How can we help?

You can also find more resources in our Help Center.

A&P I Exam 3 Chapter 21

What exactly is a closed circulatory system?
RBCs never leave the system while being transported throughout the body. This is a direct pathway from the heart to the body and back to the heart. This system allows pressure to build up in the vessels which allows the blood to flow.
_____ are composed of endothelium only.
_____ are the vessels with the thickest walls.
Vessels with valves are called _____.
_____ carry blood from capillaries to heart.
_____ carry blood from heart to capillaries.
Vessels exchanging materials with tissues are called _____.
The smallest and most numerous vessels are ______.
What is the structural and physiological difference between elastic and muscular arteries?
Elastic vessels (Aorta and vessels branching from it) have a lot of elastic fibers to allow stretching and recoil when receiving blood.

Muscular arteries have more smooth muscle and can control blood flow by undergoing vasoconstriction and vasodilation
Where would you find the following capillaries?



Continuous: Throughout most of the body

Sinusoids: Liver and Spleen

Fenestrated: Kidney
How does the body control blood flow through capillaries?
The use of sphincter muscles
What is the difference between Diffusion and Bulk flow in capillaries?
Diffusion is the standard method of moving substance from the blood to the body tissues.

Bulk Flow is used by the kidneys to help maintain osmotic balance.
There are more veins than arteries, this allows the veins to act as a ______.
Veins face low pressures. How does your body make sure that the blood carried by veins makes it back to the heart?
Skeletal Muscle Pump: Every time your skeletal muscles contract they push up against the veins pushing the blood.

Respiratory pump: Every time you breath the abdominal pressure is higher than thoracic pressure which helps the blood along its journey.
Contraction of the _____ generates blood pressure. _______ BP is the highest pressure reached in the ______, while ______ BP is the lowest. A valve of _______ is considered normal. Above normal values is known as _____, Mean arterial pressure is the ______ BP in _______. It is calculated as ______ multiplied by ______.
Contraction of the ( ventricles ) generates blood pressure. ( Systolic )BP is the highest pressure reached in the (arteries ), while ( diastolic )BP is the lowest. A valve of ( 120/80 )is considered normal. Above normal values is known as (hypertension ), Mean arterial pressure is the ( average )BP in ( arteries ). It is calculated as ( CO )multiplied by ( resistance ).
Name and describe the three factors that influence vascular resistance.
1. Blood viscosity: Measure of the thickness of blood. The thicker it is (less water) the more resistance

2. Diameter of BV: More constriction more resistance

3. Distance traveled: More miles to cover the greater the resistance.
Indicate whether the following conditions cause an increase (+) or decrease (-) in blood pressure.

An increase in peripheral resistance.

A marked decrease in blood volume.

A decrease in cardiac output.

Dilation of a great many arterioles.

A significant increase in plasma proteins.

Sympathetic impulses to arterioles.

Constriction of most arterioles.

An increase in heart rate.

A decrease in blood viscosity.

Additional blood vessel length due to weight gain.
An increase in peripheral resistance. +

