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Review slides

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Lecture Exam 3

Respiratory System

• *pulmonary ventilation• *external respiration

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):

Functions of the respiratory system

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• *external respiration• transport• internal respiration• cellular respiration

We breathe: 1. To provide O2 for cellular respiration and 2. To rid our bodies of CO2 (waste gas)

Organs of the Respiratory SystemUpper respiratory tract– nose, nasal cavity, sinuses, and pharynx

Lower respiratory tract – larynx, trachea, bronchial tree, lungs

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Conducting portioncarries air; nose to the terminal bronchioles

Respiratory portion exchanges gases;respiratory bronchioles and alveoli

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Mucous in Respiratory TractRespiratory mucosa lines the conducting passageways and is responsible for filtering, warming, and humidifying air.

Pseudostratified, ciliated columnar epithelium with goblet cells

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goblet cells

Respiratory epithelium is interrupted by stratified squamous epithelium in the oro-and laryngopharynx

Nose and Paranasal Sinuses

The nose: 1) warms 2) cleans3) humidifies air

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Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Paranasal sinuses are mucus membrane-lined, 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

Larynx

P t ti

Covered by folds of

Vestibular foldsInelastic

= major components of larynx

Prevents swallowed material from passing into trachea

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Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

PosteriorProtective

Sound

laryngeal epithelium that project into glottis

Vocal folds (cords)

Elastic

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Trachea & Primary BronchiPosterior

Note that the

(Smooth muscle)

7Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001

C-rings of cartilage: 16-20 incomplete rings completed posteriorly by trachealis musclekeep trachea open (patent)

(T5)

(T6)Anterior

trachea is anterior to the

esophagus

Bronchial Tree

Bronchi Alveolar structuresBronchiolesPrimary Alveolar ducts

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Trachea

Secondary (lobar)

Tertiary (segmental)

Intralobular

Terminal

Respiratory

Alveolar sacs

Alveoli

Know this chart

respiratory portionconducting portion

Bronchial Tree

Carina

Bronchi- Primary; w/ blood vessels- Secondary (lobar); two on left, three on right

Hilus of lung is the medial opening for air passageways, blood vessels, nerves, and lymphatics.

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- 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

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Bronchioles are to the respiratory system what arterioles are to the circulatory system

Intralobular

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Lobules of the Lung

(Intralobular)

Terminal and respiratory bronchioles are lined with

The Lobule is the basic unit of structure and function in the lung

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Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

cuboidal epithelium, few cilia, and no goblet cells

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

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• 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

Normal Inspiration• Intra-alveolar (intrapulmonary) pressure decreases to about 758mm Hg as the thoracic cavity enlarges (P 1/V)

An active process

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• Atmospheric pressure (now higher than that in lungs) forces air into the airways

• Compliance – ease with which lungs can expand

Phrenic nerves of the cervical plexus stimulatediaphragm 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.

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Maximal (Forced) InspirationThorax during normal inspiration

Thorax during maximal inspiration• aided by contraction ofsternocleidomastoid and pectoralis minor muscles

Compliance decreases as lung volume

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increases

Costal (shallow) breathing vs. diaphragmatic (deep) breathing

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

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lungs (elastic rebound) and abdominal organs

- surface tensionbetween walls of alveoli (what keeps them from collapsing completely?)

Maximal (Forced) Expiration

• contraction of abdominal wall muscles

• contraction of posterior

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posterior (expiratory) internal intercostal muscles

• An active, NOT passive, process

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Terms Describing Respiratory Rate

• Eupnea – quiet (resting) breathing

• Apnea – suspension of breathing

• Hyperpnea – forced/deep breathing

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• Dyspnea – difficult/labored breathing

• Tachypnea – rapid breathing

• Bradypnea – slow breathing

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

1) cells of alveolar wall are tightly joined together

Mechanisms that prevent alveoli from filling with fluid:

17Surfactant resists the tendency of alveoli to collapse on themselves.

2) the relatively high osmotic pressure of the interstitial fluid draws water out of them

3) there is low pressure in the pulmonary circuit

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

18Because O2 and CO2 are relatively insoluble in H2O (plasma), RBCs are used to carry or transform these gases.

tissues

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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

19But what special properties of the Hb molecule allow it to reversibly bind O2?

Lungs

Tissues

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

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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

Oxygen ReleaseAmount 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)

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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

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H2CO3 ↔ H+ + HCO3-

CO2 exchange in TISSUES

Carbon Dioxide Transport in Lungs

23CO2 exchange in LUNGS

Summary of Gas Transport

PO2 = 104 mm Hg

PO2 = 40 mm Hg

PO2 = 95 mm Hg

PO2 = 40 mm Hg

LU

TIS

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PCO2 = 40 mm Hg

PCO2 = 45 mm Hg

PCO2 = 40 mm Hg

PCO2 = 45 mm Hg

CO2 + H2O ← H2CO3 ← H+ + HCO3- H+ + HCO3

-← H2CO3 ← CO2 + H2O

UNGS

SSUES

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Control of Respiration

• Control of respiration is accomplished by:1) Local regulation

2) Nervous system regulation

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• Local regulation– alveolar ventilation (O2), Blood flow to alveoli

– alveolar ventilation (O2), Blood flow to alveoli

– alveolar CO2, bronchodilation

– alveolar CO2, bronchoconstriction

Control of Respiration

• Nervous System Control– Normal rhythmic breathing -> DRG in medulla

– Forced breathing -> VRG in medulla

• Changes in breathing

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g g– 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

Overview of the Endocrine SystemThe 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.

