Human Physiology & Pathophysiology Notes PDF

Human Physiology & Pathophysiology Notes  Nervous tissue Key INFORMATION Structure of the Nervous System Neurology - deals with normal functioning and disorders of the nervous system....

Human Physiology & Pathophysiology Notes  Nervous tissue Key INFORMATION Structure of the Nervous System Neurology - deals with normal functioning and disorders of the nervous system. Neurologist - Is the physician who diagnoses and treats disorders of the nervous system. MAs of only 2kg (4.51b), about 3% of the total body weight. Nervous system is one of the smallest yet the most complex of the ll body system. Structures of Nervous System Brain - neurons enclose within the Skull. Organization of the Nervous System Spinal cord - connects the brain and enclose between the spinal cavity. Central Nervous System (CNS) Brain (100 billion neurons) and spinal cord (100 Nerves - bundles of many axons of neurons. million neurons) source of thoughts, emotions, and memories. cranial nerves (12 pairs)emerge from brain. signals that stimulate muscles to contract and spinal nerves (31 pairs) emerge from spinal cord. glands to secrete Structures Ganglia - the neurons outside the CNS. Brain Spinal cord Enteric plexuses - networks in digestive tract (gut). Peripheral Nervous System (PNS) Sensory receptors - Monitor changes in internal and All nervous system structures outside of the CNS external environment. include nerves, ganglia, enteric plexuses, and touch in skin sensory receptors photo in eye Structure olfactory in nose cranial nerves and branches spinal nerve and branches Functions of the Nervous System ganglia sensory receptors Sensory (input)- receptor and sensory nerve. carries formation into CNS Division of peripheral Nervous System (PNS) Integration (process) - information processing. perception = awareness of sensors input Somatic (SNS) analyzing and storing information to help lead to Sensory neurons from head, body wall, limbs, special sense appropriate responses. organs Motor neurons to skeletal muscle: voluntary Motor activity (output) - efferent nerves. signals to muscles to glands (effectors) Autonomic(ANS) nervous systems Sensory neurons from viscera Motor neurons to viscera (cardiac muscle, smooth muscle, glands): involuntary  Division of PNS Dentrites: highly branched structures that carry impulses to the cell body. receiving or input portions of a neuron Autonomic (ANS) Nervous system: Sympathetic: "fight-or-flight" or fight-fright- Axon: conducts away from cell body toward another flight". ( response to emergency). neuron, muscle or gland Parasympathetic: "rest-and-digest". (Normal state Emerges at cone-shaped axon hillock or process/relax) Axon terminals: contain synaptic vesicles that can release neurotransmitters Enteric nervous (ENS): C "brain of the gut" (digestive tract) govern contraction of GI tract smooth muscle to Neuronal Structure propel food, secretions of the GI tract organs such as acid from the stomach, and activity of GI tract endocrine cells, which secrete hormones (involuntary) Structural Classes of Neuron Histology of Nervous Tissue Multipolar Have several or many dendrites Two cell types and one axon Most common Neurons type in brain Can respond to stimuli and convert stimuli to electrical and spinal cord signals (nerve impulses or action potentials) that travel along neurons. Bipolar Have one Neuroglia cells: support, nourish and protect neurons dendrite and Neuroglia critical for homeostasis of interstitial fluid one axon around neurons Example: in neuroglia continue to divide throughout an retina of eye individual’s lifetime and inner ear Unipolar Parts of A Neuron Have fused dendrite and axon Sensory neurons of Cell body (perikaryon or soma): nucleus, cytoplasm with spinal nerves typical organelles throughout an individual’s lifetime  Interneurons (association neurons) Sensory Receptors: integrate (process) incoming information from sensory neurons and then elicit appropriate Dentrites of Unipolar motor neurons. (Multipolar) Neurons Neurolgia Meissener corpuscle Cell smaller but much more numerous than neurons. Can multiply and divide