test 2 Physiology

Pain reflexes

-skeletal muscle reflexes can be triggered by painful stimulation of the skin -withdrawal reflex: used to withdraw from a painful stimulus - crossed extensor reflex: ensures the opposite limb is in a position to bear the weight of the body as the injured limb is withdrawn from the stimulus

Capillary velocity

-slow velocity of flow through capillaries -flow rate: volume of blood per unit of time flowing through a given segment of the circulatory system -velocity of flow: speed, or distance per unit of time, with which blood flows forward through a given segment of the circulatory system

Characteristics of smooth muscle

-smooth muscle can still develop tension yet inherently relaxes when stretched -the stress relaxation response -an advantage of the s,oooh muscle length-tension relationship -smooth muscle is slow an economical -latch phenomenon

Smooth muscle

-smooth muscle cells are small and Unstriated -smooth muscle cells are turned on by Ca2+ dependent phosphorylation of myosin -physic smooth muscle contracts in bursts; tonic smooth muscle maintains tone -multiunit smooth smudges is neurogenic -single-unit smooth muscle cells form functional -single-unit smooth muscle is myogenic -pacemaker and slow-wave potentials -gradation of single-unit smooth muscle contraction differs from that of skeletal muscle -modification of smooth muscle activity by the autonomic nervous system -other factors influencing smooth muscle activity

What are the 4 steps in the excitation, contraction, and relaxation process

-splitting of ATP by myosin ATPase provides the energy for power stroke of cross bridge -binding of ATP to myosin breaks cross bridge -active transport of Ca2+ back into lateral sacs of the SR during relaxation -activity of Na+ K+ puma during action potential production

Stroke volume

-stroke volume is determined by the extent of venous return and by sympathetic activity -intrinsic control: related to the extent of venous return -extrinsic control: related to the extent of sympathetic stimulation of the heart

Stroke volume and cardiac output

-sympathetic stimulation increases the contractility of the heart -contractility: strength of contraction at any given EDV -summary of factors affecting stroke volume and cardiac output - stroke volume can be graded by varying the initial length of the muscle fibers and varying the extent of sympathetic stimulation

Regulation of Blood pressure

-the baroreceptor reflex is a short-term mechanism for regulating blood pressure; influences the heart and blood vessels to adjust CO and TPR in an attempt to restore blood pressure toward normal -other reflexes and responses influence blood pressure; left atrial volume receptors, hypothalamic osmoreceptors, chemoreceptors, cardiovascular responses, etc.

The cardiovascular control center and hormone regulation

-the cardiovascular control center and several hormones regulate blood pressure -influence of epinephrine and norepinephrine; norepinephrine produces generalized vasoconstriction; Epinephrine reinforces local vasodilator mechanisms in tissues -vasopressin maintains water balance -angiotensin II regulates salt balance

mechanical events of the cardiac cycle

-the heart alternately contracts to empty and relaxes to fill -cardiac cycle consists of alternate periods of systole and diastole -Mid- late, and end ventricular diastole -nose of ventricular systole, isovolumetric ventricular contraction, ventricular ejection, and end of ventricular systole -onset of ventricular diastole, isovolumetric ventricular relaxation, and ventricular filling

Nourishing the heart muscle

-the heart receives most of its blood supply through the coronary circulation during diastole -matching of coronary blood flow to heart muscle's O2 needs -coronary blood flow is adjusted in response to changes in the heart's O2 requirements -nutrient supply to the heart - the heart can tolerate wide variations in its nutrient supply

Muscle fibers of the heart

-the heart walls are composed primarily of spirally arranged cardiac muscle fibers -endothelium,myocardium, and epicardium -cardiac muscle fibers are interconnected by intercalated discs: form functional syncytia - desmosomes and gap junctions -heart is enclosed by the pericardial sac - consists of a fibrous covering and secretory lining

Plasma

-the hematocrit is the packed cell volume of the blood; the rest of the volume is plasma -blood represents about 8% of total body weight -Blood consists of 42-45% hematocrit, less than 1% white blood cell and platelets, and 55-58% plasma -plasma is a transport medium for many inorganic and organic substances -consists of 90% water in which various substances are dissolved

Muscle tone

-the normal tension and firmness of a muscle at rest -muscle units actively maintain body position, without motion -increasing muscle tone increase metabolic energy used, even at rest -cross bridge formation decreases with age

