Cardiovascular System II Flashcards
Events in a cardiac cycle.
- Atrial Diastole (Ventricular Filling)
- Atrial Systole
- Isovolumetric Contraction
- Ventricular Systole (Ejection Phase)
- Isovolumetric Relaxation
Atrial Diastole
1. Heart is completely ____.
2. Pressure in the heart is ____.
3. AV valves are ____.
4. Blood is flowing passively through the ____ into the ____.
5. Semilunar valves are ____.
- Relaxed
- Low
- Open
- Atria > Ventricles
- Closed
Atrial Systole
1. Ventricles remain in ____ as the atria ____.
2. Force blood into the ventricles to complete ____.
- Diastole, Contract
- Ventricular Filling
Isovolumetric Contraction
1. Atrial systole ____, ventricular systole ____.
2. Initial rise in intraventricular pressure ____ the AV valves = prevent backflow of blood into the atria.
3. ____ are completely closed chambers for a moment.
- Ends, Begins
- Closes
- Ventricles
Ventricular Systole (Ejection Phase)
1. Ventricles continue to ____.
2. Intraventricular pressure surpass the pressure in the ____.
3. Causes the ____ valves to open and blood to be ejected from the ventricles.
4. ____ are relaxed and filling with blood.
- Contract
- Major arteries leaving the heart
- Semilunar Valves
- Atria
Isovolumetric Relaxation
1. Ventricular diastole ____, pressure in the ventricle ____ below in the major arteries.
2. Semilunar valves ____ to prevent backflow in the ____.
3. ____ are completely closed chambers and intraventricular pressure continues to ____.
4. Atria have been in ____, filling with blood.
- Begins, Falls
- Close, Ventricles
- Ventricles, Decrease
- Diastole
Two syllables that describe the heart sound.
Lub and Dup
- Caused by the closing of AV valves.
- Longer and louder.
First Heart Sound (Lub)
- Caused by the closing of semilunar valves at the end of ventricular systole.
- Short and sharp.
Second Heart Sound (Dup)
- Abnormal or unusual heart sounds.
- Fairly common in young children with perfectly healthy heart because their heart walls are relatively thin and vibrate with rushing blood.
Heart Murmurs
- Amount of blood pumped out by each side of the heart in 1 minute.
- Product of the heart rate (HR) and stroke volume (SV).
Cardiac Output (CO)
- Volume of blood pumped out by a ventricle with each heartbeat.
- Increases as the force of ventricular contraction increases.
Stroke Volume
Normal resting values for heart rate.
75 beats per minute
Normal resting values for stroke volume.
70 ml per beat
Average adult cardiac output: CO = HR x SV
5250 ml/min or 5.25 L/min
Normal adult blood volume.
6000 ml
- Cardiac output rises when the stroke volume ____ or the heart beats ____ or both.
- Drops when either both of these factors decrease.
Increased, Faster
Healthy hearts pumps out about ____ percent of the blood present in its ventricles.
60% approximately 70 ml or 2 ounces
Three factors that influence stroke volume.
- Preload
- Contractility
- Afterload
Law of the heart that states critical factor for controlling stroke volume is how much the cardiac muscle is stretched by the filling of the chambers just before they contact.
Frank-Starling Law = Preload
The more the muscle cells are stretched = the stronger the contraction, and ____ the stroke volume.
Higher
Two things that influence preload.
- Amount of venous return (blood returning to the heart)
- Length of time the ventricles are relaxed and filling (determined by heart rate)
Anything that increases the volume or speed of venous return = ____ stroke volume and forces of contraction.
Increases
____ heartbeat allows more time for the ventricles to fill.
Slow
____ speeds venous return = increased heart rate and force.
Exercise
Enhanced ____ action of active skeletal muscles on the veins help return blood to the heart.
Squeezing
Plays a major role in increasing the venous return.
Muscular Pump
- Might result from severe blood loss or an abnormally rapid heart rate.
- Decreases stroke volume.
Low Venous Return
- Ability of cardiac muscle to generate tension.
- Influenced by factors: stretch, amount of calcium ions present, sympathetic nervous stimulation, hormones.