and fill in brain areas. Gliomas: brain tumors derived from neuralgia. Functions Responsible for sense of touch do not conduct nerve impuses Do support, nourish and protect neurons Merle tactile disc Neurolgia of the CNS (4 (types) Astrocytes (star shaped): help form Blood Brain Responsible for sense of touch (free Barrier (restrict the movement of substances nerves ending ). between the blood and inertestial fluid) regulate the growth, migration of neurons in Pacinian (lamellated)corpuscle the brain & play a role in learning and memory Two types: Protoplasmic astrocytes: have many short branching processes and are found in gray matter. Fibrous astrocytes: have many long unbranched pressure receptor processes and are located mainly in white matter. Oligadentrites: produce myelin in CNS Nociceptor Microglia: protect CNS from disease function as phagocytes Ependymal cells: forms central sensory funtion (CSF) in ventricles Schwann: produce myelin around PNS neurons; help to Pain receptor regenerate PNS axons. Satellite cells: support neurons in PNS ganglia. cht Classes of Neuron Myelination Sensory (afferent) forms an action potential in its axon and Axon covered with a myelin sheath conveyed into the CNS through cranial or many layers of lipid and protein: insulates neurons spinal nerves. (unipolar). increases speed of nerve conduction. Motor (efferent) appears white( in white matter). convey action potential away from the CNS to Nodes of Ranvier: gaps in the myelin sheath effectors (muscle and glands) in the (PNS) modes are important for rapid rapid signal conduction. through cranial nerve (unipolar). Some diseases destroy myelin: four types of ion channels: Multiple sclerosis leak channels, Tay-sachs ligand-gated channels, mechanically gated channels, q voltage-gated channels Collections of Nearvous Tissue Neuron Regeneration Clusters of neuron cell bodies Ganglion: cluster of cell bodies in PNS Nucleus: cluster of cell bodies in CNS Regeneration of PNS neurons axon and dentrites can be repaired it cell body is Bundles of axons intact and Schwann cells functional. Nerve: bundle of axons in PNS these form a regeneration tube and grow axons and Tract: bundle to axons in CNS detritus if scare tissue does hot fill the tube. Gray and White Matter Regeneration of CNS neurons very limited even the cell body is intact. inhibited by neuralgia and by lack of fetal growth - White matter: primarily myelinated axons stimulator. Gray matter: cell bodies, dendrites, unmyelinated axons, axon terminals, neuroglia Ion Channels Locations of gray and white matter Spinal cord: white matter (tracts) surround centrally located Leakage channels: allow ions to leak through membranes gray matter “H” of “butterfly” there are more for k+ than for Na+. Brain: gray matter in thin cortex surrounds white matter (tracts) Distribution of Gray Matter and Ligand-gated channel: opens or closes in response White matter in the Spinal card and to binding a lingand (chemical) stimulus. brain Mechanically gated channel: opens or closes in response to mechanical stimulation for in the of vibration (sound, wave) touch, pressure, or tissue stretching. Voltage gated channels: opens in response to a Action Potentials change in membrane potential (votage). Participate in the and a generation and conduction of action potentials in the axons of all types neurons. Action potentials = nerve impulses Require A membrane potential: a charge difference across cell membrane (polarization) Ion channels: allow ions to move by diffusion from high to low concentration.  