Human Biology BIOL 104 Talk Eight The Respiratory

Human Biology (BIOL 104) Talk Eight: The Respiratory System (Chapter 30) Drug Addiction (Not in book)

The Respiratory System • Breathing is an involuntary event. How often a breath is taken and how much air is inhaled or exhaled are tightly regulated by the respiratory center in the brain. • Humans, when they aren’t exerting themselves, breathe approximately 15 times per minute on average. • Pulmonary ventilation occurs via inhalation (breathing). During inhalation, air enters the body through the nasal cavity located just inside the nose

The Respiratory System • As air passes through the nasal cavity, the air is warmed to body temperature and humidified. • The respiratory tract is coated with mucus to seal the tissues from direct contact with air. Mucus is high in water. • As air crosses these surfaces of the mucous membranes, it picks up water. • These processes help equilibrate the air to the body conditions, reducing any damage that cold, dry air can cause. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Cleaning air • Particulate matter that is floating in the air is removed in the nasal passages via mucus and cilia. • The processes of warming, humidifying, and removing particles are important protective mechanisms that prevent damage to the trachea and lungs. • Thus, inhalation serves several purposes in addition to bringing oxygen into the respiratory system. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

The Respiratory System • Gas Conditioning – as gases pass through the nasal cavity and paransal sinuses, inhaled air becomes turbulent. • The gases in the air are: • warmed to body temperature • humidified • cleaned of particulate matter • Gas Exchange - respiration • Supplies body with oxygen • Disposes of carbon dioxide • Protects respiratory surfaces • Site for olfactory sensation Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Bronchi in the Conducting Zone • Consists of: – Respiratory muscles – diaphragm and other muscles that promote ventilation • Respiratory zone – site of external respiration – respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli. • Conducting zones • Provides rigid conduits for air to reach the sites of gas exchange • Includes nose, nasal cavity, pharynx, trachea • Air passages undergo 23 orders of branching in the lungs Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Bronchi in the Conducting Zone • Bronchial tree - extensively branching respiratory passageways – Primary bronchi (main bronchi) • Largest bronchi • Right main bronchi - wider and shorter than the left – Secondary (lobar) bronchi • Three on the right • Two on the left – Tertiary (segmental) bronchi branch into each lung segment – Bronchioles - little bronchi, less than 1 mm in diameter – Terminal bronchioles - less than 0. 5 mm in diameter Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Lungs: Bronchi and Alveoli • The end of the trachea bifurcates (divides) to the right and left lungs. • The lungs are not identical. The right lung is larger and contains three lobes, whereas the smaller left lung contains two lobes. – This allows room for the heart • The muscular diaphragm, which facilitates breathing, is inferior to (below) the lungs and marks the end of the thoracic cavity. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Features of Alveoli • The terminal bronchioles subdivide into microscopic branches called respiratory bronchioles. • The respiratory bronchioles subdivide into several alveolar ducts. Numerous alveoli and alveolar sacs surround the alveolar ducts. • Alveoli cell types • Type I cells site of gas exchange • Type II cells - secrete surfactant • Macrophages • Mucous glands secrete mucus into the airways, keeping them moist and flexible. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Features of Alveoli • At the end of each duct are approximately 100 alveolar sacs, each containing 20 to 30 alveoli that are 200 to 300 microns in diameter. • Gas exchange occurs only in alveoli. Alveoli are made of thin-walled parenchymal cells, typically one-cell thick • Alveoli are in direct contact with capillaries (one-cell thick) of the circulatory system. • Such intimate contact ensures that oxygen will diffuse from alveoli into the blood and be distributed to the cells of the body. • In addition, the carbon dioxide that was produced by cells as a waste product will diffuse from the blood into alveoli to be exhaled. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Features of Alveoli • The anatomical arrangement of capillaries and alveoli emphasizes the structural and functional relationship of the respiratory and circulatory systems. • Ae there are so many alveoli (~300 million per lung) within each alveolar sac and so many sacs at the end of each alveolar duct, the lungs have a sponge-like consistency. • This organization produces a very large surface area (75 m 2) that is available for gas exchange. • This large surface area, combined with the thin-walled nature of the alveolar parenchymal cells, allows gases to easily diffuse across the cells. