Respiratory system
The Respiratory System
The respiratory system is made up of organs and tissues that help you breathe. The main parts of this system are the airways, the lungs and linked blood vessels, and the muscles that enable breathing.
The Respiratory System
The airways are pipes that carry oxygen-rich air to your lungs. They also carry carbon dioxide, a waste gas, out of your lungs. The airways include your:
Nose and linked air passages (called nasal cavities)
Mouth
Larynx (LAR-ingks), or voice box
Trachea (TRA-ke-ah), or windpipe
Tubes called bronchial tubes or bronchi, and their branches
Air first enters your body through your nose or mouth, which wets and warms the air. (Cold, dry air can irritate your lungs.) The air then travels through your voice box and down your windpipe. The windpipe splits into two bronchial tubes that enter your lungs.
A thin flap of tissue called the epiglottis (ep-ih-GLOT-is) covers your windpipe when you swallow. This prevents food and drink from entering the air passages that lead to your lungs.
Except for the mouth and some parts of the nose, all of the airways have special hairs called cilia (SIL-e-ah) that are coated with sticky mucus. The cilia trap germs and other foreign particles that enter your airways when you breathe in air.
These fine hairs then sweep the particles up to the nose or mouth. From there, they're swallowed, coughed, or sneezed out of the body. Nose hairs and mouth saliva also trap particles and germs.
Lungs and Blood Vessels
Your lungs and linked blood vessels deliver oxygen to your body and remove carbon dioxide from your body. Your lungs lie on either side of your breastbone and fill the inside of your chest cavity. Your left lung is slightly smaller than your right lung to allow room for your heart.
Within the lungs, your bronchi branch into thousands of smaller, thinner tubes called bronchioles. These tubes end in bunches of tiny round air sacs called alveoli (al-VEE-uhl-eye).
Each of these air sacs is covered in a mesh of tiny blood vessels called capillaries. The capillaries connect to a network of arteries and veins that move blood through your body.
The pulmonary (PULL-mun-ary) artery and its branches deliver blood rich in carbon dioxide (and lacking in oxygen) to the capillaries that surround the air sacs. Inside the air sacs, carbon dioxide moves from the blood into the air. At the same time, oxygen moves from the air into the blood in the capillaries.
The oxygen-rich blood then travels to the heart through the pulmonary vein and its branches. The heart pumps the oxygen-rich blood out to the body.
The lungs are divided into five main sections called lobes. Some people need to have a diseased lung lobe removed. However, they can still breathe well using the rest of their lung lobes.
Muscles Used for Breathing
Muscles near the lungs help expand and contract (tighten) the lungs to allow breathing. These muscles include the:
Diaphragm (DI-ah-fram)
Intercostal muscles
Abdominal muscles
Muscles in the neck and collarbone area
The diaphragm is a dome-shaped muscle located below your lungs. It separates the chest cavity from the abdominal cavity. The diaphragm is the main muscle used for breathing.
The intercostal muscles are located between your ribs. They also play a major role in helping you breathe.
Beneath your diaphragm are abdominal muscles. They help you breathe out when you're breathing fast (for example, during physical activity).
Muscles in your neck and collarbone area help you breathe in when other muscles involved in breathing don't work well, or when lung disease impairs your breathing.
Introduction
Primary Function: obtaining oxygen and removing carbon dioxide
Other functions: Filter air, produce sounds, sense of smell, regulation of blood pH
Respiration: the process of gas exchange between the atmosphere and body cells
Movement of air into the lungs – Ventilation
Gas exchange between blood and air (external respiration)
Gas transport in blood
Gas exchange between the blood and body cells (internal respiration)
Cellular Respiration – the process of oxygen use and CO2 production at the cellular level
Organs of the Respiratory System
Upper Respiratory Tract – nose, nasal cavity, paranasal sinuses, pharynx
Lower Respiratory Tract – larynx, trachea, bronchial tree, lungs
Nose – bones and cartilage support nose, two openings (nostrils), hair filters large particles
Nasal Cavity – hollow space behind the nose | Nasal septum – divides the nose (bone)
Nasal conchae – bones that divide the nasal cavity, support the mucus membrane and increase surface area (superior, middle, inferior)
* deviated septum – when the septum bends to one side
-- air is warmed as it enters the nasal cavity, sticky mucus traps particles which are pushed toward the pharynx and swallowed.
Paranasal Sinuses – spaces within the maxillary, frontal, ethmoid and sphenoid bones; reduce the weight of skull and are resonant chambers for voice.
