Respiration

Easier version ata

Requirements for Respiration

• Respiratory medium– Medium that will transport the gases

• Respiratory surface– Where diffusion of the gases will occur

Respiratory medium

• Water – No problem of hydrating respiratory surface– Heavy– Less O2 per volume

• Air – Highly dehydrating– Light – High O2 concentration

Respiratory surface

• Should be moist• Should have high SA• Should be thin

WHY?

Other questions…..

• How does size of organism, its habitat and its metabolic activity affect the structure of its respiratory surface?

The lowly animals……

• Use of cell membrane as respiratory medium• Part of the body with direct contact with the

respiratory medium is used for respiration– E.g. poriferans, protists, cnidarians

Highly evolves animals (tayo yun)

• Use of a highly extensive respiratory structure– Respiratory medium is separated from blood and

capillaries– Give examples- student number 12

Cutaneous respiration

• How does this work student number 21?

The commoners (common respiratory organs)

• Tracheal system– Arthropods

• Gills– E.g. amphibians, fish

• Lungs – E.g. birds, mammals

Ang problema ng tubig, bow

• Due to low amount of oxygen per volume its energy cost is higher compared to air

• Ventilation is present if oxygen is minimal– Increased contact between respiratory medium

and respiratory surface– Without ventilation region of high O2 conc and

region of high CO2 conc will occur

Fish ventilation

• They swim against the current

What is the consequence of this method of ventilation?

Countercurrent exchange

• Water moves opposite the direction of blood

• Gills are highly extensive– Lessens the energy cost

Countercurrent exchange pa rin…..

• Ensures the presence of a diffusion gradient between the respiratory medium (water) and transporting medium (blood)

• Very efficient

Counter current pa rin, kaya dapat matandaan nyo to

Ayaw talaga pa awat ng countercurrent

(no) Air as a respiratory medium

Tracheal system

Tracheal system

• Direct transport of gas between respiring cells and respiratory medium

• Tubular structure• Trachea- large tube– Plural tracheae

• Spiracles- opening to the outside• Tracheole- fine tubes directly connected to

cells

Lungs

• Confined inside the body cavity• Circulatory system bridges the respiratory

medium and transport tissue• Respiratory structure- epithelium + dense

capillaries

The lungs

Bronchiole, alveoli and BVs

Mammalian respiration

• Give the sequence of structures where gases will travel from the environment to the body then back to the environment

Air we breath

• Filtered by hairs and cilia• Warmed, humidified and sampled for odors

Mammalian respiration….

• The act of swallowing moves the larynx upward tipping the epiglottis over the glottis

• Glottis- opening of the windpipe• Larynx- adapted as voicebox• Syrinx- vocal organ of birds– Found at the base of the trachea– Produce sound without the vocal chords found in

mammals

Sound Sound: produced when voluntary muscles stretch and vibrate during the processHigh-pitched sound: tight, rapid vibrationLow-pitched sound: less tense, slow vibration

The Phlegm

• Epithelial lining is covered with mucus and beating cilia

• Mucus traps contaminant, while, the cilia moves this to the pharynx where it can be swallowed

Breathing

• Negative vs Positive pressure breathing– Recitation of the whole process

Positive pressure breathingIn a breathing cycle:•Muscles lower the oral cavity floor (becomes

enlarge and draws air through the nostrils)• Closing of the mouth and nostril (oral cavity

floor rises and forces air into the trachea)• Air is force out/exhaled (elastic recoil of lungs

and muscular contraction of chest)

Negative pressure breathing

• Works like a suction pump (air is pulled rather than pushed)

• Negative pressure is produced due to action of chest muscle– Relaxation of chest muscle pushes air; contraction pulls air in

• Expansion of lungs is possible due to its double-walled sac– Inner sac adheres to the lungs– Outer sac adheres to the chest cavity walls– Space in between is filled with fluid

Surface tension

• Which is harder to separate: two plastics with water between them or two plastics without water between them

Inhalation

• Contraction of muscles (rib muscles and diaphragm)– Increases volume of chest cavity– Decreases alveolar air pressure– Rib cage expands (ribs pulled upward; breastbone

pushed forward)

Exhalation

• relaxation of muscles– Rib muscles and diaphragm relax – Lung volume is reduced– Inc in alveolar air pressure

Breathing

Overview

• http://www.youtube.com/watch?v=HiT621PrrO0

Factors that affect breathing

• Tidal volume- volume of air inhaled and exhaled in each breath– Ave human tidal volume is 500 ml

• Vital capacity- max tidal volume during forced breathing– 3.4 L female; 4.8 L male

• Residual volume- air left in the lungs during exhalation– Lungs hold more air than the vital capacity

