Biology 224

Respiration

the exchange of respiratory gases (oxygen and carbon dioxide)

what do animals do with carbon dioxide and oxygen?

animals absorb oxygen from in the air and release carbon dioxide from within the body must be cleared out of the body. the body has a constant need for oxygen

external respiration

 transport of 02 into and CO2 out of the body, exchange of gases in the lung

• process by which: environmental O2 → membrane → tissues → dissolved CO2 → membrane → environment

gas exchange membrane

it is a thin layer of one or two simple epithelia

• It separates internal tissues from the environmental medium (air or water) 

internal respitration

transports O2 into and CO2 out of the cells

cellular respiration

intracellular catabolic reactions that convert stored energy to ATP

what is the rate of diffusion (ficks law)?

J= D.A. C1-C2/X

• C1 and C2- regions of high and low concentrations of solutes

• A- diffusion area

• X- distance separating the concentration regions

• D- diffusion co-efficient, influenced by physico-chemical properties of the solute and temperature

what is the diffusion of gases

use P1- P2 instead P1 and P2- regions of high and low partial pressure, respectively

why isnt diffusion alone not enough?

sufficient only for very small animals such as rotifers, for some animals diffusion is not enough to diffuse oxygen to all the tissues and muscles  in the body

• Oxygen requirements increase with mass: diffusion distance increases

• Their surface area gets proportionally smaller

• Need for respiratory organs with larger surface area and shorter diffusion distance

respiration in large animals

there are multiple steps:

• Most vertebrates gas-transfer systems involves

• Breathing movements→ ventilation

• Diffusion of gases across the respiratory epithelial

• Circulatory system→ bulk transport of gases (perfusion)

• Diffusion of gases across capillary walls

the structure of the gas

exchange system in animals is influenced by properties of the medium (air vs water) and requirements of the animals

physical properties of gases

• The daltons law states that total pressure exerted by a gas mixture is the sum of individual pressures exerted by each gas in the mixture

• The partial pressure of a gas is its individual pressure in a mixture

• The rate of diffusion of a gas is proportional to its partial pressure within the total gas mixture

• O2 and CO2 will flow based on their pressure gradient (high to low)

• Total atmospheric pressure 1atm= 760 mmHg at sea level

• High altitude reduces the inspired pressure of oxygen not the % of oxygen in the atmosphere

• People in Peru live in very high altitudes because they have special respiratory adaptations (if we were to go there we would have severe respiratory problems

why does oxygen limited in water

Water is much more dense than air- the environment is more oxygen limited (less oxygen in the water)

what does a change in temperature do to oxygen levels in water

Oxygen solubility in the water will change as temp changes- oxygen level will decrease with increasing temperatures

respiratory physiology

all the processes if gas exchange and transport between the atmosphere and the body tissue

respiration in water breathing and air breathing animals

water breathers (fish)

Gills are invaginations of the body

• Respiratory surfaces

• Branched and folded structures

• Increase diffusion area (increasing in diffusion area for increase in gas exchange)

Water moves over the gills

-beating of cilia; and contractions of body muscles pump water over gills

external gils

extend from the body and do not have protective coverings

• ex) sea slug, very bright colours

internal gils

located within the body, protected by chambers of the body

• Water flows in through one opening and ventilates before exiting through another opening (filter feeders)

• Currents of water to be directed over the gills

double pumping mechanism

found in bony and cartilaginous fish

• Buccal pump and opercular pump: muscles pump water between the 2 pumps, when the water reaches operculum, the pump close and cycle begins again

• + and - indicate pressure gradient across the gills and pressure relative to surrounding water

Ram ventilation

• Pelagic fish like some sharks and mackerel

• Mackerel can't fully oxygenate their blood if prevented from active swimming

structure of fish gills

Fish will typically have 4 gill arches per side

• The primary lamli of the gill is the filament of gill

countercurrent flow

the blood and the water move in opposite directions 

• Blood leaving the capillaries has the same O2 content as fully oxygenated water entering the gills

• counter current flow; equilibrium is never achieved

the tracheal system

for gas exchange

trachea= windpipe

• Invaginations of the outer epidermis that branch repeatedly (tracheoles)