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Gas Exchange across the Alveoli • The partial pressures of oxygen and carbon dioxide change as blood moves through the body. • In short, the change in partial pressure from the alveoli to the capillaries drives the oxygen into the tissues and the carbon dioxide into the blood from the tissues. • The blood is then transported to the lungs where differences in pressure in the alveoli result in the movement of carbon dioxide out of the blood into the lungs, and oxygen into the blood. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Internal – External Respiration • Internal Respiration • The diffusion of O 2 from an area of high concentration ( the alveoli) to an area of low concentration ( deoxygenated blood in capillary bed around each of the 300 million alveoli). • High concentration of CO 2 in this blood (from cell respiration) so it diffuses from the capillaries into the alveoli. • External Respiration • In short the exact opposite occurs, O 2 diffuses from blood to cells for cell respiration to occur, and the waste from cell respiration (a high level of CO 2) diffuses into the blood. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Lung Volumes and Capacities • Human lung size is determined by genetics, sex, height, and, ultimately, athletic/occupational training. • At maximal capacity, an average lung can hold almost six liters of air, but lungs do not usually operate at maximal capacity. • Air in the lungs is measured in terms of lung volumes and lung capacities • Tidal volume (TV) measures amount of air that is inspired and expired during a normal breath. • On average, this volume is around onehalf liter, which is a little less than the capacity of a 20 -ounce drink bottle. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Lung Volumes and Capacities • The expiratory reserve volume (ERV) - additional amount of air that can be exhaled after a normal exhalation. It is the reserve amount that can be exhaled beyond what is normal. • The inspiratory reserve volume (IRV) is the additional amount of air that can be inhaled after normal inhalation. • The residual volume (RV) - amount of air that is left after expiratory reserve volume is exhaled. The lungs are never completely empty: • The vital capacity (VC) measures the maximum amount of air inhaled or exhaled during a respiratory cycle. Sum of the expiratory reserve volume, tidal volume, and inspiratory reserve volume. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Lung Volumes and Capacities • The inspiratory capacity (IC) is the amount of air that can be inhaled after the end of a normal expiration. • It is, therefore, the sum of the tidal volume and inspiratory reserve volume. • The functional residual capacity • (FRC) includes the expiratory reserve volume and the residual volume. • The FRC measures the amount of air that can be exhaled after a normal exhalation. • The total lung capacity (TLC) is a measurement of the total amount of air that the lung can hold. • It is the sum of the residual volume, expiratory reserve volume, tidal volume, and inspiratory reserve volume. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Pulmonary Ventilation (breathing) • Inspiration (A) • This results from the contraction of the intercostal muscles, the muscles that are connected to the rib cage. • Lung volume expands because the diaphragm contracts and the intercostals muscles contract, thus expanding the thoracic cavity. • This increase in the volume of the thoracic cavity lowers pressure compared to the • atmosphere, so air rushes into the lungs, thus increasing its volume. • The resulting increase in volume is largely attributed to an increase in alveolar space, because the bronchioles and bronchi are stiff structures that do not change in size. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Pulmonary Ventilation (breathing) • Expiration (B) • The lungs recoil to force the air out of the lungs, and the intercostal muscles relax, returning the chest wall back to its original position. • The diaphragm also relaxes and moves higher into the thoracic cavity. • This increases the pressure within the thoracic cavity relative to the environment, and air rushes out of the lungs. • The movement of air out of the lungs is a passive event. No muscles are contracting to expel the air. Copyright: Open. Stax Biology for AP Courses, Open. Stax, and Rice University

Breathing at High Altitude • At sea level, because air is compressible, the weight of all that air above us compresses the air around us, making it denser. • As you go up a mountain, the air becomes less compressed and is therefore thinner. • The important effect of this decrease in pressure is this: – in a given volume of air, there are fewer molecules present. This is really just another way of saying that the pressure is lower (this is called Boyle's law). This bottle was photographed at 3600 m (left) then again at sea level (right) From Wikimedia Commons, a freely licensed media file repository

Breathing at High Altitude • The percentage of those molecules that are oxygen is exactly the same: 21%. • The problem is that there are fewer molecules of everything present, including oxygen. • So although the percentage of oxygen in the atmosphere is the same, the thinner air means there is less oxygen to breathe. This bottle was photographed at 3600 m (left) then again at sea level (right) From Wikimedia Commons, a freely licensed media file repository

