SIu Bio 213 - Test #3

What are the gases involved gas exchange

O2 & CO2

What is O2 function in gas exchange

It is required for aerobic respiration (cellular production of ATP)

What is CO2 function is gas exchange

Waste product of aerobic respiration and is driven by diffusion

What are the 5 steps of gas exchange?

1. Ventilation

2. Diffusion at respiratory surface

3. Circulation

4. Diffusion at tissues

5. Cellular respiration

How much oxygen is actually available depends on what

its partial pressure (P02)

What holds more O2, air or water?

Air holds more 02 than water

Does cold water hold more 02 or warm water?

Cold water holds more because it is less soluble

How does O2 and CO2 diffuse?

Higher partial pressure to lower partial pressure

How does all gas exchange occur?

It occurs via diffusion

What maintains high 02 partial pressure at cell surface through out body?

Respiratory and Circulatory System

What is fick's law

the rate of diffusion of a substance across unit area (such as a surface or membrane) is proportional to the concentration gradient.

What is the equation for rate of diffusion?

K A (p2-p1)/D

During cellular respiration animals cells use _____ to produce _____

oxygen and carbon dioxide

What is ventilation?

movement of air in and out of the lungs or gills

What is diffusion at the respiratory surface?

where O2 moves from the air or water into the blood and CO2 moves from the blood into the air or water

What is circulation?

The transport of dissolved O2 and CO2 throughout the body via the circulatory system.

What is diffusion at the tissues?

Where the O2 moves from the blood into the tissues, and CO2 moves from the tissues into the blood

What is cellular respiration?

the cell's use of O2 and production of CO2

ventilation and diffusion at respiratory surfaces are controlled by

the respiratory system

Explain why diffuses into the blood from alveoli, but diffuses out of the blood into tissues.

Oxygen diffuses into the blood from the alveoli because the concentration of oxygen is higher in the inhaled air in the alveoli than it is in the blood in lung capillaries. Oxygen diffuses along its concentration gradient.

Where is O2 high and low?

it is high in the environment & low in tissues. Moving from the environment to tissues.

Where is CO2 high and low

It is high in the tissues, and low in the environment. Moving from tissues to the environment

What percentage is nitrogen and oxygen in the atmosphere?

76% Nitrogen & 21% Oxygen

Does the percentage of O2 vary with elevation?

No, it does not vary with elevation.

So why is it harder to breathe at higher elevations?

The difference is that far fewer molecules of oxygen because atmospheric pressure is lower at high elevations.

What is pressure?

It is a force exerted per unit area.

What is partial pressure

the pressure of a particular gas in a mixture of gases.

Dalton's Law

The total pressure of a mixture of gases is the sum of the individual pressures (Ptotal=P1+P2+P3...)

Why is it hard to breathe at a higher elevation?

It is because the partial pressure of oxygen is low there. The diffusion gradient between the atmosphere and your lung tissues is small, so fewer molecules of diffuse into your tissues when you take a breath.

Do water breathers expend more energy to ventilate or air breathers?

Water breathers have to expend more energy to ventilate their respiratory surfaces.

What affects the amount of gas in a solution?

-solubility of the gas in water

-temperature of the water

-presence of other solutes

-partial pressure of the gas in contact with the water

How do animals like sponges, jellyfish, and flatworms fulfill their requirements for taking in O2 and expelling CO2

Diffusion across the body surface is rapid enough to fulfill the requirements.

Why do these animals live in wet environments?

Living in wet or humid environments allows animals to exchange gases across their outer surface while avoiding dehydration.

Do respiratory organs have small or large surface areas?

They have large surface areas for gas exchange

Where are respiratory organs in terrestrial animals?

The organs are located inside the body, to help minimize water loss.

What are gills?

Outgrowths of the body surface or throat in aquatic animals and are used for gas exchange as well as for osmoregulation

How does water move over the gills?

The pumping action creates a pressure gradient that moves water over the gills.

What is another way fish ventilate their gills?

Ram Ventilation: Fast swimming fish just swim with their mouths open to breathe.

What are gill filaments?

Thin projections on the gill that aid in respiration and excretion

What are gill lamellae

sheetlike structures where gas exchange occurs, with countercurrent flow between blood and water.

What is the result of the flow of blood through the capillaries in each lamella is in the opposite direction to the flow of water.

Each lamella functions as a countercurrent exchanger

Predict what would happen to oxygen transfer from water to blood if the flow were concurrent.

If concurrent flow occurred, less oxygen would be transferred from water to blood.

Trachea in insects

extensive system of air-filled tubes

What do the tracheae tubes connect to ?

it connects to the exterior through opening in the exoskeleton called spiracles

What do spiracles do?

allow gases to enter and leave the tracheal system and open/close to minimize the loss of water by evaporation

How does air move through insects?

From the atmosphere into the spiracles and then through the tracheae to the tissues in the insect's body.

What do the muscle contractions and relaxations produce?

They produce pressure changes that alter the volume of the tracheal system

When does the volume of the tracheal system increase?

When muscles relax, causing pressure inside the system to go down and air from the atmosphere to rush in.

In larger insects, how is movement of gases promoted?

It is promoted by larger tracheal diameters.

What is the major hypothesis for why insects were so much larger in the Paleozoic era?

