Lecture_24_Cardiovascular_System 2.pptx

GENERAL BIOLOGY II Lecture 24: Cardiovascular & Respiratory Systems Chapters: 39 & 40 Respiratory System Respiratory System Gas exchange within large organisms depends on two processes: Diffusion – Movement from an area of high concentration to an area of low concentration Bulk Flow – Movement of fl...

GENERAL BIOLOGY II Lecture 24: Cardiovascular & Respiratory Systems Chapters: 39 & 40 Respiratory System Respiratory System Gas exchange within large organisms depends on two processes: Diffusion – Movement from an area of high concentration to an area of low concentration Bulk Flow – Movement of fluids down a pressure or temperature gradient Respiratory System Diffusion Gases move from high pressure to low pressure Partial Pressure (P) – Respiratory System Bulk Flow Moves environmental medium across specialized respiratory surface Moves circulatory fluid (blood or hemolymph) through the body Respiratory System Blood vs Hemolymph Hemolymph – fluid that many invertebrates use to circulate oxygen and / or nutrients through an open circulatory system Blood – circulatory fluid in closed circulatory systems that contains blood cells that deliver oxygen cells Respiratory System Respiration Respiratory Gas Exchange Gills – extract oxygen from water Lamellae – thin, sheetlike structures that extend up from each gill filament lined with capillaries that bridge an artery to a vein give the gills enormous surface area Respiratory Gas Exchange Counter Current Exchange – mechanism by which dissolved gasses or electrolytes in one closed system are diffused into a second system using diffusion. Respiratory Gas Exchange 45 55 65 Blood Water 130 110 90 60 90 120 Water Blood 56 83 109 Respiratory Gas Exchange Terrestrial organisms were able to increase their uptake of oxygen O2 in air ~50x more concentrated than in water O2 in air diffuses ~8000x faster than in water Water is 800 times more dense, and 50 times more viscous than air less energy to pump oxygen in air Respiratory Gas Exchange Insects use spiracles, which are openings along the sides of their abdomen, to provide a direct path for air to enter their system. Insects network of tracheae, branching tubes from their spiracles, ventilate air directly to their cells. Respiratory Gas Exchange Tidal Ventilation – Most vertebrates have lungs that inflate and deflate to move air with high O2 in and air with high CO2 out. Inhalation – air enters the lungs, lungs expand, and the diaphragm moves posteriorly Exhalation – gases leave the lungs, the lungs contract, and the diaphragm moves towards the head Respiratory Gas Exchange Diaphragm – domed sheet of muscle located at the base of the lungs, which forms a barrier between the thoracic and abdominal cavities Intercostal muscles – elevate the ribs during inhalation, and contracting the chest cavity on exhalation Respiratory Gas Exchange Tidal volume – the amount of air you generally breath at rest (~0.5 L) Maximum possible inhalation Maximum possible exhalation Total lung capacity Respiratory Gas Exchange Anatomy of the Vertebrate Respiratory System Mouth / Nasal passages Larynx - organ in the throat made of cartilage, which contains the vocal cords, and helps separate swallowing from breathing Trachea – central airway leading to the lungs Primary bronchi – fork in the trachea that goes to each lung Respiratory Gas Exchange Anatomy of the Vertebrate Respiratory System Secondary bronchi Bronchioles – finer subdivisions of the secondary bronchi Terminal bronchioles – less than 1 mm diameter Respiratory bronchioles Alveoli – sacs where gas exchange takes place Respiratory Gas Exchange Anatomy of the Vertebrate Respiratory System Pulmonary capillaries – supply each alveolus with blood Capillaries are ~2µm from the alveolus, allowing for rapid diffusion of gases Alveoli and airway surfaces are always kept moist with mucus A surfactant is also secreted to reduce mucus surface tension to prevent partially deflated alveoli from being able to reinflate Respiratory Gas Exchange Anatomy of the Vertebrate Respiratory System Pulmonary capillaries – supply each alveolus with blood Capillaries are ~2µm from the alveolus, allowing for rapid diffusion of gases Alveoli and airway surfaces are always kept moist with mucus A surfactant is also secreted to reduce mucus surface tension to prevent partially deflated alveoli from being able to reinflate Respiratory Gas Exchange Respiratory Gas Exchange Carotid bodies – sensors in the carotid arteries Aortic bodies – sensors in the aorta Detect variation in CO2, H+, and O2 in the blood Respiratory Gas Exchange Carotid bodies – sensors in the carotid arteries Aortic bodies – sensors in the aorta Detect variation in CO2, H+, and O2 in the blood They send signals to the brainstem, which sends action potentials to motor neurons which control breathing rate Oxygen Transport by Hemoglobin Blood Composition Fluid Fraction – Plasma Cellular Fraction Red Blood Cells White Blood Cells Oxygen Transport by Hemoglobin Hematocrit – the percentage (by volume) of red blood cells in your blood Oxygen Transport by Hemoglobin Solubility – the ability of a substance to be dissolved in water The relative amounts of substances that can be dissolved in a set amount of water allows us to compare relative solubilities Oxygen Transport by Hemoglobin For gases, the solubility is dependent on the partial pressure of the gas in the atmosphere. CO2 is 30 times more soluble in water than O2 Hemoglobin – a protein in RBCs that increases O2 solubility by 100 times Oxygen Transport by Hemoglobin Hemoglobins are ancient molecules that are found in organisms of every kingdom Probably evolved as a terminal