SDV1 Second Semester
TEST 2 – Physiology II
7 May 2012 (Time 10:00 – 11:00 AM)
Name ……………………………….…………..
Matric No. ……………………………
PART A
Answer briefly.
1. (a) Define inspiratory reserve volume.
(b) Describe muscles involved in the inspiration and expiration process.
(2 marks)
(4 marks)
(a) The inspiratory reserve volume is amount of air that can still be inspired
after inhaling the tidal volume.
(b) Muscles involved in inspiration and expiration
Muscles involved in inspiration
1.
2.
3.
Diaphragm:
-- contraction draws air into lungs
-- 75% of normal air movement
External intercostal muscles:
-- assist inhalation by raising rib cage
-- 25% of normal air movement
Accessory muscles assist in elevating ribs:
-- E.g. serratus , pectoralis, scalene muscles
Muscles involved in expiration
1. Internal intercostal and transversus thoracis muscles:
-- depress the ribs
2. Abdominal muscles:
-- compress the abdomen
-- force diaphragm upward
2. Discuss at least SIX (6) factors affecting respiratory rate.
(6 marks)
•
Body size: Larger body size vs small animal – based on metabolic body size; oxygen need
increased in smaller animals (e.g. rat) than large animals (e.g. elephant); therefore, increased
respiration rate.
•
Age: Young- higher respiration (growing, higher metabolism; old- lower respiration)
•
Exercise: increase oxygen demand, increased carbon dioxide removal – high respiratory rate
•
Excitement: stimulatory impulses to higher center
•
Environmental temperature: increase in respiration; to reduce temperature through perspiration
•
Pregnancy: increased respiration to support oxygen; increased metabolism for fetal growth
•
Degree of digestive fill : higher metabolism, – increased respiration
•
State of health: either decrease or increase in respiratory depending on the type of health. E.g.
fever – increased respiratory rate.
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3. Describe alveolar respiratory clearance.
(6 marks)
Alveolar Respiratory Clearance
Particles deposited in the alveoli, usually smaller than 1 in diameter, are removed by (a) Phagocytosis by macrophages or continued as free particles
(b) Directed to moving mucous blanket with alveolar fluid-film
(c) Particles in the interstitial space of alveoli
-- transported to lymph nodes
-- dissolved and transferred in solution either to lymph/blood
(d) Unphagocytized and /or insoluble particles
-- Sequestered (isolated) within the lung C/T
-- e.g., asbestosis, silicosis, and anthracosis (coal dust)
4. Discuss voluntary control of respiration.
(6 marks)
Normal respiration is involuntary in nature. It rhythmically done by the
higher center – medulla oblongata. However, it can be altered voluntarily
within wide limits.
E.g., hasten, slowed, stopped -- for a while
-- Voluntary system -- located in the cerebral cortex.
-- Sends impulses to the respiratory motor neurons via the corticospinal tracts.
-- The automatic system is driven by a group of pacemaker cells in the medulla.
-- Impulses from these cells activate motor neurons in the cervical and thoracic
spinal cord that innervate inspiratory muscles.
-- Those in the cervical cord activate the diaphragm via the phrenic nerves.
-- Those in the thoracic spinal cord activate the external intercostal muscles.
However, the impulses also reach the innervation of the internal intercostal muscles
and other expiratory muscles.
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5. Discuss two-breath cycle of avian respiration.
(6 marks)
Two breaths, or two respiratory cycles,
are required to move one inhaled unit of air through the
avian respiratory system.
The first inhalation is made by expansion of the thoracoabdominal space (birds do not have a diaphragm), and
most of the air moves directly into the abdominal air sacs.
The first expiration pushes air into the lungs. This is where gas
exchange with the blood occurs.
The second inspiration moves the air into the cranial thoracic
pairs of air sacs (anterior thoracic and posterior thoracic).
The second expiration moves the air out through the trachea.
Air flow is pushed into the lungs, not pulled.
PART B
Mark squares with “T” if the answer is true or “F” if the answer is false.
Note: there can be more than one true or one false answer in each question.
1. The primary functions of the respiratory system are:
T A. delivery of O2 in the tissues.
T B. removal of CO2 from the tissues.
T C. ventilation.
F D. thermoregulation.
F E. phonation.
(1 mark)
2. The lung sound “wheezes” is caused by:
T A. bronchoconstriction.
T B. bronchial wall thickening.
T C. pneumonia.
F D. edema.
(1 mark)
F E. hemothorax.
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3. Blood capillaries have efficient gas exchange property due to their:
T A. dense network.
T B. large surface area.
T C. epithelial lining with one cell thickness.
F D. mucus secretion property.
F E. macrophages.
(1 mark)
4. When the lungs are diseased by inhalation of coal dusts, it is known as:
T A. anthracosis.
F B. asbestosis.
F C. silicosis.
F D. pneumothorax.
F E. hemothorax.
(1 mark)
5. Mucous blanket is
F A. for the blockage of smaller bronchioles.
T B. the mixture of foreign materials and mucus.
F C. usually removed towards the lung alveoli.
T D. expelled out of the respiratory tract by the action of cillia.
T E. produced by the goblet cells.
(1 mark)
6. Respiratory centers include:
T A. pontine respiratory group.
T B. apneustic center.
T C. dorsal respiratory group.
T D. medulla oblongata.
T E. pneumotaxic center.
(1 mark)
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7. CO2 released in the tissues is carried to the lung:
T A. in dissolved form in the plasma.
T B. in the form bound to the hemoglobin.
T C. as bicarbonate in the plasma.
F D. in the form bound to plasma proteins.
F E. after reacting with the electrolytes in the plasma.
(1 mark)
8. VA/Q ratio may be:
T A. 1 (one).
T B. 0 (zero).
T C. 0.8.
T D. 0.7.
T E. 0.5.
(1 mark)
9. Ventilation is:
T A. increased by an increase in CO2 in the blood.
T B. increased by an increase in H+ concentration.
T C. increased by a decrease in O2 in the blood.
T D. decreased by a decrease in CO2 in the blood.
F E. decreased by an increase in CO2 in the blood.
(1 mark)
10. In the avian respiration system gas exchange occurs:
F A. in the cranial air sacs.
F B. In the caudal air sacs.
F C. in both cranial and caudal air sacs.
T D. in the parabronchi.
F E. In the bronchi.
(1 mark)
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