BIOL 141 Study Guide 3
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This 15 page Study Guide was uploaded by Camryn McCabe on Friday March 18, 2016. The Study Guide belongs to Biol 141 at a university taught by Janelle Malcos in Spring 2016. Since its upload, it has received 88 views.
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Date Created: 03/18/16
Study Guide 3 Volume and pressure • For a fixed volume of fluid, pressure depends on the volume of the space it occupies – Large space = lower pressure – Small space = high pressure Pressure gradient: difference in pressures between 2 regions (P – P1) 2 Fluid flows from high pressure to low pressure o Pressure at first point will decrease; pressure at second point will increase Volume and pressure Volume of chambers change during a heartbeat Also pay attention to pressure in vessels Relaxation Diastole o Space of chamber increases , volume of fluid remains constant pressure decreases Contraction Systole o Space of chamber decreases, volume of fluid remains constant pressure increases Cardiac Cycle = complete contraction and relaxation Phase 1: Quiescent Period (before threshold, no action potential) o Atria and Ventricles are in diastole Pressure of blood vessels > pressure in heart No pressure in ventricles, therefore AV valves are open and semilunar valves are closed Blood fills atria and flows through the AV valves to ventricles o Heart fills with blood from bottom up (through atria to ventricles) Some blood is leftover from previous contraction Ventricles contain about 90mL of blood (at this point) NOT the maximum capacity of ventricle o SA node cells are depolarizing (but not to threshold yet) o Pressure in arteries in veins > pressure in chambers o Chambers are all relaxed, high volume Phase 2: Atrial Systole o SA node depolarizes to threshold (action potential across atria) o Atria contract (systole) Pressure in atria > pressure in ventricles o Blood is forced into ventricles Study Guide 3 About 40mL more blood 90mL + 40mL = 130mL total This is the End Diastolic Volume (ventricles) Phase 3: Isovolumetric contraction o Atria repolarize and relax (diastole) Start to refill from veins o Ventricles depolarize and begin to contract (early systole) Contract from bottom up Blood forces AV valves closed This makes first heart sound o Pressure in ventricles increases o Blood does not leave ventricles yet Pressure in aorta and pulmonary artery > pressure in ventricles Isovolumetric contraction: no change in volume of blood, but ventricles start to contract Phase 4: Ventricular Ejection o Ventricles fully contract (full systole) o Pressure in ventricles > pressure in vessels Forces pulmonary and aortic valves open Semilunar valves are open; AV valves are shut Blood leaves ventricles Only 70mL leaves (stroke volume) o Stroke volume: amount that leaves after one stroke (contraction) 60 mL left behind (End Systolic Volume) o End Systolic volume: volume left when completely contracted o Atria are still in diastole Continue to fill with blood Phase 5: Isovolumetric Relaxation o Ventricles repolarize and relax (diastole) o Pressure decreases in ventricle Pressure in pulmonary artery and aorta > pressure in ventricle Blood tries to flow back, but valves shut and prevent this This makes the second heart sound o Both sets of valves are still closed so volume of blood in ventricles doesn’t change Isovolumetric relaxation o When atria are filled, AV valves are forced open cycle brings again with quiescent period Study Guide 3 End Diastolic Volume – End Systolic Volume = Stroke Volume About 130 mL - About 60 mL = About 70 mL Cardiac Output (CO) o CO- the amount of blood pumped by the left ventricle in one minute (measures how efficiently our heart pumps blood) o Heart rate (beats/minute) X stroke volume (mL/beat) – HR X SV = CO o On average, total blood volume is pumped through the heart per minute o This is resting cardiac output What affects heart rate? o Average heart rate = about 75 beats/minute o Autonomic nervous system modulates SA node activity Without nervous system control, heart would beat about 100 beats/minute (SA node depolarization rate due to leak channels) Visceral motor responses are initiated from interneurons in “brain centers” o Center- collection of interneurons that