Pharynx – behind the oral cavity, between the nasal cavity and larynx (space, not a structure) - nasopharynx, oropharynx, laryngopharynx
Larynx – enlargement at the top of the trachea and below pharynx, conducts air in and out of trachea, houses vocal cords
- composed of a framework of muscles and cartilages (thyroid (Adam’s apple), cricoids, epiglottic cartilages)
- false vocal folds (do not produce sound) – help close airway during swallowing
- true vocal folds (produce sound) – changing shape of the pharynx, and oral cavity changes sounds into words
- contracting and relaxing muscles changes pitch (increased tension = higher pitch)
Glottis – triangular slit that opens during breathing/talking, and closes during swallowing
Epiglottis – flaplike structure that stands upright, allows air to enter larynx, during swallowing it presses downward and prevents food from entering air passages
*Laryngitis – when the mucus membrane becomes swollen and prevents the vocal cords from vibrating freely
Trachea (windpipe) – flexible cylinder, about 12.5 cm long, extends downward in front of the esophagus
- contains about 20 C-shaped pieces of hyaline cartilage that prevent trachea from collapsing
Bronchial Tree – branched airways leading from the trachea to the air sacs in the lungs
Primary bronchii – left and right bronchioles alveolar ducts alveolar sacs alveoli
Gases are exchanged between alveoli and the blood stream
Lungs – soft spongy, cone-shaped organs in the thoracic cavity. The visceral pleura attaches to each lung surface and folds back to form the parietal pleura. The space between the visceral and parietal pleura is called the pleural cavity. Pleural cavity contains serous fluid to lubricate surfaces during breathing.
Left Lung – smaller, 2 lobes | Right Lung – larger than left, 3 lobes
Breathing Mechanism
Inspiration = inhalation | Expiration = exhalationINHALATION
1. The diaphragm moves downward and the atmospheric pressure in the alveoli falls, which forces air into the airways
2. External intercostals muscles contract, raising ribs and sternum and enlarges the cavity even more
3. Pleural membranes held tightly together, move with the contractions of muscles
4. Surface tension in the alveoli (caused by water) makes it difficult to inflate them. Surfactant reduces tendency of alveoli to collapse. (Lack or surfactant in preemies can cause respiratory distress)
5. A deeper breath can be achieved through other muscles – pectoralis minor and sternocleidomastoid
6. The first breath of a newborn is the hardest because all of the alveoli are only partially inflated.
*Since our breathing is based on atmospheric pressure (and the difference in the pressure in the lungs), if there is a hole in the pleural cavity, the lung collapses (deflates). This can happen if a person is stabbed or a broken rib pierces the lung.
EXHALATION
1. As diaphragm and other muscles relax, elastic recoil from surface tension
forces air out
2. If a person needs to exhale more air, internal (expiratory) intercostals muscles contract. Abdominal wall muscles (internal and external obliques, rectus abdominus and transverses abdominus) can help squeeze out more air.
3. These contractions increase the air pressure within the pleural cavity, forcing air out
NON-RESPIRATORY MOVEMENTS - Used to clear air passageways (coughing, sneezing) or express emotion (laughter, crying) – result from reflexes -- A hiccup is a sudden inspiration due to a spasm of the diaphragm, air striking vocal folds makes the sound ---A yawn may be caused by not enough blood becoming oxygenated, a yawn forces a deep breath
RESPIRATORY AIR VOLUMES AND CAPACITIES
Spirometry – measures volumes of air moving in and out of the lungs. 4 distinct respiratory volumes