Breathing at High Altitude • The function of the lungs is to expose blood to fresh air, and breathing faster essentially increases the flow of fresh air past the blood. • This means that whenever an oxygen molecule is taken away by the blood, it is quickly replaced by another one. • Carbon dioxide (CO 2) is constantly produced by the body and the lungs remove it by allowing it to diffuse into the fresh air in the lungs. • Increasing the flow of fresh air through the lungs, by hyperventilating, increases the rate at which CO 2 is lost. From Wikimedia Commons, a freely licensed media file repository

Breathing at High Altitude • Because CO 2 is an acid gas, losing more of it from the blood leaves the blood relatively alkaline. • At altitudes up to about 6000 m, the kidneys correct the alkalinity of the blood over a few days by removing alkali (in the form of bicarbonate ions, HCO 3) from the blood. • When the blood passing through an area of lung isn’t picking up enough oxygen, the blood vessels carrying that blood tighten, so that less deoxygenated blood can get through the lungs. • This is called hypoxic pulmonary vasoconstriction. – means that less deoxygenated blood gets through, so there is more oxygen in the mixture of blood leaving the lungs. From Wikimedia Commons, a freely licensed media file repository

Non-respiratory Air Movements • Coughing: deep inspiration, closure of the glottis, followed by strong expulsion that forces open the glottis • • Sneeze: = air exits via nasal cavity rather than oral cavity • Yawn: = deep inspiration, pause, sudden expiration • Laugh: = deep inspiration followed by sudden & rapid expirations • Crying: is very similar, but glottis remains open the entire time…why you often choke when you cry • Hiccup: = spastic diaphragm contractions

Drugs and addiction Important but NOT in book

Drugs and addiction • Drug addiction is a condition characterized by compulsive drug intake, craving and seeking, despite negative consequences associated with drug use. • The activity of any drug varies with dose – The amount of the drug taken over time • The amount of a drug taken to be toxic or lethal depends upon the chemical structure of the drug – Also body size and other physiological variables From Wikimedia Commons, a freely licensed media file repository

How drugs enter the body • In the US, most drugs are inhaled and quickly enter the blood system and affect the brain. • However, it is important to remember that the most popular drug in the US is caffeine! • The second is alcohol! • It is important to remember what is a drug! From Wikimedia Commons, a freely licensed media file repository

Drugs and addiction • Although being addicted implies drug dependence, it is possible to be dependent on a drug without being addicted. • People that take drugs to treat diseases and disorders, which interfere with their ability to function, may experience improvement of their condition. From Wikimedia Commons, a freely licensed media file repository

How drugs enter the body • The way in which a drug enters the body often affects its resulting concentration in body tissues. • Example: Cocaine – A product of the coca plant – grows in the high Andes • Cocaine exists in many forms that differ in both conc of the drug and its molecular form. • Coca leaves are chewed by South American Indians – Concentrations absorbed by the gut are low. From Wikimedia Commons, a freely licensed media file repository

How drugs enter the body • By contrast: • When cocaine is purified into a powder and sniffed the rate and concentration of absorption is increased many times. – Cocaine is sometimes further purified into crack • Whether cocaine is sniffed or smoked, it is inhaled not as a gas, but as small particles • For these chemicals to be absorbed they must first adhere to lung tissue. From Wikimedia Commons, a freely licensed media file repository

How drugs enter the body • Other drugs are injected into the body. • Can be injected into veins, or under the skin • Continued uses always leads to infection and amputation of damaged tissue. From Wikimedia Commons, a freely licensed media file repository

How drugs enter the body • Chemicals can be highly concentrated within a particle • Thus these particles cause substantial damage to lung tissue • Sniffing cocaine powder also causes substantial damage to cells in the nasal passage and rot a person nose • Can also eat away at the roof of the mouth. From Wikimedia Commons, a freely licensed media file repository

Addiction • Addiction has been defined as – “Compulsive physiological and psychological need for a substance” • This implies there is both a biological basis and a mental basis for addiction. • However, as all brain function is biochemically based, the distinction between physiological and psychological addiction is becoming blurred.

