Control of Breathing Breathing control centers in the brain Breathing control centers in the brain Keep breathing in tune with body needs, sensing and responding to the CO2 level in the blood Brain Cerebrospinal fluid Pons Medulla Nerve signals trigger contraction of muscles Breathing control centers stimulated by: CO2 increase / pH decrease in blood indicating CO2 and O2 levels CO2 and O2 sensors in aorta Diaphragm Rib muscles

Neural Regulation of ventilation rate Activity of respiratory muscles is transmitted to the brain by the nerves Neural centers that control rate and depth are located in the medulla Normal respiratory rate is 12–15 respirations per minute increased respiratory rate often due to extra oxygen needs

Factors Influencing Respiratory Rate and Depth Chemical factors Carbon dioxide levels Level of carbon dioxide in the blood is the main regulatory chemical for respiration Oxygen levels is Less effective than changes in blood CO2 level Changes in Co2 and O2 concentration in the blood are detected by chemoreceptors in the aorta and carotid artery Information is sent to the medulla oblongata

Homeostasis of blood CO2 level helps regulate breathing rate – negative feedback

Factors Influencing Respiratory Rate and Depth Physical factors Increased body temperature Exercise Talking Coughing Conscious control Emotional factors

Chronic Bronchitis

Emphysema airways and air sacs have been damaged. need to forcefully blow the air out in order to empty the lungs --- puts pressure on the airways and causes them to collapse. walls of the air sacs are destroyed-- less surface area for gas exchange.. Emphysema is characterized by shortness of breath (SOB).

Destruction of tissue leaves little surface area, few capillaries, and large air spaces Much normal tissue creates large surface area with many capillaries, which are filled with RBCs (red cells)

Emphysema Alveoli enlarge as adjacent chambers break through Loss of elastic recoil of lung tissue Over-inflation of the lungs leads to a permanently expanded barrel chest Cyanosis appears late in the disease Cyanosis--A bluish discolouration of the skin and mucous membranes; a sign that oxygen in the blood is dangerously diminished --as in carbon monoxide poisoning

Asthma -- reference only Chronic inflamed hypersensitive bronchiole passages Response to irritants with dyspnea*, coughing, and wheezing Dyspnea--Difficult or laboured respiration

Volume of air moved in / out of the Lungs Between which points is air moving into the lungs? Between which points is air moving out of the lungs? At which point is the lungs most inflated / lung volume largest?

Between which points is air moving into the lungs? A1-A3 Between which points is air moving out of the lungs? A3-A5 At which point is the lungs most inflated / lung volume largest? A3 / C2