• Air enters and leaves through spiracles

• O2 →ECF → cells

• CO2 → ECF → tracheoles

Gas transport in insects

• Length od tissue diffusion path limit the size of the tissue

• Simple diffusion in tracheoles may work for small insects → larger ones use ventilation

• Ventilation involves opening/ closing of spiracles and abdominal muscles

respiratory systems in brids

air sacs and lungs

• Trachea is the main air tube

• Lung is associated with a bunch of air sacs, the one attached to the front of the lungs are called the anterior air sacs, the ones attached in the back are called posterior air sacs

• 6-9 air sacs

• Mammalian lung is very elastic (stretches and moves), birds are very rigid( do not inflate or deflate)

the 2 cycles of oxygen flow in birds

• During the first inhalation cycle, most oxygen flows directly to the posterior air sacs, during the following exhalation, both anterior and posterior air sacs contract

• During inhalation , air from the lung (deoxygenated) moves into the anterior air sacs, in the second exhalation air from the anterior sacs is expelled to the outside through the trachea

Parabronchi

Oxygen exchange occurs in the parabronchi in birds, the parabronchi is always in contact with oxygenated air

• Blood flows cross currently, air always flows in one direction

cross current

• Blood flows branches into multiple streams, each of which meets the air only part of the airs pathway

• Blood farther down the tubes runs alongside O2 poor medium

• PO2 of blood leaving the breathing organ is higher than that of exhaled medium

what are the respiratory adaptations in high altitudes?

1. Increased hypoxic ventilatory response

2. Larger lungs

3. Hemoglobin → greater affinity for O2

4. Higher capillarity in flight muscles (greater blood flow and increased use of oxygen)

5. Greater aerobic capacity in the flight muscle (oxygen is used in the mitochondria to produce ATP. 

People who have lived in higher altitudes may have some of these adaptations

respiration in breathing animals (mammals)

• Gas flow is different in mammals

• Tidal exchange/ tidal ventilation- always stale oxygen in the long, that mixes with the deoxygenated air coming in

• The partial pressure of oxygen drops (means the process is less efficient)

what is the respiratory system

• Moves through the mouth, 

• down the pharynx (for air and food consumed),

•  air goes down the trachea (windpipe)

• epiglottis - closes off the larynx when swallowing

• Trachea divides into 2 bronchitis (each go into a lung), then enters the lung

• There are branches in the lungs that are called bronchioles, the final air tubes are called terminal bronchioles (branches 16 times (generations) , each tie they get narrower)

• Then the alveoli form at the base- structure in the lung where gas exchange occurs

• The alveoli sacs are covered in a thick layer of capillaries

the mammalian lung

• The lung od  mammal consists if sequentially branching airways: the trachea divides to form two primary bronchi

• Primary bronchi branch and rebranch into bronchioles

• Bronchioles branch multiple times and eventually end in tiny outpocketings known as alveoli

• In an adult human, about 700 million alveoli- a total gas exchange membrane alveoli of 100 square meters

The outer fluid layer is called the pleural sac

boyles law

when pressure goes up ventilation goes down

The human lung operates by maintaining the balance between the 2

Diaphragm

 at the bottom of the lung- separates lung from the abdominal cavity

the diaphragm expands on inhalation and deflates with exhalation

External and internal intercoastal muscles

the muscle between the ribs, when contracted they lift the rib cage.

when the lungs expand vs. when the muscles relax

the air pressure within the lungs drops, the drop of pressure draws the fresh air into the lungs

the diaphragm moves upwards 

total lung capactiy for 70 kg male

(TLC) maximum amount of air that the lungs can hold (5.7L in humans)

tidal volume for 70 kg male

(TV)volume of air entering or leaving the lungs during a single breath

functional residual capacity

(FRC) the amount of air that is in the lung after passive exhalation

residual volume

 (RV) minimum volume of air remaining in the lungs after a maximal expiration (without air in the lung it will collapse)

vital capacity

(VC) maximum volume of air that can be moved out during a single breath following maximal inspiration

Tidal ventilation

• Fresh inhaled air mixes with stale air left behind from the previous breath

• PO2 of air adjacent to the respiratory membrane is lower than PO2 in the external environment

