Bio 2601: Gas Exchange and Respiratory Pigments

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Questions and Answers

What physiological mechanism primarily regulates breathing in mammals?

Lung capacity adjustments

Blood pressure changes

Peripheral and central chemoreceptors (correct)

Muscle contractions in the diaphragm

How do water breathers primarily excrete CO2?

Through the skin

Via urine

Using lungs

Through gills (correct)

What happens to excreted CO2 in water?

It remains as gaseous CO2 indefinitely

It accumulates in water

It converts into sulfuric acid

It reacts with water to form carbonic acid (correct)

What is the significance of partial pressure differences in gas exchange?

It affects the diffusion rate of gases (A) Signup and view all the answers

What role does the medulla play in mammalian gas exchange?

It detects changes in blood CO2 levels (C) Signup and view all the answers

Which of the following describes bimodal breathers' gas exchange system?

They use lungs and gills for gas exchange. (C) Signup and view all the answers

In unusual air-breathing situations, what is a potential issue for CO2 excretion?

High CO2 concentration in the air (A) Signup and view all the answers

What type of nitrogenous waste is commonly excreted by freshwater fish?

Ammonia (B) Signup and view all the answers

What is the primary form in which carbon dioxide is transported in the blood?

As bicarbonate (HCO3-) (A) Signup and view all the answers

What role does carbonic anhydrase play in CO2 transport?

It facilitates the conversion of CO2 to bicarbonate (B) Signup and view all the answers

What is the effect of H+ ions produced during CO2 conversion on hemoglobin?

It decreases oxygen affinity (A) Signup and view all the answers

In which location does carbon dioxide primarily diffuse from tissues to plasma?

Capillaries (B) Signup and view all the answers

What is the primary mechanism of bicarbonate transport in the plasma?

Anion exchange via band 3 protein (C) Signup and view all the answers

How does the presence of bicarbonate in plasma affect CO2 equilibrium during gas exchange?

It favors re-conversion to CO2 for diffusion (C) Signup and view all the answers

What advantage might Antarctic icefish gain from lacking respiratory pigments?

Increased oxygen solubility at low temperatures (A) Signup and view all the answers

During CO2 excretion in working tissues, which process occurs first?

Diffusion of CO2 into plasma (D) Signup and view all the answers

Study Notes

Lecture 6: Gas Exchange

Lecture date: January 17
Topics covered: CO2 exchange, regulating breathing
Readings: pages 677-685, 620-638
Review pages: 654-677

Respiratory Pigments

Covered in Bio 2601
Students are expected to know the material
Hematocrit is a topic to review

Antarctic Icefish

Lives at -1.9°C
Lacks respiratory pigments
Has to get enough oxygen
Possible advantages of not having pigments
Other animals that lack respiratory pigments

Pigments & Oxygen Carrying Capacity

Graph describing oxygen equilibrium curve
Shows total oxygen
Indicates dissolved oxygen
Measures partial pressure of oxygen (02)
Measurement of Oxygen content of blood (mmHg)
Discusses high and low hemoglobin content

Percent Saturation of Oxygen

Graph displaying percent saturation of oxygen
Demonstrates the relationship between partial pressure of oxygen and percent saturation

Oxygen Concentration of Blood

Graph depicting oxygen concentration in blood
Illustrates the relationship between oxygen partial pressure and blood oxygen concentration at rest and during exercise
Shows blood flow in lungs and systemic tissues

What can Change Oxygen Partial Pressure?

Graph illustrating changes in oxygen partial pressure based on temperature.
Shows percent saturation
Illustrates partial pressure of oxygen in blood

Hemoglobin at Working Tissues

Multiple graphs showing hemoglobin saturation at different pH levels and CO2 partial pressures
Shows oxygen delivery in different conditions

CO₂ Excretion

CO2 production location
CO2 diffuses freely across epithelia and membranes.
CO2 is not very soluble in its normal form
Conversion to bicarbonate (HCO3-) is possible.
Carbonic anhydrase helps with conversion
Most CO2 is transported as HCO3-

CO₂ Excretion: Working Tissues

CO2 diffuses from tissue to plasma and RBC.
Very little CO2 binds to hemoglobin (Hb).
Most CO2 is converted to H2CO3 by carbonic anhydrase (CA).
The H+ ions produced by the reaction affect Hb.
Bicarbonate is then transported in the plasma using band 3 and exchanging chloride in the process

CO₂ Excretion: Gas Exchange

Bicarbonate (HCO3-) cannot cross cell membranes.
CO2 is reconverted and diffuses out of the lungs.

CO₂ Excretion: Air Breathers

Air breathers face a CO2 challenge due to low CO2 in air, needing higher pCO2 for diffusion.
Diagrams show how partial pressure is related to oxygen partial pressure.

Blood Gases & Breathing

Chemoreceptors (peripheral and central) in animals detect blood gases and regulate breathing
Peripheral chemoreceptors: carotid and aortic bodies
Central chemoreceptors: medulla

What Regulates Breathing?

Diagrams show how air versus water-breathing organisms respond to changes in oxygen partial pressure (PO2) and carbon dioxide partial pressure (PCO2).
Data indicate how breathing rates vary with these values.

Unusual Air-Breathers

Focuses on how CO2 becomes a challenge for unusual air-breathers.
Graphs display correlation between inspired CO2 and respiratory rate.

CO₂ Excretion: Water Breathers

CO2 excretion in water breathers is typically much easier because water has relatively high CO2 solubility
Explains what happens to excreted CO2, and the consequences of this process.

What About Water Breathers?

Discussion of extra-branchial chemoreceptors and their role in respiratory reflexes in the neotropical fish.
Some data displays shows ventilation rates versus oxygen partial pressure

Gas Exchange: Bimodal Breath

O2: mostly lungs from air
CO2: mostly gills to water
Re-routing of blood is necessary

Gas Exchange: Skin Breathers

O2: lungs in air, permeable skin in water
CO2: interpret the data about skin-breathing organisms

Unusual Water Breathers

Discusses nitrogenous waste excretion in freshwater fish.
Explains why ammonia (NH3) is the usual waste product, and how it's treated by animals.
Presents an example of a location (Lake Magadi, Kenya) with high CO2 partial pressures, and its affect on breathing, and NH3 excretion

Ornithine-Urea Cycle

Diagram of the ornithine-urea cycle
Shows the metabolic pathway for the synthesis and excretion of urea in ureotelic organisms.

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Description

Explore the intricacies of gas exchange in animals, focusing on respiratory pigments and oxygen transport. This quiz covers key concepts including CO2 exchange, the role of hematocrit, and the unique adaptations of Antarctic icefish. Review the provided readings for deeper understanding and analysis of oxygen carrying capacity.