The sinoatrial node

-the sinoatrial node (SA node) is the normal pacemaker of the heart -SA node -atrioventricular node -bundle of His (atrioventricular bundle) -purkinje fibers -normal and abnormal pacemaker activity -rates of slow depolarization and action potentials generated differ

Cardiac excitation and contraction

-the spread of cardiac excitation is coordinated to ensure efficient pumping -atrial excitation and contraction should be complete before ventricular contraction onset -excitation of cardiac muscle fiber should be coordinated to ensure each heart chamber contracts as a unit to pump efficiently -the pair of atria and pair of ventricles should be functionally coordinated so the birth members of the pair contract simultaneously

Load, velocity, work, and force

-the velocity of shortening is related to the load -load-velocity relationship -although muscles can accomplish work, much of the energy is converted to heat -work: force multiple by distance -force: muscle tension required to overcome the load (the weight of the object)

Cardiac output (CO)

-the volume pumped by left ventricle in 1 minute - CO= HR x SV CO= cardiac output (mL/min) HR= heart rate (beats/min) SV= stroke volume (mL/beat)

Important functions of blood

-transportation of dissolved substances -regulation of pH and ions -restriction of fluid losses at injury sites -defense against toxins and pathogens -stabilization of body temperature

Heart sounds

-two normal heart sounds are associated with valve closures -first and second heart sounds -turbulent blood flow produces heart murmurs - Stenotic and insufficient valves -timing of murmurs

Universal blood donors and recipients and Rh blood-group system

-universal blood donors and recipients; Type O blood can be transfused into people of any blood type; Type O individuals can receive only type O blood -Rh blood-group system; people who have the Rh factor are said to have Rh-positive blood; those lacking the Rh factor are considered Rh-negative

Venous return

-venous return is enhanced by several extrinsic factors -sympathetic activity on venous return -skeletal muscle activity on venous return -countering effect of gravity on the venous system -venous valves on venous return -Respiratory activity on venous return -cardiac suction on venous return

Veins

-venues communicate chemically with nearby arterioles; vital to matching capillary inflow and outflow within organ -veins serve as blood reservoir and as passageways back to the heart; when demands for blood are low, veins can store extra blood in reserve because of their passive distensibility

Vessel repair and clot dissolution

-vessel repair: fibroblasts form a scar at the vessel defect -clot dissolution: plasmin becomes trapped in the clot and later dissolves it by slowly breaking down the fibrin meshwork -preventing inappropriate clot formation: plasmin functions continually to prevent clots from forming inappropriately

Flow rate

-volume of blood passing through per unit of time -directly proportional to the pressure gradient -inversely proportional to vascular resistance F=DP/R

Characteristics of capillaries

-water filled capillary pores permit passage of small, water soluble substances; pores: narrow, water filled clefts -many capillaries are not open under resting conditions -role of precapillary sphincters; wisps of spring smooth muscle cells, act as stopcock to control blood flow through the particular capillary that each one guards

Skeletal muscle mechanics

-whole muscles are groups of muscle fibers bundled together and attached to bones -tendons attach the muscle to bones -muscle tension is transmitted to bone as the contractile component tightens the series-elastic component -tensions is produced internally within the sarcomere -contractile component os the muscle

ECG

- The Electrocardiogram (ECG) -a recording of electrical events in the heart -obtained by electrodes at specific body locations -abnormal patterns diagnose damage -ECG is a record of the overall spread of electrical activity through the heart -electrical activity present in body fluids from the cardiac impulse that reaches the body surface

Bands and Cross-Bridges

-A and I bands A band: thick filaments along with portions of thin filaments that overlap I band: remaining portion of thin filaments that do not project into A band -Cross bridges -project from each thick filament in six directions toward the surrounding thin filaments

Morton neurons and Golgi tendon organs

-Coactivation of gamma and alpha motor neurons -gamma motor neurons initiate contraction of the muscular end regions of intrafusal fibers - Alpha-gamma coactivation: simultaneous stimulation of gamma and alpha motor-neuron system -golgi tendon organs -located in muscle tendons - respond to changes in the muscle's tension

Edema

-Edman occurs when too much interstitial fluid accumulates -categories; reduced concentration of plasma proteins, increased permeability of the capillary walls, increased Venmo's pressure, blockage of lymph vessels

