Respiratory System Normal breathing rate 14-20 breaths/min Average person uses about .25 liters of oxygen/min Lungs hold about 4-6 liters of air Oxygen is needed to metabolize glucose and release water and carbon dioxide

Respiration 3 Components of Respiration Breathing  entrance/exit of air to/from lungs 2a. External respiration  movement of air to blood 2b. Internal respiration  movement of blood/oxygen to tissue Aerobic cellular respiration  production of ATP in cells from metabolism of glucose

Respiratory Structures Description Function Nasal Cavity Hollow space in nose Filters and warms air Pharynx Chamber behind oral cavity Connection to surrounding regions Glottis Opening to larynx Passes air into larynx Larynx Vocal chords Sound production Trachea Tube that connects larynx with bronchi Passage of air to bronchi Bronchi Major divisions that enter lungs Passage of air to each lung Bronchioles Small branched tubes that lead to alveoli Passage of air to alveoli Lungs Organs that occupy thoracic cavity Gas exchange

Lungs Right lung has 3 lobes; left lung has 2 lobes Lie at either side of the heart Base of the lung is broad and concave to fit into the convex diaphragm Approximately 300 million alveoli in lungs Alveoli increase the surface area of the lung so more oxygen can be taken up Alveoli are bathed in surfactant, which reduces their surface tension and prevents collapse Gas filled alveoli are very light; a piece of lung usually floats on water Ear Lobes 3 lobes  <---2 lobes

Alveoli with attached arterioles and venules (Capillaries)

The Anatomy of Breathing During ventilation, there is continuous air flow from pharynx to alveoli The rib cage forms the top and sides of the thoracic cavity. The diaphragm forms the bottom of the thoracic cavity The outer pleural membrane is attached to the rib cage and diaphragm

The Physiology of Breathing Inspiration Respiratory center is located in the medulla oblongata Neurons in the RC fire automatically in a rhythmic cycle Carbon dioxide levels in blood, lungs, or brain can cause changes in the activity of the RC When carbon dioxide levels rise, receptors in body send message to MO to increase the firing of respiratory neurons MO sends impulses directly to the diaphragm and rib muscles In relaxed state the, diaphragm is dome shaped. When excited by the MO, the dome falls, intercostal muscles contract, pushing the rib cage out These actions create a vacuum of negative space in the lungs, the volume of the lungs increases, and air rushes in Humans inhale by negative pressure Deep inspiration excites stretch receptors in alveoli, which in turn send a message in MO to stop inhalation

The Physiology of Breathing Expiration Diaphragm and rib muscles relax and push upward and inward on the lungs Deep expiration excites stretch receptors in alveoli, which in turn send a message in MO to stop inhalation

Lung Capacity Lungs hold about 4-6 liters of air Tidal Volume  amount of air moved in and out in 1 breath (.1-.2 liters) Vital Capacity  Maximum amount of air taken in 1 breath (3.1 liters) Residual Volume After all air is expelled, there is still some air in lungs (<1 liter) Healthy Lung Smoker’s lung

Internal & External Respiration Alveoli and blood vessels both consist of a thin layer of cells Both the alveoli and blood vessels allow for the free passage of oxygen, carbon dioxide Diffusion ALONE governs the exchange of oxygen and carbon dioxide at the alveoli Oxygen diffuses from the O2 rich alveoli to the O2 poor blood vessels Carbon dioxide diffuses from the CO2 rich blood vessels to CO2 poor alveoli

Oxygen & Hemoglobin Breathing at high altitude is less effective than at low altitudes because the concentration of oxygen is low, therefore less O2 diffuses into the blood Hemoglobin tends to attach to oxygen at cooler temperatures and tends to release oxygen at warmer temperatures

Internal Respiration Blood that enters the tissues is bright red because the pigment hemoglobin turns red when attached to oxygen Oxygen diffuses out of the blood and into the tissues (at the capillaries) Carbon dioxide diffuses from the tissue to the blood (at the capillaries) Deoxygenated red blood cells have no oxygen; turning the RBC blue Red blood cells also pick up carbon dioxide and deliver it to the lungs