Chapter 17- Circulation Flashcards
What is the function of the myocardium?
To pump blood
The myocardium is also referred to as the heart muscle.
What must the myocardium have to perform its function?
A continuous supply of oxygen and nutrients
What does the myocardium require during periods of physical exertion or stress?
More oxygen
How does the heart increase cardiac output?
By increasing heart rate or stroke volume
What is cardiac output?
The amount of blood the heart pumps in a given time
How does a normal heart meet the increased oxygen demand of the myocardium?
By increasing blood flow through dilation of the coronary arteries
What are the coronary arteries?
Blood vessels that supply blood to the heart muscle
Where do the coronary arteries begin?
At the first part of the aorta, just above the aortic valve
What does the right coronary artery supply blood to?
The right atrium and right ventricle, and the bottom part of the left ventricle
What does the left coronary artery supply blood to?
The left atrium and left ventricle
What are the two major branches of the left coronary artery?
They divide shortly after the aorta
What are the two major arteries branching from the upper aorta?
Right and left carotid arteries, right and left subclavian arteries
These arteries supply blood to the head, brain, and upper extremities.
What do the right and left carotid arteries supply?
Blood to the head and brain
Essential for cerebral circulation.
What do the right and left subclavian arteries supply?
Blood to the upper extremities
Located under the clavicles.
What does the subclavian artery become as it enters each arm?
Brachial artery
This is the major vessel supplying blood to each arm.
What are the two major branches of the brachial artery below the elbow?
Radial and ulnar arteries
These arteries supply blood to the lower arms and hands.
Fill in the blank: The brachial artery divides into the _______ and _______ arteries.
radial, ulnar
These arteries are crucial for blood supply to the forearms and hands.
What divides into the right and left iliac arteries at the level of the umbilicus?
The descending aorta
The iliac arteries supply blood to the groin, pelvis, and legs.
What do the iliac arteries become as they enter the legs through the groin?
The right and left femoral arteries
The femoral arteries are responsible for supplying blood to the legs.
At the level of the knee, the femoral artery divides into which arteries?
Anterior tibial artery, posterior tibial artery, peroneal artery
These arteries supply blood to the lower legs and feet.
What are the tiny blood vessels called that connect arterioles to venules?
Capillaries
Capillaries are about one cell thick and facilitate nutrient and waste exchange.
What is the primary function of capillaries?
Allow the exchange of nutrients and waste at the cellular level
Blood gives up oxygen and picks up carbon dioxide in capillaries.
What are venules?
The smallest branches of veins
Venules collect oxygen-poor blood from capillaries.
What two large veins form from the larger veins as blood returns to the heart?
Superior vena cava, inferior vena cava
These veins carry blood back to the right atrium of the heart.
What does the superior vena cava carry blood from?
The head and arms
It returns blood to the right atrium.
What does the inferior vena cava carry blood from?
The abdomen, pelvis, and legs
It also returns blood to the right atrium.
What happens to blood at the right atrium of the heart?
It is returned into the pulmonary circulation for oxygenation
This process is essential for replenishing oxygen levels in the blood.
What is the most numerous type of cell in blood?
Red blood cells
They carry oxygen and give blood its color.
What color is blood when it is oxygenated?
Bright red
Blood appears darker red when low on oxygen.
What is the function of white blood cells?
Help to fight infection
They are larger than red blood cells.
What are platelets responsible for?
Helping blood to clot
Platelets are much smaller than red or white blood cells.
What is plasma?
The fluid in which blood cells float
Plasma is a mixture of water, salts, nutrients, and proteins.
What is blood pressure?
The force of circulating blood against the walls of the arteries
What does systolic blood pressure measure?
The maximum pressure generated during the contraction of the left ventricle
What is the relationship between systole and diastole?
Systole is the contraction phase, while diastole is the relaxation phase of the left ventricle
What happens to arterial pressure during diastole?
The arterial pressure falls
What closes when the left ventricle relaxes?
The aortic valve
What is diastolic blood pressure?
The pressure exerted against the walls of the arteries while the left ventricle is at rest
Which number represents systolic pressure in a blood pressure reading?
The top number
Which number represents diastolic pressure in a blood pressure reading?
The bottom number
What does the cardiac cycle consist of?
One systolic and one diastolic time period
What does mean arterial pressure (MAP) measure?
The average blood pressure
Why is MAP a good measure?
It indicates perfusion
What generates a pulse during systole?
Blood passing through an artery
What are peripheral pulses?
Pulses felt in the extremities, such as radial and posterior tibial pulses
What are central pulses?
Pulses near the trunk of the body, such as femoral and carotid pulses
How can the rate of cardiac contractions be altered?
By the autonomic nervous system
What is cardiac output?
The volume of blood pumped by the heart in 1 minute
How is cardiac output calculated?
By multiplying heart rate by stroke volume
What is stroke volume?
The volume of blood ejected with each contraction
What do we rely on to estimate cardiac output in the field?
Heart rate and the strength of the pulse
What is the constant flow of oxygenated blood to the tissues known as?
Perfusion
Perfusion is crucial for maintaining tissue health and function.
What are the three primary components required for good perfusion?
- A well-functioning heart (pump)
- Adequate volume of fluid (blood)
- Proper-size container (blood vessels)
Each component plays a critical role in ensuring adequate blood flow to tissues.
What happens if the heart operates at a rate that is too slow or too fast?
Reduces the volume of blood circulated and decreases cardiac output
Cardiac output is essential for maintaining tissue perfusion.
How does a rapid heart rate affect perfusion?
There is not enough time for the heart to refill completely
This can lead to inadequate blood volume being pumped to the body.
What effect does a slow heart rate have on blood circulation?
Decreases the volume of blood circulated per minute
A slow pulse rate can lead to insufficient perfusion of tissues.
What is the consequence of blood loss through hemorrhage on perfusion?
Limits the amount of tissue that can be perfused
Adequate blood volume is necessary for effective perfusion.
What does it mean for blood vessels to be appropriately constricted?
They must match the volume of blood available
Proper constriction ensures that circulation occurs efficiently.
What happens to perfusion if blood vessels dilate while blood volume remains the same?
Perfusion will be reduced
This occurs because there will not be enough blood to fill the enlarged container.
What can lead to a fall in perfusion?
Problems with the heart, blood vessels, or volume of blood
Any of these issues can result in inadequate blood supply to tissues.
What is the ultimate consequence of reduced perfusion?
Cellular death and eventually death of the patient
Sustained inadequate perfusion is life-threatening.