Erythrocytes (RBC)

-Erythrocytes are well designed for their main function of O2 transport in the blood; shape and content is ideally suited for O2 transport; an atomic structure contributes to efficiency -Role of hemoglobin; found int in RBC; made of globin and heme groups; a pigment -lack of nucleus and organelles; RBC contain o nucleus or organelles -key erythrocytes enzymes; not a few crucial, non renewable enzymes remain within a mature erythrocyte; glycolytic enzymes and carbonic anhydrase -RBC survive an average of only 120 days

Myosin and Actin

-Myosin forms thick filaments -Protein consisting of two identical subunits, each shaped somewhat like a gold club -Actin is the email structural component of thin filaments -interacts with he myosin cross-bridges - two other proteins, tropomyosin and troponin (interact with thick filament) lie across the surface of actin

Function of each leukocyte

-Neutrophils; engulf and destroy bacteria intracellularly -Increase in eosinophils is associated with allergic conditions and parasite infestations -Basophils synthesize and store histamine and heparin -monocytes perform phagocytosis -lymphocytes provide specific immune defense

Skeletal muscle fibers

-Striated by a highly organized internal arrangement -Consists of muscle fibers lying parallel to one another -Bundled together by connective tissue -Muscle fibers are composed of myofibrils -Each myofibril is made of a regular arrangement of thick and thin filaments

ABO Blood types and transfusion

-Type A blood contains A antigens -Type B blood contains B antigens -Type AB blood has both A and B antigens -Type O blood does not have any A or B red blood cell surface antigens -Transfusion reaction; agglutination and hemolysis of donor RBCs by antibodies in plasma; can be fatal

Heart failure

-a failing heart cannot pump out enough blood -heart failure (HF): inability of CO to keep pace with the body's demands for supplies and removal of wastes -systolic and diastolic -defect in systolic heart failure -prime defect is decreed cardiac contractility

the frequency of stimulation

-a single neural stimulation produces: -a single contraction or twitch -which lasts about 7-100 msec -sustained muscular contractions -require many repeated stimuli

Plasma proteins

-albumins -globulins (alpha, beta, and gamma) -fibrinogen (factor in clotting)

Cross-reaction s in transfusions

-also called transfusion reaction -plasma antibody meets its specific surface antigen -blood will agglutinate ad hemolyze -occurs if donor and recipient blood types not compatible

The lymphatic system

-an accessory route for return of interstitial fluid to the blood -pickup and flow of lymph; lymph vessels -functions of the lymphatic system; return of excess filtered fluid, defense against disease, transport of absorbed fat, return of filtered protein

Polycythemia

-an excess of circulating erythrocytes -too many circulating RBCs and an elevated hematocrit (more viscous takes on more work, shear stress, effect on blood flow, risk of clots) -two general types, depending on what causes the excess RBC production; primary and secondary polycythemia

Surface antigens on erythrocytes affected blood types

-antigen: large, complex molecule that triggers a specific immune response against itself when it gains entry to the body -antibody: binds with the specific antigen against which it is produced and leads to the antigen's destruction by various means

Load and speed of contraction

-are inversely related -the heavier the load (resistance) on a muscle -the longer it takes for shortening to begin - and the less the muscle will shorten

Intermediate fibers

-are mid sized -have low myoglobin -have more capillaries than fast fibers, slower to fatigue

Slow fibers

-are slow to contract -have small diameter, more mitochondria -have high oxygen supply -contain myoglobin (red pigment, binds oxygen) Ex; calf

Arteries

-arteries serve as rapid-transit passageways to the organs and as a pressure reservoir; heart contracts to pump blood into arteries and relaxes to refill with blood from veins -arterial pressure fluctuates in relation to ventricular systole and diastole; systolic pressure averages 120 mmHg, diastolic pressure averages 80 mm Hg -blood pressure can be measured indirectly by using a sphygmomanometer; externally applied inflatable cuff attached to a pressure gauge -means arterial pressure is the main driving force for blood flow; average pressure driving blood forward into the tissues throughout the cardiac cycle

Arterioles

-arterioles are the major resistance vessels -radius is small enough to offer considerable resistance to flow -vasoconstriction; narrowing of a vessel -vasodilation; enlargement in circumference and radius of a vessel -vascular tone; state of partial constriction of arteriolar smooth muscle; establishes baselines of arteriolar resistance

