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Lecture Exam 3
1
Respiratory System
Respiration (in the respiratory system) is the process of
exchanging gases between the atmosphere and body cells.
It consists of the following events (in order):
• *pulmonary ventilation
• *external respiration
• transport
• internal respiration
• cellular respiration
Functions of the respiratory system
We breathe: 1. To provide O2 for cellular respiration and
2. To rid our bodies of CO2 (waste gas)
2
Organs of the Respiratory System
Upper respiratory tract
– nose, nasal cavity,
sinuses, and pharynx
Lower respiratory
tract – larynx, trachea,
bronchial tree, lungs
Conducting portion
carries air; nose to the
terminal bronchioles
Respiratory portion
exchanges gases;
respiratory bronchioles
and alveoli
3
Mucous in Respiratory Tract
Respiratory mucosa lines the conducting passageways and is
responsible for filtering, warming, and humidifying air.
Pseudostratified,
ciliated columnar
epithelium with
goblet cells
Respiratory epithelium
is interrupted by
stratified squamous
epithelium in the oroand laryngopharynx
4
Nose and Paranasal Sinuses
The nose:
1) warms
2) cleans
3) humidifies air
Figure from: Martini,
Anatomy & Physiology,
Prentice Hall, 2001
Paranasal sinuses are mucus membranelined, air-filled spaces in maxillary, frontal,
ethmoid, and sphenoid bones that drain into
the nasal cavity
Sinuses:
1. Reduce skull weight
2. Serve as resonating
chambers
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Larynx
Prevents
swallowed material
from passing into
trachea
= major components of larynx
Inelastic
Vestibular folds
Covered by
folds of
laryngeal
epithelium
that project
into glottis
Protective
Posterior
Sound
Vocal folds (cords)
Elastic
Figure from: Martini,
Anatomy & Physiology,
Prentice Hall, 2001
6
Trachea & Primary Bronchi
Posterior
(Smooth muscle)
Note that the
trachea is
anterior to the
esophagus
(T5)
(T6)
Anterior
C-rings of cartilage: 16-20 incomplete rings
completed posteriorly by trachealis muscle
keep trachea open (patent)
Figures from: Martini, Anatomy & Physiology,
Prentice Hall, 2001
7
Bronchial Tree
Bronchi
Bronchioles
Alveolar structures
Primary
Alveolar ducts
Secondary (lobar)
Alveolar sacs
Tertiary (segmental)
Alveoli
Intralobular
Trachea
conducting portion
Terminal
Respiratory
Know this chart
respiratory portion
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Bronchial Tree
Hilus of lung is the medial opening
for air passageways, blood vessels,
nerves, and lymphatics.
Bronchi
- Primary; w/ blood vessels
- Secondary (lobar);
two on left, three on right
- Tertiary (segmental); supplies
a broncho- pulmonary segment;
10
on right, 8 on left
Bronchioles
- Intralobular; supply lobules,
the basic unit of lung
- Terminal; 50-80 per lobule
- Respiratory; a few air sacs
budding from theses
Carina
Bronchioles are to the
respiratory system
what arterioles are to
the circulatory system
Figure from: Martini,
Anatomy & Physiology,
Prentice Hall, 2001
Intralobular
9
Lobules of the Lung
(Intralobular)
The Lobule is the
basic unit of
structure and
function in the lung
Terminal and respiratory
bronchioles are lined with
cuboidal epithelium, few
cilia, and no goblet cells
Figure from: Martini,
Anatomy & Physiology,
Prentice Hall, 2001
10
Gases and Pressure
• Our atmosphere is composed of several gases and
exerts pressure
– 78% N2, 21% O2, 0.4% H2O, 0.04% CO2
– 760 mm Hg, 1 ATM, 29.92” Hg, 15 lbs/in2,1034 cm H2O
• Each gas within the atmosphere exerts a pressure of
its own (partial) pressure, according to its
concentration in the mixture (Dalton’s Law)
– Example: Atmosphere is 21% O2, so O2 exerts a partial
pressure of 760 mm Hg. x .21 = 160 mm Hg.
– Partial pressure of O2 is designated as PO2
11
Normal Inspiration
• Intra-alveolar
(intrapulmonary)
pressure decreases to
about 758mm Hg as
the thoracic cavity
enlarges (P  1/V)
• Atmospheric
pressure (now higher
than that in lungs)
forces air into the
airways
• Compliance – ease
with which lungs can
expand
An active process
Phrenic nerves of the cervical plexus stimulate
diaphragm to contract and move downward and
external (inspiratory) intercostal muscles contract,
expanding the thoracic cavity and reducing
intrapulmonary pressure.
