bio 225 final - part 1

With concurrent flow, the blood’s Po2 can only approach

the Po2 of the exhaled medium

Crosscurrent flow can result in

the blood’s Po2 exceeding the Po2 of the exhaled medium

cellular respiration

the conversion of macronutrients (glucose) into energy (ATP) in the mitochondria

external respiration

the sequence of events that results in gas exchange between the external environment and mitochondria

diffusion for gas exchange

For single cells or very small/thin organisms

example of organisms that use diffusion for gas exchange

* Lepadella rotifers
* marine flatworms

Fick Equation

quantifies the rate of diffusion through a tissue sheet

Rate of Diffusion is

diffusion coefficient \* area over where diffusion is taking place \* concentration gradient/distance

D

* diffusion coefficient(area per second)

A

area over which diffusion is taking place

dc/dX

concentration gradient/distance

Bulk flow of water or air

deliver O2 directly to internal cells and tissues, moved across a specialized respiratory surface by ventilation

Bulk flow of water examples

* sponges
* cnidarians

Bulk flow of air example: insects

* bulk flow or diffusion through spiracles


* O2 dissolves and diffuses at tracheoles
* bulk flow or diffusion through trachea

higher radius of cells explains why

we have respiratory systems to get oxygen as diffusion alone cannot get oxygen into a cell if it was a big cell

Ideal Gas Law

pv=nrt

Dalton’s Law

Ptotal= sum of all partial pressures

Boyle’s law and relation to respiratory systems

* Plays a role in our lungs because there is a gas pressure outside the body and inside our lungs - pressure differential

Diaphragm and Boyle’s law

* a way to manipulate the lungs to draw in oxygen or gas through changing the volume, and as a result, changing the pressure differential

Boyle’s Law

P1V1= P2V2

Gas exchange between what things relies on diffusion

respiratory medium, blood, interstitial fluid

Gas exchange between the respiratory medium and the blood and the blood and the interstitial fluid relies on

diffusion at the alveoli in the lungs to mov O2 from air/water across the membrane into the blood

In order to diffuse into a cell,

gas molecules must first dissolve in liquid

How are gases driven to dissolve in liquids?

by partial pressure gradients

High elevations

* decrease partial pressure of O2 due to less atmosphere pushing down, so less O2 is being dissolved

How to acclimate to high elevations

* Tired for a few days due to less push of O2 to dissolve in water
* Able to acclimate through EPO, which increases hemoglobin in the blood so carrying capacity of O2 can be increased

Why Olympians train at high altitudes

* Increases amount of O2 in their cells which increases the amount available for glycolysis

Lance Armstrong and blood doping

* Lance Armstrong: taking EPO to increase Hb, got in trouble for it
* blood doping: travel to high altitudes, take blood samples and transfuse their own blood to increase Hb when they return back to their normal environments

Diffusion of a gas in liquid depends on

solubility and molecular mass

Molecular mass and diffusion rate w/ O2 and CO2

* oxygen has a different molar mass than CO2, so it changes the solubility between the two molecules

Diffusion of a gas in liquid depends on

diffusion coefficient, surface area, partial pressure, solubility, diffusion distance, square root of molecular mass

Cystic fibrosis example

* Have thicker mucus membranes in their lungs, which impacts breathing and makes it difficult for diffusion to occur(changes X)

Taking mucinex and drinking water makes it easier for oxygen to

diffuse across the membrane, which makes it easier to breath

Surface Area to Volume Area increases

as radius increases

Oxygen diffusion coefficient

higher in air than water

Carbon Dioxide diffusion coefficient

higher in air than water

Oxygen solubility

higher in air than water

Carbon Dioxide solubility

equal in air and water

Oxygen concentration

very high in air and low in water

Carbon dioxide concentration

equal in air and water

The mode of respiratory perfusion affects

the efficiency of gas exchange

In tidally ventilated respiratory organs

the Po 2 of the blood can approach the Po 2 of the exhalant

Tidal ventilation efficiency

* Not very efficient because movement of air in oxygen diffuses across and then CO2 moves across, and then we exhale, so there is no length to it

Animals can’t completely empty and refill respiratory cavities with each breath beause

* the lungs would collapse since they are made of wet membranes, so getting to close would cause them to stick, which prevents us from breathing

_________ ventilation makes greater exchange efficiency possible

unidirectional

Concurrent flow

* doesn’t occur in nature, thought of as a model
* respiratory media and blood are flowing in the same direction, which means many points of diffusion can occur until their PO2s reach equilibrium

Concurrent flow

* examples: fish gills and legs of geese
* media(water or air) moving in one direction and blood is flowing in the opposite direction
* much more efficient because the pressure differential remains, so oxygen diffusion can constantly occur

Crosscurrent flow

* Most efficient of all models
* example: bird lungs
* every two breathes, air will move across their lungs but not parallel to the blood, and it still crosses the media many times to get the most out of oxygen

The combination of unidirectional ventilation and countercurrent flow makes it possible for the Po2 of blood to

approach the Po2 of the inhaled medium

______ exchange increases gas extraction

countercurrent

___________ventilation makes greater efficiency possible

unidirectional

What type of ventilation do fish have?

countercurrent

What type of ventilation do birds have?

crosscurrent

Cutaneous respiration

* diffusion across a specialized surface
* internal: lung

O2 diffusion efficiency overview

* terrestrial animals: don’t need to put too much energy to being efficient since environment is rich with O2
* fish: O2 concentration is low in water, so need more efficient lungs
* birds: evolved to fly, so PO2 drops and adapts to get the most out of the low PO2 air