Old age

• Age or disease decrease the elasticity of the lungs– Residual volume increases at the expense of vital

capacity– Max O2 conc in the alveoli decreases– Gas exchange efficiency is decreased

Bird breathing

• Presence of air sacs• Do not function directly in gas exchange; acts

as bellows• Lungs and air sacs- ventilated during breathing• Presence of parabronchi rather than alveoli– Air moves in one direction – Air is completely exchanged– Max O2 conc is higher in birds than in mammals

Bird respiration

Regulation of Breathing

• Breathing – controlled by the medulla oblongata and the pons

• This ensures that respiration is coordinated with circulation

• Medulla oblongata- major control center of breathing

• Control center in the pons works synergistic with the control center of the medulla oblongata

Regulation of Breathing

• Negative feedback- helps maintain breathing• Stretch sensors- found in the lungs send impulses to

the medulla (inhibits the breathing control center)• Medulla- monitors CO2 level of the blood – CO2 conc is detected through slight change in blood and

tissue fluid pH– Carbonic acid lowers pH– Drop in pH increases rate of rate and depth of breathing

Oxygen Concentration

• Oxygen Concentration- have little effect to breathing control center

• Severe depression of O2 conc stimulates O2 sensors in the aorta and carotid arteries to send alarm signals

• Breathing rate is increased by the control centers

• Increase in CO2 conc is a good indicator of decrease in O2 conc

Hyperventilation

• Excessive deep, rapid breathing inc CO2 conc in the blood

• Breathing centers temporarily stops working• Impulses to the rib muscles and diaphragm are

inhibited• Breathing resumes when CO2 conc inc

Different Factors Affect Breathing

• Nervous and chemical signals affects rate and depth of breathing

• Most efficient if it works in tandem with the circulatory system

• E.g. Exercise: inc cardiac output-inc breathing rate– Enhances O2 uptake and CO2 removal

Respiratory pigments: transports gases and buffers the blood

• Low solubility of O2- problem if O2 is transported via the circulatory system– E.g. Normal human consume 2L of O2 per minute– Only 4.5 ml of O2 can dissolve into a L of blood in the

lungs– If 80% dissolved O2 would be delivered, 500 L of

blood should be pumped per minute (a ton per 2 mins)

– Unrealistic!!!!– Special respiratory pigments are used

Respiratory Pigments

• Transports O2 instead of dissolving into a solution

• Inc O2 that can be carried in the blood (~200 mL O2 per L in mammalian blood)

• Decreases cardiac output (20-25 L per min)

Respiratory Pigments

• Binds O2 reversibly– Loads O2 from respiratory organ; unloads in other

parts of the body• Hemocyanin- found in hemolymph of

arthropods and many mollusks• Copper- acts as the oxygen-binding component• Hemoglobin- respiratory pigment of all

vertebrates

Hemoglobin

• Consists of four heme subunits• Iron acts as the binding site of O2• Loading and unloading of O2 depends on the

property of each subunits called cooperativity• Affinity is dependent to the conformation of each

subunit– Binding of one O2 molecule to one subunit induces the

inc in affinity of other subunits– Unloading of one O2 molecule decreases the affinity of

other subunits

Dissociation Curves of Gases

• Cooperativity of heme subunits is shown in a dissociation curve

• Steep slope- slight change in Po2 causes substantial loading or unloading of O2

• Because of cooperativity, slight drop in Po2

causes a relatively large inc in O2 to be unloaded

The Bohr Shift

• A shift to the right of the oxygen hemoglobin dissociation curve

• Brought about by increase CO2 or low blood pH• Decrease in affinity of hemoglobin to O2• Greater efficiency of O2 unloading

Carbon Dioxide transport

• Hemoglobin- also transports CO2 not only O2– Assists in buffering the blood

• Blood released by respiring cells:– 7%- transported in the solution of blood plasma– 23% - bind to amino group of hemoglobin– 70% - transported in the blood in the form of

carbonic acid

Carbon Dioxide Transport

• CO2- converted in the red blood cells into bicarbonate– Reacts first with water to form carbonic acid (carbonic

anhydrase)– Dissociates into H+ and bicarbonate– H ions- attach to different sites in the Hb and other

proteins– Bicarbonate ions- diffuse into the plasma– Movement of blood through the lungs reverses the

process favoring the conversion of bicarbonate to CO2

Deep-diving air breathers

• Stockpile oxygen- O2 is reserved in the blood and muscles (e.g. Weddell seal)

• High percentage of myoglobin• Dec heart rate and O2 consumption• 20-min dive- O2 in myoglobin is used up– Energy is derived from fermentation rather than

respiration