ch 11.2 respiratory system

Question 1

lungs

Answer 1

located in the thoracic cavity and are
covered by the rib cage. The left lung has two lobes
and is smaller than the right lung, which has three
lobes.

Question 2

pleura

Answer 2

The pleura covers the lungs and is a dual-layered
membrane.

Question 3

diaphgragm

Answer 3

a large skeletal muscle at the
bottom of the lungs and is involved in inspiration and
expiration. This is the only organ that only and all
mammals have.

Question 4

pleural space

Answer 4

fluid-filled space in between
the two layers of the pleura. This space is at a lower
pressure than the atmosphere, and creates the
intrapleural pressure.

Question 5

inhalation

Answer 5

Inspiration or inhalation involves the contraction of
the diaphragm (pulls lungs downwards) and the
external intercostal muscles (expands the rib cage).
These contractions cause the pressure of the
intrapleural space to decrease and the volume of the
lungs to increase, bringing air into the lungs.

Question 6

exhlalation

Answer 6

relaxation of
the diaphragm and the external intercostal muscles,
bringing the lungs back up and closing up the rib cage
through elastic recoil. This causes the pressure of the
intrapleural space to increase and the volume of the
lungs to decrease, driving air out of the lungs. The
internal intercostal muscles can also contract
during a more forced expiration, closing the rib cage
even more.

Question 7

pathways of air

Answer 7

1. Air is inhaled through the nose and mouth.
2. The pharynx is the beginning of the throat, after
   the nasal cavity and mouth. Both food and air
   enter the pharynx. The epiglottis diverts food
   and liquids into the esophagus, and prevents
   anything but air from entering the larynx and
   lungs.
3. The larynx receives air and contains the voice
   box.
4. The trachea is below the larynx and splits into
   the bronchi.
5. The left and right bronchi (main lung tubes) split
   into smaller bronchioles (branched, smaller lung
   tubes), and eventually into alveoli. Alveoli
   contain specialized cells that produce surfactant.
   Surfactant is a substance that prevents the
   alveoli from collapsing by reducing the surface
   tension within them.

Question 8

goblet cells

Answer 8

Within the respiratory tract, the nasal cavity, bronchi, and bronchioles contain goblet cells (secrete mucus) to trap and remove debris that enters the respiratory tract.

Question 9

ciliated epithelial cells

Answer 9

Within the respiratory tract, the nasal cavity, bronchi, and bronchioles contain ciliated epithelial cells (possess beating cilia) to trap and remove debris that enters the respiratory tract.

Question 10

what drives gasses to move

Answer 10

Differences in partial pressure allow gases to flow
from areas of high pressure to areas of low pressure
through simple diffusion. This is required for external
respiration and internal respiration

Question 11

external respiration

Answer 11

(gas exchange between inspired air and
lung alveolar capillaries)

Question 12

internal respiration

Answer 12

(gas exchange between blood and tissues).

Question 13

hemoglobin

Answer 13

tetrameric and has a heme cofactor
in each of its four subunits. Heme cofactors are
organic molecules that contain iron atoms, which
bind oxygen. Thus, each hemoglobin can carry up to
four oxygen molecules.

Question 14

oxyhemoglobin

Answer 14

(HbO2) transports most of the oxygen traveling in the blood.

Question 15

cooperativity

Answer 15

the process by which the
binding of one oxygen molecule to hemoglobin
makes it easier for others to bind due to changes in
the shape of the hemoglobin polypeptide. This also
works in reverse, allowing efficient unloading of
oxygen in body tissues.

Question 16

oxygen dissocation curve

Answer 16

The oxygen dissociation curve reveals the
relationship between the saturation of hemoglobin
with oxygen in the blood and the partial pressure of
oxygen. Certain conditions will shift this curve either
left or right.

Question 17

right shifted oxygen dissociation curve

Answer 17

CADET = Carbon dioxide, Acid,
2,3-Diphosphoglycerate, Exercise and Temperature.
CADET Increase → Right shifted curve

corresponds to a lowered
affinity for oxygen in hemoglobin. Below are the
main reasons for a right-shifted curve:

● Decreased pH: A lower pH means there is a
higher concentration of protons (H+
), which
produces reduced hemoglobin. Reduced
hemoglobin (H+Hb) has a lowered affinity for
binding oxygen, resulting in less HbO2
.
● High partial pressure of carbon dioxide: More
carbon dioxide is converted to bicarbonate anions
(HCO3
-) and protons (H+

), which lower oxygen
binding affinity through decreased pH.
● 2,3-diphosphoglycerate (2,3-DPG) aka
2,3-bisphosphoglycerate (2,3-BPG):
Accumulates in cells that undergo anaerobic
respiration as a result of the loss of oxygen. This
compound decreases oxygen binding affinity so
more oxygen is released from hemoglobin to
fuel aerobic respiration.
● Increased body temperature: Correlates to
more cellular respiration, which uses up oxygen
and produces more carbon dioxide. Thus,
hemoglobin will need to unload more oxygen for
tissues to use and have decreased oxygen
binding affinity.