How do fish ventilate their gills directionally?

through the buccal-opercular pump

Teleost fish combine

unidirectional flow and countercurrent exchange

Fish ventilation

1. Water enters buccal cavity expanding it (opercular valve is closed), Opercular cavity expands and pressure drops
2. Water enters opercular cavity (buccal cavity is compressed, opercular valve is closed, mouth closed)
3. Water flows out of opercular cavity (opercular valve is open, buccal cavity is compressed, opercular cavity is compressed),
4. water enters buccal cavity expanding it (opercular valve is open and opercular cavity is compressed)

Anatomy of teleost fish

* Mouth: breathes water into mouth
* buccal activity: mouth cavity
* operculum: piece of cartilaginous and scaly tissue that covers the gills
* gill arch: holds the gills
* opercular valve: where water leaves, similar to is-volumetric contraction of heart

Birds have ___ __lungs and have _____respiration__

stiff, hexagonal, unidirectional

Bird respiration

1. expansion of chest during the first inhalation causes fresh air to flow through the bronchi to the posterior air sacs
2. Compression of the chest during first exhalation pushes the fresh air from the posterior air sacs into the lungs
3. Expansion of the chest during the second inhalation causes stale air to flow from the lungs into the anterior air sacs
4. Compression of the chest during the second exhalation pushes stale air from the anterior air sacs out via the trachea

How is ventilation of the lungs in mammals controlled?

through the contraction and relaxation of the diaphram

Breathing in

* Diaphragm contracts
* Volume of thoracic cavity(chest) increases and decreases the pressure within
* Pulls air into the lungs for diffusion to occur

Breathing out

* Diaphragm goes back to curve shape/relaxes to allow lungs to retract
* Moves air out because pressure inside the lungs is higher than outside
* Air moves passively

Air knocked out of you

* pushed in the abdomen, which pushes diaphragm up and pushes air out, which is unnatural

Pathway of air in mammals

trachea, bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs

Anatomy of mammalian airways

* Mouth: breathes in air
* Nares: nostril
* Trachea: has ridges and made of hard cartilage
* Bronchi: branches
* Bronchiole: further branches
* Alveoli: little sacs where diffusion takes place

Purpose of increased cross-section surface area of the trachea

increases so fast so that there is a huge area for O2 to absorb and to increase the diffusion rate

sites of gas exchange in mammals between the blood and the atmosphere

alveoli

Type II alveoli cell

* replaces Type I cells
* similar to stem cells but in the lungs

Type I cell

* cells across where diffusion occurs
* thin
* don’t do much metabolically other than diffusion and being a gateway

Both Type I and II cells also make

mucus to keep the lungs wet

Alveolar pores

where air passes through

Alveolar macrophages

part of the immune system and cleans up messes

hemoglobin

a mellaloprotein that increases the oxygen carrying capacity of blood

Hemoglobin structure

* 4 iron hemes that are bound together

__________is bound by the hemoglobin within red blood cells

dissolved O2

Red blood cell structure

* Have hole in the middle because they don’t have a nucleus
* contain thousands of Hb molecules which transport molecules

Hematocrit

clinical measurement of RBC concentration

Leukemia

* affects bone marrow and decreases RBC
* decreased hematocrit
* decreases energy due to less O2 and less ETC

Living in places of high altitude can also

increase hematocrit because we want to increase O2 carrying capacity

Heme-Iron

well digested and absorbed, comes from meat sources (not eggs and milk)

Non-Heme Iron

Poorly absorbed, comes from vegetable sources

Heme

made in the mitochondria of the bone marrow and liver, has porphyrin and liver, helps bind oxygen in the bloodstream

Can increase hematocrit by

* taking hormones such as EPO
* occurring naturally through raises in atmospheric levels

Higher PO2

more likely that hemoglobin is saturated

Renal failure

* can’t make EPO, so we will have lower Hb concentration

O2 Equilibrium Curve for Hemoglobin

Higher hemoglobin content leads to more milliliters of oxygen

Making too much hemoglobin condition

* Increases hematocrit
* water content in his blood is really low, so can drop the BP
* treatment: transfusions where he takes blood out/RBC to decrease Hb concentration

How does ph affect the oxygen equilibrium of hemoglobin (Bohr Effect)

higher ph leads to higher percent saturation of hemoglobin

Acidic pH and oxygen equilibrium

* PO2 is higher
* decreased affinity for Hb

From highest to lowest, which of the following have the highest carbon dioxide concentrations: dissolved CO2, deoxygenated blood, oxygenated blood

Deoxygenated Blood, Oxygenated Blood, Dissolved CO2

CO2 doesn’t have a

carrying capacity

What are three ways Carbon Dioxide can be transported?

Dissolved CO2 (7%), Carbaminohemoglobin (23%), Bicarbonate (70%)

* all three change pH

Hb with CO2 and O2

* has to carry both CO2 and O2, but works like a shuttle system
* must carry CO2 if you want to carry O2 in the blood
* not on Hb at the same time

________________catalyzes the formation of bicarbonate (HCO 3- )

Carbonic anhydrase

CO2 to carbonic acid

spontaneous

Carbonic acid to bicarbonate

carbonic anhydrase

Law of Mass Action

Carbon Dioxide and Water spontaneously changes between carbonic acid, carbonic acid used carbonic anydrase to change between it and bicarbonate and water

At the tissues, conditions favor the release of ___ __and the conversion of__ __ __to__ ____

oxygen, carbon dioxide, bicarbonate