chapter 22: respiration: the exchange of gases fig. 22.1 new aim: how have different organisms...

Chapter 22: Respiration: The Exchange of Gases

Fig. 22.1

NEW AIM: How have different organisms evolved to perform gas exchange (respiration)?


Fig. 22.1

AIM: How have different organisms evolved to perform gas exchange (respiration)?


Respiratory surface

- the site of gas diffusion (O2 in, CO2 out)



Respiratory surface – 4 properties

1.Made of cells2. thin3. must be moist (wet)4. large surface area



Respiratory surfaceFour types of resp. organs in animals

1. Entire outer skin (“skin-breathers”)

- Annelida- What type of environment would you expect to find them?- Why must they be narrow and long?

- How come all animals don’t “skin-breathe”?

Fig. 22.2A


- What other organ system is a must with this type of resp. sys?



2. Gills

- Aquatic animals- Why are they able to be outside the body?- The shape?

Fig. 22.2B




2. Gills

- Aquatic animals- Why are they able to be outside the body?- The shape?

- Ventilation

Fig. 22.3 Fig. 22.4

i. Countercurrent flow (exchange)

i. Energy Intensive – water is denser than air

- Oxygen in water is 3-5% that of air


- Circulatory system needed



2. Gills

Fig. 22.3 Fig. 22.4


Chapter 22: Respiration: The Exchange of GasesAIM: How have different organisms evolved to perform gas exchange (respiration)?


3. Tracheal system- Why is the system now within the body?

- Insects (class of arthropoda)i. Tracheal system

- Easier to breathe air than water.

- tracheae- tracheoles

Fig. 22.4C



3. Tracheal system- Why are they now within the body?

- Insects (class of arthropoda)

Fig. 22.5A

i. Tracheal system


- tracheae- tracheoles- air sacs

Fig. 22.5C

ii. Circulatory system?(spiracles)



3. Tracheal system- Why are they now within the body?

- Insects (class of arthropoda)

Fig. 22.5A

i. Tracheal system


- tracheae- tracheoles- air sacs

Fig. 22.5B

ii. Circulatory system NOT involved(spiracles)



4. Lungs- Terrestrial Vertebrates- Restricted to one part of body

i. What other system do we need?Fig. 22.2D



4. Lungs- Terrestrial Vertebrates- Restricted to one part of body

i. What other system do we need?

- Special Casei. Amphibians

a. Small lungsb. Also uses body surfaces



4. LungsWhich type of organisms would you predict to have a greater lung surface area, endotherms or ectotherms? Explain.

Endotherms (warm-blooded) need to maintain their body temperatures and therefore will need to perform a greater number of chemical reactions to generate heat = more oxygen needed and more CO2 generated.


Respiratory surface of single celled organisms?


Human respiration Fig. 22.6A


Human respiration

- surface area =- Respiratory Path

Fig. 22.6A

100m2


Human respiration

- surface area = 100m2

- Respiratory Path

1. Nasal Cavity (nostril breathing)

a. Filtered by hairs/mucus/ciliab. Warmed or cooled to 1 degree within body temp. as to not disrupt fluidity of membranes of epithelial cells of lungs (alveoli).

c. Humidified to keep respiratory surface (alveoli) from drying out.

d. Sampled for odors

Air is:


Human respiration


- Respiratory Path

1. Nasal Cavity (nostril breathing) 2. Pharynx

i. Tonsils and Adenoids


Human respiration


- Respiratory Path

1. Nasal Cavity (nostril breathing) 2. Pharynx3. larynx - voice box

a. Vocal cords

b. Surrounded by cartilage (adam’s apple)


Human respiration


- Respiratory Path


a. Vocal cords4. Trachea


Human respiration


- Respiratory Path


a. Vocal cords4. Trachea

a. Enforced with rings of cartilage like a vacuum cleaner hose to prevent collapse when breathing due to drop in pressure

b. Lined with ciliated cells and mucus producing goblet cells. Mucus producing cells secrete mucus, which lines the trachea and traps dust/bacteria/viruses/etc… and the ciliated cells use their cilia to push the mucus up the trachea into the pharynx to be swallowed and digested. This is always happening.


Human respiration


- Respiratory Path


a. Vocal cords4. Trachea5. Bronchi6. Bronchioles


Human respiration


- Respiratory Path


a. Vocal cords4. Trachea5. Bronchi6. Bronchioles7. Alveoli – dead end

Fig. 22.6B

- millions per lung- Simple squamos epithelium- The respiratory surface

- Site of diffusion


Human respiration


- Respiratory Path


a. Vocal cords4. Trachea5. Bronchi6. Bronchioles7. Alveoli

Fig. 22.6C

- millions per lung- Simple squamos epithelium- resp. surface

- site of diffusion

Alveoli in yellow interacting with capillaries in red (notice the surface area)


Smoking

- 43 carcinogens- destroy cilia and macrophages (type of WBC that fights infection)- coughing becomes last line of defense- 430,000 people die a year

(more than the sum of deaths caused by AIDS, alcohol, drug abuse, traffic accidents and murders)

- lung cancer


Smoking

- 43 carcinogens- destroy cilia and macrophages- coughing becomes last line of defense- 430,000 people die a year

(more than the sum of deaths caused by AIDS, alcohol, drug abuse, traffic accidents and murders)

- lung cancer- emphysema

ii. Inflammatory chemicals released by your own cells break down walls of alveoli leading to collapse

i. Toxins trapped in lungs cause inflammation

v. Heart needs to beat harder, gets thicker/larger and eventually fails

iii. Not getting enough oxygen into blood, leads to hyperventilationiv. Blood vessels near damage constrict to divert blood to working regions of lungs

Chapter 22: Respiration: The Exchange of GasesAIM: How have different organisms evolved to perform gas exchange (respiration)?Bronchitis

-itis:

Suffix denoting diseases characterized by inflammation itself often caused by an infection.