- As ____ increases, stroke volume increases.
Contractility
- Amount of pressure the ventricles must overcome to eject blood.
- Determined by the blood pressure in the pulmonary trunk and aorta pressing back on the semilunar valves.
- To pump blood, ventricles must generate a force greater than the ____.
- If ____ increases, stroke volume will decrease as it will be difficult for the ventricles to pump blood.
Afterload
Stroke volume tends to be relatively ____ in healthy people.
Constant
When blood volume drops suddenly or when heart has been seriously weakened, stoke volume ____ and cardiac output is maintained by a ____ heartbeat.
Declines, Faster
Rate of heart contraction can be changed temporarily.
Autonomic Nerves
Most important external influence on heart rate.
Activity of the Autonomic Nervous System
Modify heart rate.
- Chemicals
- Hormones
- Ions
- During times of physical or emotional stress, the nerves of the sympathetic division strongly stimulate the SA and AV nodes and cardiac muscle itself.
- Heart beats more rapidly.
Neural (ANS) Controls
- A faster blood flow increases the rate at which fresh blood flow reaches body cells, more ____ and ____ are made available to them during periods of stress.
- When demand declines, the heart ____.
- Oxygen and Glucose
- Adjusts
Nerve fibers that slow and steady the heart, giving it more time to rest during noncrisis times.
Parasympathetic nerves, primarily vagus nerve fibers
Mimics sympathetic nerves and is released in response to sympathetic nerve stimulation.
Epinephrine
A thyroid hormone that increases heart rate and contractility.
Thyroxine
- ____ level of ionic calcium in the blood depresses the heart.
- ____ level of blood calcium ions causes prolonged contractions that the heart may stop entirely.
- Reduced
- Excessive
Ions that modify heart activity.
Sodium and Potassium Ions
Causes the heart to beat feebly and abnormal heart rhythms appear.
Deficit in Potassium Ions
Physical factors that influence heart rate.
- Age
- Gender
- Exercise
- Body Temperature
Resting heart rate is fastest in the fetus.
140 to 160 beats per minute
Average adult heart rate is faster in females.
72 to 80 beats per minute
Average adult heart rate in males.
64 to 72 beats per minute.
Increases heart rate by boosting the metabolic rate of heart cells.
Heat
Directly decreases heart rate.
Cold
Pumping action of the heart maintains a balance between ____ and ____.
Cardiac Output and Venous Return
- Occurs when pumping efficiency of the heart is reduced so that circulation is inadequate to meet tissue needs.
- Reflects weakening of the heart, hypertensive heart disease, or multiple myocardial infarctions.
- Heart pumps weakly and is nearly worn out.
- Results in lower stroke volume.
Congestive Heart Failure (CHS)
Left heart fails and unable to eject returning blood into the systemic circulation.
Pulmonary Congestion
Become swollen with blood as blood backs up in the lungs and pressure within them increases and fluid leaks into the lung tissue.
Pulmonary Edema
Right side of the heart fails as blood backs up in the systemic circulation.
Peripheral Congestion
Blood circulates inside the blood vessels forming a closed transport system.
Vascular System
Proved that blood move in circles.
William Harvey
As the heart beats, it propels blood into the ____ leaving the heart.
Large Arteries
As the large arteries branch, blood moves into successively smaller and smaller arteries and then into the ____.
Arterioles
Arterioles feed the ____ in the tissues.
Capillaries
Clusters of capillaries that are drained by venules.
Capillary Beds
Drain the capillary beds which in turn empty into veins that merge and empty into great veins.
Venules
Conducting vessels.
Arteries and Veins
- Extend and branch through the tissues and connect smallest arteries to the smallest veins and directly serve the needs of the body cells.
- Only through their walls that exchanges between tissue cells and blood can occur.
Tiny Hairlike Capillaries
Red indicates ____ which is the normal status of blood in most body’s arteries.
Oxygen-rich Blood
Blue indicates ____which is carbon-dioxide rich blood, the normal status of blood in most of the veins.
Oxygen-poor Blood
An exception wherein oxygen-poor blood is carried.
Pulmonary Trunk
An exception wherein oxygen-rich blood is transported back to the heart.
