Exam 2b Flashcards
What are the three primary types of blood vessels?
Arteries, Capillaries, Veins
Blood vessels are classified based on their function.
What is the function of arteries?
Transport blood away from the heart to the capillaries
What is the function of capillaries?
Exchange of substances between blood and tissues
What is the function of veins?
Drain blood from the capillaries and transport it back to the heart
What are tunics in blood vessels?
Layers that the vessel walls are composed of
What is the lumen of a blood vessel?
The inside space of the vessel that blood flows through
What are the three tunics of blood vessels?
Tunica intima, Tunica media, Tunica externa
What is the tunica intima?
The innermost layer of a blood vessel composed of endothelium and subendothelial layer
What role does the endothelium play in blood vessels?
Provides a smooth surface for blood flow and regulates smooth muscle contraction
What is the tunica media composed of?
Circularly arranged layers of smooth muscle cells supported by elastic fibers
What is vasoconstriction?
Narrowing of the blood vessel lumen due to contraction of smooth muscle
What is vasodilation?
Widening of the blood vessel lumen due to relaxation of smooth muscle
What is the tunica externa composed of?
Areolar connective tissue containing elastic and collagen fibers
What are companion vessels?
Arteries and veins that supply the same body region and tend to lie next to one another
How do arterial walls differ from venous walls?
Arterial walls can expand and recoil, are more resilient, and arteries remain patent
What are the three basic types of arteries?
Elastic arteries, Muscular arteries, Arterioles
What are elastic arteries?
The largest arteries with a large proportion of elastic fibers
What is the function of elastic arteries?
Conduct blood from the heart to smaller muscular arteries
What are muscular arteries?
Medium-sized arteries that distribute blood to specific body regions
What are arterioles?
The smallest arteries with fewer than six layers of smooth muscle in their tunica media
What is atherosclerosis?
A progressive disease characterized by the presence of an atheroma leading to thickening of the tunica intima
What is vasomotor tone?
The slightly contracted state of smooth muscle in arterioles
What are capillaries?
The smallest blood vessels connecting arterioles to venules
What are the types of capillaries?
Continuous capillary, Fenestrated capillary, Sinusoid
What is the primary function of capillaries?
Allow for the exchange of substances between blood and surrounding tissues
What distinguishes continuous capillaries?
Endothelial cells form a complete lining with intercellular clefts
Where are fenestrated capillaries commonly found?
Small intestine, kidneys, endocrine glands
What are sinusoids?
Discontinuous capillaries with large openings allowing transport of large substances
What is a capillary bed?
A group of capillaries functioning together
What is a metarteriole?
A branch of an arteriole that connects to a capillary bed
What is a precapillary sphincter?
A smooth muscle ring that controls blood flow into true capillaries
What is perfusion?
The specific amount of blood entering capillaries per unit of time per gram of tissue
What are venules?
The smallest veins that drain blood from capillaries
What is the role of valves in veins?
Prevent blood from pooling in the limbs
What percentage of blood is typically within systemic circulation?
About 70%
What is a simple pathway in blood circulation?
One major artery, a capillary bed, and one vein associated with an organ
What are end arteries?
Arteries that provide only one pathway through which blood can reach an organ
What is an anastomosis?
The joining together of blood vessels
What is a portal system?
Blood flows through two capillary beds separated by a portal vein
What is blood flow velocity?
The rate of blood transported per unit time
What is diffusion?
Random movement of molecules down their concentration gradient
What is the primary function of capillaries?
To allow for the exchange of substances between the blood and surrounding tissues
This includes respiratory gases, nutrients, wastes, and hormones.
What are the three exchange processes in capillaries?
- Diffusion
- Vesicular transport
- Bulk flow
Define diffusion in the context of capillary exchange.
Random movement of molecules or particles down their concentration gradient.
How do substances like oxygen and nutrients move in systemic capillaries?
By diffusion from high concentration in the blood to lower concentration in tissue cells.
What type of solutes can diffuse via endothelial cells or intercellular clefts?
Very small solutes such as O2, CO2, glucose, and ions.
What is vesicular transport?
A process where endothelial cells use pinocytosis to form fluid-filled vesicles for transport.
What is bulk flow?
The movement of large amounts of fluids and their dissolved substances in one direction down a pressure gradient.
What occurs during filtration in capillaries?
Movement of fluid by bulk flow out of the blood through openings in the capillaries.
What is reabsorption in the context of capillary exchange?
The movement of fluid by bulk flow back into the blood.
What two opposing forces determine the direction of movement in capillary exchange?
- Hydrostatic pressure
- Colloid osmotic pressure
Define hydrostatic pressure (HP).
The physical force exerted by a fluid on a structure.
What is blood hydrostatic pressure (HPb)?
The force exerted per unit area by the blood against the vessel wall.
What is colloid osmotic pressure (COP)?
The pull of water back into a tissue by the tissue’s concentration of proteins.
What is the equation for Net Filtration Pressure (NFP)?
NFP = (HPb – HPif) – (COPb – COPif)
What percentage of fluid is typically reabsorbed at the venous end of the capillary?
About 85%.
What system is responsible for returning excess fluid to the blood?
The lymphatic system.
What is edema?
Excess interstitial fluid characterized by swelling of the tissue.
What does perfusion refer to?
The specific amount of blood entering capillaries per unit time per gram of tissue.
Name one factor that influences the amount of blood delivered to a specific organ or tissue.
- Degree of vascularization
- Myogenic response
- Local regulatory factors
- Total blood flow
What is angiogenesis?
The formation of new blood vessels in tissues that require them.
What is the myogenic response?