Vasodilation Nitric Oxide

-arterioles release vasodilation NO in response to an increase ins hear stress; longitudinal force applied on the endothelial cells in the direction of the flow -local heat application dilates arterioles -cold application constricts arterioles

Iron ions

-associate easily with oxygen (oxyhemoglobin HbO2) -dissociate easily from oxygen (deoxyhemoglobin)

Atherosclerotic coronary artery disease

-atherosclerotic coronary artery disease can deprive the heart of essential O2 -vascular spasm: abnormal spastic constriction that transiently narrow the coronary vessels -development of atherosclerosis: progressive, degenerative arterial disease -leads to occlusion of affected vessels, reducing blood flow through them

Electrical activity of the heart

-automaticity: the heart contracts rhythmically as a result of action potentials that it generates by itself -contractile cells: 99% of the cardiac muscle cells do the mechanical work of pumping - autorhythmic cells: initiate and conduct the action potentials responsible for contraction of working cells

Patterns and physics of blood flow

-blood is transported to all parts of the body through a system of vessels -brings fresh supplies to the vicinity of all cells while removing their wastes -to maintain homeostasis, reconditioning organs receive blood flow in excess of their needs -adjust the extra blood to achieve homeostasis -blood flow through a vessel depends on: -the pressure gradient and vascular resistance

Blood pressure

-blood pressure is regulated by controlling cardiac output, total peripheral resistance, and blood volume -determinants of mean arterial pressure; CO and TPR -short term and long term control measures; short-term adjustments are made by alterations in CO and TPR; Long-term control involves adjusting total blood volume by restoring normal salt and water balance

Erythropoiesis (EPO hormone)

-bone marrow generation of new red blood cells -too much stimulation can cause cancer -reduced O2 delivery to kidneys stimulates them to secrete erythropoietin into the blood; in turn stimulates erythropoiesis by the red marrow -Reticulocytes: immature erythrocytes -Synthetic erythropoietin: often used to boost RBC production in patients with suppressed erythropoietin activity

Abnormal pacemaker function

-bradycardia; abnormally slow heart rate -tachycardia; abnormally fast heart rate -ectopic pacemaker; abnormal cells, generate high rate of action potentials, bypass conducting system, disrupt ventricular contractions

Capillaries

-capillaries are ideally suited to serve as sites of exchange -factors that enhance diffusion across capillaries; diffusion molecules have only a short distance to travel between blood and surrounding cells; each capillary is so narrow red blood cells have to squeeze through; scarcely any cell is farther Han 0.1 mm from a capillary

Cardiac muscle

-cardiac muscle blends features of both skeletal and smooth muscle -found only in the heart - highly organized, Striated, slender, and short fibers -clear length-tension relationship -interconnected by gap junctions found in intercalated discs that join cells together - heart is innervated by the autonomic nervous system

Cardiac output and its control

-cardiac output depends on heart rate and stroke volume -volume of blood pumped by each ventricle per minute -heart rate is determined primarily by autonomic influences on the SA node -effect of parasympathetic and sympathetic stimulation on the heart -control of heart rate

Types of heart failure

-compensatory measure for systolic heart failure -sympathetic stimulation - retention of salt and water by kidneys to expand blood volume -decompensated systolic heart failure - forward and backward failure -diastolic heart failure - heart failure with preserved ejection fraction

Other types of contractions

-concentric contractions; muscle shortens -eccentric contractions; muscle lengthens -some skeletal muscles do not attach at bones at both ends but still produce moevement (tongue muscles)

The vascular tree

-consists of arteries, arterioles, capillaries, venues, and veins -arteries transport blood from the heart to organs -arterioles control the amount of blood that flows through each organ -capillaries are vessels where material are exchanged between blood and tissue cells -veins return blood to the heart

Fast fibers

-contract very quickly -have large diameter, large glycogen reserves, few mitochondria -have strong contractions, fatigue quickly Ex; eyes

Skeletal Muscle Relaxation

-contraction duration -depends on: -duration of neural stimulus -number of free calcium ions in sarcoplasm -availability of ATP -relaxation Ca2+ concentration fall Ca2+ detaches from troponin active sites are re-covered by tropomyosin -rigor Morris -a fixed muscular contraction after death -Caused when: -ion pumps cease to function; ran out of ATP -calcium builds up in the sarcoplasm

