Chapter 22 & 23. Respiratory & Circulatory Systems in Humans. Anatomy of Breathing Apparatus. Three phases of gas exchange in humans

Transcription

1 Chapter 22 & 23 Chapter 22: Big Ideas Respiratory & Circulatory Systems in Humans Mechanisms of Gas Exchange The Human Respiratory System Respiratory System Transport of Gases in the Human Body Three phases of gas exchange in humans 1. Breathing Inhale O2 in, Exhale CO2 out 2. Transport of oxygen and carbon dioxide in blood O2 diffuses from lungs to RBCs in bloodstream, CO2 diffuses from blood to lung cells 3. Exchange of gases with body cells Body tissues take up oxygen from blood and release carbon dioxide. Anatomy of Breathing Apparatus! The diaphragm Separates abdominal cavity from thoracic cavity helps ventilate lungs Contraction = flattens = lungs inflate due to negative pressure = inhale Relax diaphragm = exhale Pathway of air for gas exchange Pathway of air for gas exchange Air enters nostrils and into nasal cavity Filtered by hairs and mucus, warmed and humidified to the pharynx Paths for food and air intake cross then larynx (voicebox) Vocal cords and contracting muscles can create sound into the paired bronchi forks: one to each lung Branches into finer tubes called bronchioles to the alveoli grapelike clusters of air sacs, where gas exchange occurs with blood Millions in each lung! into the trachea (windpipe) held open by cartilage rings

2 Breathing Apparatus details Smoking = an attack on your respiratory system! Entire system is lined with moist Epithelium Breath is always moist! Surfactants & cilia can be damaged by long-term exposure to air pollutants and by smoking tobacco (4,000 chemicals!) Without healthy cilia, smokers must cough to clear dirty mucus from the trachea. Chronic obstructive pulmonary disease (COPD) can result, limiting! Cilia + mucus ( surfactants a lung ventilation and = cleaning system in trachea and bronchioles gas exchange. phospholipoprotein) Preterm babies suffer respiratory distress now administer artificial surfactants Traps dust, pollen, etc. and moves up for cough or swallow Smoking = an attack on your respiratory system Healthy vs. Cancerous lungs! Smoking accounts for 90% of all lung cancer cases & increases risk of other cancers.! Smoking also increases the risk of heart attacks and strokes, raises blood pressure (stresses heart), and increases harmful types of cholesterol.! Every year in the United States, smoking? Lung kills about 440,000 people, Heart more than all the deaths from accidents, alcohol, drug abuse, HIV, and murders combined.! Adults who smoke die 1314 years earlier than nonsmokers.! If you quit, risks of premature death decrease! Negative pressure causes lung inflation = inhale! Breathing = alternate inhalation and exhalation of air (ventilation). Figure 22.8 Rib cage expands as rib muscles contract Air inhaled Rib cage gets smaller as rib muscles relax Air exhaled! Inhalation occurs when the diaphragm moves downward, Lung the rib cage expands, Diaphragm the pressure around the lungs decreases, and air is drawn into the respiratory tract. Called negative pressure breathing The diaphragm contracts (moves down) The diaphragm relaxes (moves up) Inhalation Exhalation

3 Negative pressure breathing ventilates your lungs Vital Capacity! Exhalation occurs when the diaphragm muscle relaxes & moves upward, the rib cage contracts, the pressure around the lungs increases, and air is forced out of the respiratory tract.! Not all air is expelled during exhalation. Some air still remains in trachea, bronchi, bronchioles, and alveoli -- dead air.! The volume of air breathed during maximum inhalation/exhalation = vital capacity. Emphysema causes loss of lung elasticity, hence smaller vital capacity (amt. of dead air increases) We have some conscious control of our breathing Breathing is mostly automatically controlled! We can modulate our breathing for a short time, but breathing is usually under automatic control. Hold your breath for a moment! Breathing control centers in brain sense and respond to CO 2 levels in blood. A drop in blood ph (means [CO 2 ] is up) increases the rate and depth of breathing (O 2 regulated by default). Figure 22.9_s3 Brain Cerebrospinal fluid Hyperventilation 1 Nerve signals trigger contraction of the rib muscles and diaphragm. Medulla 2 Breathing control center responds to the ph of blood and cerebrospinal fluid.! Excessive, rapid breaths! [CO 2 ] down so much that control centers stop sending signals 3 Nerve signals indicate CO 2 and O 2 levels.! One technique (for anxietycaused HV) is bag over mouth/ face increases [CO 2 ] to get breath back to normal. Diaphragm Rib muscles CO 2 and O 2 sensors in the aorta Heart! If no treatment, worst case = pass out, and brain will recalibrate breathing Don t use paper bag for heart attack or asthma attack!

4 Blood transports respiratory gases TRANSPORT OF GASES IN THE HUMAN BODY! Oxygen enters (& carbon dioxide leaves) bloodstream by diffusion between alvioli and blood capillaries Diffusion occurs down concentration gradients Figure 22.UN03 Chapter 23: Big Ideas a. b. c. d. e. f. g. Circulatory Systems The Human Cardiovascular System and Heart Circulatory System h. Structure and Function of Blood Vessels Structure and Function of Blood NON-HUMAN CIRCULATORY SYSTEMS Circulatory systems facilitate exchange with all body tissues! Most animals need a system to spread vital chemicals around in body circulatory system! Parts: Specialized fluid to carry chemicals " BLOOD Vessels for fluid to travel through " ARTERIES / VEINS Pump to push fluid through body " HEART