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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

Hormones

Amino Acid Derivatives

Amino acids

Peptides

Proteins, glycoproteins

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Hormones

Eicosanoids (cell membranes)(locally acting)

Steroids (cholesterol-derived)

Lipid Derived

Actions of Steroid Hormones• hormone crosses membranes

• hormone combines with receptor in nucleus or cytoplasm

• synthesis of mRNA activated

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• mRNA enters cytoplasm to direct synthesis of protein, e.g., aldosterone->Na/K Pump

Magnitude of cellular response proportional to the number of hormone-receptor complexes formed

(Thyroid hormone has a similar mechanism of action, even though it is a tyrosine derivative)

Actions of Amino Acid-Derived Hormones

• adenylate cyclase activated

• hormone (first messenger) binds to receptor on cell membrane

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• 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

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Control of Hormonal Secretions

• primarily controlled by negative feedback mechanism

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1) Hormonal 2) Neural 3) Humoral

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

Bl d l l f th h

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– 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

Pituitary Gland Control• Hypothalamic releasing hormonesstimulate cells of anterior pituitary (adenohypophysis) to release their hormones

• Nerve impulses from

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phypothalamus 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)

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Hormones of the Anterior Pituitary (SeT GAP)

34Tropic hormones control the activity of other endocrine glands

All anterior pituitary hormones use second messengers

(an ‘axis’)

Overview of the Pituitary Hormones

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

All anterior and posterior pituitary hormones bind

SeT GAP

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to membrane receptors and use 2nd

messengers (cAMP)

Hormone Summary Table ITissue

Name Origin Destination Action on Target Tissue Control of Release1

FOLLICLE STIMULATING

HORMONE (FSH)

anterior pituitary

males: semiiferoustubules of testes;females: ovarian

follicle

males: sperm productionfemales: 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 secretionfemales: ovulation

Gonadotropin Releasing Hormone (GnRH)

THYROID STIMULATING

HORMONE (TSH)

anterior pituitary

thyroid secrete hormonesThyrotropin Releasing

Hormone (TRH)

Se(x)

T

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HORMONE (TSH)

GROWTH HORMONE (GH)

anterior pituitary

bone, muscle, fat growth of tissuesGrowth Hormone Rleasing

Hormone (GHRH)

ADRENOCORTICO-TROPIC HORMONE

(ACTH)

anterior pituitary

adrenal cortex secrete adrenal hormonesCorticotropin Releasing

Hormone (CRH)

PROLACTIN (PRL)anterior pituitary

mammary glands produce milkProlactin Releasing Hormone

(PRH)

ANTI-DIURETIC HORMONE (ADH)(VASOPRESSIN)

posteriorpituitary

distal convoluted tubule (DCT)

reabsorption of water; increases blood pressure

increase in osmolarity of plasma or a decrease in blood

volume

OXYTOCIN (OT)posteriorpituitary

uterine smooth muscle; breast

contraction during labor; milk letdownStretching of uterus; infant

suckling

G

A

P

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Hormone Summary Table IITissue

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)

CALCITONIN Thyroid (C cells)Intestine, bone,

kidney

Decreases plasma [Ca2+]( intestinal absorp of Ca; action of

osteoclasts; excretion of Ca by kidney plasma [Ca2+]

PARATHYROID HORMONE (PTH)

ParathyroidsIntestine, bone,

kidney

Increases plasma [Ca2+]( intestinal absorp of Ca; action of

osteoclasts; excretion of Ca by kidney plasma [Ca2+]

EPINEPHRINE/NOREPINEPHRINE

(Catecholamines)Adrenal Medulla

cardiac muscle, arteriole and

bronchiole smooth muscle,

increases heart rate and blood pressure...(fight or flight)

Sympathetic Nervous System

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diaphragm, etc

ALDOSTERONE(Mineralocorticoids)

Adrenal CortexKidneys; 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 cellsDiabetogenic; anti-inflammatory

(glucocorticoid)ACTH

INSULINβ-cells of

Pancreatic Isletsall cells, liver and skeletal muscle

pushes glucose into cells from blood, glycogen formation (decreases blood glucose)

plasma [glucose]SNS

GLUCAGONα-cells of

pancreatic Isletsliver and skeletal

musclebreakdown of glycogen (increase in blood

glucose) plasma [glucose]

TESTOSTERONE Testessecondary sex

organsdevelopment and maintenance LH

ESTROGEN Ovariessecondary sex

organsdevelopment at puberty and maintenance

throughout lifeLH

NATRIURETIC PEPTIDES

atria and ventricles of heart

adrenal cortex, kidneys

increased excretion of sodium and water from kidneys, blood volume, blood pressure

Stretching of atria and ventricles

Renin-angiotensin Pathway

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Stress

Types of Stress• physical stress• psychological (emotional) stress

(Stress is any condition, h i l ti l th t

Stress Response (General Adaptation Syndrome [GAS])

• hypothalamus triggers sympathetic impulses to various organs• epinephrine is released

ti l i l d t

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physical or emotional, that threatens homeostasis)

• cortisol is released to promote longer-term responses

Three general phases of the GAS to stress ARE:

• Alarm phase• Resistance phase• Exhaustion phase

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Responses to StressExhaustion- lipid reserves

- production of glucocorticoids- electrolyte imbalance- damage to vital organs

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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

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Dwarfism hyposecretion of GH in children

Age 9 Age 16 Age 33 Age 52

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

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• 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