Respiratory System - Chapter 10

Respiratory System

1) a system of passageways for getting air to and from the lungs
2) the lungs themselves, where gas exchange actually occurs

Respiratory System -Functions

-gas exhange between blood and air
-moves air to and from exchange surfaces
-protects from environmental variations and pathogens
-produces sound
-detect olfactory stimuli

Respiratory System - Components

nose, nasal cavity, paranasal sinuses, pharynx, larynx, trachea, bronchi, lungs: bronchioles and alveoli

Important to Respiration

Bones, muscles, components of the nervous system that cause air to move into and out of the lungs.

Respiration Processes - 4

1) Breathing (ventilation)
2) External respiration - the exchange of gases between inhaled air and blood.
3) Internal respiration. The exchange of gases between the blood and tissue fluids.
4) Cellular respiration - the process of using oxygen to product ATP within cells.

upper respiratory tract

comprises the nose, nasal cavity, pharynx -- structures above the "Adam's apple"

lower respiratory tract

larynx, trachea, two bronchi, lungs with bronchioles and alveoli

external nose

visible portion of the nose; consists of cartilage in the front and two nasal bones behind the cartilage.

nasal cavity

internal portion of nose.

pharynx (throat)

connects the mouth and nasal cavity to the larynx
- upper pharynx - extends from nasal cavity to the roof of mouth.
- lower pharynx - common passageway for both food (to esophagus) and air (to lower respiratory tract).

larynx

produces sound (voice box)
-extends 5 cm (2 in) below the pharynx
- contains epiglottis and vocal cords.
-passageway for air moving from pharynx to trachea

glottis

Opening between the vocal cords in the larynx.

epiglottis

Flaplike structure of elastic cartilage at the back of the throat that covers the opening of the larynx during swallowing.

vocal cords

consist of two folds of connective tissue that extend across the airway; supported by ligaments; enclosed with a cartilaginous structure nicknamed the "Adam's apple"
- sound produced by vibration of

the trachea

-"windpipe" extends from the larynx to the left and right bronchi
-series of stiffened C-shaped incomplete cartilage rings held together by connective tissue and muscle which hold trachea open
-lined with cilia covered epithelial tissue that secretes mucus
- throat receptors stimulate cough reflex

the bronchi

-trachea forms two branches. right and left primary bronchi as enters the lung cavity.
divide into network of smaller and smaller bronchi
- walls contain fibrous connective tissue and smooth muscle reinforced with cartilage which declines as airways get smaller

the bronchioles

smaller bronchi contain no cartilage
-smallest 1.0mm
- thin layer of smooth muscle surrounded by small amount of elastic connective tissue
- deliver air to a single lobule.

Bronchi and Bronchioles Functions

- Air transport
- clean air
- warm air to body temperature
-saturate air with water vapor before reaches gas-exchange surfaces of lungs.
- lined with ciliated epithelial cells and some mucus-secreting cells.

Lungs

- organs of gas exchange
- Air filled structures consisting almost entirely of bronchioles, alveoli, and blood vessels.
-right lung - 3 lobes
-left lung - 2 lobes

Lungs - Structure

- consist of supportive tissue enclosing the bronchi, bronchioles, blood vessels, and the areas where gas exchange occurs.
- occupy most of the thoracic cavity.
- one on right, one on left separated by heart
- base of each is broad and shaped to fit against the convex surface of the diaphragm
- enclosed in two layers of thin epithelial membranes (pleural membranes)

Alveoli

- within Lung - gas exchange occurs
-soft and frothy - contains mostly air
-system of branching airways ending in 300 mil air filled sacs
- arranged in clusters at the end of every terminal bronchiole
-single = alveolus

anatomy of the alveolus

respiratory membrane, simple squamous, capillary ednothelium, shared basement membrane

septal cells

epilthelial cells that secrete a lipoprotein called surfactant which coats the interior of the alveoli and reduces surface tension.

Infant Respiratory Distress Syndrome

- in infants; underdeveloped lungs; treated with surfactant replacement therapy.