• PO2 in blood leaving the breathing organ must be even lower, a partial pressure gradient is necessary for O2 to diffuse across the membrane into the blood

what does Pa O2 stand for

 partial pressure of oxygen in the arterial blood

what does PEO2 stand for?

partial pressure of oxygen in exhaled air

what is the Pons and medulla?

part of the hind brain, helps to regulate the breathing activity

Pons- depth and length of breathing

Medulla- rhythm of the breathing

chemorecptors

 detect CO2, Ph, O2, peripheral

Control of breathing

peripheral chemoreceptors

• Located in the aortic bodies within the aortic arch, and also at the bifurcation of common carotid arteries

• Forest response- monitor PCO2, PH

• Second response- Monitor PO2

• Information travels via vagus and glossopharyngeal nerves to the respiratory centres in the medullae and pons

ways blood is carried

1. RBC- bound to hemoglobin

2. Dissolved O2 in plasma

why hemoglobin is needed in the blood

• Oxygen is not very soluble in plasma water

• At PO2 of 100 mmHg, O2 solubility is 0,003 ml/ml

• An athlete may need 14ml O2/100 ml of bllod

• Therefore we need a carrier protein, hemoglobin, that can transport lots of )2 at arterial PO2 to the tissues

• Typically human blood contains 15g hb/100ml

O2 transport

• Partial pressure of O2 is higher in alveolar ar than in blood capillary networks surrounding alveoli

• Most O2 entering the blood combines with hemoglobin inside RBC

what is heme?

 non protein component of molecule (4)

• Iron-containing O2 transport metalloprotein

• Presents RBC of almost all vertebrates

• In mammal, 96% of the RBC dry content

the artic fish

only vertebrate known not to have any hemoglobin

• Their blood is translucent and blue

• How?- cold temp has higher oxygen, the water they live in is very oxygenated

• Transparent body- carry out gas exchange with both gills and the skin

• They carry gene that is responsible for hemoglobin production (it is not used)

hemoglobin- O2 dissociation curve

• Binding th eO2 in one site increases the affinity of the other sites fro O2

• Larger quantities of O2 combine with hemoglobin maintain a larger partial pressure gradient between O2 in alveolar air and blood plasma

• Oxygen binding saturates at high partial pressure

affinity of hemoglobin for oxygen

The affinity of Hb for oxygen is affected by

• Temperature

• pH

• CO2

Favor oxygen binding in the respiratory epithelia and oxygen release in tissues

reduced affinity= right shift, requires more oxygen

Increased affinity= left shift, less oxygen in the blood is required 

The body cells produce carbon dioxide which is then diffused out of the body

• This produces hydrocarbonic acid

O2 diffusing into the body tissues

• PO2 in interstitial fluid and body cells is lower than in blood plasma

• O2 diffuses from the blood into interstitial fluid, and from interstitial fluid into body cells

• PO2 of the blood is entirely based on the amount of oxygen dissolved in the plasma

CO 2 diffusing out of the body

• PO2 is higher in tissue than in blood

• About 10% of CO2 dissolves in blood plasma

• 70% is converted into H and HCO3 (Bicarbonate) ions

• 20% combines with hemoglobin

fast reaction for the transfer of CO2 from the body cells to the RBC

• CO2 diffuses into RBC and combines with hemoglobin, forming carbaminohemoglobin

• Some CO2 combines with H2O to form HCO3 and H

• H combine with hemoglobin

• HCO is transported out of RBC to plasma

slow reaction of transfer of CO2 from body cells to RBC

some CO2 is released into the blood and combines with plasma H2O to form HCO and H

what is CA

reaction that happens in RBC and is very rapid

Carbonic Anyydrase (CA)

A metalloenzyme- requires zinc

• Catalyze the rapid interconversion of CO2 and H2O to bicarbonate and H

• Capable of converting one million molecules of COP2 per second

• Contributes to transport CO2 out of tissue

• Maintains acid-base balance on blood and other tissues

CO2 transfer in the lungs

• In the lungs, PCO2 is higher in blood  than in alveolar air

• Reactions packing CO2 into blood are reversed

• CO2 is released from blood into alveolar air

CO2 from the blood to the air

the reverse reaction of CO2 to the lungs

Fast-

• Most of the HCO43 in RBC combines with H released from hemoglobin to form CO2 and h2O

