Busy. Please wait.
or

show password
Forgot Password?

Don't have an account?  Sign up 
or

Username is available taken
show password

why


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.


Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
Don't know
Know
remaining cards
Save
0:01
To flip the current card, click it or press the Spacebar key.  To move the current card to one of the three colored boxes, click on the box.  You may also press the UP ARROW key to move the card to the "Know" box, the DOWN ARROW key to move the card to the "Don't know" box, or the RIGHT ARROW key to move the card to the Remaining box.  You may also click on the card displayed in any of the three boxes to bring that card back to the center.

Pass complete!

"Know" box contains:
Time elapsed:
Retries:
restart all cards
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

A&P ch. 9,10,17,18

muscle tissue, muscle ID, blood, heart

QuestionAnswer
The functional unit of contraction in a skeletal muscle fiber is the - sarcomere
"Cross bridges" that link between the thick and thin filaments are formed by the _________ globular head of thick filaments
Area of the sarcomere with overlapping thick and thin filaments A band
Acetylcholinesterase Enzyme released into neuromuscular junction to break down acetylcholine
The thin myofilaments of skeletal muscle are composed chiefly of __ actin
Oxygen storage molecules in skeletal muscle myoglobin
Type of contraction represented by a single stimulus/contraction/relaxation sequence twitch
Rodlike contractile elements within a muscle fiber containing myofilaments myofibril
Cross bridges myosin heads
Area in the center of the A band containing only thick filaments H zone
blood fluid connective tissue composed of plasma and formed elements
formed elements Erythrocytes (red blood cells, or RBCs) Leukocytes (white blood cells, or WBCs) Platelets
Hemacrit formed elements Percent of blood volume that is RBCs 47% ± 5% for males 42% ± 5% for females
Blood characteristics Sticky, opaque fluid Color scarlet to dark red pH 7.35–7.45 38 degrees C ~8% of body weight Average volume: 5–6 L for males, and 4–5 L for females
Functions of blood Distribution Regulation Protection
Distribution (function of blood) distributes: O2 and nutrients to body cells Metabolic wastes for elimination Hormones transport
Regulation (function of blood) regulates: Body temperature Normal pH using buffers Adequate fluid volume
Protection (function of blood) protects against: Blood loss clot formation Infection Antibodies Complement proteins WBCs defense
Blood plasma 90% water Proteins are mostly produced by the liver 60% albumin – Abundant - osmotic pressure 36% globulins - antibodies 4% fibrinogen – clotting
Formed elements info Only WBCs are complete cells RBCs have no nuclei or organelles Platelets are cell fragments Most formed elements survive in the bloodstream for only a few days Most blood cells originate in bone marrow and do not divide
Erythrocytes (RBC) Biconcave discs Anucleate no organelles Filled with hemoglobin (Hb) Are the major factor contributing to blood viscosity
Erythrocytes (RBC) structure Structural characteristics contribute to gas transport Biconcave shape—huge surface area relative to volume >97% hemoglobin (not counting water) No mitochondria; ATP production is anaerobic; no O2 is used in generation of ATP
Function of Erythrocytes RBCs are dedicated to respiratory gas transport Hemoglobin binds reversibly with O2 structure: Protein globin: two alpha and two beta chains Heme pigment bonded to each globin chain
Erythrocytes O2 transport info Iron atom in each heme can bind to one O2 molecule Each Hb molecule can transport four O2
Composition of blood plasma nutrients: carbs, glucose, amino acids respiratory gasses: 02 and CO2 Electrolytes: Na+, Ca+, K+, Cl, HCO3 by products of metabolism: urea and creatinine hormones
02 loading in the lungs Produces oxyhemoglobin (ruby red)
O2 unloading in tissue Produces deoxyhemoglobin or reduced hemoglobin (dark red)
CO2 loading in tissues Produces carbaminohemoglobin (carries 20% of CO2 in the blood)
Hematopoiesis (hemopoiesis): blood cell formation Occurs in red bone marrow of axial skeleton, girdles and proximal epiphyses of humerus and femur
Hemocytoblasts (hematopoietic stem cells) Give rise to all formed elements Hormones and growth factors push the cell toward a specific pathway of blood cell development
Where do new blood cells go? they enter blood sinusoids
What do reticulocytes become? become mature erythrocytes