Alternate pathways for forming ATP

-creatine phosphate -oxidative phosphorylation -glycolysis -lactate production

What does the ECG record

-different parts of the ECG record can be correlated to specific cardiac events -P wave ( atria depolarization) , QRS complex, and T wave (ventricles repolarize) -The ECG can detect abnormal heart rates and rhythms and heart muscle damage -abnormalities in rate -abnormalities in rhythm -cardiac myopathies

Molecular basis of skeletal muscle contraction

-during contraction, cycle of cross-bridge binding and bending Paul thin filaments inward -sliding filament mechanism -contraction is accomplished by thin filaments from the opposite sides of each sarcomere sliding closer together between the thick filaments -power stroke -stroking motion pulls the thin filament toward the center of the sarcomere (requires ATP)

Reactive hypermedia

-endothelial-derived vasoactive paracrines -endothelium cause arteriolar smooth muscle contraction -angiogenesis: vascular endothelial growth factor (VEGF( stimulates new vessel growth -reactive hypermedia; post occlusion increase in blood flow

Extrinsic control of arteriolar radius

-extrinsic control of arteriolar radius is important in regulating blood pressure -influence of total peripheral resistance on mean arterial pressure -norepinephrine's influence on arteriolar smooth muscle -local controls overriding sympathetic vasoconstriction -no parasympathetic innervation to arterioles

What are the three major types of skeletal muscle?

-fast fibers -slow fibers -intermediate fibers

Fatigue

-fatigue may be of muscle or central origin -muscle fatigue occurs when an exercising muscle can no longer respond to stimulation with the Sam degree of contractile activity -central fatigue occurs when the CNS no longer adequately activates motor neurons -increased O2 consumption is necessary to recover from exercise —excess post-exercise oxygen consumption

High blood pressure

-high blood pressure increase the workload of the heart -afterload: workload imposed on the heart after contraction has begun -sustained extra workload placed on the heart can eventually cause pathological changes in the heart that lead to heart failure

Hypertension

-hypertension is national public-health problem, but its causes are largely unknown -types of hypertension: primary and secondary -baroreceptor adaptation during hypertension: adapt to operate at a higher level -complications of hypertension: left ventricular hypertrophy, stroke, heart attack, kidney failure, and progressive vision loss

Bulk flow across the capillary walls

-important in Extracellular fluid distribution; forces influencing bulk flow -capillary blood pressure, plasm-colloid osmotic pressure, interstitial fluid hydrostatic pressure, and interstitial fluid-colloid osmotic pressure -net exchange of fluid across the capillary wall; positive and negative net exchange pressure -role of bulk flow; regulate the distribution of ECF between plasma and interstitial fluid

How do muscle fibers adapt to the response to the demands placed on them?

-improvement in oxidative capacity -muscle hypertrophy -influences of testosterone -interconversion between fast muscle types -muscle atrophy -limited repair of muscle

Thromboembolism and hemophilia

-inappropriate clotting produces thromboembolism -thrombus: abnormal intravascular clot attached to a vessel wall -emboli: freely floating clots -hemophilia is the primary condition that produces excessive bleeding; deficiency of one of the clotting cascade factors

Controlling stroke volume

-increased end-diastolic volume results in increased stroke volume -intrinsic control of stroke volume: heart's inherent ability to vary SV -Frank-Starling law of the heart: intrinsic relationship between EDV and SV - Advantages and mechanism of the cardiac length-tension relationship

Lever systems

-interactive units of skeletal muscles, bones, and joints form lever systems -lever: rigid structure capable of moving around a pivot point known as a fulcrum -bones are lever -joints are fulcrums -skeletal muscles provide the force to move the bones

Interstitial fluid and diffusion

-interstitial fluid is passive intermediary between blood and cells; interstitial fluid makes up 80% of extracellular fluid -diffusion across capillary walls is important in solute exchange; extent of exchanges for each solute is independently determined by the magnitude of its concentration gradient between blood and surrounding cells