Respiratory cycle – 1 inspiration + the following expiration
1. Resting Tidal volume – amount of air that enters the lungs during 1 cycle
2. Inspiratory and 3. Expiratory reserve volume – after forced inhalation or exhalation
4. Residual Volume – air remaining in the lungs even after forceful exhalation
*** Combining two or more of the respiratory volumes = respiratory capacities.
Inspiratory Reserve Volume + Expiratory Reserve Volume + Tidal Volume = Vital Capacity (maximum amount of air a person can exhale)
Tidal Volume + Inspiratory Reserve Volume = Inspiratory Capacity (max amount that can be inhaled)
Expiratory Reserve Volume + Residual Volume = Functional Residual Capacity (volume that remains in the lungs, resting)
Vital Capacity + Residual Volume = Total Lung Capacity (varies by sex, age, body size)
LABELING
Control of Breathing
Breathing is an involuntary act, the muscles are under voluntary control (we can choose to hold our breath)
Respiratory Center – groups of neurons in the brain that control inspiration and expiration (based in the medulla and the pons)
Medulla Rhythmicity Area (Medulla) – two neuron groups extend the length of the medulla oblongata
Dorsal Respiratory Group – controls basic rhythm of respiration
Ventral Respiratory Group – generate impulses o increase respiratory movements, forceful expiration
Pneumotaxic Area (Pons) – inhibit respiratory bursts originating from the dorsal resp group
Factors Affecting Breathing
*Chemosensitive areas – detect concentrations of chemicals like carbon dioxide and hydrogen
1. Rise in CO2
2. Low blood oxygen (peripheral chemoreceptors, carotid and aortic bodies, sense changes)
3. Inflation reflex – regulates the depth of breathing, prevents overinflation of the lungs
4. Emotional upset, fear and pain
*hyperventilation – increase breathing for a short time lowers the blood CO2 concentration and will allow you to hold your breath for a longer period
The thin respiratory membrane allows other solutes (alcohol) to diffuse across it and be exhaled breath analysis
Alveolar Gas Exchanges
Alveoli – clusters or air sacs at the end of the bronchioles
Respiratory Membrane – layers of simple squamous cells and capillaries
Oxygen and CO2 exchange occurs by diffusion
Gas Transport
Oxygen combines with hemoglobin in the blood (oxyhemoglobin / deoxyhemoglobin)
Hypoxia – oxygen defiency. Can be caused by inadequate bood flow, poisons (cyanide and carbon monoxide)
Asphyxia – excess CO2 in the blood, lack of oxygen
ILLNESSES RELATED TO THE RESPIRATORY SYSTEM
1. Cystic Fibrosis (genetic)
2. Asthma
3. Bronchitis
4. Apnea
5. Emphysema
6. Lung Cancer
7. Altitude Sickness
8. Chronic Obstructive Pulmonary Disease (COPD)
9. Sinusitis
10. Bacterial or Viral Infections (cold, flu, pneumonia
Review Guide: Respiratory System
1. Microorganisms that are removed by mucus are destroyed by the _____________________________
2. How can you change the pitch of the sound in the vocal cords? ___________________________
3. What causes altitude sickness? ____________________________
4. What is a deviated septum? __________________________
5. The area located behind the oral cavity and between the nasal cavity and the larynx is the ____________
6. What happens when the diaphragm is lowered? ____________________________
7. What is the function of the hyaline cartilage of the trachea? ________________________________
8. What protein combines with oxygen in the blood (for transport)? ________________________________
9. What is the function of the nasal conchae? ____________________________________
10. What is the triangular slit that opens and closes during talking called? ____________________
11. Where is the respiratory center located? ________________________________________
12. What structure resembles a bunch of grapes? _____________________________
13. What is the function of the mucus membrane that lines the nasal cavities? _______________________
14. The amount of air that enters and leaves the lungs during a normal respiratory cycle is the ___________
15. What is the main force for pushing air out of the lungs? ________________________
16. Which bone of the skull does NOT have a sinus? ______________________________________
17. What is the Adam's Apple? ____________________________________
18. What part of the respiratory center is responsible for maintaining breathing patterns? ________________
19. Oxygen travels from the pharynx to the ________________________ to the _____________________ and finally to the ________________________ where oxygen is exchanged with the bloodstream.
20. Why is the first breath of a newborn the most difficult? ___________________________________
21. How many lobes are in the right lung? _________ The left lung? __________
22. What happens to your respiration rate with the level of CO2 rises? ________________________
23. What tool would be used to measure "vital capacity"? ______________________________
24. What is hypoxia? _______________________________________
25. The respiratory membrane (at the alveoli) is made of what type of cells? _____________________
26. What is the function(s) of the respiratory system? ___________________________________
27. Name the organs of the upper respiratory tract? _________________________________________
lower respiratory tract? __________________________________________
28. In what body cavity are the lungs located? __________________________________
29. The taking in of air is called _______________________________________________
30. What structure prevents food from entering the airway during swallowing? _________________________
31. What fluid lubricates the lungs? ________________________________
32. Where does the trachea lie in relation to the esophagus? __________________________________
33. What is the main vessel the sends deoxygenated blood from the heart to the lungs? ______________
34. Name a genetic disorder that affects the respiratory system: _________________________________
35. Is breathing a voluntary or involuntary act? _______________________________________________
36. What is internal respiration? _________________________________________________
external respiration? ________________________________________________
37. How does oxygen enter blood capillaries? _______________________