Question 18

y axis of oxygen dissociation curve

Answer 18

Hb-O (% saturation)

Question 19

x axis of oxygen dissociation curve

Answer 19

P o2 (mmHg)

Question 20

left shifted oxygen dissociation curve

Answer 20

A left-shifted curve corresponds to an increased
affinity for oxygen in hemoglobin. Below are the main
reasons for a left-shifted curve:
● Increased pH (more basic): Fewer protons (H+
)
to produce reduced hemoglobin (H+Hb), so more
oxyhemoglobin (HbO2
) remains.

● Low partial pressure of carbon dioxide: Less
carbon dioxide is converted to bicarbonate anions
(HCO3
-) and protons (H+

), leading to increased
oxygen binding affinity through increased pH.
● Fetal hemoglobin: Binds oxygen better than adult
hemoglobin to help give oxygen to the fetus.
● Decreased body temperature: Less cellular
respiration, so hemoglobin isn’t influenced to
unload more oxygen and has an increased
oxygen binding affinity.

Question 21

bohr effect

Answer 21

Hemoglobin has decreased oxygen
affinity when carbon dioxide is high. Carbon dioxide
is converted to bicarbonate anions and protons,
which produce reduced hemoglobin (H+Hb).

Question 22

haldane effect

Answer 22

Hemoglobin has increased carbon
dioxide affinity when oxygen is low. As a result of low
oxygen, reduced hemoglobin (H+Hb) levels are higher
and have a greater affinity for carbon dioxide.

Question 23

bicarbonate buffering system

Answer 23

the main extracellular buffering system in the body. It maintains our blood pH of 7.4 and can be described by the equation below: CO2+ H2O ↔ H2CO3 ↔ HCO3-+ H+ Carbonic acid (H2CO3) Bicarbonate anion (HCO3–)

Question 24

what catalyzes the bicarbonate buggering system

Answer 24

This system is catalyzed by carbonic anhydrase in
both directions based on concentrations. Carbonic
anhydrase is an enzyme present in red blood cells.

Question 25

gas exchange in tissues

Answer 25

1. In erythrocytes (red blood cells) in the systemic
   circulation, the partial pressure of carbon
   dioxide is low. As a result, carbon dioxide
   continuously diffuses in from the tissues, and is
   converted into bicarbonate and protons.
   Bicarbonate is able to diffuse out of the cell,
   however, protons (H+) cannot leave. As some
   bicarbonate diffuses out, this creates a positive
   charge within the erythrocyte, and chloride ions
   (Cl-) must diffuse into the blood cell to cancel out
   the positive charge of the protons. This process is known as the chloride shift.
2. Influx of protons causes the pH to decrease within the erythrocyte, resulting in the conversion of oxyhemoglobin into reduced hemoglobin. Reduced hemoglobin has lower affinity for O2,
   leading to release of oxygen which diffuses to the tissues.

Question 26

gas exchange in the lungs

Answer 26

1. Blood travels to the lungs through bulk flow.
2. Since most of the carbon dioxide is present in the blood plasma as bicarbonate ions (HCO3-), the bicarbonate ions re-enter erythrocytes at the lungs and chloride ions leave through the reverse chloride shift.
3. The bicarbonate buffer system equation
   proceeds in the reverse direction, producing
   carbon dioxide and water. The carbon dioxide
   exits into the alveoli as gas while oxygen enters
   the blood, forming oxyhemoglobin.

Question 27

medulla oblongata

Answer 27

located in
the brain and controls the diaphragm to
regulate respiratory rate. Central
chemoreceptors and peripheral
chemoreceptors signal to the medulla.

Question 28

central chemoreceptors

Answer 28

located
in the medulla oblongata and are
contained within the blood-brain
barrier. Since carbonic anhydrase is
present in the cerebrospinal fluid,
carbon dioxide is converted into
bicarbonate ions and protons here.
However, protons cannot exit through
the blood-brain barrier. As carbon
dioxide accumulates, acidity increases
and is directly sensed by central
chemoreceptors, which signal to the
medulla oblongata to increase
breathing rate.

Question 29

peripheral chemoreceptors

Answer 29

surround
the aortic arch and carotid arteries.
These peripheral chemoreceptors
directly sense oxygen, carbon dioxide,
and proton levels to signal to the
medulla oblongata. When carbon dioxide
is high and oxygen is low, peripheral
chemoreceptors signal to the medulla
oblongata to increase breathing rate.
Blood oxygen levels have significantly
less of an effect on the respiratory center
than carbon dioxide levels. Carbon
dioxide in the blood is the primary
stimulator for breathing.

Question 30

respiratory acidosis

Answer 30

Lowered blood pH occurs due
to inadequate breathing (hypoventilation).

Question 31

respiratory alkalosis

Answer 31

Increased blood pH occurs
due to rapid breathing (hyperventilation).

Question 32

metabolic acidosis and metabolic alkalosis

Answer 32

(lowered blood pH) and metabolic
alkalosis (increased blood pH) occur as a result of
imbalances in carbon dioxide, oxygen, or proton
levels.