Intrinsic and extrinsic clot pathways

-intrinsic pathway precipitates clotting within damaged vessels, and clotting of blood samples in test tubes -extrinsic pathways initiates clotting of blood that has escaped into the tissues -clot retraction; platelets trapped within the clot contract and shrink the fibrin mesh, pulling the edges of the damaged vessel closer together

Primary types of contraction

-isotonic; load remains constant as the muscle changes -isokinetic; velocity remains constant as the muscle fibers shorten. Ex; heart -isometric; muscle length remains constant as tension increases

Leukocyte production

-leukocytes are produced at varying rates depending on the body's changing needs -granulocyte colony; stimulating factor stimulates increased replication and release of granulocytes; especially neutrophils from bone marrow -abnormalities in leukocyte production; too few or too many WBCs can be produced

leukocytes

-leukocytes: mobile units of the body's immune defense system -immunity: the body's ability to resist or eliminate potentially harmful foreign materials or abnormal cells -immune system: internal defense system that recognizes and either destroys or neutralizes materials that are foreign to the "normal self" -leukocytes primarily function as defense agents outside the blood; to carry out their functions, WBCs largely use a "seek out and attack"; go to sites of invasion or tissue damage -main reason WBCs are in the blood is for rapid transport from their site of production of storage to wherever they are needed

Local control of arterioles radius

-local control of arteriolar radius is portent in determining the distribution of cardiac output -the fraction of the total CO derived to each organ varies depending on demands for blood -differences in flow to organs are determined by differences in vascularization and differences in resistance offered by arterioles supplying each organ

Histamine release and Myogenic response

-local histamine release pathologically dilates arterioles; when organs are injured or during allergic reaction, histamine is released and acts as a paracrines in the damaged region -the myogenic response to arterioles to stretch helps tissues autoregulate their blood flow; local mechanism keep tissue blood flow fairly constant despite rather wide deviations

Local influences on arteriolar radius

-local metabolic influences on arteriolar radius help match blood flow with the organs' needs -active hypermedia: increased blood flow in response to enhanced tissue activity -local metabolic changes that influence articles radiu: decreased )2, adenosine release, and increases in CO2, acid, K+, and osmolarity

Muscle receptors

-muscle receptors provide afferent information needed to control skeletal muscle activity -for effective control of motor output, the CNS needs continual information regarding ongoing changes in muscle length and tension -muscle spindles monitor muscle length -golgi tendon organs detect changes in tension

Muscle spindles and the stretch reflex

-muscle spindle structure -distributed throughout the fleshy part of a skeletal muscle -consist of collections of specialized muscle fibers known as intrafusal fibers -stretch reflex - local negative-feedback mechanism to sense and resist changes in muscle length when an additional load is applied

Five types of leukocytes

-neutrophils, eosinophils, basophils, monocytes, and lymphocytes -the five types fall into the granulocytes or agranulocytes

Length-tension relationships

-number of pivoting cross-bridges depends on: -amount of overlap between thick and thin fibers -optimum overlap produces greatest amount of tension -too much or too little reduces efficiency -normal resting sarcomere length -is 75% to 130% of optimal length

What disorders can cause anemia?

-nutritional anemia -pernicious anemia -aplastic anemia -renal anemia -hemorrhagic anemia -hemolytic anemia -malaria and sickle cell disease

Cardiac auto-rhythmic cells

-pacemaker potential in autorthythmic cells -complex interaction of several different ionic mechanisms are responsible for pacemaker potential -action potential in autorhythmic cells -rising phase of the action potential occurs in response to activation of a long-lasting, voltage-gated Ca2+ channel

Platelets and Hemostasis

-platelets are cell fragments shed from megakaryocytes (extraordinarily large bone marrow-bound cells) -hemostasis prevents blood loss from damaged small vessels; arrest of bleeding from a broken blood vessel, stopping hemorrhage -vascular spasm reduces blood flow through an injured vessel; immediate constriction of cut or torn blood vessel -platelets aggregate to form a plug at a vessel injury; layer of stuck platelets formed at defect sites; adhesion prevents these platelets from being swept forward in circulation

Factors in blood flow

-pressure gradient; the difference in pressure between the beginning and end of a vessel -resistance; hindrance to blood flow through a blood vessel. Viscosity; friction developed between molecules of a fluid as they slide over each other during fluid flow -poiseuille's law; integrates factors affecting flow rate through a vessel