5 Functions of circulatory systems Open vs. Closed Circulatory Systems! Functions: Oxygen and nutrients to all parts of body Waste products (i.e. CO2) to lungs and kidneys (for disposal) Open circulatory systems Closed circulatory systems! arthropods + many molluscs! vertebrates, earthworms, squids, and octopuses a heart, open-ended vessels, and blood that directly bathes the cells and functions as the interstitial fluid. Maintain constant internal environment in body (ph, nutrients, temperature, etc.) a heart and vessels that confine blood, keeping it distinct from interstitial fluid ( middleman for gas exchange). 3 Types of Vessels THE HUMAN CARDIOVASCULAR SYSTEM AND HEART! Cardiovascular system includes three types of vessels: 1. Arteries* carry blood away from the heart. 2. Veins* return blood to the heart. 3. Capillaries move blood between arteries and veins. *Arteries & veins distinguished not by O2-rich or poor, but by direction of blood flow. Direction of Blood Flow Anatomy of the Heart 2 Basic Circuits: 1. Pulmonary Circuit: heart lung heart 2. Systemic Circuit: heart body heart (Cardiac Circuit = part of systemic circuit blood to heart tissue) *Blue = low O2 *Orange = high O2 L & R Atria L & R Ventricles Pulmonary Arteries Pulmonary Veins Aorta Superior / Inferior Vena Cava 2 AV valves 2 Semilunar valves SinoAtrial Node (pacemaker) Atrioventricular Node

6 Unique properties of Cardiac Anatomy The SA node sets tempo of heartbeat! The SA (sinoatrial) node! Ventricles & arteries have more layers of contractile muscle (than atria & veins) higher pressure blood Generates electrical signals in atria Sets rate of heart contractions! The AV (atrioventricular) node relays these signals to the ventricles causes ventricular contraction (delayed following complete atrial contraction).! Veins have valves to prevent blood flowing backwards! Capillaries have very thin walls to allow for diffusion (no muscle layer) Figure 23.5B Cardiac Cycle: rhythmic heartbeat! The repeated contraction and relaxation of pumping blood is called the cardiac cycle: Wire leading to SA node Artificial pacemaker 1. During diastole Heart muscle is relaxed Blood flows from veins into heart chambers Heart 2. During systole Heart muscle contracts Blood flows from atria into ventricles, then out of ventricles into arteries. Figure 23.4_s3 Systole Diastole 1 The heart is relaxed. The semilunar valves are closed. 2 The atria contract. 0.1 sec STRUCTURE AND FUNCTION OF BLOOD VESSELS 3 The ventricles contract. 0.4 sec 0.3 sec The AV valves are open. The semilunar valves are open. The AV valves are closed.

7 Blood pressure and velocity reflect the structure and arrangement of blood vessels! Blood pressure is the force blood exerts on vessel walls, depends on cardiac output and resistance of vessels to expansion, and Figure 23.8A Pressure (mm Hg) Diastolic pressure Relative sizes and numbers of blood vessels Systolic pressure is highest in arteries and lowest in veins. Contracting muscles help blood in veins flow against gravity. Velocity (cm/sec) Aorta Arteries Arterioles Capillaries Venules Veins Venae cavae Smooth muscle controls distribution of blood Figure Precapillary sphincters Thoroughfare channel! Only about 510% of capillaries in body are full of blood at one time! Eat: more blood near digestive tract Exercise: more blood to skeletal muscles! Blood flow through capillaries is controlled by precapillary sphincters (rings of smooth muscle around capillary origins). Arteriole Capillaries 1 Sphincters are relaxed. Venule Thoroughfare channel i.e. hot/cold Body Temperature Regulation " shower constrict blood flow to surface = warmer dialate arteries = surface flow = more heat loss Arteriole Venule 2 Sphincters are contracted. STRUCTURE AND FUNCTION OF BLOOD Blood consists of red and white blood cells + platelets suspended in plasma 1. Blood Plasma 2. Blood Cells 4-6 liters = ~8% body mass 1. Red Blood Cells (RBC) 2. White Blood Cells (leukocytes) 3. Platelets (bone cell fragments)

8 Fluid Plasma 50 55% of blood volume Figure 23.12_2 Cell type Red blood cells (erythrocytes) Cellular elements (45%) Number per µl (mm 3 ) of blood) 56 million Functions Transport of O 2 and some CO 2 Vitamins, salts, hormones, proteins, dissolved wastes White blood cells (leukocytes) 5,00010,000 Defense and immunity Basophils Eosinophils Lymphocytes Neutrophils Monocytes Platelets 250, ,000 Blood clotting Red and White blood cells Red Blood Cells carry Oxygen! Two classes of cells are suspended in blood plasma. 1. Red blood cells or erythrocytes transport O 2 bound to hemoglobin. No nucleus, die in 4 months, broken down in liver New RBCs constantly made in bone marrow 2. White blood cells, or leukocytes, Function mostly outside blood vessels (i.e. interstitial fluid & lymphatic system) Defend body against invading microorganisms 5 kinds, each with slightly different function! In Red Blood Cells (RBCs), oxygen molecules attach to iron-containing hemoglobin Each hemoglobin = 4 polypeptides, each with one Heme group + iron atom O 2 attaches directly to Heme group, so each hemoglobin carries 4 O 2. Hemoglobin carries some CO 2 on return trip (rest breaks down) Platelets help heal vessel injuries! When a blood vessel is damaged platelets rapidly adhere to exposed connective tissue a cluster of sticky platelets forms a plug Clotting factors released from platelets trigger conversion: fibrinogen " fibrin, threadlike protein that helps form clot. Platelets: triage and healing! Within an hour after a fibrin clot forms, the platelets contract, pulling the torn edges closer together.! Chemicals released by platelets also stimulate cell division in smooth muscle and connective tissue, initiating the healing process. Hemophilia = disease where blood does not clot *Platelets do not function properly*

9 p. a. b. o. n. c. d. m. l. k. j. e. f. g. h. i.