Chapter 10 Cardiovascular System, The Heart Flashcards
Which of the following proteins of a sarcomere binds calcium?
A. Myosin
B. Actin
C. Tropomyosin
D. Troponin
D. Troponin
Which of the following processes does not require ATP?
A. Opening of calcium channels on the sarcoplasmic reticulum during an action potential
B. Breaking of cross-bridges between myosin and actin
C. Activation of the myosin head to the extended position
D. Movement of calcium ions back into the sarcoplasmic reticulum
A. Opneing of calcium channels on the sarcoplasmic reticulum during an action potential
What is the hypothesis of Cardiac Cells?
- Current hypothesis (2011) is that there are two type of cardiac cells
- First, working cardiomyocytes (muscle cells)
- One nucleus, striated, branched, excites, contracts
- Second conductive cardiomyocytes
- Function in initiating and communicating action potentials for heart beat
- Arise from the same “progenitor’ (initial) cells during development
- Work together to cause heart contraction based on action potentials
What are Cardiomyocytes?
Cardiomyocytes are “connected” to each other by junctions
What are the two different types of junctions?
- Mechanical junctions
- Physical connection
- Desmosomes cell adhesion proteins
- Allows muscle cells to pull on each other without damaging membrane
- Electrical/Gap junctions
- Cytoplasmic connection
- Connexons proteins that are non-specific, leaky ion channels
- Allows sodium to diffuse between cells during depolarization
- Propagation of signal
- Connected by communication
A toxin destroys connexons of cardiac tissue. Which result might you expect?
A. Muscle cells will not adhere to each other.
B. The sarcomeres will start to degrade.
C. Propagation of action potentials between cells will be disrupted.
D. Calcium will be spontaneously released from the sarcoplasmic reticulum.
C. Propagaton of action potentials between cells will be disrupted
Explain how the heart is an organized structure.
- During embryonic development, the heart actually starts as a tube
Pictured here is how the muscle of the heart can be “unwound” from its mature form.
The complex organization allows for contraction of chambers to move blood
But it needs something to pull on…
What is the Hearts Fibrous “Skeleton”?
- Cardiac muscle cells bound to fibrous skeleton
- Valves and associated structures
- Provides three main functions
- Provide structural support for the heart
- Gives the muscle cells something to pull against
- Electrical insulator, helps regulate beating of heart
Explain the Cardiovascular System
- Function
- Heart pumping blood
- Deliver oxygen/nutrients to body, move wastes to kidneys
- Pulmonary circuit
- Blood to lungs only
- Pick up oxygen
- Systemic circuit
- Blood to rest of body
- Drop of oxygen
- Normal flow of blood:
- Heart artery capillary
- At the capillary bed exchange of materials occur
- Capillary vein back to heart
What are the Great Vessels?
- Vessels that bring blood to or take blood away from the heart
- On right side:
- Superior and inferior vena cava
- Pulmonary arteries
- On left side
- Pulmonary veins
- Aorta
What are the four chambers of the heart?
- Two atria (right and left)
- Thin-walled muscle
- Pumps blood to ventricles
- Two ventricles (right and left)
- Thick-walled muscle
- Pumps blood lungs (right) and body (left)
How does the blood flow through the heart?
- Atria
- Superior and inferior vena cava (from body) Right atrium
- Pulmonary veins (from lungs) Left atrium
- Valves
- Right atria pumps blood through right AV valve (tricuspid) to ventricle
- Left atria pumps blood through left AV valve (bicuspid) to ventricle
- Ventricles
- Right Ventricle Pulmonary trunk (to lungs)
- Left ventricle Aorta (to body)
- Right structures are oxygen poor
- Left structures are oxygen rich
- The two sides of the heart are working simultaneously
What is different about Cardiac Tissue Actionn Potential?
- Same sodium, potassium voltage-gated channel mechanism
- Difference Voltage-gate calcium channels open during depolarization
- This provides an extracellular source of calcium for troponin (in addition to sarcoplasmic reticulum)
- Causes plateau in action potential (peak stays positive longer than muscle)
Which of the following is structure associated with oxygen-rich blood?
A. Right AV valve
B. Pulmonary vein
C. Right ventricle
D. Pulmonary artery
B. Pulmonary Vein
What is the resting membrane potential and the threshold of the action potential of Cardiac tissue?
- Resting membrane potential = -90mV
Threshold = -75mV
What is the difference of Cardiac Tissue and what is the same with the other stuff?
- Same sodium, potassium voltage gated channel mechanism
- Difference Voltage-gate calcium channels open during depolarization
- This provides an extracellular source of calcium for troponin (in addition to sarcoplasmic reticulum)
- Causes plateau in action potential (peak stays positive longer than muscle
During cardiac depolarization, calcium enters the cell via voltage-gated channels. This, in turn, causes the SR to release more calcium. This is an example of a _______.
A. positive feedback
B. negative feedback
B. Negative Feedback
What is the Sinoatrial (SA) and the Atrioventricular Node of the conduction system?
- Sinoatrial (SA) node pacemaker
- Specialized group of cells in the right atria
- Cells do not have a stable resting membrane potential because of cation leak channels
- Active transport after action potential redistributes ions
- Atrioventricular (AV) node
- Electrical gateway to the ventricles
- Ventricles are otherwise insulated by the fibrous skeleton
What is the atrioventricular bundle and the purkinje fibers?
- Atrioventricular bundle
- Collection of cells
- AKA Bundle of His
- Pathway the electric signal follows as it leaves the AV node
- Splits into left and right bundles
- Purkinje fibers
- Collection of cells
- Spread throughout the ventricles
- Coordinate contraction of the ventricles
- Because of the direction of the bundles, ventricles contract from the bottom upwards
What occurs during the contraction of the heart?
- Cells of the SA node triggers an action potential
- Action potential moves through the two atria causing contraction
- This is also called atria systole (diastole is relaxed)
- The action potential depolarizes the cells of the AV node
- This is also called ventribular systole (diastole is relaxed)
- Action potential propagated down the bundle of His
- Action potential propagated throughout the ventricles, causing contraction
- Process begins again…and again…and again…
What is systole and diastole?
- systole - contraction
- diastole - relaxation
What does the electrocardiograms (ECG/EKG) do?
ECG’s measure small changes in voltage between the heart and the rest of the body
NOT the same as an action potential, but is a result of the moving ions during all the action potentials of a heartbeat
Electrical signal precedes contractions by milliseconds
What are the three parts of the EKG/ECG?
- P wave atria depolarize
- Atria contract at PR segment
- QRS ventricle depolarize
- Ventricle contract at ST segment
- T wave ventricle repolarize
What are the first two steps of heart contraction?
