Respiration

Chapter 42

Respiration

Gas exchange

Movement of gas across membrane

Diffusion (passive)

To improve gas absorption

Increase surface area for diffusion

Decrease distance diffused gas travels

Respiratory organs

Fish

Amphibians

Lungs

Cutaneous respiration

Amphibians

Birds

Parabronchi (lungs) Air sacs

Fig. 42-26

Anteriorair sacs

Posteriorair sacs Lungs

Air

Lungs

Air

1 mm

Trachea

Air tubes(parabronchi)in lung

EXHALATIONAir sacs empty; lungs fill

INHALATIONAir sacs fill

Anatomy

Mouth (nose)

Pharynx (back of throat)

Larynx (voice box)

Trachea

Anatomy

Anatomy

Anatomy

Bronchi (Bronchus)

Bronchioles

Alveoli

Air sacs

Gas exchange

One cell layer thick

Lung tissue consists of millions

Anatomy

Anatomy

Anatomy

Lungs

3 right lobes

RUL, RML, RLL

2 left lobes

LUL, LLL

Anatomy

Anatomy

Anatomy

Lung covered by a double folded membrane

Visceral pleural membrane:

Covers the lung

Parietal pleural membrane:

Lines inner wall of thoracic cavity

Anatomy

Pleural cavity:

Space between two membranes

Filled with fluid

Helps with movement of lungs

Breathing

Diaphragm

Muscle

Separates thoracic cavity from abdominal cavity

Intercostal muscles

Muscles between the ribs

Inhalation (inspiration)

Diaphragm contracts & flattens

Intercostal muscles contract

Raises the ribs

Increases volume (decreases pressure)

Air flows into the lungs

Exhalation (expiration)

Diaphragm relaxes & elevates

Intercostal muscles relax

Ribs lower

Decreased volume

Forces air out

Breathing

Breathing measurements

Tidal volume

Amount of air moved into & out of lungs at rest

Vital capacity

Maximum amount of air that can be expired after forceful exhalation

Breathing measurements

Control of breathing

Normal breathing Medulla oblongata Respiratory control center Neurons send impulse for muscles

(diaphragm/intercostal) to contract Inspiration (inhalation) Stop sending impulse Expiration (exhalation)

Control of breathing

Blood O2 & CO2 in normal range Neurons respond to a change in O2

& CO2

More response to CO2

Increase CO2 Increases carbonic acid (H2CO3) CO2 + H2O ⇆H2CO3 ⇆ H + HCO3

Lowers pH

Control of breathing

Stimulates peripheral chemoreceptors

Aorta & carotids

Send impulses to respiratory control center (medulla oblongata)

Stimulates increased breathing

Control of breathing

Central chemoreceptors

Located in brain

Respond to increased amount of CO2

Peripheral receptors immediate response

Central receptors maintained response until pH is back to normal

Transport of gas

Hemoglobin

Contains four heme groups

Center of each heme group is an iron

Oxygen binds the iron (4 O2 molecules)

Oxygen in blood is mostly bound to Hgb

Little is dissolved plasma

Transport of gas

Transport of gas

Oxyhemoglobin

Hemoglobin full of oxygen

Lungs

Deoxyhemoglobin

Hemoglobin releases some oxygen

Capillaries

Transport of gas

Blood that leaves lungs 97% saturated

Circulates oxygen diffuses into tissues

75% saturated

Allows for reserves of oxygen

Exercise

Cardiac arrest

Transport of gas

Decreased pH Lower affinity of oxygen for

hemoglobin Releases oxygen Increased temperature Lower affinity Exercise Increased CO2, decreased pH,

increased temperature Increased release of O2 to muscles

Transport of gas

CO2

In tissues

Small amount bound to protein part of Hgb

Remaining CO2 in RBC

Forms carbonic acid H2CO3

Carbonic anhydrase

Transport of gas

Carbonic acid separates

Bicarbonate (HCO3-1) & H+1

Buffer

Blood at alveoli

Carbonic anhydrase reverses

Forms water & CO2

CO2 diffuses into lungs

Abnormalities

Emphysema Lung disease that destroys alveoli sacs Decreases vital capacity Traps air Hypoventilation Decreased air movement increased CO2

Hyperventilation Increased air movement decreased CO2

Emphysema