receive sensory input about a specific function and create motor output to alter that function o “Cardiovascular control center” (CVCC): Cardiac control (heart) Cardioacceleratory neurons Cardioinhibitory neurons Vasomotor control (vessels) o Together they regulate blood pressure and heart function Why out body needs to alter heart rate? o Energy balance o O d2mand o Waste removal (CO ) 2 o Regulate blood pressure Organ function Interneurons of the cardioacceleratory center will lead to an increased heart rate o Efferent neurons excited by this center are visceral motor neurons of the sympathetic system o Postganglionic neuron secretes norephinephrine (NE) Adrenergic receptors on cells of the SA node bind NE Study Guide 3 Cause an increase rate of action potentials of SA node o Maximum heart rate = 230 beats/minute Limit of SA node excitation Interneurons of the cardioinhibitory center will lead to an increased heart rate o Visceral motor neurons of the parasympathetic system o Postganglionic neuron secretes Ach Cholinergic receptors on cells of the SA node bind Ach Allow potassium to leave the cell hyperpolarizing reaction Rate of action potentials decrease o Normal heart rate = 70 beats/minute Without nervous control the heart would beat about 100 beats/minutes Sensory input is integrated to create motor output to SA node o Proprioceptors, baroreceptors, chemoreceptors are all integrated together o Proprioceptors (sensory input from muscles and tendons) Informs brain on changes in physical activity o Baroreceptors (sensory input from blood vessels) Informs brain on changes to pressure in vessels o Chemoreceptors (sensory input from blood vessels) Informs brain on changes in CO or2O le2els in the blood (change in chemicals) Cardiovascular System Blood vessels: network of transport throughout the body Starting point: the heart o Arteries- take blood AWAY from the heart Oxygen rich (except pulmonary trunk) o Veins- take blood towards the heart Oxygen poor (except pulmonary veins) Capillaries- exchange locations Circulatory Routes Normal flow of blood: o Heart artery arteriole capillary Arteriole = small artery Capillary bed = bunch of capillaries Where exchange of materials occurs o Capillary venule vein heart Study Guide 3 Venule= small vein Portal system- exception to normal route o Has 2 capillary beds instead of one = 2 places for exchange of materials 2 main systems o Pulmonary (to lungs) o Systemic (to rest of body) Structure of vessels Vessels have smooth muscle (involuntary control) All vessels (except capillaries) have 3 layers of tissue: o Tunica intima- in intimate contact with blood; lines interior portion (the lumen = open space inside of tube) o Tunica media- middle; primarily made up of muscle (and collagen); allows for it to constrict and relax o Tunica externa- helps anchor the vessel to surrounding tissue Tunica = layer Variations between arteries and veins o Arteries have more tunica media (more muscle and collagen) because they are under higher pressure o Veins have valves Capillary beds o Only tunica intima is present Promotes rapid diffusion of material into tissue or capillary Very narrow, single file travel Tunica intima = 1 cell thick o Flow of blood is controlled by sphincter muscle cells Sphincter- circular muscle; single muscle cell Respond to chemicals in tissue and chemicals from CNS Contraction of sphincters determines if capillary beds are open or closed Only about ¼ of body’s capillaries are “open” at any given time Muscle cells are relaxed blood flows into capillaries Muscle cells are contracted > lacking blood, passes through without any exchange Veins Carry blood back to heart Study Guide 3 o Usually deoxygenated Thin walls (less muscle and elastic) Have valves that prevent backflow o Use skeletal muscle contraction as pump to move blood to heart o When valves are closed, blood is forced back up to heart Blood pressure- the force blood exerts against an arterial wall (usually the brachial artery) Systolic pressure: pressure during ventricle contraction o 1 number of BP o Peak pressure during contraction Diastolic pressure: pressure during ventricle contraction o 2 ndnumber of BP o Lowest pressure because ventricles are relaxed and not pushing blood into arteries Mean arterial pressure: average