Addiction • Ventral tegmental area (VTA) • Thought to be positive enforcement area (pleasure center). • Experiments on rats and rhesus monkeys have show that both would rather electrically stimulate this area of the brain than eat – even if near to starvation • Nucleus accumbens (NA) • joined to the VTA by synaptic connections • Interprets the stimulation signal from the VTA From Wikimedia Commons, a freely licensed media file repository

Addiction • Frontal cortex (FC) • Play a part in impulse control, judgment, language production, working memory, motor function, problem solving, sexual behavior, socialization and spontaneity. • Assist in planning, coordinating, controlling and executing behavior. • This is why behavioral changes occur which are hard to break. From Wikimedia Commons, a freely licensed media file repository

Addiction • So these positive reinforcement areas are affected by drugs • Amphetamines indirectly stimulate the neurons of the VTA – Used as a treatment for depression • Cocaine acts on the brain cells of the VTA that secrete dopamine – Produces euphoria. From Wikimedia Commons, a freely licensed media file repository

Addiction • Opiates, marijuana, caffeine, and alcohol all produce VTA self-reinforcing effects. • Drugs of abuse take over the neuronal circuitry involved in motivation and reward, leading to altered engagement of learning processes. • Because of this, drugassociated cues can trigger cravings as well as unconcious or compulsive drug-seeking behavior, with the sense that voluntary control over drug use is lost. From Wikimedia Commons, a freely licensed media file repository

Addiction • The stages of problematic use could be defined as Pre-occupation/anticipation, binge/intoxication & withdrawal/negative effect • As drugs activate neuronal pathways in the brain we effectivly learn to use them, these pathways in the brain not only get 'laid down' stronger and stronger with sucessive use but also activate faster – the quicker the effect or 'high' the stronger this dysfunctional learning.

Addiction • Objects, people or places also seem to to be strongly associated with the drug experience, making them 'Triggers' to 'Cravings' – increase the chances of further use. • Animal studies have shown drug availabilty over and above the actual effects of the substance) are associated with stimuli, exposure to objects associated with use trigger the release of adrenaline (Fight or flight) – this excitation can be perceived as a 'need' to use.

Addiction • Users in addictive drugs in the US in 1991 • The top three are widely not considered drugs by most of the population • All of these three produce addictive behavior. From Wikimedia Commons, a freely licensed media file repository

METH • Methamphetamine or “Meth”, a derivative of amphetamine is an extremely powerful stimulant that affects the central nervous system. • Developed in 1919 by Japanese pharmacologist. • Although its initial uses were for medical purposes, its ability to increase energy and to enable users to function without sleep made it attractive for military purposes during World War II.

METH • Meth has undergone both legal and illegal uses in the United States. – As early as the 1930 s it was used therapeutically to treat asthma and epileptic seizures – In the 1950 s it was given to housewives to cope with bordem and depression – During the 1970 s meth was a primary appetite suppressant in prescription diet pills. • The illicit demand for meth resulted in forged prescriptions, theft and a black market.

METH labs • How is Meth Made? – ephedrine reduction. • In this process, ephedrine or psuedoephedrine are chemically extract from over the counter cold medicines. • Red phosphorous (match tips), iodine (table salt), acetone (nail varnish remover), and sulphuric acid (car battery) are all that is required.

METH labs • Lastly, drain cleaner, camping fuel and paint thinner are used to dry out the drug into a powder. • Clandestine labs are often simple, crude and consist of common household items. • Meth can be cooked in basements, old buildings, motel rooms, camping trailers and moving vehicles.

From Wikimedia Commons, a freely licensed media file repository

How to tell if Someone is on or has been using Meth • Meth affects nerve endings throughout a user's body. • Many people feel a sensation of small bugs, known as "Meth Mites", moving right under their skin. • They scratch, pick and dig the spots, trying to relieve the itching. • The Meth Mites and the scratching result in sores and serious infections. From Wikimedia Commons, a freely licensed media file repository

How to tell if Someone is on or has been using Meth • The heated substance, when fully aspirated, swirls through the users' teeth and gums, inevitably leading to sores which never heal Meth Mouth • Tooth enamel wears away quickly as entire rows of teeth dissolve to the gum line. • Collects in the nasal passages which drain in the back of the throat, effectively corroding your entire face. From Wikimedia Commons, a freely licensed media file repository

How to tell if Someone is on or has been using Meth • Chronic meth users are typically gaunt, maintain poor hygiene. • Lose interesting in eating – Digestive system shuts down due to chemicals used to make meth • Kidney and liver shut down – Due to all the toxic chemicals • Skin scratched off, infections • Blindness. From Wikimedia Commons, a freely licensed media file repository

Environmental Damage • Each pound of meth produced leaves behind five -seven pounds of toxic waste. • Toxic byproduct is often poured down drains or directly into the ground, creating long term hazards. • Mobile labs and meth lab dump-sites are found threaten our state’s natural resources. • Clean-up costs range from $5, 000 to $50, 000. . 5, 000 -$50, 000