Circulatory System 1 Flashcards
What does “cardiovascular” refer to?
The heart (“cardio”) and blood vessels (“vascular”).
What is the main function of the heart in the circulatory system?
The heart pushes blood through the circulatory system via its constant pumping action.
What are some functions of blood as it travels through the body?
Answer:
Carrying substances to cells (e.g., O2, nutrients, hormones)
Carrying substances away from cells (e.g., CO2, wastes).
Regulating the acid-base balance in the body through the use of buffers.
Regulating body temperature by absorbing heat internally and releasing it peripherally (i.e., in the skin).
Helping defend against disease (e.g., WBCs, antibodies).
C.C.R.R.H
What are the three basic layers of most blood vessels?
Tunica externa - composed of connective tissue.
Tunica media - consists of smooth muscle and elastic connective tissue.
Tunica interna - made up of epithelial tissue.
Tunica externa
composed of connective tissue.
Tunica media
consists of smooth muscle and elastic connective tissue.
Tunica interna
made up of epithelial tissue.
How do slight differences in the composition and thickness of these layers affect blood vessels?
Slight differences in the composition and thickness of these layers account for the functional differences between the different types of blood vessels.
What is the primary difference between different types of blood vessels?
In general, the thickness and composition of the tunica media are the primary differences between different types of blood vessels.
How are contractions of smooth muscle within the tunica media used?
Contractions of the smooth muscle within the tunica media are used to regulate the diameter of the blood vessels and therefore the distribution of blood to different regions and tissues in the body.
Define vasoconstriction and vasodilation.
Vasoconstriction: Refers to a decreased blood vessel diameter resulting from smooth muscle contraction.
Vasodilation: Refers to an increased blood vessel diameter resulting from smooth muscle relaxation.
Elastic connective tissue within blood vessel:
allows the blood vessel to stretch and recoil as the pressure within it fluctuates
What types of vessels usually contain oxygenated blood?
Arteries and arterioles usually contain oxygenated blood.
What types of vessels usually contain deoxygenated blood?
Venules and veins usually contain deoxygenated blood.
What is the composition of blood in capillaries?
Capillaries contain a mixture of oxygenated and deoxygenated blood.
purpose of arteries:
Carry blood away from the heart
arteries have relatively ___ ___ (compared to veins).
Have relatively thick walls (compared to veins)
What is the primary reason for the thick walls of arteries?
The thick walls of arteries are primarily due to their thick tunica media, which allows for an increased ability to stretch with each heartbeat.
What is the composition of the tunica media in large arteries close to the heart?
The tunica media of large arteries close to the heart contains an abundance of elastic tissue.
How does the composition of the tunica media in large arteries affect blood pressure?
The elastic tissue in the tunica media of large arteries allows these vessels to expand and recoil with each heartbeat, thereby increasing the pressure of the blood being propelled away from the heart.
What is the composition of the tunica media in medium-sized arteries branching off from large arteries?
The tunica media of medium-sized arteries branching off from large arteries contains an abundance of smooth muscle.
What are elastic arteries?
Elastic arteries are the larger arteries of the body, such as the aorta and its major branches, the pulmonary trunk.
What is the predominant tissue in the tunica media of elastic arteries?
The tunica media of elastic arteries is predominantly elastic connective tissue.
How do elastic fibers in elastic arteries contribute to blood flow?
The recoil of elastic fibers in elastic arteries helps propel blood away from the heart.
What are muscular arteries?
Muscular arteries are medium-sized arteries.
What is the predominant tissue in the tunica media of muscular arteries?
The tunica media of muscular arteries is predominantly smooth muscle.
What advantage does the abundance of smooth muscle in muscular arteries provide?
The abundance of smooth muscle in muscular arteries allows for more control of blood flow.
What are arterioles?
Arterioles are small blood vessels that connect arteries to capillaries.
What is the primary function of the smooth muscle in the tunica media of arterioles?
The smooth muscle in the tunica media of arterioles is used to tightly regulate the amount of blood entering capillaries.
what do arteries give rise to?
arterioles
Describe the scenario depicted in the left image. (slide 10)
In the left image, all precapillary smooth muscle sphincters are relaxed, allowing blood to distribute fully through the entire capillary bed.
Describe the scenario depicted in the right image. (slide 10)
In the right image, some of the precapillary sphincters are contracted, preventing blood from being distributed to certain portions of the capillary bed.
What are capillaries?
Capillaries are very small, highly-branched blood vessels that form networks among the individual cells of the body.
What is unique about the structure of capillaries compared to other blood vessels?
Capillaries do not contain a tunica externa or tunica media. Their walls are so thin that they allow the exchange of substances between the blood and surrounding cells.
What are venules?
Venules are small veins that collect deoxygenated blood from capillary beds and start transporting it back to the heart.
What is the primary function of veins?
Veins carry blood to the heart.
How do the walls of veins compare to those of arteries?
Veins have relatively thin walls compared to arteries.
What prevents veins from collapsing?
Veins would essentially collapse if they were not filled with blood.
What are the mechanisms that assist the flow of blood through veins?
- Pumping action of the heart.
- Valves projecting into the interior that prevent the backflow of blood.
- “Skeletal muscle pump” – contraction of skeletal muscles compresses the veins of the upper and lower limbs.
- “Respiratory pump” – fluctuations in abdominal cavity pressure during respiration compress abdominal veins.
“Pumping, Valves, Skeletal muscles, Respiratory Pump.”
What can happen if valves in veins fail?
If valves in veins fail, it can allow blood to pool in certain regions, such as the lower limbs, leading to distension and twisting of veins, a condition known as varicose veins.
What is Deep Vein Thrombosis (DVT)?
DVT is when a clot (thrombus) forms in a deep vein, most commonly in the lower limbs.
What are some risk factors for DVT?
Risk factors for DVT include trauma, long periods of immobilization (e.g., flights, casts), and certain drugs (e.g., HRT, oral contraceptives).
What are the symptoms of DVT?
Symptoms of DVT (if present) include swelling/warmth, local pain/tenderness, and distension of superficial veins.
What is Pulmonary Embolism (PE)?
PE occurs when a clot (embolus) detaches and gets trapped within blood vessels, such as the pulmonary artery.
What are some symptoms of PE?
Symptoms of PE include chest pain, shortness of breath, and cyanosis.
What are the potential consequences of severe cases of PE?
Severe cases of PE can affect both the right side (increased pressure) and left side (decreased ejection) of the heart, potentially leading to cardiac arrest and death.
Why is the amount of blood contained within the systemic veins greater than the blood contained within all other types of blood vessels in the body?
The amount of blood contained within the systemic veins is greater due to the sheer number of systemic veins compared to other types of blood vessels in the body.
what is the distribution of blood?
9% pulmonary vessels
7% heart
13% systemic arteries and arterioles
7% systemic capillaries
64% systemic veins and venules (blood reservoirs)
What is Blood Pressure (BP)?
Blood Pressure (BP) is the pressure exerted on blood vessel walls by the blood.
What does Systolic BP represent?
Systolic BP represents the pressure on arterial walls during ventricular contraction.
What does Diastolic BP represent?
Diastolic BP represents the pressure on arterial walls during ventricular relaxation