This preview shows page 1. Sign up to view the full content.
Unformatted text preview: r 6 L 6. (a) During strenuous exercise, PV increases
(b) Increased PV is achieved as a result of an
increase in both breathing rate and tidal volume. 7. (a) There is 90X more CO2 in exhaled air than in
inhaled air (3.6 ÷ 0.04). Biozone International 2009 Photocopying Prohibited Control of Breathing (page 167)
1. The basic rhythm of breathing is controlled by
the respiratory center in the medulla which sends
rhythmic impulses to the intercostal muscles and
diaphragm to bring about normal breathing. 2. (a) Phrenic nerve: Innervates the diaphragm (which
contracts and moves down in inspiration).
(b) Intercostal nerves: Innervate the intercostal
muscles (internal and external intercostal nerves
and muscles) to bring about ribcage movements.
(c) Vagus nerve: Sensory portion carries impulses
from stretch receptors in the bronchioles to the
respiratory center to inhibit inspiration.
(d) Inflation reflex (also known as the Hering-Breuer
reflex): The inhibition of the inspiratory center to
end the breath in. Note: Sensory impulses from
the stretch receptors in the bronchioles travel
(via the vagus) to inhibit the inspiratory center
and expiration follows. When the lungs deflate,
the stretch receptors are not stimulated and the
inhibition of the inspiratory center stops. Anatomy and Physiology (a) Oxygen is high in the lung alveoli and in the
capillaries leaving the lung.
(b) Carbon dioxide is high in the capillaries leaving
the tissues and in the cells of the body tissues. Surfactant reduces the surface tension of the lung
tissue and counteracts the tendency of the alveoli to
recoil inward and stick together after each expiration. 4. 1. 2. 3. 28
3. (a) Low blood pH increases rate and depth of
(b) Sensory information from aortic and carotid
chemoreceptors is sent to the respiratory center,
which mediates the increase in breathing rate.
Note: Sensory impulses are sent from the
carotid bodies (chemoreceptors) via the carotid
sinus nerve and then the glossopharyngeal
nerve. Sensory impulses from the aortic bodies
View Full Document
This document was uploaded on 01/28/2014.
- Winter '13