Attachment of parietal pleura to thoracic wall pulls
visceral pleura, and lungs follow.
12
Maximal (Forced) Inspiration
Thorax during normal
inspiration
Thorax during maximal inspiration
• aided by contraction of
sternocleidomastoid and pectoralis minor
muscles
Compliance
decreases as
lung volume
increases
Costal (shallow)
breathing vs.
diaphragmatic
(deep) breathing
13
Normal Expiration
• due to elastic recoil of the lung tissues and abdominal organs
• a PASSIVE process (no muscle contraction involved, no energy needed)
Normal expiration is
caused by
- elastic recoil of the
lungs (elastic rebound)
and abdominal organs
- surface tension
between walls of alveoli
(what keeps them from
collapsing completely?)
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Maximal (Forced) Expiration
• contraction of
abdominal wall
muscles
• contraction of
posterior
(expiratory)
internal intercostal
muscles
• An active, NOT
passive, process
15
Terms Describing Respiratory Rate
• Eupnea – quiet (resting) breathing
• Apnea – suspension of breathing
• Hyperpnea – forced/deep breathing
• Dyspnea – difficult/labored breathing
• Tachypnea – rapid breathing
• Bradypnea – slow breathing
16
Know these
Alveoli and Respiratory Membrane
• Respiratory Membrane consists of the walls of the alveolus and the
capillary, and the shared basement membrane between them
Mechanisms that prevent alveoli
from filling with fluid:
1) cells of alveolar wall are tightly
joined together
2) the relatively high osmotic
pressure of the interstitial fluid
draws water out of them
3) there is low pressure in the
pulmonary circuit
Surfactant resists the tendency of alveoli to collapse on themselves.
17
Diffusion Through Respiratory Membrane
The driving for the exchange of gases between alveolar air
and capillary blood is the difference in partial pressure
difference between the gases.
alveolus
tissues
Because O2 and CO2 are relatively insoluble in H2O (plasma), RBCs are used
18
to carry or transform these gases.
Oxygen Transport
• Most oxygen binds to hemoglobin to form oxyhemoglobin (HbO2)
• Oxyhemoglobin releases oxygen in the regions of body cells
• Much oxygen is still bound to hemoglobin in the venous blood
Tissues
Lungs
But what special properties of the Hb molecule allow it to reversibly bind O2?
19
The O2-Hb Dissociation Curve
Recall that Hb can bind
up to 4 molecules of O2 =
100% saturation
At 75% saturation, Hb
binds 3 molecules of O2
on average
Sigmoidal (S) shape of
curve indicates that the
binding of one O2 makes
it easier to bind the next
O2
This curve tells us what the percent saturation of Hb will be at
various partial pressures of O2
20
Oxygen Release
Amount of oxygen released from oxyhemoglobin increases as
• partial pressure of carbon dioxide increases
• the blood pH decreases and [H+] increases (Bohr Effect; shown below)
• blood temperature increases (not shown)
• concentration of 2,3 bisphosphoglycerate (BPG) increases (not shown)
21
Carbon Dioxide Transport in Tissues
• dissolved in plasma (7%)
• combined with hemoglobin as carbaminohemoglobin(15-25%)
• in the form of bicarbonate ions (68-78%)
CO2 + H2O ↔ H2CO3
H2CO3 ↔ H+ + HCO3-
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CO2 exchange in TISSUES
Carbon Dioxide Transport in Lungs
CO2 exchange in LUNGS
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Summary of Gas Transport
PO2 = 40
mm Hg
PO2 = 95
mm Hg
PO2 = 104
mm Hg
L
U
N
G
S
T
I
S
S
U
E
S
PO2 = 40
mm Hg
PCO2 = 45
mm Hg
PCO2 = 40
mm Hg
PCO2 = 40
mm Hg
PCO2 = 45
mm Hg
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CO2 + H2O ← H2CO3 ← H+ + HCO3-
H+ + HCO3- ← H2CO3 ← CO2 + H2O
Control of Respiration
• Control of respiration is accomplished by:
1) Local regulation
2) Nervous system regulation
• Local regulation
–
–
–
–
 alveolar ventilation (O2),  Blood flow to alveoli
 alveolar ventilation (O2),  Blood flow to alveoli
 alveolar CO2, bronchodilation
 alveolar CO2, bronchoconstriction
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Control of Respiration
• Nervous System Control
– Normal rhythmic breathing -> DRG in medulla
– Forced breathing -> VRG in medulla
• Changes in breathing
– CO2 is most powerful respiratory stimulant
– Recall: H2O + CO2 ↔ H2CO3 ↔ H+ + HCO3– Peripheral chemoreceptors (aortic/carotid bodies)
•  PCO2,  pH ,  PO2 stimulate breathing
– Central chemoreceptors (medulla)
•  PCO2,  pH stimulate breathing
26
Overview of the Endocrine System
The endocrine system consists of
- collections of cells located in tissues scattered throughout the body
- that produce substances released into the blood (hormones)
- to ultimately affect the activity and metabolism of target cells.
