Transcript Ch 28: Circulatory System

Ch 29: Respiratory System
Sec 22-1: Adaptations for Gas Exchange
Diffusion
Gas exchange in all organisms relies on diffusion…
- Passive movement of molecules from high to low
concentration
C6H12O6 + 6O2 → 6CO2 + 6H2O
Cellular respiration
- Depletes oxygen
- Increases carbon dioxide
- Creates concentration gradients that favor diffusion of
CO2 out of cells & O2 into cells
General Features of Respiration
All respiratory systems share 3 features that facilitate
diffusion:
1) Respiratory surface must remain wet
-
O2/CO2 must dissolve in water before they can diffuse
2) Cells lining surfaces must be very thin
3) Must have large surface area in contact w/ environment
-
Allows for adequate gas exchange
General Features of Respiration
General Stages of Gas Exchange: (all organisms)
1) Pulmonary ventilation
-
Air (or water) high in O2 & low in CO2 is moved past
respiratory surface…usually by muscular movements
2) External respiration
-
O2 & CO2 are exchanged through respiratory surface
by diffusion…O2 diffuses into capillaries, CO2 back out
General Features of Respiration
General Stages of Gas Exchange: (all organisms)
3) Respiratory gas transport
-
O2 & CO2 transported from respiratory system to
body tissues as blood is pumped through body
4) Internal respiration
-
O2 & CO2 exchanged between blood supply & body
tissues
5) Carbon dioxide output
-
CO2 returned to respiratory system from body
tissues & exchanged w/ O2 in lungs
Ch 29: Respiratory System
Sec 22-2: How the Human Respiratory
System Works
Organs of the Respiratory System
Respiratory system divided into two main parts:
1) Conducting portion
-
Series of passageways that carry air in/out of lungs
2) Gas-exchange portion
-
Where gases are exchanged between air & blood
Organs of the Respiratory System
Respiratory system includes:
1)
2)
3)
4)
5)
6)
7)
Nose
Pharynx
Larynx
Trachea
Bronchi
Lungs
Alveoli
Functions of the Respiratory System
Special functions of respiratory system:
1) Oversee gas exchange between blood & external
environment
2) Purify, warm, & humidify incoming air
3) Aids in temperature control
Upper Respiratory Tract
Anatomy of the Respiratory System
Nasal Cavity
- Olfactory receptors located in lining of the superior
surface…provide sense of smell
- Rest of cavity lined w/ tissue that moistens incoming
air & traps foreign particles
Anatomy of the Respiratory System
Paranasal Sinuses
- Cavities within bones surrounding nasal cavity
- Functions:
1) Lighten the skull
2) Act as resonance chambers for speech
3) Produce mucus that drains into nasal cavity
Anatomy of the Respiratory System
Pharynx
- Separates food/water into esophagus & air into the
larynx
Larynx (voice box)
- Opening to trachea
- Plays role in speech…vocal cords found here
- Thyroid cartilage (anterior portion) forms Adam’s
Apple
Anatomy of the Respiratory System
Trachea
- Commonly known as the “windpipe”
- Lined with ciliated cells
*Cilia expel mucus loaded w/ dust & other debris away
from lungs
- Walls reinforced w/ C-shaped hyaline cartilage
Anatomy of the Respiratory System
Primary Bronchi
- Division of the base of the trachea
- Branches off into left & right sides…lead to lungs
- Right bronchus wider, shorter, & straighter than left
- Once in lungs, they subdivide into smaller & smaller
branches
Anatomy of the Respiratory System
Lungs
Anatomy of the Respiratory System
Lungs
- Occupy most of thoracic cavity
- Each lung divided into lobes
1) Left lung = 2 lobes
2) Right lung = 3 lobes
Anatomy of the Respiratory System
Bronchioles
- Smallest branches of bronchi
- End in alveoli
Alveoli
- Sites for actual gas exchange
Anatomy of the Respiratory System
Alveoli (“Air-Blood Barrier”)
- Each alveolus is wrapped in capillaries for maximum
O2/CO2 exchange
- Capillaries are only 1 cell thick & coated in a thin layer
of fluid
- Fluid allows gases to dissolve & diffuse into blood
stream easily
Mechanics of Breathing
Pulmonary Ventilation
- Completely mechanical process
- Depends on volume changes in thoracic cavity
- Volume changes lead to pressure changes which
ultimately leads to flow of gases to equalize pressure
Mechanics of Breathing
Two Phases
1) Inspiration
- Air flowing
INTO lungs
2) Expiration
- Air flowing
OUT of lungs
Mechanics of Breathing
Inspiration
- Requires energy
- Diaphragm & external intercostal muscles (between
ribs) contract
- Size/volume of thoracic cavity increases
- External air pulled into lungs due to increased volume
(*Don’t forget your Gas Laws from Chem!!)