Diaphragm

main muscle of respiration;
broad sheet of muscle that separates the thoracic cavity from abdominal cavity

pulmonary capillaries

Pulmonary arteries, arterioles terminate into a capillary bed called __________________.
-separate blood from air at this point
- squamous epithelial of alveolus & cell of capillary wall

Bones & Muscles of Respiration

Ribs, intercostal muscles betwen the ribs, & main muscle of respiration called diaphragm.

Principles of Gas Pressure/Movement

- Gas pressure caused by colliding molecules of gas
-GASES FLOW FROM AREAS OF HIGHER PRESSURE TO AREAS OF LOWER PRESSURE

LUNG EXPANSION CONTRACTION

-compliant (stretchable)
- surrounded by pleural cavity (airtight and sealed)
-when pleural cavity expands, lungs will expand with it.

Inspiration

(Inhalation)
- pulls air into the respiratory system as lung volume expands
1. diaphragm contracts, flattening it, pulls center downward.
2. Simultaneously, the intercostal muscles contract, pulling the ribs upward and outward.
These two actions increase the volume of the pleural cavity and LOWER pressure within pleural space.

Expiration

(Exhalation)
- pushes air out as lung volume declines again
-muscles relax; diaphram returns to domed shape.
- ribs move downward and inward
-plueral cavity becomes smaller
-lungs become smaller, pressure within the lungs RISES and air flows OUT

Relaxed State

-diaphragm and intercostal muscles are relaxed; diaphragm dome shaped

quiet breathing

-inspiration is active; expiration is passive.
diaphragm and external intercostals are involved

Tidal Volume

- 12 breaths a minute at rest
represents approximately 500 milliliters or pint of air.
-only 350 ml actually reach the alveoli
- other 150 ml remain in airways (called dead space volume)

Vital Capacity

- maximal volume that you can exhale after a maximal inhalation
- about 4,800 ml (10x normal tidal volume)

Expiratory reserve volume

- amount of air that we can forcibly exhale beyond the tidal volume ( about 1200 ml)

Residual Volume

- some air always remains in lungs -- approx 1200 ml

Pressure in Lungs

- same as atmospheric pressure at rest

Atmospheric Pressure

at sea level of about 760 mm Hg
- same as pressure in our lungs when resting between breaths.

the direction of air flow is determined

by the relationship of atmospheric pressure and pressure inside the respiratory tract. flow is always from higher to lower pressure

Venous blood

Deoxgenated blood

goblet and gland cells

secrete mucus

mucus

traps inhaled dirt, pathogens, etc

alveolar macrophages

engulf foreign particles

pulmonary ventilation

moving air into and out of the respiratory tract; breathing

gas transport

movement of oxygen from alveoli to cells, and carbon dioxide from cells to alveoli

pulmonary ventilation

inspiration (inhalation) and expiration (exhalation)

alveolar ventilation

movement of air into and out of the alveoli

forced breathing

muscles become active. expiration is then active

external respiration

takes place within lungs. Diffusion of gases between alveolar air and pulmomary capillary blood across the respiratory membrane

internal respiration

takes place in the tissues throughout the body. Diffusion of gases between blood and interstitial fluids across the capillary endothelium.

Air as it moves from nose to pulmonary capillary

-Enters through nostrils (filtered by nose hairs)
-Flows into the nasal cavity (lined with moist epithelial tissue and blood vessels that warm incoming air)
-Enters the pharynx (throat)
-Passes into the trachea (windpipe)
-Trachea branches into right and left bronchi
-then to the bronchioles
-then to the lungs and on to the alveoli
-finally the alveolar wall and the capillary wall
Gas exchange occurs ONLY between the alveolus and the capillary.

Partial pressure of 02 and CO2 in alveoli

Average about 104 and 400 mm Hg respectively

Diffusion

-the spontaneous movement of gases, without the use of any energy or effort by the body, between the gas in the alveoli and the blood in the capillaries in the lungs.

Partial Pressure

-pressure of each individual gas in a mexture of gases.
- diffusion of each gas depends on its partial pressure.

C02 Waste

-formed during metabolism
-combines with water to form carbonic acid (H2CO3)
-carbonic acid dissociates into bicarbonate (HCO3) and hydrogen ion (H+)

Gas Volume

- When volume in a space increases, molecules are farther away from each other -- pressure inside space DECREASES.
-When volume in a space decreases, molecules are closer to each other -- pressure inside space INCREASES