pressure in vessels o Important when considering blood flow to prevent organ failure Pulse pressure = systolic – diastolic Main variables of blood pressure (3) Cardiac output o Amount of blood the heart pumps per minute into arteries Overall arterial volume is constant, but amount of fkuid in arteries is altered o Higher output more blood in arteries higher pressure (Sympathetic response) o Lower output less blood in arteries lower pressure (parasympathetic response) o Normal Cardiac output (resting)- majority of blood in veins o High Cardiac output- volume in veins lowers, more in arteries Higher pressure in arteries Resistance of blood flow in vessels o Combined effect of blood composition, vessel diameter, and vessel length o Vessel diameter can change vasomotion Vasoconstriction smaller vessels, higher blood pressure Sympathetic action Anything that raises pressure = sympathetic Study Guide 3 Vasodilation (relaxation) larger vessels, lower blood pressure Parasympathetic action Response to lack of stimulation to contract Blood volume- total volume of blood in vessels o Mainly controlled by kidneys and hormones Maintaining blood pressure at rest When at rest, goal is to maintain pressure using a visceral neural circuit o Things that can alter blood pressure at rest: hydration state, posture, stress, disease Must gather sensory input o Input from baroreceptors (pressure monitors) about current pressure in major arteries o Proprioceptors (in muscles) also provide input BUT not important during rest Situation changes during exercise or fight or flight CNS must integrate sensory input o Occurs at cardiovascular control center (CVCC) in medulla Motor output negates any changes away from homeostasis o Negative feedback loops Blood pressure neuronal circuit Starts with sensory input to integrating center Baroreceptors and chemoreceptors provide sensory input to cardiovascular centers in the hindbrain o Baroreceptors: neurons with mechanical-gated sodium channels in membranes of dendrites o Increase in pressure artery stretches channel opens neurons depolarize o Rate of action potentials = amount of stretch More stretch more action potentials o Chemoreceptors: important for monitoring pH that alters respiration Motor output from integrating center o Cells of parasympathetic release Ach Ach binds to SA node cells and cause them to depolarize slower o Cells of sympathetic release norepinephrine Study Guide 3 Norepinephrine causes SA node cells to depolarize faster Visceral motor responses (either sympathetic or parasympathetic depending on sensory input) o Sympathetic response Occurs when blood pressure is too low (baroreceptors tell brain pressure is too low) Visceral motor neurons cause… Increased heart rate o Activation of cardioacceleratory neurons Vasoconstriction o Constriction of blood vessels regulated by sympathetic release of norepinephrine or epinephrine (from adrenal gland) o Parasympathetic response Occurs when blood pressure is too high Visceral motor neurons cause… Decreased heart rate o Activation of cardioinhibitory neurons Vasodilation o Dilation of blood vessels due to decrease in norepinephrine (lack of secretion from adrenal gland) Respiratory System Main functions of neuronal circuits involved with the heart Altering blood pressure o Cardiac output alters the amount of blood in the arterial system o This volume has an effect on the blood pressure Regulating the pH of the blood o CO 2 dissolved in the blood results in an acidic pH o Altering how fast blood moves to the lungs alters pH Ensuring proper filtration of blood at kidneys o Remove wastes, preserve water o Filtration of blood at kidneys depends on blood pressure Respiration can mean… Exchange of gases between tissues Transport of gases to tissues Ventilation of lungs (inhalation) o Pulmonary ventilation- inhalation, exhalation Use of oxygen for metabolism Study Guide 3 The lungs Composed of a series of tubes (bronchi) that either transport gas or allow for gas exchange o Air conduction tubes- transport gas o Gas exchange tubes- gas exchange A bronchus has smooth muscle and a plate of cartilage that helps hold the tube open o Smooth muscle can contract and relax (this alters the diameter of the tube) At the end of each tube is an alveolus, a balloon-like structure