Secrete into
Affect activity
Endocrine glands
Blood
Inside cells
Exocrine glands
Ducts or on to free surface
Outside cells
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Classification of Hormones
Amino acids
Amino Acid
Derivatives
Peptides
Proteins, glycoproteins
Hormones
Steroids (cholesterol-derived)
Eicosanoids (cell membranes)
Lipid
Derived
(locally acting)
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Actions of Steroid Hormones
• hormone crosses membranes
• hormone combines with
receptor in nucleus or
cytoplasm
• synthesis of mRNA
activated
• mRNA enters cytoplasm to
direct synthesis of protein, e.g.,
aldosterone->Na/K Pump
(Thyroid hormone has a similar
mechanism of action, even
though it is a tyrosine derivative)
Magnitude of cellular response proportional to the number
of hormone-receptor complexes formed
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Actions of Amino Acid-Derived Hormones
• hormone (first messenger) binds
to receptor on cell membrane
• adenylate cyclase activated
• ATP converted to cAMP
• cAMP (second messenger)
promotes a series of reactions
leading to cellular changes
Magnitude of response is not directly proportional to the
number of hormone-receptor complexes – it’s amplified
30
Control of Hormonal Secretions
• primarily controlled by negative feedback mechanism
1) Hormonal
2) Neural
3) Humoral
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Control mechanisms for hormone release
Target Cell Activation By Hormones
• Target cells must have specific receptors to
be activated by hormones
• Magnitude of target cell activation depends
upon
– Blood levels of the hormone
• Rate of release from producing organ
• Rate of degradation (target cells, kidney, liver)
• Half-life
– Relative numbers of receptors for the hormone
• Cellular receptors can be up- or down-regulated
– Affinity (strength) of binding of the hormone to its
receptor
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Pituitary Gland Control
• Hypothalamic
releasing hormones
stimulate cells of
anterior pituitary
(adenohypophysis) to
release their hormones
• Nerve impulses from
hypothalamus
stimulate nerve
endings in the posterior
pituitary
(neurohypophysis)
gland to release its
hormones
Note the hypophyseal portal system of the adenohypophysis
(two capillaries in series)
33
Hormones of the Anterior Pituitary (SeT GAP)
(an ‘axis’)
Tropic hormones control the activity of other endocrine glands
All anterior pituitary hormones use second messengers
34
Overview of the Pituitary Hormones
Figure from: Martini,
Anatomy & Physiology,
Prentice Hall, 2001
All anterior
and posterior
pituitary
hormones bind
to membrane
receptors and
use 2nd
messengers
(cAMP)
SeT GAP
35
Hormone Summary Table I
Tissue
Origin
Destination
Action on Target Tissue
Control of Release1
anterior
pituitary
males: semiiferous
tubules of testes;
females: ovarian
follicle
males: sperm production
females: follicle/ovum maturation
Gonadotropin Releasing
Hormone (GnRH)
LUETINIZING
HORMONE (LH)
anterior
pituitary
In males: interstitial
cells in testes;
in females: mature
ovarian follicle
males: testosterone secretion
females: ovulation
Gonadotropin Releasing
Hormone (GnRH)
T
THYROID
STIMULATING
HORMONE (TSH)
anterior
pituitary
thyroid
secrete hormones
Thyrotropin Releasing
Hormone (TRH)
G
GROWTH
HORMONE (GH)
anterior
pituitary
bone, muscle, fat
growth of tissues
Growth Hormone Rleasing
Hormone (GHRH)
A
ADRENOCORTICOTROPIC HORMONE
(ACTH)
anterior
pituitary
adrenal cortex
secrete adrenal hormones
Corticotropin Releasing
Hormone (CRH)
P
PROLACTIN (PRL)
anterior
pituitary
mammary glands
produce milk
Prolactin Releasing Hormone
(PRH)
ANTI-DIURETIC
