?

Mostly collagen.

What is the primary function of arteries?

Carry blood from the heart to tissues.

What are key adaptations of arteries?

Large lumen, thick walls, elastic fibers, and high-pressure tolerance.

What is the primary function of arterioles?

Regulate blood pressure and blood flow distribution.

Do arterioles have parasympathetic nerves?

No.

What do alpha adrenergic receptors cause in arterioles?

Vasoconstriction.

What do beta adrenergic receptors cause in arterioles?

Vasodilation.

What is the primary function of capillaries?

Gas, nutrient, and waste exchange.

What are key adaptations of capillaries?

One endothelial cell thick, no smooth muscle, large surface area, and slow blood flow.

Which muscle type has higher capillary density?

Oxidative muscle.

Which muscle type has lower capillary density?

Glycolytic muscle.

What is the primary function of veins?

Return blood from tissues to the heart.

What do venous valves do?

Prevent backflow of blood.

Do veins have parasympathetic nerves?

No.

What is VO2?

Oxygen consumption.

What is VO2max?

Maximal oxygen consumption; best index of aerobic capacity.

What is the Fick equation?

VO2 = cardiac output × a-vO2 difference.

What is cardiac output?

Heart rate × stroke volume.

What is resting cardiac output?

About 5 L/min.

What happens to cardiac output during graded exercise?

It increases with intensity.

What is cardiac output matched to during exercise?

VO2.

What is heart rate proportional to during exercise?

VO2 and exercise intensity.

What is estimated HRmax?

220 - age.

Why does HR initially increase during exercise?

Vagal withdrawal.

Why does HR continue increasing at higher intensities?

Increased sympathetic activity.

What is stroke volume?

Volume of blood ejected from the left ventricle per beat.

What determines stroke volume?

Preload, contractility, and afterload.

Why does stroke volume increase during exercise?

Increased preload and increased contractility.

What happens to stroke volume at higher exercise intensities?

It plateaus.

What happens to blood flow distribution during maximal exercise?

Most cardiac output goes to active muscle.

What percent of cardiac output can go to muscle during max exercise?

About 85–90%.

What is venous return?

Blood returning to the heart.

What mechanisms increase venous return during exercise?

Pressure gradient, sympathetic venoconstriction, respiratory pump, and muscle pump.

What is functional sympatholysis?

Local vasodilators override sympathetic vasoconstriction in active muscle.

What local factors promote vasodilation in active muscle?

NO, prostaglandins, EDHF, K+, H+, CO2, and adenosine.

What is a-vO2 difference?

The difference in oxygen content between arterial and venous blood.

What happens to a-vO2 difference during exercise?

It increases.

What is central command?

Feed-forward signal from the brain that activates muscle, cardiovascular, and respiratory systems.

What is the exercise pressor reflex?

Feedback from active muscle that helps match oxygen delivery to demand.

What do group III afferents sense?

Mechanical changes/contraction.

What do group IV afferents sense?

Metabolites.

What is the baroreflex goal?

Regulate arterial pressure.

What happens to the baroreflex operating point during exercise?

It resets to a higher pressure.

What happens to systolic blood pressure during dynamic exercise?

Increases.

What happens to diastolic blood pressure during dynamic exercise?

Stays about the same or slightly decreases.

What happens to MAP during exercise?

Increases moderately.

What mainly determines systolic blood pressure?

Cardiac output.

What mainly determines diastolic blood pressure?

Systemic vascular resistance and heart rate.

What is the primary function of the respiratory system?

Deliver O2 and remove CO2 to support metabolism.

What are the 5 steps of gas transport?

Ventilation, lung diffusion, circulation, capillary exchange, and metabolism.

What is the conducting zone?

Airway region for air movement, not gas exchange.

What is the respiratory zone?

Airway region where gas exchange occurs.

What is the primary site of gas exchange?

Alveoli.

What is the blood-gas barrier?

Thin barrier between alveoli and pulmonary capillaries where gas exchange occurs.

What is the primary muscle of inspiration?

Diaphragm.

What accessory muscles assist inspiration?

External intercostals.

Is expiration passive at rest?

Yes.

What muscles assist forced expiration during exercise?

Internal intercostals and abdominals.

Air flows from _____ pressure to _____ pressure.

High to low.

During inspiration, alveolar pressure is _____ atmospheric pressure.

Lower than.

During expiration, alveolar pressure is _____ atmospheric pressure.

Higher than.

What is tidal volume?

Air moved in and out with one breath.

What are IRV and ERV?

Extra volume that can be inhaled or exhaled when needed.

What is ventilation?

VE = tidal volume × breathing frequency.

What happens to ventilation during exercise?

It increases.

What causes tidal volume to increase during exercise?

Decrease in both IRV and ERV.

What is ventilatory threshold?

The point where ventilation increases disproportionately.

At what intensity does ventilatory threshold usually occur?

About 65–75% VO2max.

What is PAO2?

Partial pressure of oxygen in alveoli.

What is PaO2?

Partial pressure of oxygen in arterial blood.

What is typical alveolar PO2?

About 105 mmHg.

What is typical arterial PO2?

About 100 mmHg.

What is typical venous/tissue PO2?

About 40 mmHg.

Why is PaO2 lower than PAO2?

Diffusion is not perfect and some blood bypasses the lungs.

How is oxygen transported in blood?

Mostly bound to hemoglobin, with a small amount dissolved.

What percent of oxygen is bound to hemoglobin?

About 99%.

What percent of oxygen is dissolved in plasma?

About 1%.

How much O2 can 1 g of hemoglobin carry?

1.34 mL O2.

What determines hemoglobin saturation?

PO2.

What happens to Hb saturation at high PO2?

Hemoglobin binds more oxygen.

What happens to Hb saturation at low PO2?

Hemoglobin releases more oxygen.

What is the Bohr Effect?

Right shift of the O2 dissociation curve that promotes O2 unloading.

What causes a right shift of the O2 dissociation curve?

Decreased pH, increased temperature, and increased CO2.

Why is the Bohr Effect useful during exercise?

It helps release more O2 to active muscle.