1 Homeostasis and the Organization of the Animal Body
2 Homeostasis Homeostasis (“steady state”)Maintenance of nearly constant internal conditions Snakes are cold-blooded (ectothermic or poikilothermic) Heat & thus their body temperature is absorbed from environment Humans are warm-blooded (endothermic or homeothermic) Body temperature is generated internally
3 Feedback Systems Homeostasis is controlled by feedbackFeedback loops used by organisms to help maintain homeostasis & have 3 major components: Receptors - respond to various stimuli to which organism may be exposed Control center - decides to which stimuli organism should respond to & what is the right response Effectors - receive instructions from control center
4 Homeostasis A. Negative feedback is used toSlow down, shut off, or reverse a physiological process & Return it to an optimal condition B. Positive feedback enhances or intensifies a process
5 uterus signal (temperature to control center) Negative feedbackhypothalamus (control center) signal to turn off effector signal to turn on effector nerve signal to turn off effector nerve signal (temperature) to control center control center nerve signal to turn on effector heat output (shivering) increases nerve endings (sensor) heat output increases heater (effector) thermometer (sensor) heat output (shivering) decreases Skeletal muscles (effector) heat output decreases hypothalamus (control center) signal to control center Figure: 19-01 Title: Negative and positive feedbacks. Caption: (top) Both our homes (left) and our bodies (right) use negative feedback to maintain appropriate temperatures. (bottom) Positive feedback is seen in this hypothetical model (left) and in childbirth (right). Positive feedback nerve signal to control center oxytocin release (signal to turn on effector) signal to turn on effector uterine muscles (effector) uterus output level (contraction) increases stretch receptors in cervix (sensor) output level increases
6 Circulation and Respiration
7 II. Circulatory systemsA. Circulatory system basics 1. Fluid—blood 2. Channels—vessels 3. A pump—the heart
8 III. The vertebrate circulatory systemA. Functions 1. Transport of O2 and CO2 2. Distribution of nutrients Transport of waste 4. Distribution of hormones 5. Regulation of body temperature 6. Protection of the body against blood loss
9 The vertebrate circulatory systemB. The heart 1. Structure a. Atria b. Ventricles
10 pulmonary artery (to left lung) superior vena cavaaorta pulmonary artery (to left lung) superior vena cava pulmonary artery (to right lung) left atrium pulmonary veins (from right lung) pulmonary veins (from left lung) atrioventricular valve right atrium Figure: 20-01 Title: The human heart and its valves and vessels. Caption: The heart is drawn as if it were in a body facing you, so that right and left appear reversed. Note the thickened walls of the left ventricle, which must pump blood much farther through the body than does the right ventricle, which propels blood to the lungs. One-way valves, called semilunar valves, are located between the aorta and the left ventricle, and between the pulmonary artery and the right ventricle. Atrioventricular valves separate the atria and ventricles. semilunar valves atrioventricular valve left ventricle right ventricle ventricular septum inferior vena cava descending aorta (to lower body) heart muscle
11 The vertebrate circulatory systemFunction a. The cardiac cycle 1) Systole—period of ventricle contraction 2) Diastole—relaxation of all the chambers followed by contraction of the atria
12 Oxygenated blood from lungs enters left ventricle.Deoxygenated blood is pumped to the lungs. Oxygenated blood from lungs enters left ventricle. Oxygenated blood is pumped to the body. Figure: 20-02 Title: The cardiac cycle. Caption: Blood fills the atria and begins to flow passively into the ventricles. Deoxygenated blood from body enters right ventricle. (a) Atria contract, forcing blood into the ventricles. (b) Then the ventricles contract, forcing blood through arteries to the lungs and the rest of the body. (c) The cycle ends as the heart relaxes.
