bio ch 42

Where is the velocity of blood flow the slowest in your body

Capillaries

Why is breathing more difficult at high altitudes, such as at the top of Mount Everest?

The lower partial pressure of oxygen in the atmosphere reduces the rate of diffusion of oxygen into your body.

When you are jogging, your muscles are using more oxygen and releasing more carbon dioxide into the blood than when you are at home on the couch. Which of the following would occur during your jog?

The medullary respiratory center would detect rising carbon dioxide levels.

The electrical activity of the heart, as recorded in an electrocardiogram (EKG), is most intense during which event of the cardiac cycle?

Ventricular systole

A significant increase in the amount of interstitial fluid surrounding the capillary beds of a human's lungs will cause _____.

a decrease in the amount of oxygen moving from the lungs into the blood

In mammals, gas exchange between the atmosphere and the pulmonary blood occurs in the ________.

alveoli

Where is the velocity of blood the highest?

aorta

Myocardial infarction occurs when ________.

blockage of blood vessels prevents adequate blood flow to the heart

Breathing is primarily regulated by ________.

carbon dioxide concentration and pH sensors

What is present in arterioles that is NOT present in capillaries?

circular smooth muscle cells

Part complete Most of the carbon dioxide produced by humans is ________. Most of the carbon dioxide produced by humans is ________.

converted to bicarbonate ions by carbonic anhydrase, an enzyme in red blood cells

Atria contract ________.

during atrial systole

If, during protein starvation, the osmotic pressure on the venous side of capillary beds drops below the hydrostatic pressure, then ________.

fluids will tend to accumulate in the interstitial fluid and tissues.

Complete the statement correctly. Fetal hemoglobin ________.

has a higher affinity for oxygen than does adult hemoglobin

Compared with the interstitial fluid that bathes active muscle cells, blood reaching these muscle cells in arteries has a _____.

higher PO2

When athletes exercise, what is the primary physiological variable responsible for their sustained increase in ventilation rate?

increased blood PCO2

Blood returning to the mammalian heart in a pulmonary vein drains first into the _____.

left atrium

Which of the four muscular chambers of the human heart directly propels blood into the pulmonary circulation?

right ventricle

When you hold your breath, which of the following blood gas changes first leads to the urge to breathe?

rising carbon dioxide

If a molecule of carbon dioxide enters the blood in your left toe and is exhaled from your nose, it must pass through all of the following EXCEPT ________.

the pulmonary vein

Air rushes into the lungs of humans during inhalation because ________.

the rib muscles and diaphragm contract, increasing the lung volume and decreasing the pressure within the lungs

The velocity of blood flow is the lowest in capillaries because _____

the total cross-sectional area of the capillaries is greater than the total cross-sectional area of the arteries or any other part of the circulatory system

As a person goes from rest to full-effort exercise, there is an increase in the _____.

tidal volume

Which of the following is the correct sequence of blood flow in birds and mammals?

vena cava → right atrium → right ventricle → pulmonary artery

Which of the following events would be predicted by the Bohr shift effect as the amount of carbon dioxide released from your tissues into the blood capillaries increases? The amount of oxygen in _____.

venous blood would decrease

What is the correct order of processes involving the movement of oxygen from the environment to mitochondria in vertebrates?

ventilation, circulation, cellular respiration

In which location would you expect the oxygen concentration to be the lowest?

within tissues