91 Questions
What is the cardiac cycle?
The mechanical events where blood flows through the different chambers of the heart
What is meant by 'diastole' in the context of the cardiac cycle?
Relaxation
What happens during mid to late ventricular diastole?
Ventricular relaxation is in its last stages
What are the semilunar valves mentioned in the text?
Pulmonary and aortic semilunar valves
During which phase of the cardiac cycle do the semilunar valves snap shut?
Isovolumetric relaxation phase
What causes the production of the 'dub' sound in the cardiac cycle?
Semilunar valve closure
Which phase of the cardiac cycle is associated with the T wave on an EKG?
Ventricular repolarization phase
What is the arterial pressure in comparison to ventricular pressure during the cardiac cycle?
Greater
What is the pressure relationship between atria and ventricles during the isovolumetric relaxation phase?
Ventricular pressure is greater than atrial pressure
What sound is produced when the AV valves close during the cardiac cycle?
Lub
What happens to the ventricles during the isovolumetric relaxation phase?
They relax
What is the duration of the cardiac cycle?
0.8 seconds
What is the function of the dicrotic notch in the cardiac cycle?
Causes a brief rise in aortic pressure
What occurs during the isovolumetric contraction phase of the cardiac cycle?
Semilunar valves close
What happens to the atrial pressure during the isovolumetric relaxation phase?
It decreases
What is the purpose of the iso-volumetric relaxation phase in the cardiac cycle?
All of the above
What causes the opening of semilunar valves?
Greater ventricular pressure than arterial pressure
Why do AV valves remain closed during blood ejection?
Greater pressure in the ventricles than in the atria
What is the pressure in the ventricles during blood ejection?
120 mmHg
What is the term for the remaining blood in the ventricles after ejection?
End systolic volume (ESV)
What causes the rise in pressure in the aorta and pulmonary trunk?
Accumulated blood
What happens to arteries in response to high pressure?
They stretch to accommodate high pressure
What causes the brief rise in aortic pressure represented by the dicrotic notch?
Valve closure
During which phase do ventricles depolarize and contract?
Mid to late ventricular systole
What is the term for the blood volume in the ventricles at the beginning of systole?
End diastolic volume (EDV)
What is the term for the volume of blood pumped by each ventricle in one contraction?
Stroke volume (SV)
What happens to elastic arteries after recoiling blood?
Aortic and pulmonary trunk pressure rises
What is the term for the phase when blood is distributed to systemic, pulmonary, and coronary circuits?
Blood ejection phase
What causes the AV valves to open during the cardiac cycle?
Atrial pressure exceeding ventricular pressure
What keeps the semilunar valves closed during the cardiac cycle?
Pressure in the aorta and pulmonary trunk exceeding that in the ventricles
What is the end diastolic volume (EDV) defined as in the cardiac cycle?
The blood accumulated in the ventricles
What initiates the iso-volumetric contraction phase in the cardiac cycle?
Ventricular depolarization and contraction
What is another term for the iso-volumetric contraction phase in the cardiac cycle?
Isovolumetric systole
What occurs when the SA node fires at the end of ventricular diastole in the cardiac cycle?
Atrial depolarization and pushing the remaining 20% of blood into the ventricles
What is the phase of the cardiac cycle that involves the period of ventricular filling?
Mid to late ventricular diastole
What is essential in comprehending the cardiac cycle according to the text?
Understanding the pressure differentials and valve movements
What percentage of blood flows passively into the ventricles when the AV valves open?
70-80%
What keeps the semilunar valves closed during the cardiac cycle?
Pressure in the aorta and pulmonary trunk exceeding that in the ventricles
What is the phase that involves the myocardium squeezing the ventricles in an attempt to push blood upwards?
Iso-volumetric contraction phase
What is the phase that is crucial in the cardiac cycle?
Iso-volumetric contraction phase
During the isovolumetric contraction phase, what is the pressure in the left ventricle?
120mmHg
What causes the semilunar valves to open?