13 III. The vertebrate circulatory systemFunction b. Coordination of heart activity 1) Atrioventricular and semilunar valves 2) The sinoatrial node (SA node) 3) The atrioventricular node (AV node)
14 pulmonary artery (to left lung) superior vena cavaaorta pulmonary artery (to left lung) superior vena cava pulmonary artery (to right lung) left atrium pulmonary veins (from right lung) pulmonary veins (from left lung) atrioventricular valve right atrium Figure: 20-01 Title: The human heart and its valves and vessels. Caption: The heart is drawn as if it were in a body facing you, so that right and left appear reversed. Note the thickened walls of the left ventricle, which must pump blood much farther through the body than does the right ventricle, which propels blood to the lungs. One-way valves, called semilunar valves, are located between the aorta and the left ventricle, and between the pulmonary artery and the right ventricle. Atrioventricular valves separate the atria and ventricles. semilunar valves atrioventricular valve left ventricle right ventricle ventricular septum inferior vena cava descending aorta (to lower body) heart muscle
15 sinoatrial (SA) node atrioventricular (AV) node excitable fibersFigure: 20-04 Title: The heart’s pacemaker and its connections. Caption: The sinoatrial (SA) node serves as the heart’s pacemaker. Its signal to contract spreads through the muscle fibers of both atria to the atrioventricular (AV) node. The AV node then transmits the signal through bundles of excitable fibers that stimulate the ventricular muscles to contract. excitable fibers
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17 The vertebrate circulatory system. Coordination of heart activity 4) Influences on heart rate a) Parasympathetic nervous system - decreases heart rate b) Sympathetic nervous system - increases heart rate c) Hormones
18 The vertebrate circulatory systemC. Blood 1. Functions a. Transport of nutrients, gases, hormones, wastes b. Immune response
19 The vertebrate circulatory system2. Composition a. Plasma—55% to 60% 1) 90% water 2) Molecules of dissolved proteins, hormones, nutrients, gases, ions, and urea as a waste b. Red blood cells—erythrocytes 1) 99% of the total cellular component in the blood 2) Carry oxygen bound to hemoglobin from the lungs to the tissue and buffer CO2 carried from the tissues c. White blood cells—leukocytes 1) 1% of the total cellular component of blood 2) Five white blood cell types d. Platelets 1) Cellular fragments from megakaryocyte in the bone marrow 2) Function in blood clotting
20 Figure: 19-07 Title: Blood. Caption: Blood contains three types of cellular components. In this color-enhanced scanning electron micrograph, red blood cells, which carry oxygen to tissues throughout the body, appear as red concave disks. White blood cells, important in the immune response, appear here as fuzzy blue balls, and platelets, cell fragments that aid in blood clotting, are lavender.
21 Figure: 20-08 Title: A white blood cell attacks bacteria. Caption: An amoeba-like white blood cell captures bacteria (the small yellow rods). These bacteria are Escherichia coli, intestinal bacteria that can cause disease if they enter the bloodstream.
22 Figure: 20-09 Title: The production of platelets. Caption: Here a single megakaryocyte is budding off dozens of platelets.
23 trapped red blood cell platelets fibrin network Figure: 20-10 Title:Blood clotting. Caption: Threadlike fibrin proteins produce a tangled sticky mass that traps red blood cells and eventually forms a clot.
24 The vertebrate circulatory systemD. Blood vessels 1. Arteries and arterioles a. Thick walls, smooth muscle with elastic tissue to withstand high pressure b. Carry blood away from the heart 2. Capillaries a. Tiniest vessels; thin, single-cell thick for easy diffusion b. Exchange of materials between blood and body cells 3. Venules and veins a. One-way valves in thin-walled vessels surrounded by thin layer of smooth muscle giving low resistance to blood flow, which is assisted by skeletal muscle b. Returns blood to the heart
25 capillaries arteriole venule endothelium capillary connective tissueFigure: 20-12 Title: Structures and interconnections of blood vessels. Caption: Oxygenated blood moves from arteries to arterioles to capillaries. Capillaries empty deoxygenated blood into venules, which empty into veins. endothelium capillary connective tissue (external layer) smooth muscle (middle layer) artery connective tissue endothelium (inner layer) vein
26 pass through capillaries in single file.Red blood cells must pass through capillaries in single file. Figure: 20-13 Title: Red blood cells flow through a capillary. Caption: Capillary walls are thin and permeable to gases, nutrients, and cellular wastes.
