EXAM 4 REVIEW, BIOL 255 SI KEY
Unit 4E
1) The respiratory zone is the site of gas exchange and consist of bronchioles, alveolar ducts, and
alveoli, while the conducting zone provides a pathway for air to reach the sites of gas exchange
and include other respiratory structure such as the nose, nasal cavity, pharynx and trachea and
also the respiratory muscles such as the diaphragm and other muscles allowing ventilation. 4E 1
2) Functions of the nasal mucosa and conchae during inhalation are to filter, heat, and moisten,
while during exhalation they reclaim heat and moisture to minimize heat and moisture loss. 4E 2
3) The Nasopharynx lies posterior to the nasal cavity is strictly an air passageway and is lined with
pseudostratified columnar epithelium. The pharyngotympanic (auditory/Eustachian) tube open into
the lateral walls of the nasopharynx. While the oropharynx serves as a common passageway for
food and air and its epithelial lining is composed of protective stratified squamous
epithelium.Wh4E3
4) The laryngopharynx serves as a common passageway for food and air and is continuous with the
trachea. It has 3 functions: to provide a patent airway, provide a switching mechanism to route air
and food into proper channels with the use of the epiglottis, which is elastic cartilage covering the
laryngeal inlet during swallowing, and finally voice production.4E 4
5) Vocal ligaments attach the arytenoid cartilage to the thyroid cartilage which are lined with
mucosal folds called true vocal cords. The medial opening between them is the glottis and these
fibrate to produce sound as air rushes up from the lungs. While the false vocal cords or vestibular
fold are the mucosal folds superior to the true vocal cords. The false vocal cords play no part in
sound production, but close the glottis when swallowing or holding your breath. 4E4
6) Speech is produced with the intermittent release of expired air while opening and closing the
glottis, while pitch is determined by the length and tension of the vocal cords along with the
bigger/smaller the thyroid cartilage the lower/higher the voice and loudness depends upon the
force of air rushing across the vocal cords. The pharynx resonates, amplifies and enhances sound
quality.4E4
7) The bronchial tree is composed of the larynx, trachea, bronchi and bronchioles. The right and
left bronchi begin at the last tracheal cartilage which is referred to as the carina. The bronchi
subdivide into secondary bronchi, each supplying a lobe of the lungs, and then subdivide again to
form tertiary bronchi.4E5
8) Bronchioles consist of cuboidal epithelium with a complete layer of circular smooth muscle and
lack cartilage support and mucus producing cells. The last segment of the bronchioles as they
enter the respiratory zone are referred to as terminal bronchioles where they feed into the
respiratory bronchioles defined by the present of alveoli.4E 6
9) The alveolar wall is a single layer of type I epithelial cell that permit gas exchange by simple
diffusion and also secrete angiotensin converting enzyme that helps increase blood pressure when
needed and along with type II cells that secrete surfactant which reduces surface tension on the
alveoli and allow them to keep open and expanded. 4E6
10) Peripheral chemoreceptors at the carotid and aortic bodies which detect the levels of oxygen
and carbon dioxide to stimulate respiration via the medulla. 4E 9
11) The medullary respiratory centers contain the Dorsal Respiratory Group(DRG) which is the
pacesetting respiratory center, it excites the inspiratory muscles and set the normal breathing
rate referred to as eupnea, and is dormant during expiration. Also located here is the Ventral
Respiratory Group (VRG) which is the expiratory area involved in forced inspiration and expiration.
12) The pons respiratory centers influence and modify the activity of the medullary centers by
smoothing the transitions between inspirations and expirations. The pneumotaxic area continuously
inhibits inspiration centers and the apneustic area stimulates inspiration centers as in the case of
taking a long deep breath.4E 9
4A
13) Blood circulates away from the heart via arteries, which carry blood away from the heart. This
blood can be deoxygenated at times and also oxygen-rich at other times. The main point is that
arteries carries blood away from the heart. 4A 1
14) Blood circulates back to the heart via veins, which brings blood back to the heart. This blood
can be oxygen-rich at times and also deoxygenated at other times. The main point is that veins
bring blood back to the heart.
15) Blood will clot when there is no anticoagulant present and this produces serum and the blood
clot. The red blood cells form the clot by using the protein that was present in the plasma, so the
serum has fewer proteins than plasma. 4A 2
16) The extracellular fluids include blood plasma which has more protein than lymph or interstitial
fluids which are fluids found between red blood cells, white blood cells and platelets that are
suspended in plasma. The protein in blood plasma helps pull fluids back into the blood.4A 1
17) In the production of formed element of the blood, hematopoiesis is the formation of blood
cells which takes place in the red bone marrow. Here red blood cell production is referred to as
erythropoiesis. The presents of reticulocytes, which are immature red blood cells, indicates that
erythropoiesis is taking place, while production of White Blood Cells is referred to as
Leukopoiesis. 4A 3
18) In a Red Blood Cell count there are 4-6 million Red Blood Cells per cubic millimetres, which is
about the size of the head of a pin. The number of reticulocytes increase with rapid
erythropoiesis is normally 1-2%.