Pulmonary Veins
Walls of blood vessels have three layers or ____.
Tunics
- Lines the lumen or interior of vessels.
- Thin layer of endothelium (squamous epithelial cells) resting on a basement membrane.
- Its cells fit closely together and form a slick surface = decreases friction as blood flows through the vessel lumen.
Tunica Intima
- Bulky middle layer made up of mostly smooth muscle and elastic fibers.
- Some of the large arteries have elastic laminae (sheets of elastic tissue)
Tunica Media
- Controlled by the sympathetic nervous system.
- Active in changing the diameter of vessels.
- Vessels constrict = blood pressure increases, vessels dilate = blood pressure decreases.
Smooth Muscle
- Outermost tunic.
- Composed largely of fibrous connective tissue.
- Support and protect the vessels.
Tunica Externa
- Walls are much thicker than veins.
- Arterial tunica media is much thicker.
- Carry blood away from the heart.
- Expland as blood is forced into them and recoil passively as the blood flows off into the circulation during diastole.
- Walls must be strong and stretchy to take continuous changes in pressure without stretching out permanently.
Arteries
- Carry blood toward the heart.
- Pressure in them tends to be low at all time.
- Have thinner walls.
- Modified to ensure that the amount of blood returning to the heart (venous return) equals the amount being pumped out of the heart (cardiac output) at any time.
- Lumens are much larger than arteries.
- Thinner tunica media but thicker tunica externa.
- Have valves to prevent backflow of blood.
Veins
- Enhances venous return.
- Muscles surrounding the veins contract and relax, blood is ____ through the veins toward the heart.
- Drop in pressure that occurs in the ____ just before we ____ causes the large veins near the heart to ____.
- Helps return blood to heart.
- Skeletal Muscle Activity or Muscular Pump
- Squeezed or Milked
- Thorax, Inhale, Fill
- Respiratory Pump
Transparent walls of the capillaries are only ____ cell layer thick = tunica intima.
One
Because of this exceptional thinness, substances are exchanged ____ between the blood and tissue cells.
Easily
Flow of blood from an anteriole to a venule through a capillary bed.
Microcirculation
Branches into 10 to 20 capillaries which are the exchange vessels which drain into a postcapillary venule.
Terminal Arteriole
If the terminal arteriole is ____, blood enters the capillary bed and exchange occurs.
Dilated
If the terminal arteriole is ____, no blood flows through the capillary bed.
Constricted
Serous membranes holding the intestines in place where the special capillary beds are found.
Mesenteries
Found in capillary beds.
- Precapillary Sphincters
- Vascular Shunt
- Regulate blood flow in the capillary bed.
- When relaxed or open, blood flows through the capillaries and takes part in exchanges with cells.
- When contracted or closed, blood flows through the shunt and bypasses the cells in that region.
Precapillary Sphincter
A vessel that directly connects the arteriole and venule at opposite ends of the bed.
Vascular Shunt
- Common in people who stand for long periods of time and in obese individuals.
- Common factors = pooling of blood in the feet and legs and inefficient venous return resulting from inactivity or pressure on the veins.
- Overworked valves give way and veins become twisted or dilated.
Varicose Veins
- Serious complication of varicose veins.
- Inflammation of a vein that results when a clot forms in a vessel with poor circulation.
Thrombophlebitis
- Along with clot detachment, is a common consequence of thrombophlebitis.
- Life-threatening condition in which the embolism lodges in a vessel in the lung.
Pulmonary Embolism
All venous blood must pass through the ____ circulation before traveling through the ____ again.
Pulmonary, Body Tissues
- Largest artery of the body.
- In adults, about the size of a garden hose and an internal diameter equal to the diameter of your thumb.
- Leaves the left ventricle of the heart.
- Decreases only slightly as it runs to its terminus.
- Named either for their location or shape.
Aorta
Aorta that springs upward from the left ventricle of the heart.
Ascending Aorta
Aorta that arches to the left.
Aortic Arch
Aorta that plunges downward through the thorax following the spine.
Thoracic Aorta
Aorta that pass through the diaphragm into the abdominopelvic cavity.
Abdominal Aorta