Repolarizing phase Resting Membrane Potential K+ channels open - as more K+ leave cell, membrane potential is returned to resting value ( + 30 0 + 55 70my) + - - Hyperpolarizing Typically –70 mV lower than -70 (overshoot). Inside of membrane more negative than outside It will happen shortly and will back again in the resting phase. Caused by presence of ions: Inside (morenegative) because cytosolhas: Typically depolarization and repolarization take place in about 1 Many negative ions (too large to leak out): amino acids (in millisecond (1/1000 sec) cellular proteins) and phosphates (as in ATP) K+ that easily leaks out through many K+ channels Outside (more positive) because interstitial fluid has: Few negative ions Na+ that does not leak out of cell: few Na+ channels Membrane “pumps” that quickly pump out Na+ that does leak (diffuse) into cell. The resting membrane potential is determined by three major factors: (1) unequal distribution of ions in the ECF and cytosol, (2) inability of most anions to leave the cell (3) the electrogenic nature of the Na/K ATPases. Absolute Refractory Period even a strong stimulus cannot initiate a second action potential, because the goal is to go back at the resting phase before it accommodate new stimulus. it happen continuously up hill, then go to axon terminals- it is the time that it will release neurotransmitter and produce response. Relative Refractory Period period of time which a second action potential can be Action Potential (impulse) initiated. After hyperpolarizing phase it will lower than -70 but eventually go back to the resting A sequence of rapidly occurring events that decrease and phase. reverse the membrane potential and then eventually Recovery restore it to testing state. Levels of ions back to normal by action of Na+/K+ pump An initial event (stimulus) is required Refractory period (brief): even with adequate stimulus, cell Triggers resting membrane to become more cannot be activated permeable to Na+ It it is strong enough it will continue. Causes enough Na+ to enter cell so that cell membrane reaches threshold (~ –55 mv) All-or-none principle If so, the following events occur: action potential if a stimulus is strong enough to cause depolarization to which spreads along neuron or muscle fiber threshold level, the impulse will travel the entire length of the neuron an constant and maximum straight. Action Potential Phases Triggers resting membrane to become more Na+ channels open- as more Na+ enters cell, membrane potential rises and becomes positive ( 70 - 55 7 0 - - - - 7 + 30) Conduction of Nerve Impulses Synaptic Transmission Nerve impulse conduction (propagation) Similar sequence of events occurs at each section triggers the next Synapse: two neurons talk (neuron-neuron) Locally as even more Na+ channels are opened (low Neuromuscular juction: neurons that send signals of domino) to neuron muscle fibers ( neuron-muscle fiber) Neuroglandular junction: (neuron-gland) Factors that increase rate of conduction Myelin, large diameter and warm nerve fibers. Triggered by action potential (nerve impulse) Components of synapse: Conduction of Nerve Impulses Sending neuron: presynaptic neuron (releases neurotransmitter) Types Space between neurons: synaptic cleft Receiving neuron: postsynaptic neuron Continuos Conduction: unmyelinated fibers; slower form of conduction. Synaptic Transmission Process Action potential arrives at presynaptic neuron’s end bulb Opens voltage gated Ca2+ channels - Ca2+ flows into presynaptic cytosol Increased Ca2+ concentration - exocytosis of synaptic vesicles Neurotransmitter (NT) released into cleft. NT diffuses across cleft and binds to receptors in postsynaptic cell membrane NT serves as chemical trigger (stimulus) of Saltatory Conduction: myelinated fibers; faster as ion channels. impulses "leap" between nodes of Ranvier Postsynaptic cell membrane may be depolarized or hyperpolarized - depend on type of NT and types of postsynaptic cell - 1000 neurons converge un synapse; the of all their NTs determines effect. If threshold reached, then postsynaptic cell action potential results One-way transmission only because: - Only presynaptic cells release NT - Only postsynaptic cells have receptors for NT binding Finally, NT must be removed from the cleft. Three possible mechanisms. - Diffusion out of cleft - Destruction by enzymes (such as ACh-ase) in cleft - Transportback (recycling)into presynaptic cell  Neuropeptides such as endorphins Signal transmission at the endorphins are produces the we exercise, excited, from spicy food etc. (A happy hormone) chemical synapse produces in pituitary gland and hypothalamus. has ability to produce analgesic endogenous ( pain reliver) Nitric oxide (NO) responsible for dilation