Exam 3

Question 1

How can you make diffusion easier?

Answer 1

Increase solubility, increase surface area, increase change in pressure, decrease barrier thickness, [change temp??]

Question 2

Fick’s Law

Answer 2

V = ((P1 - P2)*A*k)/D
V = rate of particles moving
V/A = flux
(P1-P2)/D = gradient
k = solubility/(sqrt(molecular weight))

Question 3

What happens when the chest cavity is punctured?

Answer 3

The pressure inside and outside of the chest cavity would be equal, meaning air would not be able to be pushed in and out of the lungs

Question 4

How do we breathe?

Answer 4

Inhale: Diaphragm moves downward, pressure in chest cavity decreases, air flows into lungs
Exhale: Diaphragm relaxes, pressure increases, pushing air out of the lungs and causing the lungs to contract (releases even more air)

Question 5

What is homeostatic control of ventilation?

Answer 5

The medullary respirator center stimulates the rib and diaphragm muscles to contract. The center also receives signals about O2 and CO2 levels, maintaining O2 and CO2 delivery and stabilizing pH

Question 6

What happens when you hold your breath?

Answer 6

Carbon dioxide levels rise and the body responds with pain as the diaphragm tries to force the carbon dioxide out of your lungs.

Question 7

How do oxygen and carbon dioxide behave in water?

Answer 7

they have a low solubility in water

Question 8

How are oxygen and carbon dioxide transported in blood?

Answer 8

O2 molecules bind to the iron ion in heme molecules in hemoglobin found in red blood cells
CO2 diffuses into the red blood cells and is converted to bicarbonate ions and protons

Question 9

What does the oxygen-hemoglobin dissociation curve look like? Why is it sigmoidal? What might shift the curve?

Answer 9

it is sigmoidal (s-shaped) due to cooperative binding, which is the binding of each successive O2 molecule to a subunit of hemoglobin binds easier and easier to oxygen than the previous one

Question 10

What does carbonic anhydrase do and why is it important?

Answer 10

Found in red blood cells, it catalyzes the formation of carbonic acid from carbon dioxide and water. This allows CO2 that diffuses into the red blood cells to easily break down into bicarbonate ions and protons. This is important because it keeps the flow (gradient/driving pressure) of CO2 constant. Furthermore, H+ is released, which decreases hemoglobin’s affinity for oxygen (dumps more oxygen)

Question 11

Why is hemoglobin a good buffer?

Answer 11

When not carrying O2, it takes up the protons released during the dissassociation of carbonic acid, maintaining the pH of the blood

Question 12

What does pH and temperature do to the oxygen-hemoglobin dissociation curve?

Answer 12

The curve shifts left or right. When pH decreases and temp increases, the curve shifts to the right (Bohr shift)

Question 13

Fetal hemoglobin (Fig 45.17).

Answer 13

Has a higher affinity for O2, ensuring the fetus has enough O2 during development

Question 14

What is the mechanism of H+ influence on heme? (Planar/domed)

Answer 14

Planar (oxygenated); low pH causes domed structure and O2 cannot bind

Question 15

Why does blood pressure drop in capillaries?

Answer 15

Decreased velocity and increased surface area (a bunch of narrow rivers slows flow)

Question 16

How does our body compensate when it senses a drop in blood pressure?

Answer 16

1. Cardiac output (blood volume leaving left ventricle) increases (cardiac output = heart rate X stroke volume)
2. Arterioles serving the capillaries of certain tissue constrict to divert blood to more critical organs
3. Veins constrict, decreasing their overall volume

Question 17

Why do octopi have 3 hearts?

Answer 17

two branchial hearts pumps blood to the gills to become oxygenated, while the third heart pumps the oxygenated blood to the rest of the body

Question 18

Could you brainstorm why an octopus would use hemocyanin and not hemoglobin?

Answer 18

• hemocyanin might have a higher affinity for O2 than hemoglobin, as O2 is more difficult to pull from the water vs the air
• Differences in pH in the animals
• Copper less likely to rust (become oxygenated) underwater
• Limited sources of iron underwater; maybe prey has higher copper content than iron
• Hemoglobin holds onto O2 in cooler temps; and octopi don’t regulate their own temp
• Hemocyanin performs better in colder environments with low oxygen pressure*

Question 19

How/where does blood flow through the heart?

Answer 19

Blood flows in through the vena cava, enters the right atrium, then right ventricle, then leaves the heart through the pulmonary artery, then goes to the lungs, the enters the heart again through the pulmonary veins, then to the left atrium, then left ventricle, then exits the heart through the aorta

Question 20

How did the Onyx lower its chance of sweating?

Answer 20

by increasing body temp during the day and decreasing it during the night so that it does not need to sweat

Question 21

Define homeostasis

Answer 21

The maintenance of relatively constant chemical and physical conditions in an animal’s cells, tissues, and organs.
2 approaches: conformation and regulatory homeostasis

Question 22

Why do rats have a cecum?

Answer 22

The cecum is filled with bacteria that breaks down cellulose. Called the appendix in humans.

Question 23

Explain the SA/V relationship

Answer 23

As a cell gets larger, it’s volume increases much faster than its surface area. This means that transport processes across the cell membrane have to support disproportionetaly more and more cell volume as the cell size increases

Question 24

Carbonic anhydrase equation:

Answer 24

Occurs in red blood cells:
CO2 + H2O HCO3- + H+
The CO2 comes from tissue, the H+ binds to hemoglobin

Question 25

What does the effector do?

Answer 25

structure that helps restore the desired internal condition

Question 26

What does the sensor do?

Answer 26

structure that senses some aspect of the external or internal environment

Question 27

What does the integrator do?

Answer 27

structure that evaluates the incoming sensory info and decides whether a response is needed to achieve homeostasis