Lab 9: Animal Biology: Respiratory and Circulatory Systems

Question 1

What is the byproduct of fermentation

Answer 1

lactic acid

Question 2

What would happen if your body only relied on diffusion to supply oxygen to your cells

Answer 2

• only the outermost layers of your skin would receive enough oxygen to survive, diffusion would be too slow to supply any of the deeper layers of your body

Question 3

How does the respiratory and circulatory system work to supply oxygen to our bodies

Answer 3

• respiratory: increase absorption of oxygen into the body by greatly increasing the surface area for gas exchange (gills/lungs) and constantly bringing a fresh supply of water or air in contact with these surfaces (breathing in and out).
• circulatory: use a muscular heart to circulate blood within the body so that every cell is efficiently supplied with needed nutrients and wastes are efficiently removed. in both systems the exchange surfaces are kept as thin as possible (1-2 cells thick) so that diffusion distances are minimised

Question 4

how do the partial pressures of O2 and CO2 in blood change from when it enters the tissue capillaries to when it exits those tissue capillaries? Explain why these changes occurred with consideration of the partial pressure gradients

Answer 4

O2: decreases greatly
CO2: increases slightly

• at the site of exchange: there is less O2 in the tissue cells than in the blood and more CO2 in the tissue cells than in the blood. Due to the pressure gradients solutes will dissolve across both sides (O2 into the tissue and CO2 out of the tissue).

Question 5

Why do tissue cells have low O2 and high CO2 partial pressures? What makes the partial pressures of O2 so variable among different tissues (0-40 mmHg)

Answer 5

These cells “use up” a lot of O2 to create ATP through cellular respiration. O2 partial pressure is variable depending on tissue type because some may expend more energy than others (example: while running, leg muscles expend more energy than digestive tissues). CO2 is high because it is part of the cellular respiration process

Question 6

The blood leaving the tissue capillaries is low in O2 and high in CO2. What happens to this blood as it passes through the lung capillaries?

Answer 6

The blood will become reoxygenated. By the partial pressure gradient, O2 will diffuse across the lung capillary wall into the blood and CO2 will diffuse out of the blood.

Question 7

The larger the partial pressure graident of O2 between the alveoli and the lung capillaries the more quickly oxygen will difusse into our blood. How do we manage to maintain such a high concentration of oxygen in our alveoli when oxygen is constantly diffusing out of the alveoli and into the blood?

Answer 7

There is less O2 in our alveoli than in the air we breath in, meaning O2 will diffuse into the alveoli from the air and replenish what is being diffused out into the blood.

Question 8

List 3 physiological response of your body to exercise, and explain how each one increases oxygen deliver to your muscles.

Answer 8

• increase heart rate: more blood and O2 reaches muscles quicker
• switch to mouth breathing: air can reach lungs faster (path of least resistance)
• body warms up and gas exchange becomes more efficient

Question 9

list all the structures and capillaries a red blood cell will visit as it takes one round trip through the mammalian circulatory system

Answer 9

systemic capillaries, systemic veins, vena cava, r. atrium, r. ventricle, pulmonary arteries, pulmonary capillaries, pulmonary veins, l. atrium, l. ventricle, aorta, systemic arteries, systemic capillaries.

Question 10

What is causing the pulse felt against your wrist

Answer 10

• atrial and ventricular contraction forces blood through the vessels
• blood is pushed through the arteries and the arterial walls expand and contract in response

Question 11

Why are valves necessary for returning venous blood to the heart?

Answer 11

The blood pressure in the veins isnt sufficient enough to drive the blood back up to the heart against gravity. Muscles squeeze the veins to push the blodo back up and valves prevent blood from falling back down and pooling in the feet

Question 12

What circulatory problem are plane exercises designed to prevent? Explain

Answer 12

• Deep vein thrombosis: blood clot in deep leg veins

- stretching and wiggling lower extremities contract your legs and help to return deoxygenated blood back to your heart

Question 13

Explain how the diaphragm helps us breathe.