Asthma 1. An immune response brought about by white blood cells in the lungs reacting to foreign although otherwise harmless substances (allergens) or rapid-mouth breathing during exercise (genetic and environmental).

2. Breathing passages (bronchi) become inflamed (swollen, red, warm) and smooth muscle around bronchi constrict (bronchospasm).

3. Symptoms include wheezing, coughing, chest tightness and shortness of breathe.

4. In the end, the precise cause is not known


Adrenaline (epinephrine) albuterol

Asthma Treatment Β2-andrenergic agonists


Breathing

- Ventilates the lungs

i. Diaphragm and intercostal (between rib) muscles contract

- Negative pressure breathing

Fig. 22.8A

When the muscle contract (diaphragm contracts downward and the intercostals pull the ribs toward each other), the volume of the lungs increases, which decreases the pressure inside the lungs (fewer collisions of air molecules with the walls of the bronchi, alveoli, etc…) causing higher pressure air to rush in.


How is breathing controlled?

- Some conscious control- Predominantly Involuntary

a. Breathing control centers

i. pons

ii. medulla

- coordinates respiratory and circulatory system with metabolic needs of body

- monitors pH - indirect measure of CO2

CO2 + H2O H2CO3 (carbonic acid)

The more CO2 in the blood…

…the more acidic it is.





i. pons

ii. medulla



As the blood gets more acidic (lower pH), proteins on the surface of medulla cells change shape and the cells will signal the diaphragm to contract more frequenlty (breathe heavier).





i. pons

ii. medulla



As pH decreases, breathing _________.increases




a. Breathing control centers- coordinates respiratory and circulatory system with metabolic needs of body

Oxygen sensing by the aortic body

1. There are also a bunch of cells in the aorta that sense O2 levels.

2. Blood in the aorta just came from the lungs and should be fully oxygenated.

3. Neural signals sent to pons/medulla, which will send signal to diaphragm.

4. This signal is much less important than the pH signal.



Story:

As you run, your muscle cells (majority of your cells) are using a great deal of O2 and producing CO2.

The CO2 enters the blood and combines with H2O to make H2CO3 catalyzed by carbonic anhydrase.

CO2 + H2O H2CO3 (carbonic acid)carbonic anhydrase

The H2CO3 will dissociate (fall apart) to H+ + HCO3- resulting in a slight decrease in the pH of the blood.

The pons/medulla respiratory center cells senses this drop in pH by a change in the shape of the proteins on their surface signally the cells to send a neural signal to the diaphragm to increase the frequency of contractions.



Story (continued):

At the same time, the aortic body senses a decrease in oxygen and also sends a signal to the pons/medulla with the same result as before. This signal is not a strong/important as the drop in pH.

The exact opposite happens if you hyperventilate (breathe in and out quickly). CO2 concentrations drop , pH rises and pons/medulla does not send a signal to breathe…can be very dangerous and deaths have been known to be a result.


How is oxygen transported?X 50,000,000,000 per human

250,000,000 / RBC

1. Very little dissolved in blood2. Carried by hemoglobin

- 4 subunits (polypeptides)- 1 heme per subunit- 1 O2 per heme


How is CO2 transported?

2. some binds to hemoglobin3. Remainder forms H2CO3 via carbonic anhydrase inside RBC’s

i. H2CO3 is a buffer and helps buffer blood at pH ~7.4

1. Dissolve in blood as gasFig. 21.11


Gas exchange in the fetus…



The placenta is the only human organ made of tissue from two different organisms…the mother and the child.

1. The fetus’ heart will pump blood through the fetus and out to the placenta via the umbilical cord.

2. In the placenta, the gas and nutrient exchange will occur via diffusion (mom’s and baby’s blood DO NOT MIX).

3. The blood then returns to the fetus. The placenta acts like the “lungs” and “kidneys”.

4. The mother will then get rid of the CO2 via the lungs and nitrogenous waste (urea) via the kidneys.



What about the fetus’ feces?

- There is no feces, did the fetus ever eat anything?

1. Respirationa. Respiratory surface

- skin breathers

- moist, large surface area, thin, made of cellsb. Types of systems

- gills- tracheal system- lungs

c. Human respiration- nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles- alveoli

- the resp. surface of lungsd. smoking

- lung cancer and emphysemae. breathing

- diaphragm, intercostal muscles, negative pressure breathing



f. Breathing control

-Indirect measure of CO2

- control centers - pons, medulla of brain stem- medulla monitors pH

- sends neural signals to diaphragm and intercostals- bromothymol blue

g. Transport of O2 and CO2

- RBC’s- hemoglobin

- heme cofactor containing iron - iron binds oxygen

h. Transport of CO2

- dissolved in blood, as carbonic acid, bound to hemoglobin (not at the iron)

i. Fetal respiration





Watch tutorial under misc section of website

Chapter 21: Nutrition and Digestion

Milestone Questions

AIM: How do animals obtain nutrition?

1. Explain why when you exercise your breathing rate increases.

2. What are the four requirements of a respiratory surface?

3. How does negative pressure breathing work in humans?

4. How is CO2 carried in the blood?

chapter 22: respiration: the exchange of gases fig. 22.1 new aim: how have different organisms...

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