Mechanics of Breathing
Mechanics of Breathing
Expiration
- Fairly passive process
- Depends on natural elasticity of lung
- As muscles relax, air is pushed out of lungs
- Can be forced by contracting abdominal muscles &
internal intercostals (which contract rib cage)
Mechanics of Breathing
Non-respiratory Air Movements
Air movements that have nothing to do with gas exchange:
Cough/sneeze (clearing lungs of debris)
Laughing
Crying
Yawn
Hiccup
*Caused by reflexes or involuntary actions.
O2 & CO2 Transport Mechanisms
O2 & CO2 are transported using different mechanisms:
1) Oxygen
-
Binds loosely & reversibly to hemoglobin on RBCs
-
Each hemoglobin holds 4 O2 molecules (8 oxygen atoms)
-
Nearly all O2 carried by blood is on hemoglobin molecules
O2 & CO2 Transport Mechanisms
O2 & CO2 are transported using different mechanisms:
2) Carbon Dioxide
- Transported in three different ways:
a) 70% of CO2 reacts w/ H2O to form bicarbonate ions
that then diffuse into the plasma
b) 20% binds to hemoglobin as it returns to the lungs
c) Remaining 10% is dissolved in plasma & not removed
Respiratory Volumes & Capacities
Spirometer
- Instrument used to measure respiratory capacities
Respiratory Volumes & Capacities
Total Lung Capacity (TLC)
- Approximately 6 liters of air
Tidal Volume (TV)
- Amount of air moved by a normal breath
- Usually about 500mL of air
Residual Volume (RV)
- Amount of air left in lungs after maximum exhalation
- About 1.2 L
Respiratory Volumes & Capacities
Dead Space Volume (DSV)
- Air that remains in conducting zone
- Approximately 150mL never reaches alveoli
Factors that affect respiratory capacities:
Person’s size
Age
Gender
Physical condition
Respiratory Control
Breathing Rate
- Controlled by the medulla oblongata
- Changes with the concentration of CO2 in the blood
*Increased CO2 = Increased BR
*Decreased CO2 = Decreased BR
(An increase in CO2 of just 0.3% will cause BR to double!)
Respiratory Control
Factors influencing respiratory rate:
1) Physical factors
-
Increased body temp
Exercise
Talking
Coughing
2) Volition
-
Conscious control
3) Emotional factors
Respiratory Control
Factors influencing respiratory rate:
4) Chemical factors
a) Carbon dioxide levels
- Main regulatory mechanism
- Various sensors located in blood vessels throughout body
b) Oxygen levels
- Only influence respiration if O2 levels drop drastically
- Sensors found in aorta & carotid arteries
Ch 29: Respiratory System
Sec 22-3: Homeostatic Imbalances
Carbon Monoxide Poisoning
Carbon Monoxide
- Toxic gas produced by combustion of fossil fuels
- Can be deadly at concentrations as low as 0.1%
- Binds to hemoglobin 200 times easier than O2 does…
blocks O2 from binding & leads to asphyxiation.
How can you tell difference between someone who dies of
regular asphyxiation & someone who dies of CO
asphyxiation?
Respiratory Disorders
Chronic Obstructive Pulmonary Disease (COPD)
- Major cause of death/disability in U.S.
- Features of COPD:
1) Patients almost always have history of smoking
2) Dyspnea (short of breath) becomes progressively worse
3) Coughing & frequent pulmonary infections are common
4) Most victims have difficulty clearing out CO2
5) Those afflicted ultimately develop respiratory failure
- Two major categories:
1) Chronic bronchitis
2) Emphysema
Respiratory Disorders
Chronic bronchitis
- Lining of lower respiratory passages becomes severely
inflamed
- Causes increased mucus production
- Mucus pools in base of lungs impairing ventilation &
gas exchange
- Increased risk of lung infection & pneumonia
Respiratory Disorders
Emphysema
- Alveoli become enlarged & break adjacent alveoli
- Chronic inflammation leads to lung fibrosis
- Airways collapse during expiration requiring large
amounts of energy to exhale
**Warning!! GRAPHIC PICTURES AHEAD!!**
Respiratory Disorders
Respiratory Disorders
Lung Cancer
- Accounts for 1/3 of all cancer deaths in U.S.
- Smoking & air pollution increases risks
- Three common types
Respiratory Disorders
Sudden Infant Death Syndrome (SIDS)
- Apparently healthy infant stops breathing & dies
while sleeping
- Some cases are thought to involve poorly functioning
respiratory control center in brain
- 1/3 of cases appear to be due to heart rhythm
abnormalities
Respiratory Disorders
Asthma
- Chronically inflamed, hypersensitive bronchioles
- Response to environmental irritants includes dyspnea
(shortness of breath), coughing, & wheezing
http://www.bing.com/videos/watch/video/asthma-pediatric/bdj1yf0e
Respiratory Disorders
Cystic Fibrosis (CF)
- Over-secretion of thick, sticky mucus in the airways
- Causes clogs to develop & poor gas exchange
- Result of a genetic mutation before birth
- One of the most chronic respiratory diseases in
children & young adults
- Often leads to premature death
Respiratory Disorders
Effects of Aging:
- Elasticity of lungs decreases
- Blood oxygen levels decrease
- Response to high CO2 levels decreases
- More risk of respiratory tract infection