Answer 13

Inhalation: diaphragm contracts and moves downward, lowering pressure in the lung cavity and
increasing volume. air flows into the lungs in response to the change in pressure

Exhalation: diaphragm relaxes and moves back upwards, decreasing volume and increasing pressure
in the lung cavity. air flows out of the lungs in response to the change in pressure

Question 14

List all of the structural components that an oxygen molecule passes through, as it travels from your nostril into your blood.

Answer 14

nostril, epiglottis, larnyx, trachea, bronchus, bronchiole, alveoli, capillaries

Question 15

define: vital capacity

Answer 15

• the maximum amount of air that you can expel in one breath

Question 16

define: tidal volume and resting tidal volume

Answer 16

• this is the amount of air inspired or expired during normal
  breathing (i.e. when you are not thinking about your breathing
• tidal volume while fully relaxed and
  breathing normally

Question 17

define: expiratory reserve volume

Answer 17

the maximum amount of air you can expel after normal tidal expiration

Question 18

define: inspiratory reserve volume

Answer 18

• the maximum amount of air you can inspire after normal tidal inspiration

Question 19

What behavioural characteristics might increase or decrease an individual’s vital
capacity? In other words, what activities or lifestyle choices affect your vital capacit

Answer 19

smoking, vaping, obesity

Question 20

What structural characteristics (i.e., factors other than lifestyle) might increase or
decrease an individual’s vital capacity?

Answer 20

height (body size plays a huge part into actual lung size)

Question 21

Why do we have a residual volume? How does having this reserve volume affect the
efficiency with which you can bring oxygen from the atmosphere into your blood

Answer 21

• prevents lungs from collapsing
• prevents the inner surfaces of the lungs from sticking together
• prevents large fluctuations in respiratory gas levels (O2 and CO2)

Question 22

What structural differences exist between the tissue layers of arteries and
veins?

Answer 22

• arteries: have both muscle fibres and elastic fibres in their walls; thick layer composed of smooth
  muscle fibres
• veins: thinner walls and larger interior diameter than arteries (blood is under less pressure)

Question 23

Explain how blood flows through arteries.

Answer 23

when the heart contracts, elastic fibres in the walls of the arteries expand to accept the blood being
shunted through them. after the contraction, the diameter of the arteries return to their resting state and
the elastic fibres contract, propelling blood away from the heart. the smooth muscles controlled by
signals from the nervous system can also impact the flow of blood (contract, increase blood pressure;
relax/expand, decrease blood pressure)

Question 24

Explain how blood flows through veins.

Answer 24

muscle fibres in veins contract in response to signals from the nervous system which decreases the diameter and overall volume of the vessels, helping to move the blood along and back to the heart. veins
must fight against gravity to move blood back up to the heart, a very hard task. skeletal muscle
activities in the appendages compress our large veins and help “squeeze” the blood back to the heart.
so blood doesn’t just fall back down due to gravity and pool, one way valves in the veins prevent the blood from flowing backwards

Question 25

blood pressure is normally measured in the brachial artery. Explain
why blood pressure is not measured in your brachial vein

Answer 25

Blood pressure readings are one way we can check on our cardiovascular health. A high reading
means our arteries and heart are under great strain and are at risk of becoming clogged up leading to
some severe health problems (stroke, heart attack). It is more meaningful to get a blood pressure
reading from an artery because it will always be under more pressure than a vein (because of its proximity in the pathway from once it leaves the heart) and are the blood vessels at risk of being
clogged.

Question 26

What is the physiological goal of increasing heart rate during exercise?

Answer 26

train the body to move oxygen and blood to your muscles more efficiently

Question 27

What environmental factors might lead to an increase or decrease in heart rate?

Answer 27

increase: stress (long term or immediate danger), excitement, exercise, “uppers” drugs, temperature rise

decrease: cardiovascular exercise programs will decrease resting heart rate, downer drugs, heart rate falls
during sleep, temperature drop