electron acceptor in cellular respiration Oxygen Transport by Hemoglobin When we increase the pO2 in the lung we expect the percentage of O2 saturation in hemoglobin will increase At maximum saturation, each heme hemoglobin can attach to 4 O2 molecules Oxygen Transport by Hemoglobin Oxygen dissociation curve - Oxygen Transport by Hemoglobin Oxygen dissociation curve At 25% saturation, each hemoglobin is bound to a single O2 molecule Hemoglobin exhibits cooperative binding After one O2 molecule is bound, it is easier for the other 3 to bind Oxygen Transport by Hemoglobin Oxygen Transport by Hemoglobin Hemoglobin has a variety of forms in the animal kingdom Different hemoglobins have slightly different oxygen affinities Partially explains how animals living at high altitudes meet their O2 needs Oxygen Transport by Hemoglobin It also explains how a fetus can efficiently extract O2 from their mother across a placenta Oxygen Transport by Hemoglobin Hemoglobin is also highly sensitive to changes in pH CO2 is released from cells into the plasma CO2 reduces pH in water (forms carbonic acid) Drop in pH causes hemoglobin to drop off O2 and pick up CO2 Oxygen Transport by Myoglobin Myoglobin – specialized O2 carrier in muscle cells; contains only 1 heme group Has a greater affinity for O2 than hemoglobin does Concentrated in red muscle cells that rely on aerobic respiration Oxygen Transport by Myoglobin Myoglobin – specialized O2 carrier in muscle cells; contains only 1 heme group Has a greater affinity for O2 than hemoglobin does Concentrated in red muscle cells that rely on aerobic respiration Circulatory Systems Open circulatory system – contains few blood vessels and most hemolymph is contained by the body cavity Some invertebrates have simple hearts that pump hemolymph between body regions Circulatory Systems Closed circulatory system – made up of internal vessels that contain blood, and a pump (heart) to circulate blood through the system Closed Circulatory Systems Benefits: Allows blood to be moved to specific body regions to maintain homeostasis Maintains a high rate of oxygen delivery to organs for increased activity Closed Circulatory Systems Benefits: Allows blood to be moved to specific body regions to maintain homeostasis Maintains a high rate of oxygen delivery to organs for increased activity Conflict Produce enough pressure to move blood to all tissues Supply cells with blood at low pressure Closed Circulatory Systems To overcome this conflict, closed circulatory systems evolved to have vessels of different sizes Flow (Q) = A vessel’s resistance is equivalent to Closed Circulatory Systems Organization: Arteries – large, high pressure, move blood away from the heart Arterioles – midsized, midpressure Capillaries – small size, low pressure, gas exchange Venules – midsized, midpressure, take blood towards heart Veins – large, high pressure Closed Circulatory Systems Organization: Arteries – large, high pressure, move blood away from the heart Arterioles – midsized, midpressure Capillaries – small size, low pressure, gas exchange Venules – midsized, midpressure, take blood towards heart Veins – large, high pressure Closed Circulatory Systems Blood flow adjusts to body regions to match activity level Closed Circulatory Systems Blood flow adjusts to body regions to match activity level Blood pressure is regulated via the nervous and endocrine systems by sending nerve pulses or hormones that cause: vasoconstriction or vasodilation Closed Circulatory Systems Because the veins are on the opposite side of the capillary beds from the arteries, the pressure has already been reduced, and veins are under relatively low pressure Valves prevent backflowing veins under low pressure Closed Circulatory Systems Capillaries are leaky by design to facilitate diffusion, filtration, and osmosis. Closed Circulatory Systems Capillaries are leaky by design to facilitate diffusion, filtration, and osmosis. When plasma leaks out of the capillary beds, the lymphatic system returns it to the veins near the heart The Heart and the Circulatory System Fish have two chambers in their heart: Atrium – collects blood Ventricle – pressurizes blood Blood flows into the atrium from the Vena cava. The atrium moves blood to the ventricle, which pumps it to the Aorta. Blood then moves to the gills to be oxygenated, then to the body, and then it returns to the heart. The Heart and the Circulatory System Reptiles and Amphibians have a 3 chamber heart: 2 Atria 1 common Ventricle Have partially separated pulmonary and systemic circuits The Heart and the Circulatory System Mammals and birds have a 4 chamber heart: 2 Atria 2 Ventricles Have fully separated pulmonary and systemic circuits The Heart and the Circulatory System Learn the cardiac anatomy outside of the lecture: Atrioventricular valve Pulmonary valve Pulmonary arteries Pulmonary veins Aortic valve The Heart and the Circulatory System The Heart and the Circulatory System The cardiac cycle is divided into two phases: Diastole – the atria contract, filling the ventricles with blood Systole – the ventricles contract, pumping blood out of the heart The Heart and the Circulatory System Cardiac muscles cells are like skeletal muscles with several unique distinctions: They can generate action potentials on their own (no nervous system) They can pass action potentials to each other via gap junctions. The Heart and the Circulatory System Pacemaker cells are responsible for causing the heart muscle cells to beat in rhythm Sinoatrial (SA) node – stimulates the atria Atrioventricular (AV) node – stimulates the ventricles For Next Class Complete the Quiz on CANVAS Read Chapter 34: Digestive System & Metabolism