A marked decrease in blood volume. -

A decrease in cardiac output.-

Dilation of a great many arterioles.-

A significant increase in plasma proteins.+

Sympathetic impulses to arterioles.+

Constriction of most arterioles.+

An increase in heart rate.+

A decrease in blood viscosity.-

Additional blood vessel length due to weight gain.+
A 60-year-old man complains of chest pain during moderate exercise. The pain goes away after he
rests for a while. What is the likely cause of the pain? Without treatment, what complications may arise?
Angina due to narrowing of the coronary arteries. Could led to a coronary thrombosis.
What role do carotid and atrial baroreceptors play in maintaining normal blood pressure and blood flow?
Receptors monitor blood pressure and send signals to the CV center in the brain. Role is to maintain a proper BP
Why do medium-sized veins have valves while arteries of about the same size lack valves?
Veins face really low pressures and need the extra help to return blood to the heart.
In what part of the circulatory system does blood flow most rapidly? most slowly? Explain your answers.
Most rapidly in the arteries due to blood being under high pressures. Slowly in the capillaries to maximize exchange with the body tissues.
In what part of the circulatory system is blood pressure the highest? the lowest? Explain your answers.
Highest in the arteries since they receive blood from the ventricles after contraction. Lowest in the veins because the blood just passed through extensive capillaries losing much of its pressure.
Mrs. Johnson is brought to the emergency room after being involved in an auto accident. She is hemorrhaging and has a rapid pulse, but her blood pressure is still within normal limits. Describe the compensatory mechanisms that are acting to maintain her blood pressure in the face of blood loss.
She is losing blood volume which is lowering her blood pressure. Her body is attempting to maintain homeostasis by vasoconstriction of the vessels.
When one is cold or the external temperature is low, most venous return from the distal part of the arm travels in the deep veins where it picks up heat from the nearby brachial artery en route. However, when one is hot, and especially during exercise, venous return from the distal arm travels in the superficial veins and those vines tend to bulge superficially in a person who is working out. Explain why venous return takes a different route in the second situation.
Blood transport helps with temperature homeostasis. By using the superficial veins the body can release excess body heat.
You have been lying down for two days due to nasty bout of influenza. You finally decide that enough is enough and you stand up. You immediately feel lightheaded and faint. What happened and why? Why does this not occur at a regular basis?
A sudden drop in BP means less blood flow to the head. Your baroreceptors in the carotid arteries can usually adjust quick enough that you usually do not notice.
Veins are not built to withstand great pressures. What happens to your veins around the anus if you are constipated? Why?
You develop hemorrhoids as your veins swell, stretch, and are knocked out of place. Due to the fact that when you push when on the toilet you are exposing the veins to high pressures.
Explain how coronary artery disease can lead to a coronary thrombosis.
Coronary disease is the narrowing of coronary arteries due to plague build up of cholesterol and fatty acids. This could lead to a full clot, a thrombosis.
Explain how atherosclerosis in the lower leg could lead to a stroke in the brain.
The clot could dislodge from the leg and travel the circuit until it becomes lodged in the brain.
What are varicose veins? What are hemorrhoids?
Varicose veins develop in superficial veins due to increased pressure that makes the valves defective.
Aneurysm usually present no problems but are considered ticking-time bombs. Why?
An aneurysm is a weaken arterial wall that could potentially burst leading to you bleeding out.
What is shock and how is it caused?
Shock is a decreased ability to transport oxygen around the body.

Caused by massive blood loss due to trauma, the heart not working properly, anemia, hemolytic disorder
_____ is the blood vessel that distributes blood from the heart?
The blood vessel that conveys blood from the tissues back to the heart is _____.
Elastic arteries function as a _____.
pressure reservoir
These vessels make up the largest blood reservoir.
Veins and venules
Capillaries are also known as _____.
exchange vessels
_____ is the most important capillary exchange method.
Continuous capillaries can be found in the following tissues.
skeletal muscle,
smooth muscle,
connective tissue,
Which of the below would NOT increase blood pressure?

a) Increased blood volume
b) Increased sympathetic stimulation
c) Increased heart rate
d) Increased stroke volume
e) Decreased cardiac output
e) Decreased cardiac output
Which of the below factors do NOT increase systemic vascular resistance?

a) decreased vessel lumen diameter
b) increased blood viscosity
c) decreased vessel length
d) increased vasodilation
e) size of vessel lumen
c) decreased vessel length
This depends mostly on the ratio of RBC to plasma volume.
Blood viscosity
The cardiovascular center is located
in the medulla oblongata
What wold be the response of the body as a result of decreased frequency of action potentials arising from the baroreceptors?
Increased blood pressure
Which hormone would NOT cause an increase in blood pressure?
Atrial Natriuretic Peptide
Chemoreceptors in blood vessels measuring high levels of blood carbon dioxide would NOT cause __________.
Decreased respiratory rate