19) Before birth blood cell formation takes place in the fetal yolk sac, liver and spleen. By the 7th
month red bone marrow is the primary hematopoietic area. The fetus has Hemoglobin F (HbF) in
its RBC which has a higher affinity to oxygen than Adult hemoglobin (HbA). This allows oxygen
transfer from maternal HbA to fetal HbF. 4A 6
4B
20) The left coronary artery which is located in the artioventricular groove or coronary sulcus,
supplies oxygenated blood to the circumflex artery and the anterior interventricular artery which
is located in the interventricular groove or sulcus.4B 3
21) The right ventricle pumps blood to the pulmonary trunk and on to the lungs via pulmonary
arteries, while the left ventricle, which has a much thicker myocardium because it pumps blood to
the aorta, which distributes it to the coronary arteries and the systemic circulation. 4B 4
22) The chordae tendineae connect ends of the atrioventricular valves to the papillary muscles.
When the ventricles fill the papillary muscles relax and the atrioventricular valves open. But then
the ventricles contract, the papillary muscles also contract and pull on the chordae tendineae
which prevents the atrioventricular valves from prolapsing into the atria from back pressure. 4B 5
23) In the sequence of excitation the sinoatrial (SA) node generated an impulse about 75 times a
minute which stimulate the atria to contact and the impulse is passed to the atrioventricular (AV)
node. The AV node delays the impulse for approximately 0.1 second, then the impulse passes from
the AV node to the ventricles via the atrioventricular(AV) bundle often referred to as the Bundle
of His. 4B 7
24) Age related changes that affect the heart are sclerosis which makes valves tougher and
stiffer and also thickening of the valve flaps. There is also a decline in cardiac reserve and
fibrosis or scarring of the cardiac muscle, and finally atherosclerosis in which plaques build up
within the coronary vessels. 4B9
25) The heart is derived from mesoderm. 4B 10
4C
26) Fluids escaping the circulatory system are returned by the lymphatic vessels. 4C 1
27) Large arteries like the aorta, are elastic or conducting arteries. There is not a lot of
vasoconstriction taking place. These are thin walled have less smooth muscle in the tunica media
layer. They allow low resistance conduction of blood and can withstand and diminish large blood
pressure fluctuations. 4C 1
28) Arterioles, which are smaller arteries, have less elastic fibers, are thinner and smoother
muscle. Arterioles regulate blood flow into capillaries by vasoconstriction or vasodilation.4C 2
29) The functions of the capillaries are: the exchange of oxygen and carbon dioxide by diffusion,
delivery of nutrients and hormones and removal of metabolic wastes. 4C 3
4D
30) Lymphoid cells are mainly lymphocytes T cells and B cells that protect the body against
antigens, which are anything the body perceives as foreign, such as bacteria and their toxins,
viruses and mismatched transfused RBC or other transplanted tissues as well as cancer cells.4D 2
31) T cells orchestrate immune responses in which the T cell, that mature in the thymus, attacks
and destroys foreign cells, while B cells produce plasma cells which secrete antibodies which are
proteins that bind antigens, tagging them for removal from the body. B cells mature in the bone
marrow.4 D 2
32) The functions of the lymph nodes are filtration of macrophages which destroy microorganisms
and debris entering via the afferent lymphatic vessels and immune system activation which
monitor for antigens and initiate their removal. 4D 4
33) Lymph nodes have two distinct regions, the cortex which is the outer region and the medulla
which is the inner region. The cortex contains follicles with germinal centers where you find
mitotic B cells and dendritic cells. Housed deep within the cortex are T cells in transit. These T
cells circulate continuously surveying blood, lymph nodes and the lymphatic stream. 4D 4
34) The spleen which is the largest lymphoid organ functions are the site of lymphocyte
proliferation, immune surveillance and response (white pulp area), along with, cleansing the blood,
stores and breaks down products of old RBC’s referred to as hemolysis, stores iron for later use
by bone marrow, it is the site of fetal erythrocyte production which normally ceases after birth
and store blood platelets (red pulp area). 4D 5
35) Lymphatic organs arise from the mesoderm except the thymus which is endodermal in origin.
Other than the spleen and the tonsils, lymphoid organs are poorly developed at birth.