Ventricular pressure becomes greater than the arterial pressure
What is the pressure in the pulmonary trunk during the cardiac cycle?
7-10mmHg
What produces the first heart sound, 'Lub' (S1)?
The AV valves snap shut during isovolumetric contraction phase
What is the pressure in the aorta during the cardiac cycle?
80mmHg
What happens when the ventricular pressure becomes greater than the atrial pressure?
The AV valves close
What is the pressure in the right ventricle during the isovolumetric contraction phase?
25mmHg
Why do the semilunar valves remain closed at a certain point in the cardiac cycle?
The arterial pressure is still greater than the ventricular pressure
What causes the ventricular pressure to rise and the atrial pressure to drop?
The blood accumulates and pushes the valves up
What is the pressure in the ventricles during the cardiac cycle?
Less than the aortic and pulmonary pressure
Why are the semilunar valves closed at a certain point in the cardiac cycle?
Due to pressure differences
What is the purpose of the detailed explanation provided in the text?
To provide a comprehensive overview of the physiological processes involved in the cardiac cycle
What are the ganglia called that are in front of the aorta and in front of the vertebral column?
Pre-vertebral ganglia
What term is used for the ganglia that go to a lot of the abdominal pelvic viscera?
Sub-diaphragmatic ganglia
What is another name for the ganglia known as collateral ganglia?
Paravertebral ganglia
What are the ganglia called that are also known as pre-k or Duke ganglia?
Pre-vertebral ganglia
What type of ganglia are present in the parasympathetic nervous system?
Terminal and intramural ganglia
What neurotransmitter is released at the synapse between preganglionic and postganglionic neurons in both parasympathetic and sympathetic systems?
Acetylcholine
Where are the cell bodies of preganglionic sympathetic motor neurons located?
Lateral gray horn of the thoracolumbar region of the spinal cord
What type of neurons release norepinephrine in the autonomic nervous system?
Postganglionic sympathetic neurons
Through which structure do preganglionic sympathetic motor neurons move into the ganglia?
Ventral root and ventral ramus of the spinal nerves
What is the pathway leading to the ganglia in the sympathetic nervous system characterized by?
Highly myelinated axons
What are the ganglia in the sympathetic nervous system interconnected in?
Chain-like structure
What are the ganglia filled with in the autonomic nervous system?
Cell bodies
Where are the cell bodies of preganglionic sympathetic motor neurons located?
Lateral gray horn of the thoracolumbar region of the spinal cord
What is crucial for comprehending the functioning of the autonomic nervous system?
Understanding differences in neurotransmitter release and ganglia location
What is the location of ganglia in the sympathetic nervous system?
Chain or paravertebral ganglia
Where can the postganglionic motor neurons synapse?
On cell bodies in chain ganglia
What type of fibers are found in the gray ramus?
Unmyelinated axons
Which neurotransmitter is released by postganglionic sympathetic neurons to sweat glands?
Acetylcholine
Where do splanchnic nerves go in the body?
Thoracic and abdominal viscera
What is the exception in the pathway to the adrenal medulla?
It doesn't involve chain or collateral ganglia
Where can preganglionic sympathetic motor neurons synapse?
On cell bodies in a chain ganglia at a lower level
Where can splanchnic nerves synapse when going to abdominal viscera?
In front of the vertebral column
What types of tissue can the sympathetic nervous system pathways lead to?
Erector pili muscle, blood vessels, and sweat glands
What is the neurotransmitter released by most postganglionic sympathetic neurons?
Norepinephrine
What is the term for the nerves that leave as their own nerve, such as those going to abdominal viscera?
Splanchnic nerves
What do the pathways of sympathetic nervous system motor neurons involve?
Complex and varied routes to different target tissues and organs
What is the term for the ganglia located in front of the vertebral column?
Prevertebral ganglia
Which nervous system is responsible for controlling involuntary bodily functions such as heart rate and digestion?
Parasympathetic nervous system
How many traditional branches make up the autonomic nervous system?