It is because the atomospheric oxygen concentration was much higher than it is today

How do terrestrial vertebrates breathe?

Air enter the body through both the nose and mouth, then the trachea carries the inhaled air to narrower tubes called bronchi. The bronchi branch off into smaller tubes called the bronchioles.

What are the sacs that are in lungs of mammals?

Alveoli

How do amphibians, like frogs, pump air into their lungs?

Postitive pressure (swallowing air)

How do mammals ventilate

By using negative pressure (pulling air), inhaling cause the diaphragm to contract.

When mammals are resting, the rate of breathing is established by what?

the medullary respiratory center, which is at the base of the brain and above the spinal cord.

What does the Medullary Respiratory Center do?

stimulates the rib and diaphragm muscle to expand and contract

During exercise, what happens to muscle tissues?

-The muscle tissues takes up more oxygen from the blood so the partial pressure of O2 drops

-The muscles release larger quantities of carbon dioxide to the blood, raising the partial pressure of CO2 in blood.

What factor controls the breating rate in mammals?

The rise in PCO2

What is blood?

a connective tissue that consists of cells in a watery extracellular matrix

What is plasma in the blood?

The liquid, noncellular portion of the blood, it makes up most of the blood

What makes up the remainder of the blood?

cells and cell fragment that are called formed elements, including platelets, white blood cells, and red blood cells.

What are platelets?

cells fragments that act to minimize blood loss, they aid in clotting blood.

What are white blood cells?

White blood cells are apart of the immune system, they fight infections.

What are red blood cells?

They transport oxygen from the lungs to tissues throughout the body, makes up 99% of formed elements.

What is hemoglobin?

It is a tetramer composed of heme group bound to globin protein

What is the special part of hemoglobin?

It can bind or unbind itself

What is cooperative binding of O2?

As each hemoglobin subunit binds an O2 molecules it becomes easier for the next O2 to bind

Conversely, as each subunit releases an O2 hemoglobin more easily release the next O2

What does the Oxygen-Hemoglobin Equilibrium Curve look like?

it is a sigmoidal curve

What happens as each O2 molecule binds?

it makes the remaining subunits much more likely to bind oxygen

Why is cooperative binding important?

It makes hemoglobin sensitive to small changes in oxygen demand, or PO2 (partial pressures of oxygen), of tissues. It also is a positive feedback mechanism

Hemoglobin experiences what kind of shift

It experience a Bohr shift which make hemoglobin more likely to release oxygen during exercise , with a decreasing pH.

Increasing temperature has the same result as decreasing pH: It shifts the oxygen-hemoglobin equilibrium which way?

It shifts the curve to the right, causing a greater unloading of oxygen to tissues.

What happens with a drop in blood pH

It stimulates an increase in breathing rates

How does pH affect oxygen unloading from hemoglobin?

It decrease in pH to make hemoglobin more likely to unload O2

What is a buffer

a substance that minimizes changes in pH

What are the two types of circulatory systems?

open and closed circulatory systems

What is an open

A circulatory system that is not confined to systems of vessels, the hemolymph comes into direct contact with tissues.

Is pressure high or low in open circulatory systems?

It is relatively low, for animals with low demanding oxygen rates

What is a closed circulatory system

Blood flows in a continuous circuit through a series of vessels in the body

What are capillaries

Vessels whose walls are just one cell thick, allowing for gas exchange of gases.

What is a vein?

Are thin-walled vessels that return blood to the heart.

What is an artery?

Tough, thick-walled vessels that take blood away form the heart.

When the muscle fibers relax, the vessel diameter increases, what happens?

resistance to flow is reduced, and blood flow increases in the tissues served by the vessel.

But when these muscle fibers contract, what happens?

increasing resistance to flow and slowing the flow of blood in the vessel.

What is an atrium

upper chamber of the heart, that receives blood.

What is a ventricle?

lower chamber of the heart, that generates the force required to propel blood out of the heart and through the circulatory system.

How are atria and ventricals connected

atrioventricular valves

What do pulmonary veins and arteries do ?

Carries blood to and from the heart to lungs

What is a systemic circuit?

transports blood to and from the rest of the body

Blood flow through the heart

1. Enter the right atrium

2. Enters the right ventricle

3. Pumped to lungs from right ventricle

4. Blood returns to left atrium

5. Blood enters the left ventricle

6. Blood is pumped to the body

What do cardiac muscle cells contract in response to

They contract in response to electrical signals, that come directly from the nervous system.

What is a pacemaker cell

heart cells that regularly produce spontaneous electrical impulses

Where are the pacemaker cells located?

The right atrium in the sinoatrial node (SA)

What is an EKG?

electrocardiogram. A recording of electrical events that occur as the heart beats.

Electrical Activation of the Heart

1. Signal originates at SA node

2. Signal spreads over atria; atria contract

3. Signal is delayed at AV node

4. Signal spreads along conducting fibers to bottom and then top of ventricles; ventricles contract

5. Ventricles relax

What is systole

Contraction of the heart

What is diastole

Relaxation of the heart

What are sensors in blood pressure homeostasis?

Baroreceptors in heart and artery walls

What is the integrator in blood pressure homeostasis

Brain

What is the responses medicated in blood pressure homeostasis

Sympathetic nervous system and adrenal hormones, leading to cardiac output and constriction/dilation of arterioles and veins