phases in development of RBCs Ribosome synthesis Hemoglobin accumulation Ejection of the nucleus and formation of reticulocytes
Erythropoiesis: red blood cell production A hemocytoblast -> proerythroblast -> early erythroblasts
regulation of Erythropoiesis: Too few RBCs leads to tissue -> hypoxia Too many RBCs ->increases blood viscosity Balance between RBC production and destruction depends on Hormonal controls supplies of iron, amino acids, and B vitamins
causes of hypoxia Reduces RBC numbers Hemorrhage Increased RBC destruction Insufficient hemoglobin (e.g., iron deficiency) Reduced availability of O2 (e.g., high altitudes)
Hormonal Control: Erythropoietin (EPO) (REGULATION OF ERYTHROPOIESIS) Direct stimulus for erythropoiesis Released by the kidneys in response to hypoxia
Dietary requirements for Erythropoiesis: Iron Stored in Hb (65%), the liver, spleen, and bone marrow Stored in cells as ferritin and hemosiderin Transported loosely bound to the protein transferrin Vitamin B12 and folic acid —necessary for DNA synthesis for cell division
Dietary requirements for Erythropoiesis (Nutrients) Nutrients—amino acids, lipids, and carbohydrates
Fate and destruction of Erythrocytes Life span: 100–120 days Old RBCs become fragile, and Hb begins to degenerate Macrophages engulf dying RBCs in the spleen
Anemia blood has abnormally low O2-carrying capacity A sign rather than a disease itself Blood O2 levels cannot support normal metabolism Accompanied by fatigue, paleness, shortness of breath, and chills
Polycythemia: excess of RBCs that increase blood viscosity
Causes of Anemia: Insufficient erythrocytes Hemorrhagic anemia: acute or chronic loss of blood Hemolytic anemia: RBCs rupture prematurely Aplastic anemia: destruction or inhibition of red bone marrow
Causes of Anemia: Abnormal Hemoglobin Thalassemias Absent or faulty globin chain RBCs are thin, delicate, and deficient in hemoglobin Sickle-cell anemia Defective gene codes for abnormal hemoglobin (HbS) Causes RBCs to become sickle shaped in low-oxygen situations
Causes of Anemia: Low Hemoglobin Content Iron-deficiency anemia Secondary result of hemorrhagic anemia or Inadequate intake of iron-containing foods or Impaired iron absorption Pernicious anemia low B12 Lack of intrinsic factor needed for absorption of B12
Breakdown of Erythrocytes: STEP 1 Iron -> stored as ferratin and hemosiderin -> released into blood as transferrin
Breakdown of Erythrocytes: STEP 2 transferrin is degraded to a yellow pigment called bilirubin
Breakdown of Erythrocytes: STEP 3 The liver secretes bilirubin into the intestines as bile
Breakdown of Erythrocytes: STEP 4 The intestines metabolize Bile into urobilinogen
Breakdown of Erythrocytes: STEP 5 urobilinogen leaves the body in feces, in a pigment called stercobilin
Microscopic Anatomy of Cardiac Muscle Cardiac muscle cells - striated, short, fat, branched, and interconnected Connective tissue matrix (endomysium) connects to the fibrous skeleton T tubules are wide but less numerous SR is simpler than in skeletal muscle Numerous large mitochondria
Intercalated discs junctions between cells anchor cardiac cells Desmosomes prevent cells from separating during contraction Gap junctions allow ions to pass; electrically couple adjacent cells
What do intercalated discs do? Intercalated discs anchor cardiac cells together and allow free passage of ions
How does heart muscle behave? Heart muscle behaves as a functional syncytium – cells are electrically coupled by gap junctions, the myocardium acts as a single coordinated unit.
Cardiac Muscle Contraction breakdown -1% is autorhythmic or special ability to depolarize spontaneously – pacemaker cells of the heart - 99% is contractile muscle fibers – responsible for pumping activity
Cardiac Muscle contraction Is stimulated by nerves and is self-excitable -> automaticity or autorhymicity Contracts as a unit Has a long (250 ms) absolute refractory perio
Pacemaker potential This slow depolarization is due to both opening of Na+ channels and closing of K+ channels. Notice that the membrane potential is never a flat line.
Depolarization The action potential begins when the pacemaker potential reaches threshold. Depolarization is due to Ca2+ influx through Ca2+ channels.
Repolarization due to Ca2+ channels inactivating and K+ channels opening. This allows K+ efflux, which brings the membrane potential back to its most negative voltage.
Plateau phase due to Ca2+ influx through slow Ca2+ channels. This keeps the cell depolarized because few K+ channels are open.
