Chapter 19- The heart Flashcards
Pulmonary circulation
Right side pumps deoxygenated blood to the lungs for gas exchange as part of
Heart location
In the thoracic cavity, between the lungs in the mediastinum
Systematic circulation
Left side pumps accident oxygenated blood to the rest of the body for gas, nutrients and waste exchange is a part of
Atrium
Superior chamber that receives blood
Ventricle
Inferior chamber that pumps blood away
Veins
Superior Vena cava
Pulmonary veins
Inferior vena cava
Superior & inferior vena cava
Deliver deoxygenated blood into right atrium
Pulmonary veins
Deliver oxygenated blood into the left atrium
Arteries
Aorta
pulmonary trunk
Aorta
Receives oxygenated blood from the left ventricle
Pulmonary trunk
Receives the deoxygenated blood from right ventricle
Contains valves-
Connected tissue (cusps) that ensure one-way flow
Pulmonary semilunar valve
No Chordae tendinae
Aortic semilunar valve
No Chordae tendinae
Right atrioventricular valve
Tricuspid
with Chordae tendinae
Left atrioventricular valve
Bicuspid (or mitral)
With Chordae tendinae
Cardiomyocytes
Short branched
with 1 to 2 nuclei
striated
Intercalated disc
Cells have extensively folded sarcolemma at the cell to cell junctions
- Desmosomes
- gap junctions
Desmosomes
Junctions that bind adjacent cells
Gap junctions
Channels that allow direct communication between cells
Internal structure of cardio myocytes
Sarcolemma T tubules Sarcoplasmic reticulum Myofibrils Mitochondria
And aerobic metabolism
Able to use different types of fuel molecules (fatty acids, glucose, lactic acid) but, requires constant supply of oxygen
Coronary circulation
Circulatory system of the heart
Branch off the ascending aorta
Left coronary artery
Right coronary artery
Drain into the right atrium
Great cardiac vein
Middle cardiac vein
Small cardiac vein
Atherosclerosis
Formation of Plaques
Coronary spasm
Sudden construction of a coronary artery
Angina pectoris
Pain caused by the reduced supply of oxygen
Myocardial infarction
(heart attack)
Blockage of a coronary artery leading to possible death tissue
Fibrous skeleton of the heart
(Dense irregular connective tissue)
- provide structural support for walls and valves
- place of attachment of cardiac muscle
- an electrical insulator that prevents simultaneous contraction of atria & ventricles
conduction system
Includes specialized party at muscle cells that initiate and transmit an action potential (electrical signal) to the cardiac muscle cells
Contractile cardiac muscle cells
Contract in response to the action potential transmitted along their sarcolemma
Sinoatrial (SA) node
Located in the posterior wall of the right atrium
F: initiates heartbeat (pacemaker)
Atriventricular (AV) node
Located in the floor of the right atrium
Atrioventricular (AV) bundle
Extends through interventricular septum, divides into left and right branches
Purkinje fibers
Extend from left and right bundles through the walls of ventricles
Initiation of the AP
Nodal cells in SA node initiate heartbeat by generating AP due to:
- Na+/K+ pumps, K+ & Na+ leak channels (establish RMP at -60 mV)
- Ca2+ pumps that create calcium Gradient with more outside the cell
- slow V-gated Na+ channels, fast v-gated Ca2+ channels, & v-gated K+ channels (Carry out AP)
Skeletal muscle cell RMP
neuron RMP
- 95mV
- 70mV
Reaching threshold
Slow voltage gated Na+ channels open Membrane potential (MP) changes:
-60 to -40
Depolarization
Fast voltage gated Ca2+ channels open
MP changes: -40 to above 0
Fast voltage gated Ca2+ close
Repolarization
Voted gated K+ channels open
MP returns to -60 mV
K+ channels close
Comparison of Nodal cells and neurons
-do not have a stable resting membrane potential (RMP) gradually decreasing to the threshold without stimulation termed pacemaker potential
Depolarization occurs with entrance of…
Ca2+ into cells (unlike neurons)
Autorythmicity
Ability to depolarize and fire action potential spontaneously
Transmission of the AP
spreading, passing, or conduction of AP) in a highly organized manner
1 Generated in the SA node AP spreads and causes
simultaneous contraction of the atrial myocardium
2 AV node causes a 0.1 second delay before…
Transmitting AP to the AV bundle
3 The AV bundle transmits the AP
Left and right bundle branches
-> purkinje fibers
4 The AP spreads throughout ventricular myocardium leading to the…
simultaneous contraction of the ventricles
(Bottom -> up)
Hand pray squeeze
Innervation of the heart
-While the heartbeat is initiated by the SA node (hearts own conduction system) the heart rate and the strength of contraction are regulated by the autonomic nervous system (sympathetic increased, parasympathetic decrease)
Cardiac center
(In medulla) -Receives and reflexively response of the info from chemo receptors (with CO2 and H+ levels) baroreceptors (blood pressure changes) -To maintain homeostasis
Heartbeats very ____ sec = HR ___ beats/min
0.8
75
Inherent rhythm
(set by the SA nodal cells) is faster - 100 beats/min
Slow rate is due to _________ simulation by vagus nerve, ________
Parasympathetic
Vagal tone