Three
Where are the preganglionic cell bodies of the sympathetic nervous system found?
Thoracolumbar outflow, extending from T1 to L2 in the spinal cord
Which nervous system is often referred to as the 'fight or flight' system?
Sympathetic nervous system
How many motor neurons does the autonomic nervous system require to reach the effector organ?
Two
Which specific chemical is released by the alpha motor neuron of the somatic nervous system?
Acetylcholine
Which system is responsible for conserving energy and is often referred to as the 'rest and digest' system?
Parasympathetic nervous system
Where are the preganglionic cell bodies of the parasympathetic nervous system located?
Brainstem and sacral region of the spinal cord
What is the primary function of the sympathetic nervous system?
Using energy in stressful situations
What is the primary function of the parasympathetic nervous system?
Conserving energy
Which part of the nervous system is responsible for regulating various bodily functions, including heart rate, respiratory rate, and digestion?
Sympathetic nervous system
Which part of the nervous system plays a crucial role in maintaining homeostasis within the body?
Sympathetic nervous system
Study Notes
Cardiac Cycle Overview
- The text describes the myocardium beginning to slowly depolarize and contract, leading to the blood moving up towards the pulmonary trunk and aorta.
- The pressure in the aorta is about 80mmHg, while in the pulmonary trunk it is around 7-10mmHg.
- The pressure in the ventricles is less than the aortic and pulmonary pressure, about 60mmHg and 7mmHg respectively.
- The semilunar valves are closed at this point due to the pressure differences.
- As the blood accumulates, it pushes the valves up and back together, causing the ventricular pressure to rise and the atrial pressure to drop.
- The atrioventricular valves close when the ventricular pressure becomes greater than the atrial pressure.
- The semilunar valves remain closed as the arterial pressure is still greater than the ventricular pressure.
- During the isovolumetric contraction phase, no blood leaves the ventricles, and the AV valves snap shut, producing the first heart sound, "Lub" (S1).
- The left ventricle pressure rises to about 120mmHg, while the right ventricle pressure remains at around 25mmHg.
- The ventricular pressure becomes greater than the arterial pressure, causing the semilunar valves to open and blood to move out.
- The text aims to maintain a consistent flow throughout all phases of the cardiac cycle, ensuring clarity in the explanation of atrial versus ventricular pressure dynamics.
- The detailed explanation provides a comprehensive overview of the physiological processes involved in the cardiac cycle, including pressure differentials, valve actions, and sound production.
Autonomic Nervous System Overview
- The autonomic nervous system is made up of three traditional branches: the sympathetic nervous system, the parasympathetic nervous system, and the enteric nervous system.
- The autonomic nervous system is responsible for controlling involuntary bodily functions such as heart rate and digestion.
- The somatic nervous system is under voluntary control, while the autonomic nervous system is not.
- The somatic motor fibers only require one motor neuron to reach the effector organ, while the autonomic nervous system requires two motor neurons: preganglionic and postganglionic.
- The sympathetic nervous system is often referred to as the "fight or flight" system and is designed to use energy in stressful situations.
- The preganglionic cell bodies of the sympathetic nervous system are found in the thoracolumbar outflow, extending from T1 to L2 in the spinal cord.
- The parasympathetic nervous system is responsible for conserving energy and is often referred to as the "rest and digest" system.
- The preganglionic cell bodies of the parasympathetic nervous system are located in the brainstem and the sacral region of the spinal cord.
- Acetylcholine is the specific chemical released by the alpha motor neuron of the somatic nervous system, while the autonomic nervous system releases different neurotransmitters.
- The autonomic nervous system regulates various bodily functions, including heart rate, respiratory rate, and digestion.
- The autonomic nervous system plays a crucial role in maintaining homeostasis within the body.
- The autonomic nervous system is a key component of the peripheral nervous system, which also includes the sensory and motor systems.
Test your knowledge of the cardiac cycle with this quiz. Explore the dynamics of atrial and ventricular pressures, valve actions, and sound production in each phase of the cycle.
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