of blood vessels. Remember!! not all NT will bind to receptor, it is finite (limited) those who was left will be broken down or will go back to presynaptic and recycle again. there is an enzyme in the synaptic cleft. graded potential is produce when ligand gate open into the ligan-gated chanel. Ach-ase: enzymes that broke neurons Neurotransmitters Acetylcholine (ACh): common in PNS Stimulatory (on skeletal muscles) Inhibitory (on cardiac muscle) Amino acids Stimulatory (on skeletal muscles) Inhibitory (on cardiac muscle): make us relax and calm. Bionic amines Norepinephrine (NE) - for emergency (sympathetic) Dopamine (DA) - make us hyper, it increases the heart beat Serotonin - happy hormones  Divisions of the Nervous System Preganglionic neuron from CNS to neuron in Introduction to the ANS autonomic ganglion Postganglionic neuron from cell body in ganglion to effector Somatic nervous system (SNS) + ANS - peripheral nervous system (PNS) ANS Not under conscious control Is regulated by hypothalamus, brainstem The ANS supplies nerves to viscera Smooth muscle (stomach, blood vessels) Cardiac muscle (heart) Glands (sweat and digestive glands) Comparison: SNS vs ANS Somatic Nervous System Controls skeletal muscle Division of the ANS Conscious, voluntary control Motor pathway: one neuron from CNS to Sympathetic (S) division + Parasympathetic (P) effector division Does include sensory neurons (from skin, Most viscera supplied with nerves of both S and P skeletal muscles, and special sense organs) divisions: dual innervation All release the neurotransmitter ACh S and P have opposite (antagonistic) effects Heart rate: S stimulates, P inhibits Digestive organs: S inhibit, P stimulate S: “fight,fright, or flight,” P: “rest and digest” n Some viscera receive only S (not P) nerves: Sweat glands, many blood vessels, hair muscles Sympathetic (S) Division Sympathetic preganglionic neurons Autonomic Nervous System Have cell bodies located in lateral gray of spinal cord segments T1-T12 + L1-L2 So S division is called “thoracolumbar” Controls viscera: smooth and cardiac Axons pass through ventral roots of spinal nerves muscle, and glands Unconscious, involuntary May branch many times Motor pathway: series of two neurons May ascend or descend to many levels of S from CNS to effector trunk ganglia (from cervical to sacral) Does include sensory neurons (monitors n Can synapse with 20 or more postganglionic viscera) neuron cell bodies Two divisions: sympathetic, parasympathetic n Results: widespread S effects (viscera respond “in Release either ACh or NE sympathy with one another”) ANS Motor Pathways Sympathetic (S) Division Autonomic motor pathway includes two motor Sympathetic postganglionic neurons neurons S postganglionic neurons cell bodies located From cervical to sacral regions - widespread S effects. Many axons from these cell bodies pass back into spinal nerves to reach viscera in skin (sweat glands, hair muscles, blood vessels) In S “prevertebral ganglia” anterior to 3 large abdominal arteries Named celiac, superior and inferior mesenteric ganglia q Supply abdominal viscera: stomach, intestine, kidneys, liver, spleen Axons pass from ganglia to viscera in S nerves Sympathetic Effects Parasympathetic (P) Division Fight-or-flight activities - Increase heart rate and contraction, and blood pressure (BP) -Dilate pupils (mydriasis) P preganglionic neurons -Dilate airways (bronchodilation) Cell bodies located in brainstem + in spinal cord -Dilate vessels to skeletal muscles, heart, liver and segments S2-S4 adipose tissue (vasodilation) Therefore P division is called “craniosacral” -Constrict blood vessels to nonessential organs: Axons in cranial nerves III, VII, IX and X and in pelvic skin, GI tract, kidneys nerves from S2-S4 -Mobilize nutrients for energy: glucose and fats Vagus nerves (cranial nerves X) carry 80% of all P nerve impulses. Vagus nerves carry both motor and sensory neurons to/ from viscera within the thorax and most of the Parasympathetic Effects abdominal cavity. P preganglionic axons do not branch or pass though S Rest-and-digest activities trunk ganglia but pass directly almost to SLUDD -Salivation