Heart valves

-pressure-operated heart valves ensure that blood flows in the right direction through the heart -atrioventricular valves between the atria and ventricles -let blood flow from the atria into the ventricles during ventricular filling -prevent back flow of blood from the ventricles into the atria during ventricular emptying -semilunar valves between the ventricles and major arteries - aortic and pulmonary valves -no valves between the atria and veins - backflow of blood from the atria into the veins usually is not a significant problem -fibrous skeleton of the valves - four interconnecting rings of dense connective tissue of the heart surround and support the four heart valves

Hemoglobin

-protein molecule that transports respiratory gases -complex quaternary structure -four globular protein subunits; each with one molecule of heme; each heme contains one iron ion

Pulmonary and systemic circuation

-pulmonary; between the heart and lungs -systemic; between the heart and all body systems

function of controlled muscle contractions

-purposeful movement of the whole body or parts of the body -manipulation of external objects -propulsion of contents through various hollow internal organs -emptying of contents do certain organs to external environment

Coronary artery disease (CAD)

-reduction in blood flow to heart muscle produces a corresponding reduction in cardiac performance -reduced circulatory supply, coronary ischemia, results from partial or compete blockage of coronary arteries -usual cause is formation of a fatty deposit, or atherosclerotic plaque, in the wall of a coronary vessel -the plaque, or an associated thrombus (clot), then narrows the passageway and reduces blood flow -spasms in smooth muscles of vessel wall can further decrease or stop blood flow -one of the first symptoms of CAD is commonly angina pectoris

Muscle performance and the distribution of muscle fibers

White muscles; mostly fast fibers, pale (chicken breast) Red muscles; mostly slow fibers, dark (chicken legs) Most human muscles are mixed fibers and are pink

what is the link between excitation and contraction?

Calcium is the link between excitation and contraction -spread of action potential down transverse tubules -calcium release from sarcoplasmic reticulum -ATP-powered cross-bridge cycling -Rigor Morris and relaxation -Contractile activity far outlast the electrical activity that initiated it

Cardiac muscle

Classification: Striated muscle, involuntary muscle Description: Interlinked network of short, slender, cylindrical, striated, branched, contractile cells connected cell to cell by intercalated discs Location: wall of heart Function: pumping of blood out of heart

Smooth muscle

Classification: Unstriated muscle, involuntary muscle Description: Loose network of short, slender, spindle shaped, Unstriated, contractile cells that are arranged in sheets Typical location: walls of hollow organs and tubes, such as stomach and blood vessels Function: movement of contents within hollow organs

Clot formation

Clot formation: conversion of fibrinogen into fibrin Roles of thrombin: prothrombin is converted into thrombin when blood clotting is desirable -the clotting cascade: series of sequential reactions that occurs until thrombin catalyzed the final conversion of fibrinogen into fibrin

Myocardial infarction (MI)

Heart attack -part of the coronary circulation becomes blocked, and cardiac muscle cells die from lack of oxygen -the death of affected tissue creates a nonfunctional area known as an infarct -heart attacks most commonly result from severe coronary artery disease (CAD) - a crisis often develops as a result of thrombus formation at a plaque (the most common cause of an MI), a condition called coronary thrombosis -a vessel already narrowed by plaque formation may also become blocked by a sudden spasm in the smooth muscles of the vascular wall -individuals having an MI experience intense pain, similar to that felt in angina, but persisting even at rest

incomplete and complete tetanus

Incomplete tetanus; twitches reach maximum tension. If rapid stimulation continue and muscle is not allowed to relax, twitches reach maximum even of tension Complete tension; if stimulation frequency is high enough, muscle never begins to relax, and is in continuous contraction

How are muscle types categorized?

categorized according to structure and function control -Striated: skeletal and cardiac muscle (organized) -Unstriated: smooth muscle -Voluntary: skeletal muscle -Involuntary: cardiac and smooth muscle

Isotonic and isometric contraction

Isotonic contraction -skeletal muscle changes length -resulting in motion -if muscle tension > load (resistance): -muscle shortens (concentric contraction) -if muscle tension < load (resistance): - muscle lengthens (eccentric contraction) Isometric contraction -skeletal muscle develops tension, but is prevented from changing length - iso= same, metric=measure

neuromuscular junction

special intercellular connection between the nervous system and skeletal muscle fiber control s calcium ion release into the sarcoplasm

Twitches

1.) Latent period -the action potential moves through sarcolemma -causing Ca2+ release 2.)contraction phase -calcium ions bind -tension builds to peak 3.)Relaxation phase -Ca2+ levels fall -Active sites are covered and tension falls to resting levels

What are the steps of impulse conduction through the heart?