• CO2 is released from hemoglobin

• Plasma Co2 diffuses to alveolar air

why does CO cause tissue hypoxia (low PO2)

• CO is colourless and odourless, exposure to high levels, meaning our blood becomes very low on oxygen

• Co binds to hemoglobin with great affinity (200 times more than oxygen)

what must cells do in all animal cells

• Have adequate O2, nutrients

• Eliminate toxic byproducts of cell metabolism (CO2, nitrogen, etc)

transport of O2 in some species

• Rely on diffusion directly to/from the environment

• The body of these animals will be only a few cell layers thick

transport of O2 in more complex animals

require an internal, rapid, transport system

• Cells are too far away from ‘environment’ (diffusion is simply not fast)

• Animals may have an impermeable ‘skin’ to prevent dehydration, for protection, support (need circulatory systems)

what needs to be transported in homeostasis and metabolism

• Water, respiratory gases, nutrients

• Waste products and metabolic intermediates and ions

-CO2, NH3, NH4, urea, uric acid, Lactic acid, HCO3, NA, K, Ca, Mg

• Blood clotting factors

• Chemical messengers: hormones

• Antibodies, cells of immune system

heats role in the circulatory system

control of blood flow to the skin and to the extremities plays an important role in controlling and maintaining body temperature

Open body cavities (a gastrovascular cavity)

• The simplest form, found in sponges and cnidarians

• Water currents (bring nutrients, release of waste)

open circulatory system

• Many invertebrate animals

• Blood is pumped by the heart empties into an open fluid space

Heart, blood vessels open to the animals body cavity → hemocoel, blood and interstitial fluid= hemolymph

Contains hemocyanin in many animals

• Metalloprotein with 2 copper atoms

• Major O2 transporter in invertebrates

• Reversibly bind a single O2

No bound to blood cells

• Suspended in the hemolymph

Oxygenation causes color change

• Colourless Cu deoxygenated

• Blue Cu oxygenated form
  

functions of insects hemolymph

• Transport of nutrients, hormones, waste products and immune molecules

• Hemolymph cells involved in wound repair and immune response

• Hydraulic skelton→ specially in larvae

• Heat transfer

what is hemolymph

a fluid, analogous to the blood of vertebrates

closed circulatory system

Share some basic common elements in most species

A fluid:

• Solutes in solution

• Cells in suspension

A pump to move fluids:

• Usually hearts, and associated terms such as cardio (greek fro heart)

• All vertebrates and some invertebrates (cephalopods)

• Blood flows in a s continuous circuit of tubes

• Ideal for larger animals→ blood reaches all cells

• Capillaries beds allow firm control of blood distribution (can increase delivery of oxygen to tissue very rapidly

vessels

vascular (small vessels) system

• Carry the fluid between the pump and body tissues

cardiovascular system design in vertebrates

Single circulation→fish

Parallel circulation → amphibians

Double circulation→ mammal, birds, and crocodiles (runs between the heart and lungs, where blood gets oxygenated, blood come back to the heart and gets pumped to the body)

evolution of vertebrate- fish

• Undivided (single circuit)

• Blood is oxygenated before going to body

• Higher BP than in open system (20/30) but BP is still somewhat low

• The BP is low to avoid fluid leak

amphibians and most reptiles (snakes, lizards and turtles)

• Partially divided- 2 chambers (left and right atrium)

• Blood is still oxygenated before going to body

• BP =30/20, but still one pump = one BP

crocodiles birds and mammals

• Completely divided (double circuit)- 4 chambers of the heart (left and right atrium, left and right ventricle)

• Blood still oxygenated first, but now 2 pumps= 2 BP

• 30/20 (pulmonary circuit)

• 120/80 (systemic) 

• Means high velocity to systemic tissues

• Supports high rates of cellular respiration(metabolism)

• It has both double pump and double circulation (most efficient system)

fish heart

three chambers