Contraction and relaxation of smooth muscle within blood vessels in response to changes in stretch.
Define local regulation of blood flow.
Alteration of blood flow in response to changes in metabolic activity of tissues.
What are vasodilators?
Substances that cause smooth muscle relaxation, increasing blood flow.
What are vasoconstrictors?
Substances that cause smooth muscle contraction, decreasing blood flow.
What is autoregulation?
The process by which a tissue regulates its local blood flow based on metabolic needs.
What is reactive hyperemia?
A marked increase in blood flow to a tissue after it has been deprived of blood.
What is blood pressure?
The force per unit area that blood exerts against the inside wall of a vessel.
What is Mean Arterial Pressure (MAP)?
The average measure of blood pressure on the arteries.
What does a MAP of 70 to 110 mm Hg indicate?
Good perfusion.
What is venous return?
The movement of blood from the capillaries back to the heart via the veins.
What assists venous return?
- Valves within veins
- Skeletal muscle pump
- Respiratory pump
What is resistance in the context of blood flow?
The amount of friction blood experiences as it is transported through blood vessels.
What is viscosity?
The resistance of a fluid to its flow, or thickness of a fluid.
What is laminar flow?
The difference in flow rate within a blood vessel.
What equation describes the relationship between blood flow and resistance?
F ∝ (ΔP) / R
What are baroreceptors?
Specialized sensory nerve endings that respond to stretch.
Where are the main baroreceptors located?
- Aortic arch
- Carotid sinuses
What do chemoreceptors regulate?
Primarily respiration but also blood pressure.
Name two important hormones involved in regulating blood pressure.
- Angiotensin II
- Aldosterone
What is the role of Antidiuretic Hormone (ADH)?
Increases the absorption of water in the kidneys, helping maintain blood volume.
What does Atrial Natriuretic Peptide (ANP) do?
Helps regulate blood pressure and volume.
What signals the posterior pituitary to release ADH?
Increased concentration of blood or stimulation of the hypothalamus by angiotensin II
ADH stands for Antidiuretic Hormone, which plays a crucial role in regulating water balance in the body.
What effect does ADH have on the kidneys?
Increases the absorption of water, decreasing its loss in urine
This action helps maintain blood volume and pressure.
Which hormones work together to decrease urine output and maintain blood volume and pressure?
- Angiotensin II
- Aldosterone
- ADH
These hormones are critical in the body’s response to dehydration or low blood pressure.
What does Atrial Natriuretic Peptide (ANP) do?
- Stimulates vasodilation, decreasing peripheral resistance
- Increases urine output, decreasing blood volume
ANP is released from the atrium of the heart in response to increased blood volume.
What triggers the release of ANP?
Increase in stretch of the atrial walls due to increased blood volume and increased venous return
This response helps to counteract high blood pressure.
How do pulmonary arteries differ from systemic arteries?
- Less elastic connective tissue
- Wider lumens
These differences contribute to the unique function of pulmonary circulation.
Why do pulmonary vessels have less resistance to blood flow?
Because the lungs are close to the heart and the vessels are relatively short
This anatomical feature results in lower blood pressure throughout pulmonary circulation.
In comparison to systemic circulation, how does blood pressure in pulmonary circulation differ?
Lower throughout the pulmonary circulation
This is due to the structural differences of pulmonary vessels.
What two systems regulate blood pressure?
- Nervous system (short-term mechanisms)
- Endocrine system (long-term mechanisms)
Both systems work together to maintain stable blood pressure in the body.
During exercise, blood flow will increase to what areas?
Skeletal Muscles
Skin
Coronary Vessels
Vasoconstriction of veins shift blood from venous reservoirs and circulating blood volume ______.
increases
what hormones help to regulate blood pressure?
antidiuretic hormone
aldosterone
atrial natriuretic peptide
the vasomotor center has what type of axons that extend from it to the blood vessels?
sympathetic only
A main arterial branch emerging from the aortic arch, that bifurcates into the right common carotid artery and right subclavian artery is called the what trunk?
brachiocephalic trunk
the right and left brachiocephalic veins merge to form what?
the superior vena cava
What vessels in the lung are associated with the alveoli of the lungs?
pulmonary capillaries
arterial supply to the head and neck comes from the branches of the what?
aortic arch
The arteries that supply the mammary gland and anterior thoracic wall are the
internal thoracic arteries
Which three main arterial branches emerge from the aortic arch?
left subclavian artery
brachiocephalic trunk
left common carotid artery
The bronchial arteries that supply the bronchi, bronchioles, and connective tissue of the lungs emerge as tiny branches from the anterior wall of the ______.
descending thoracic aorta
what veins drain the head, neck and upper limbs?
brachiocephalic veins
the left gastric artery supplies what?
part of the stomach
the esophagus
the veins that drain the head and neck and lead into the brachiocephalic veins are
jugular veins
Which artery emerges from the subclavian artery to supply the mammary gland and anterior thoracic wall?
internal thoracic artery
the adrenal gland gets its blood supply from
middle suprarenal artery
the kidney gets its blood supply from
the renal artery
the testes/ovaries get its blood supply from
the gonadal artery
the left and right bronchial veins drain into
azygos venous system
Which branch of the celiac trunk supplies blood to the lesser curvature of the stomach and esophagus?
the left gastric artery
the artery that provides the main arterial supply to the lower limb
external (or common) iliac artery
Which paired arterial branches emerge from the sides of the descending abdominal aorta?
gonadal arteries
middle suprarenal arteries
renal arteries
the external iliac artery is renamed the ______ artery when it descends into the thigh.
femoral