P postganglionic neurons -Lacrimation n Urination Cell bodies lie in terminal ganglia -Digestion -Located within or near the innervated organ -Defecation -So P nerves cause precise, localized (not widespread) -Decrease heart rate, airway diameter, pupil effects diameter Because of anatomical arrangement, S nerves supply all viscera but P nerves do not reach some viscera. These include sweat glands, arrector pili muscles of hairs in skin, kidneys, spleen, adrenal medullae, and the walls of most blood vessels. - Axons pass from ganglia to viscera in P nerves  The Cardiovascular System: The Heart Location of the Heart Thoracic cavity between two lungs ~2/3 to left of midline surrounded by pericardium: (2 parts) Fibrous pericardium - Inelastic and anchors heart in place Inside is serous pericardium - double layer around heart Parietal layer fused to fibrous pericardium Inner visceral layer adheres tightly to heart Filled with pericardial fluid - reduces friction during beat. CLINICAL CONNECTION | Myocarditis and Endocarditis Myocarditis is an inflammation of the myocardium that usually occurs as a complication of a viral infection, rheumatic fever, or exposure to radiation or certain chemicals or medications. Endocarditis refers to an inflammation of the endocardium and typically involves the heart valves. Most cases are caused by bacteria (bacterial endocarditis). Tx- intravenous antibiotics Heart Wall Chambers of the Heart Epicardium - outer layer Myocardium - cardiac muscle. Responsible for the pumping action of the heart 4 chambers makes up approximately 95% of the heart wall. 2 upper chambers = Atria The thickness layer of the heart receive blood from blood vessels returning Endocardium - thin layer of endothelium (part of stomach) blood to the heart, called veins provides a smooth lining for the chambers of the 2 lower chambers = ventricles heart and covers the valves of the heart. eject the blood from the heart into blood vessels called arteries Wall thickness depends on work load Atria thinnest Right ventricle pumps to lungs & thinner than left  Left Atrium receives blood from the lungs through four pulmonary veins. Blood passes from the left atrium into the left ventricle through the bicuspid (mitral) valve. It is also called the left atrioventricular valve. Right Atrium Forms the right border of the heart and receives blood from three veins: the superior vena cava, inferior vena cava, and coronary sinus. interatrial septum - thin partition between the right left atrium A prominent feature of this septum is an oval depression called the fossa ovalis, the remnant of the foramen ovale, an opening in the interatrial septum of the fetal heart that normally closes soon after birth tricuspid valve - blood passes from the right atrium into the right ventricle Left Ventricle the thickest chamber of the heart, averaging 10–15 mm blood passes from the left ventricle through the aortic valve into the ascending aorta. Great Vessels Of Heart-Right Superior & inferior Vena Cavae Delivers deoxygenated blood to R. atrium from body Coronary sinus drains heart muscle veins R. Atrium - R. Ventricle pumps through Pulmonary Trunk - R & L pulmonary arteries - lungs Right Ventricle forms most of the anterior surface of the heart. inside of the right ventricle contains a series of ridges formed by raised bundles of cardiac muscle fibers called trabeculae. interventricular septum – separate right ventricle from the left ventricle blood passes from the right ventricle through the pulmonary valve into a large artery called the pulmonary trunk, which divides into right and left pulmonary arteries and carries blood to the lungs.  