27 III. The vertebrate circulatory system4. Distribution of blood flow a. Regulated by muscular walls of the arterioles b. Influenced by autonomic nerves, hormones, and other chemicals released from nearby tissues
28 jugular vein carotid artery aorta superior lung capillaries vena cavainferior vena cava pulmonary artery heart liver kidney intestine femoral vein Figure: 20-11 Title: The human circulatory system. Caption: Most veins (shown on the figure’s right side) carry deoxygenated blood to the heart, and most arteries (shown on left) conduct oxygenated blood away from the heart. The pulmonary veins (carrying oxygenated blood) and arteries (carrying deoxygenated blood) are exceptions. femoral artery
29 valve open valve closed relaxed muscle muscle contraction compressesvein valve closed Figure: 20-14 Title: Valves direct the flow of blood in veins. Caption: Veins and venules have one-way valves that maintain blood flow in the proper direction. When the vein is compressed by nearby muscles, the valves allow blood to flow toward the heart but clamp shut to prevent backflow.
30 Figure: 20-03 Title: Measuring blood pressure. Caption: Blood pressure is measured with an inflatable blood pressure cuff and a stethoscope. The cuff is inflated until its pressure closes off the arm’s main artery, blood ceases to flow, and no pulse can be detected below the cuff. Then the pressure is gradually reduced. When the pulse is first audible in the artery, the pressure pulses created by the contracting left ventricle are just overcoming the pressure in the cuff and blood is flowing. This is the upper reading: the systolic pressure. Cuff pressure is then further reduced until no pulse is audible, indicating that blood is flowing continuously through the artery and that the pressure between ventricular contractions is just overcoming the cuff pressure. This is the lower reading: the diastolic pressure. The numbers are in millimeters of mercury, a standard measure of pressure also used in barometers.
31 (a) endothelium smooth muscle fatty core fibrous cap plaquecholesterol in blood Figure: 20-E20_01 Title: Plaques clog arteries. Caption: (a) Diagram of an artery with a plaque. (b) In this remarkable photo of coronary arteries, plaques are seen in glowing yellow. If they block a coronary artery, a heart attack will occur. fatty core fibrous cap plaque
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33 (Myocardial Infarction)Heart Attack (Myocardial Infarction) A heart attack (myocardial infarction) occurs when heart muscle is damaged or destroyed because it does not get enough oxygen-rich blood to sustain life. Just as the heart supplies oxygen and nutrients to other parts of the body, blood vessels called coronary arteries supply needed blood to the heart. If one or more coronary arteries or the blood vessels that feed blood into the major arteries are blocked or narrowed, the heart muscle is deprived of oxygen. If the oxygen supply is cut off for more than several minutes, the heart cells suffer permanent injury or death.
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35 Lymphatic system 1. Structurea. Complex network of thin-walled vessels b. In proximity to the capillary network c. Composed of cells with openings between them that act as one-way valves
36 thoracic duct enters vein to vena cavasuperior vena cava thoracic duct enters vein to vena cava thymus heart spleen thoracic duct lymph vessels lymph nodes Figure: 20-15 Title: The human lymphatic system. Caption: (a) Lymph vessels, lymph nodes, and two auxiliary lymph organs, the thymus and spleen. Lymph is returned to the circulatory system by way of the thoracic duct, which empties into the vena cava, a large vein. (b) A cross section of a lymph node. The node is filled with channels lined with white blood cells that attack foreign matter in the lymph. valve prevents backflow white blood cells (b) lymph node
37 Lymph is transported into larger lymph vessels. interstitial fluidFigure: 20-16 Title: Lymph capillary structure. Caption: Lymph capillaries end blindly in the body tissues, where pressure from the accumulation of interstitial fluid forces the fluid into the lymph capillaries. Interstitial fluid enters through valvelike openings between lymph capillary cells. Blood capillaries leak fluid filtered from blood plasma.