consisting of a single cell layer o Where exchange occurs Air-conducting vs. gas-exchange structures o Conducting zone: mucosa-lined, allows no gas exchange with blood Supported by cartilage and smooth muscle o Respiratory zone: (gas exchange) thin walled simple squamous epithelium, allows gas exchange with blood Smooth muscle only in bronchioles Single cell later in alveoli Alveolus- balloon-like structure at the end of bronchi that is one cell layer thick o Contain 3 cell types: Squamous cells: flat cells that make the pouch Great alveolar cells: produce surfactant that helps reduce water tension so alveolus doesn’t stick to itself Dust cells: type of immune cell Help engulf inhaled debris or pathogens Mobile, travel around alveoli Alveolus + Capillary = Respiratory Membrane o Each alveolus is intimately associated with a capillary bed o Respiratory membrane is where the alveolus and capillary interact Separates the air (in alveoli) and blood (in bloodstream) Only 2 cells thick (capillary epithelium and alveolus squamous cell) Creates very thin membrane for rapid gas exchange Study Guide 3 1 cell from alveolus + 1 cell from capillary + basement membrane Basement membrane- non-cellular “glue” between other 2 layers o In alveolus- hi O ,2low CO 2 o In capillary- lo O 2 high CO 2 Gas transport- Oxygen o O i2 required by cells to synthesize ATP through cellular respiration o Transported directly by red blood cells Blood = blood cells + plasma (liquid bathing the cells) O binds to hemoglobin (protein found in red blood 2 cells) Hemoglobin unloads oxygen down a concentration gradient in tissues where O le2els are lower Gas transport- Carbon Dioxide o CO i2 a waste product from cellular respiration It’s dissolved in blood plasma as carbonic acid (unstable) that is converted to bicarbonate and protons (carbonic acid equation) - + CO 2 H O 2 H CO 2CO 3 3 + H o Dissolved CO rel2tes to pH of blood because of protons o High protons very small pH o Low protons very large pH Gas Homeostasis – pH of blood o Carbonic acid equation is reversible o Reactants and products determine the direction of the reaction o Products and reactants want to reach equilibrium o pH of blood is maintained at about 7.4 Measurement is associated with the amount of CO 2 o If CO l2vels rise too high: Production of protons increases pH lowers This is called hypercapnia (too much CO ) 2 Study Guide 3 Which results in acidosis (acidic blood; less than 7.35) o If CO levels drop too low: 2 Decrease in protons pH raises This is called hypocapnia (too little CO )2 Which results in alkalosis (basic blood; greater than 7.45) Respiratory Neural Circuits Lungs require its neural connections to work o Do not have internal “pacemaker cells” like the heart Nervous system monitors and maintains pH homeostasis o Involves respiratory, cardiovascular, and renal systems Involves afferent, interneurons, and efferent neurons o Afferent- supply sensory input o Interneurons- integrate sensory input at respiratory centers in brain Located in pons and medulla These centers set the pace of respiration (involuntary) o Efferent- cause a response Target diaphragm and rib cage skeletal muscles Examples of voluntary muscle that are involuntarily activated by the brain Lungs do not have muscles Alter contraction of muscles, altering respiratory rate Afferent neurons o Afferent input travels on sensory neurons o All afferent input is integrated in CNS control centers to determine a motor response o Higher brain centers (cortex) Emotions Conscious control o Stretch receptors in lungs Prevent over inflation of lungs o Irritant receptors in lungs Tell brain to increase respiratory rate to get irritants out o Proprioceptors Tell brain to increase respiratory rate to remove CO 2 during high muscle activity o Chemoreceptors Study Guide 3 Peripheral- detect oxygen of blood Located in major arteries leaving the heart They increase action potentials when O lev2ls drop Central- detect CO o2 blood Located in medulla Monitor CO l2vels and pH in cerebral spinal fluid They increase action potentials when CO 2 levels rise (pH drops) Alter respiratory rate to maintain oxygen levels and pH Cause motor neurons to increase respiratory rate Interneurons o Located in brain centers o Action is altered based on input from sensory