Great Vessels Of Heart-Left CLINICAL CONNECTION | Heart Valve Disorders Pulmonary Veins from lungs narrowing of a heart valve opening that restricts blood oxygenated blood flow is known as stenosis. - L. atrium - Left mitral stenosis - scar formation or a congenital defect ventricle causes narrowing of the mitral valve (bicospid). - ascending aorta - Mitral valve prolapse (MVP) backflow of blood from the body left ventricle into the left atrium. Between pulmonary aortic stenosis - aortic valve is narrowed, and in aortic trunk & aortic arch is insufficiency there is backflow of blood from the aorta into ligamentum arteriosum the left ventricle. (fetal ductus arteriosum Rheumatic fever - acute systemic inflammatory disease that remnant) - which usually occurs after a streptococcal infection of the throat. connects the arch of the aorta and pulmonary trunk. Valves Designed to prevent back flow in response to pressure changes Atrioventricular (AV) valves Between atria and ventricles Right = tricuspid valve (3 cusps) Left = bicuspid or mitral valve Semilunar valves near origin of aorta & pulmonary trunk Aortic & pulmonary valves respectively Atrioventricular Valves: Bicuspid Valves Blood Supply Of Heart Blood flow through vessels in myocardium = coronary circulation Left & right coronary arteries Branch from the ascending aorta and supply oxygenated blood to the myocardium Most of the deoxygenated blood from the myocardium drains into a large vascular sinus in the coronary sulcus on the posterior surface of the heart, called the coronary sinus Empties into right atrium Conduction System only 1% of the cardiac muscle fibers become autorhythmic fibers; Two important functions: 1. They act as a pacemaker, setting the rhythm of electrical excitation that causes contraction of the heart. 2. they form the cardiac conduction system, a network of specialized cardiac muscle fibers that provide a path for each cycle of cardiac excitation to progress through the heart. Sequence of AP propagate through the conduction system: Electrocardiogram Normally begins at sinoatrial (SA) node Recording of currents from cardiac conduction on skin = - Atria & atria contract electrocardiogram (EKG or ECG) - AV node - slows ECG is a composite record of action potentials produced by all - AV bundle (Bundle of His) the heart muscle fibers during each heartbeat. - bundle branches - Purkinje fibers 3 waves -apex and up- then ventricles contract P wave = represents atrial depolarization pushing the blood upward toward Contraction begins right after peak semilunar valve. Repolarization is masked in QRS QRS complex = rapid ventricular depolarization Contraction of ventricle T-wave = ventricular repolarization Just after ventricles relax Pacemaker Depolarize spontaneously sinoatrial node ~100times /min also AV node ~40-60 times/min in ventricle ~20-35 /min CLINICAL CONNECTION Fastest one run runs the heart = pacemaker n Normally the sinoatrial node size of the waves can provide clues to abnormalities: Larger P waves indicate enlargement of an atrium; CLINICAL CONNECTION | Artificial Pacemakers Enlarged Q wave may indicate a myocardial infarction; if the pacing rate is so slow (20–35 bpm) that blood flow Enlarged R wave generally indicates enlarged to the brain is inadequate. ventricles. artificial pacemaker - a device that sends out small If T wave is flatter than normal = heart muscle is electrical currents to stimulate the heart to contract. receiving insufficient oxygen—exp, in coronary artery A pacemaker consists of a battery and impulse generator disease. and is usually implanted beneath the skin just inferior to The T wave may be elevated in hyperkalemia (high the clavicle. blood K level). Many of the newer pacemakers, referred to as activity- adjusted pacemakers, automatically speed up the heartbeat during exercise.  P–Q interval lengthens in coronary artery disease and Cardiac output (CO) is the volume of blood ejected from rheumatic fever. the left ventricle (or the right ventricle) into the aorta S–T segment is elevated in acute myocardial infarction (or pulmonary trunk) each minute. and depressed when the heart muscle receives insufficient Cardiac output equals the Stroke volume, multiplied by oxygen. the Heart rate (HR). Q–T interval may be lengthened by myocardial damage, myocardial ischemia (decreased blood flow), or conduction abnormalities. CARDIAC CYCLE A single cardiac cycle includes all the events associated with one heartbeat. Thus, a cardiac cycle consists of systole and diastole of the atria plus systole and diastole of the ventricles. atrial systole - lasts about 0.1 sec, the atria are contracting (P -wave). The ventricles are relaxed (diastole). Regulation of Stroke Volume ventricular systole, which lasts about 0.3 sec, the ventricles are contracting. The atria are relaxed in (atrial diastole). Three factors regulate SV and ensure that the left and after T-wave - ventricular diastole right ventricles pump equal volumes of blood: Ventricular pressure drops below atrial pressure & AV valves (1) preload, the degree of stretch on the heart before it open è ventricular filling occurs (150mL) contracts; (end diastolic volume, hifh stroke volume) After P-waveè atrial systole (2) contractility, the forcefulness of contraction of Finishes filling ventricle (25mL) individual ventricular muscle fibers; After QRSè ventricular systole (3) afterload, the pressure that must be exceeded Pressure pushes AV valves closed before ejection of blood from the ventricles can occur. Pushes semilunar valves open and ejection occurs Ejection until ventricle relaxes enough for arterial pressure to close semilunar valves Control of Stroke Volume (S.V.) Preload Degree of stretch = Frank-Starling law Increase diastolic Volume increases strength of contraction - increased S.V. Increased venous return - increased S.V. When HR exceeds about 160 beats/min, SV usually declines due to the short filling time High back pressure in artery - decreased S.V Slows semilunar valve opening Control of Stroke Volume (S.V.) Contraction positive inotropic agents - substances that increase contractility Flow Terms Ex. stimulation of the sympathetic div of ANS, hormones such as Epi & NE increase Ca2+ Stroke volume, the volume ejected per beat from each level and drug digitalis. ventricle, equals end-diastolic volume minus end- negative inotropic agents - decrease systolic volume: contractility SV=EDV-ESV. Ex. inhibition of the sympathetic div of the At rest, the stroke volume is about 130 mL - ANS, anoxia, acidosis, some anesthetics, and 60mL = 70 mL (a little more than 2 oz). increased K level in the interstitial fluid have negative inotropic effects. Calcium channel blockers - reduce Ca2+ inflow,  pressure that must be overcome before a Exercise and the Heart semilunar valve can open. increase in afterload causes stroke volume to Aerobic exercise (longer than 20 min) decrease, strengthens cardiovascular system: More blood remains in the ventricles at the end Brisk walking, running, bicycling, cross- of systole. country skiing, and swimming are examples Conditions that can increase afterload include of aerobic activities. hypertension and narrowing of arteries by Well trained athleteè doubles maximum C.O. atherosclerosis n Resting C.O. about the same but resting H.R.decreased (40–60 bpm) Regular exercise also helps to reduce blood CLINICAL CONNECTION | pressure, anxiety, and depression; control Congestive Heart Failure weight; and increase the body’s ability to dissolve blood clots. loss of pumping efficiency by the heart. Causes: coronary artery disease, congenital defects, long-term high blood pressure, myocardial infarctions, and valve disorders. As a result, blood backs up in the lungs and causes pulmonary edema, that can cause suffocation if left untreated. If right ventricle fails first, blood backs up in the systemic veins and, over time, the kidneys cause an increase in blood volume. Resulting peripheral edema - most noticeable in the feet and ankles. Right Side Heart Failure (RSHF): It is the back flow in the systemic circulation, that cause Systemic edema. left side heart failure (LSHF): back flow from the lungs that cause pulmunary edema. Controls- Heart Rate Pacemaker adjusted by nerves Cardiovascular center in Medulla Parasympathetic- ACh slows via vagus nerve (CN X) Sympathetic - Norepinephrine speeds Sensory input for control: Baroreceptors (aortic arch & carotid sinus)- monitor the stretching of major arteries and veins caused by the pressure of the blood flowing. Chemoreceptors- O2, CO2, pH Other Controls Hormones: Epinephrine & norepinephrine increase H.R. Thyroid hormones stimulate H.R. Hyperthyroidism causes tachycardia Ions Increased Na+ or K+ decrease H.R. & contraction force Increased Ca2+ increases H.R. & contraction force