38 Lymphatic system 2. Functions a. Removal of excess fluidb. Transport of fats from the intestine c. Cellular body defense
39 The respiratory systemA. Functions of the respiratory system 1. Works in conjunction with the circulatory system 2. Provides oxygen for cellular respiration
40 Respiratory systems and gas exchangeA. Interrelated with circulatory system B. Mechanisms of gas movement 1. Bulk flow from areas of higher pressure to areas of lower pressure 2. Simple diffusion at the tissue or lung level
41 of the lungs by breathing.1. Gases move in and out of the lungs by breathing. 2. O2 and CO2 are exchanged in the lungs by diffusion. alveoli (air sacs) right atrium 3. Gases dissolved in blood are transported by the circulatory system. left atrium Figure: 20-21 Title: An overview of gas exchange. Caption: right ventricle left ventricle 4. O2 and CO2 are exchanged in the tissues by diffusion.
42 VII. Human respiratory systemA. The conducting portion 1. Carries air to the lungs 2. Warms and moistens air moving through it 3. Cilia that line the trachea, bronchi, and bronchioles filter dust particles
43 branch of pulmonary vein larynx esophagus bronchiole trachea bronchi nasal cavity pharynx epiglottis branch of pulmonary vein larynx esophagus bronchiole trachea bronchi alveoli branch of pulmonary artery Figure: 20-18 Title: The human respiratory system. Caption: (a) The passages and vessels of the respiratory system and its interface with the circulatory system. (b) Close-up of alveoli (their interiors are shown in this cut-away section) and their surrounding capillaries. bronchioles capillary network (b) pulmonary artery pulmonary vein
44 VII. Human respiratory systemB. Gas exchange portion 1. The alveoli have an enormous surface area 2. Capillaries surround the alveoli 3. The mechanism of gas exchange and transport a. Oxygen and hemoglobin b. Carbon dioxide and bicarbonate ions
45 interstitial fluid capillary fluid layer capillary cellnucleus alveolar cell nucleus red blood cell air in alveolus Figure: 20-20 Title: Gas exchange between alveoli and capillaries. Caption: The alveoli and capillary walls are only one cell thick, very close to one another, and the cells are coated in a thin layer of fluid. This allows gases to dissolve and diffuse easily between the lungs and circulatory system. alveolar membrane plasma capillary wall
46 VII. Human respiratory systemC. Mechanics of breathing 1. Inspiration—active inhalation of air a. Diaphragm and rib muscles contract, making the chest cavity larger b. Chest expansion causes the lungs to expand; vacuum draws in air 2. Expiration—passive exhalation of air when muscles are relaxed
47 air moves in air moves out ribcage contracts ribcage contracts ribcageexpands ribcage expands lungs compress lungs compress lungs compress lungs expand lungs expand Figure: 20-22 Title: The mechanics of breathing. Caption: (a) During inhalation, the diaphragm is pulled downward and the ribs move up and outward. The size of the chest cavity increases, causing air to rush in. (b) During exhalation, relaxation of the muscles that moved the diaphragm and ribs allows the diaphragm to dome upward and the rib cage to collapse, forcing air out of the lungs. diaphragm relaxes upward diaphragm contracts downward (a) Inhalation (b) Exhalation
48 VII. Human respiratory systemD. Control of respiration 1. Description of breathing 2. Regulation of breathing by carbon dioxide
49 Figure: 20-E20_02 Title: Smoking causes lung cancer. Caption: A tumor of lung cancer is visible as a large, pale mass; the lung tissue surrounding it is blackened by trapped smoke particles.
50 (a) (b) Figure: 20-E20_03 Title: Smoking causes emphysema. Caption:(a) Normal lung tissue from a nonsmoker has nearly invisible small openings, the alveoli, surrounded by healthy tissue. (b) The lung of a smoker suffering from emphysema is full of large holes, each caused by the rupture of hundreds of alveoli. (a) (b)
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