neurons o Cause change to 2 sets of efferent neurons Efferent neurons o Efferent signals travel on motor neurons (parasympathetic or sympathetic) o Target tissue determines if visceral or somatic o Inspiratory neurons Used in “quiet” or normal breathing AND forced breathing Cause contraction of diaphragm and rib muscles (inhalation) Exhalation is passive (relaxation of muscles) More action potentials per time from interneurons in brain center increases respiratory rate (altered by sensory input) o Expiratory neurons Used in forced/active breathing Cause contraction of accessory rib muscles and abs (forcing exhalation) Different muscles than in inhalation Rhythm is created between inspiratory and expiratory during forced breathing Because one is sending action potential, and the other is at rest Examples o At rest Study Guide 3 Baroreceptors/chemoreceptors are monitoring for homeostasis Changes in pressure/waste in arteries will be negated by efferent path Either sympathetic or parasympathetic changes o Action Proprioceptors play a role Efferent path stimulates sympathetic changes Parasympathetic is needed to return to rest Structures of the respiratory system Upper o Nasal cavity o Pharynx Splitting point- Larynx Lower o Trachea o Bronchi Nose and pharynx o Cleanse, warm, and humidify the air as it enters the body o Walls are lined with mucous-producing cells (goblet cells) o Ciliated cells- help move mucous down toward esophagus Larynx, trachea, bronchi o Provide passage of air to the lungs o All part of air conducting system Called anatomical dead space because no gas exchange is going on o Trachea- has cartilage in ring like structures o Bronchi- has cartilage plates Lung Pleura o Lungs are located in thoracic cavity Thoracic cavity- space enclosed by ribs and muscular diaphragm o Each lung is associated with 2 continuous membranes (pleura) Visceral pleura- on surface of the lung Parietal pleura- on inner surface of rib cage Actually touches the wall Study Guide 3 Space between contains small amount of fluid (pleural fluid) Causes tension between membranes so they stick o Lung pleura stick together Therefore, lung volume changes as volume of thoracic cavity changes Changes caused by muscle contraction 3 pressures of ventilation o Gases move in our lungs based on relationship of 3 pressures o Intrapleural pressure- pressure between membranes Constant unless injured Prevents lungs from collapsing (with help of surfactant) Also helps lungs change size with changing size of thoracic cavity o Atmospheric pressure- air pressure outside the body o Intrapulmonary pressure- air pressure in lungs If there is a decrease in lung volume, intrapulmonary pressure increases compared to atmospheric pressure The reverse is true also Gradients of pressure cause air movement into or out of our lungs (pulmonary ventilation) o Boyles Law The pressure of a given quantity of gas is inversely proportional to its volume Gases move high pressure low pressure Inhalation o Diaphragm contracts and lowers o Rib muscles contract and expand the cage Thoracic volume increases Poutside Pinside o Air moves high pressure low pressure Passive exhalation o Diaphragm relaxes and moves up o Rib muscles relax Thoracic volume decreases Pinside Poutside Study Guide 3 o Air moves high pressure low pressure o During “forced” exhalation, other muscles are involved (like abs) Respiratory rate (f) = breaths per minute (avg. 15) Tidal volume (V )t= amount of gas inhaled during one breath (avg. 500 mL) Respiratory Minute Volume (V ) =evolume inhaled in one minute o V = f x V e t o V =e15/minute x 500 mL = 7500 mL or 7.5 liters/minute Alveolar Ventilation (V e = air at the alveolar respiratory membrane per minute Respiration process o Pulmonary ventilation- physical movement of air into lungs o Gas diffusion- across respiratory membrane o Gas transport- to tissues in the body Diffusion at alveoli in lungs or capillary beds of tissue relies on the partial pressure of gases o Each gas contributes a partial pressure to total pressure o Overall pressure- weight of the air on us o Atmospheric pressure = 760 mmHg Concentration Gradients of Gases o Differences in partial pressure allow for diffusion Gases diffuse down pressure gradient
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