Intrinsic Conduction System: Autorhythmic cells Initiate action potentials Have spontaneously changing membrane potential or unstable resting potentials called pacemaker potentials Use calcium influx (rather than sodium) for rising phase of the action potential
Sequence of Excitation (1) Sinoatrial (SA) node (pacemaker) Generates impulses about 75 times/minute (sinus rhythm) Depolarizes faster than any other part of the myocardium
Sequence of Excitation (2) Atrioventricular (AV) node Smaller diameter fibers; fewer gap junctions Delays impulses approximately 0.1 second Depolarizes 50 times per minute in absence of SA node input
Sequence of Excitation (3) AV bundle - Connect the atria to the ventricles
Sequence of Excitation (4) Right and left bundle branches - Two pathways in the interventricular septum that carry the impulses toward the apex of the heart
Sequence of Excitation (5) Purkinje fibers - Complete the pathway into the apex and ventricular walls - AV bundle and Purkinje fibers depolarize only 30 times per minute in absence of AV node input
Tachycardia A rapid heart rate, usually defined as greater than 100 beats per minute
Bradycardia A slow heart rate, usually defined as less than 60 beats per minute
Fibrillation rapid, irregular contractions; useless for pumping blood
Arrhythmias irregular heart rhythms
What modifies the heartbeat? the Autonomic Nervous System (ANS)
Where are cardiac centers located? medulla oblongata
Cardioinhibitory center inhibits SA and AV nodes through parasympathetic fibers in the vagus nerves
Cardioacceleratory center innervates SA and AV nodes, heart muscle, and coronary arteries through sympathetic neurons
vagus nerve decreases heart rate
sympathetic cardiac nerves increases heart rate and force of contraction
ECG/EKG a composite of all the action potentials generated by nodal and contractile cells at a given time
P wave: - depolarization of SA node - atrial contraction
QRS complex - ventricular depolarization - ventricular contraction
T wave - ventricular repolarization - ventricular relaxation
Heart sounds Two sounds (lub-dup) associated with closing of heart valves - 1st sound: AV valves closing and signifies beginning of systole - 2nd sound: when SL valves close at the beginning of ventricular diastole
Heart Murmur abnormal heart sounds most often indicative of valve problems
Cardiac cycle Blood flow through heart during one complete heartbeat: -atrial systole and diastole followed by ventricular systole and diastole
systole contraction -Blood is ejected from atria and ventricle -Atrial contraction -Ventricular contraction
systole -relaxation -Blood flow to the atria and ventricles -Atrial filling -Ventricular filling
Cardiac cycle phases Phase 1 – Ventricular Filling Phase 2 – Atrial Contraction Phase 3 – Isovolumetric Contraction Phase 4 – Ventricular Ejection Phase 5 – Isovolumetirc Relaxation
Ventricular Filling Atrial – relaxed Ventricles – relaxed Valves: AV valves – open SL valves – closed Blood flows from: SVC, IVC ->Right Atrium Pulmonary veins -> Left Atrium Atria -> ventricles
Atrial Systole Atria – contraction or depolarization ECG Wave – P wave Ventricles – diastole Valves: AV valves – open SL valves – closed Blood flows from: Right Atrium -> Right Ventricle Left Atrium -> Left Ventricle
End diastolic volume (EDV): Volume of blood in the ventricles after the atrial contraction
Ventricular systole Ventricular contraction - begins Atria relaxing ventricular pressure > Atrial pressure ECG – QRS wave
Isovolumetric Contraction Ventricle contracting with no change in the volume Atrial relaxing Ventricles: systole V. pressure > A. pressure Closing of AV 1st Heart sound ->LUB SL valve – closed
Ventricular Ejection V. pressure > Aortic or Pulmonary artery pressure SL valves open Blood ejected to aorta and pulmonary trunk
Ventricular Isovolumetric Relaxation Ventricles relaxing No change in the volume of the ventricle Valves: AV valves – closed SL valves – closing SL valve closing  2nd Heart Sound Dub sound ECG - T wave
End Systolic Volume (ESV) Volume of blood in the ventricles after the ejection
stroke volume the volume of blood ejected from the heart in one beat (b-a)
The plateau portion of the action potential in contractile cardiac muscle cells is due to: influx of calcium ions
Cardiac Output Volume of blood pumped by each ventricle in one minute CO = heart rate (HR) x stroke volume (SV) HR = number of beats per minute SV = volume of blood pumped out by a ventricle with each beat
The stimulus for the heart’s rhythmic contractions comes from a pacemaker potential
Created by: davisobr