HORMONE (ADH)
(VASOPRESSIN)
posterior
pituitary
distal convoluted
tubule (DCT)
reabsorption of water; increases blood
pressure
increase in osmolarity of
plasma or a decrease in blood
volume
OXYTOCIN (OT)
posterior
pituitary
uterine smooth
muscle; breast
contraction during labor; milk letdown
Stretching of uterus; infant
suckling
Name
FOLLICLE
STIMULATING
HORMONE (FSH)
Se(x)
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Hormone Summary Table II
Tissue
Name
Origin
Destination
Action on Target Tissue
Control of Release
TRIIODOTHYRONINE
(T3) & THYROXINE
(T4)
Thyroid (follicular
cells)
all cells
increases rate of metabolism (BMR)
Thyroid Stimulating Hormone
(TSH)
Thyroid (C cells)
Intestine, bone,
kidney
Decreases plasma [Ca2+]
( intestinal absorp of Ca;  action of
osteoclasts;  excretion of Ca by kidney
 plasma [Ca2+]
Parathyroids
Intestine, bone,
kidney
Increases plasma [Ca2+]
( intestinal absorp of Ca;  action of
osteoclasts;  excretion of Ca by kidney
 plasma [Ca2+]
cardiac muscle,
arteriole and
bronchiole smooth
muscle,
diaphragm, etc
increases heart rate and blood pressure...
(fight or flight)
Sympathetic Nervous System
CALCITONIN
PARATHYROID
HORMONE (PTH)
EPINEPHRINE/
NOREPINEPHRINE
(Catecholamines)
Adrenal Medulla
ALDOSTERONE
(Mineralocorticoids)
Adrenal Cortex
Kidneys; sweat
glands; salivary
glands; pancreas
reabsorption of water and Na (increases blood
pressure) and excretion of K
(mineralocorticoid)
Angiotensin II
 plasma [Na+]
 plasma [K+]
CORTISOL
(Glucocorticoids)
Adrenal Cortex
all cells
Diabetogenic; anti-inflammatory
(glucocorticoid)
ACTH
INSULIN
β-cells of
Pancreatic Islets
all cells, liver and
skeletal muscle
pushes glucose into cells from blood, glycogen
formation (decreases blood glucose)
 plasma [glucose]
SNS
GLUCAGON
α-cells of
pancreatic Islets
liver and skeletal
muscle
breakdown of glycogen (increase in blood
glucose)
 plasma [glucose]
TESTOSTERONE
Testes
secondary sex
organs
development and maintenance
LH
ESTROGEN
Ovaries
secondary sex
organs
development at puberty and maintenance
throughout life
LH
NATRIURETIC
PEPTIDES
atria and ventricles
of heart
increased excretion of sodium and water from
kidneys,  blood volume,  blood pressure
Stretching of atria and ventricles
adrenal cortex,
kidneys
37
Renin-angiotensin Pathway
38
Stress
Types of Stress
• physical stress
• psychological
(emotional) stress
(Stress is any condition,
physical or emotional, that
threatens homeostasis)
Stress Response (General
Adaptation Syndrome [GAS])
• hypothalamus triggers
sympathetic impulses to
various organs
• epinephrine is released
• cortisol is released to
promote longer-term
responses
Three general phases of the GAS
to stress ARE:
• Alarm phase
• Resistance phase
• Exhaustion phase
39
Responses to Stress
Exhaustion
-  lipid reserves
-  production of glucocorticoids
- electrolyte imbalance
- damage to vital organs
40
GH Abnormalities
Growth Hormone Ups and Downs
• Gigantism - hypersecretion of GH in children
• Acromegaly – hypersecretion of GH in adults
• Dwarfism – hyposecretion of GH in children
Age 9
Age 16
Age 33
Age 52
41
Diabetes (= Overflow)
• Diabetes Mellitus (DM)
– Hyposecretion or hypoactivity of insulin
– Three P’s of Diabetes Mellitus (mellitum = honey)
• Polyuria (increased urination)
• Polydipsia (increased thirst)
• Polyphagia (increased hunger)
– Hyperglycemia, ketonuria, glycosuria
• Renal Glycosuria
– excretion of glucose in the urine in detectable amounts
– normal blood glucose concentrations or absence of
hyperglycemia
• Diabetes Insipidus (insipidus = tasteless)
– Hyposecretion or hypoactivity of ADH
– Polyuria
– Polydipsia
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