1.) SA node activity and atrial activation begin 2.) Stimulus spreads across the atrial surfaces and reaches the AV node 3.) There us a 100-msec delay at the AV node. Atrial contraction begins 4.) The impulse travels along the interventricular septum within the AV bundle and the bundle branches to the Purkinje fibers and, via the moderator band 5.)The impulse is distributed by Purkinje fibers and relayed throughout the ventricular myocardium. Atrial contraction is completed, and ventricular contraction begins

Three important effects of RBC shape on function

1.) high surface-to-volume ratio; quickly absorbs and release oxygen 2.) discs form stacks called rouleaux; smooth the flow through narrow blood vessels 3.) discs bens and f;ex entering small capillaries ; 7.8um RBC passes through 4um capillary

Six functions of skeletal muscle tissue

1.) produce skeletal movement 2.) maintain posture and body position 3.) support soft tissues 4.) guard entrances and exits 5.) maintain body temperature (shivering) 6.) store nutrient reserves (calcium)

The contraction cycle

1.) the contraction cycle, which involved a series of interrelated steps behind with the arrival of calcium ions within the zone of overlap. 2.) Calcium ions bind to troponin, weakening the bond between actin and the troponin-tropomyosin complex. The troponin molecule then changes position, rolling the tropomyosin molecule away from the active sites on actin and allowing interaction with the energized Hosie heads. 3.) Once the active sites are exposed, the energized myosin heads bind to them, forming cross-bridges 4.) After cross-bridge formation, the energy that was stored in the resting state is released as the myosin head pivots toward the M line. This action is called the power stroke; when it occurs, the bound ADP and phosphate group are released. 5.) When another ATP binds t. the myosin head, the link between the myosin head and the active site on the actin molecule is broken. The active site is now exposed and able to form another cross-bridge 6.) Myosin reactivating occurs when the free myosin head splits ATP into ADP and P. The energy released is used to record the myosin head.

what are the steps in the neuromuscular junction?

1.) the cytoplasm of the synaptic terminal contains vesicles filled with molecules of acetylcholine, or ACh. Acetylcholine is a neurotransmitter, a chemical released by a neuron to change the permeability or other properties of another cell's plasma membrane. the synaptic cleft and the motor end plate contain molecules of the enzyme actylcholinesterase (AChE), which breaks down ACh. 2.) The stimulus for ACh release is the arrival of an electrical impulse , or action potential, at the synaptic terminal. An action potential is a sudden change in the transmembrane potential that travels along the length of the axon. 3.)When the action potential reaches the neuron's synaptic terminal, permeability changes in the membrane trigger the exocytosis of ACh into the synaptic cleft. Exocytosis occurs as vesicles fuse with the neuron's plasma membrane 4.)ACh molecules diffuse across the synaptic cleft and bind to ACh receptorson the surface of the tor end plate. ACh binding alters the membrane's permeability to sodium ions. Because the Extracellular fluid contains a high concentration of sodium ions, and sodium ion concentration inside the cell is very low, sodium ions rush into the sarcoplasm 5.) The sudden inrush of sodium ions results in the generation of an action potential in the sarcolemma. AChE quickly breaks down the ACh on the motor end plate and in the synaptic cleft, thus inactivating the ACh receptor sites.

Tension production by skeletal muscles

Depends on: -internal tension produced by muscle fibers -external tension exerted by muscle fibers on elastic Extracellular fibers -total number of muscle fibers simulated

Motor units and tension production

Motor units in a skeletal muscle: -contain hundreds of muscle fibers -that contract at the same time -controlled by a single motor neuron Recruitment ( multiple motor unit summation) -in a whole muscle or group of muscles, smooth motion and increasing ensign are produced by slowly increasing the size or number of motor units stimulated Maximum tension -achieved when all motor units reach tetanus -can be sustained only a very short time Sustained tension -less than maximum tension -allows motor units rest in rotation

What are the two phases in the cardiac cycle

Systole (contraction) Diastole (relaxation)