lecture 10 & 11 objectives

Question 1

artery

Answer 1

Artery – any of the tubular branching muscular and elastic walled vessels that carry blood from the heart through the body (primarily oxygenated)

Question 2

capillary

Answer 2

Capillary – a minute thin-walled vessel in the body; any of the smallest blood vessels connecting arterioles with venules and forming networks throughout the body

Question 3

vein

Answer 3

Vein – any of the tubular branching vessels that carry blood from the capillaries toward the heart

Question 4

tunica intima

Answer 4

Tunica intima (outer layer) – made of simple squamous epithelium lining the lumen, with a layer of subendothelial connective tissue. Functions to provide a smooth surface for blood flow, regulate the movement of substances between the blood and vessel walls.

Question 5

tunica media

Answer 5

Tunica media (middle layer) – made of smooth muscle cells, elastic fibers, and collagen fibers. Functions to help with blood pressure regulation by contracting or relaxing muscle cells and help to maintain vessel fluctuations without ruptures.
Vasoconstriction and vasodilation are regulated here. Also regulates stretching

Question 6

what is most commonly regulated by the tunica media

Answer 6

vasoconstriction and vasodilation

Question 7

tunica externa

Answer 7

Tunica externa (outer layer) – made of fibroblasts, collagen fibers, and elastic fibers with varying densities. It anchors by attaching blood vessels to provide stability and prevent movement, maintains structural support and integrity by helping it to resist excessive expansion of the walls, it helps with vascular supply by providing nutrients to the outer layers of the vessel walls, and innervates the vessels.

Question 8

compare and contrast tunica thickness in arteries, capillaries, and veins

Answer 8

o Arteries: have a thick tunica media to withstand and regulate high bp, the tunica intima is relatively thin, and the tunica externa is present but less pronounced than veins.
o Veins: have a tinner tunica media due to less pressure, have a thicker tunica externa to offer structural support and help return blood to the heart
o Capillaries: have a single layer of endothelial cells (intima), and is to facilitate exchange of gases, nutrients, and wastes between blood and tissues

Question 9

compare and contrast tunica composition in arteries, capillaries, and veins

Answer 9

o Arteries: Tunica media: primarily smooth muscle and elastic fibers which allow for expansion and contraction with hear beat to help maintain bp and flow. Tunica externa has collagen fibers that provide structural support
o Veins: Tunica media is thinner and has less smooth and elastic tissue. The tunica externa is rich in collagen to help with structural support.
o Capillaries: no smooth of elastic, purely endothelial cells and a basement membrane

Question 10

compare and contrast tunica lumen diameter in arteries, capillaries, and veins

Answer 10

o Arteries: have a relatively large lumen to allow for rapid blood flow at high pressure
o Veins: has a lumen that is larger than arteries and capillaries, but a smaller diameter. This is so that they can accommodate for the large volume of blood in veins
o Capillaries: have a small lumen which allows for efficient transport of different things

Question 11

structure and function of elastic conducting arteries

Answer 11

Elastic conducting arteries: have a large diameter with thick walls, high content of elastic fibers in the tunica media to allow for stretch and recoil, relatively thin tunica intima and externa. Functions to act as a pressure reservoir by expanding during systole and recoiling during diastole.
- are termed conducting because they conduct blood from the heart to the muscular arteries

Question 12

example of elastic conducting arteries

Answer 12

aorta, pulmonary arteries

Question 13

structure and function of muscular distributing arteries

Answer 13

Muscular distributing arteries: are medium sized arteries that have a thicker tunica media than elastic arteries. The tunica media is rich in smooth muscle fibers but few elastic. It has a thick tunica externa. Helps to distribute blood to specific regions of the body, and allows for vasoconstriction and vasodilation and helping regulate blood flow and pressure by adjusting the diameter of the vessel
- are termed distributing arteries because they are what actually distributes and delivers blood to specific locations

Question 14

examples of muscular distributing arteries

Answer 14

Brachial artery, femoral artery, renal arteries

Question 15

structure and function of arterioles

Answer 15

Arterioles: are the smallest arteries with a very thin tunica externa and a relatively thicker tunica media composed mostly of smooth muscle. The lumen diameter is narrow in comparison to larger arteries. Works to regulate blood flow to the tissues and bp by contracting or relaxing the smooth muscle in their walls. The primary site of resistance in the circulatory system which helps to influence peripheral resistance and bp.
- can also be termed resistance vessels because they help to control changing pressure and how things move

Question 16

examples of arterioles

Answer 16

Found throughout the body, are just before the capillaries

Question 17

structure and function of capillaries

Answer 17

Capillaries: the smallest and thinnest blood vessels with walls of a single layer of endothelial cells and a thin basement membrane, no smooth or elastic tissue. Allows for easy exchange of gases, nutrients and waste across the walls; allows for diffusion.
- are seen as the spot for change or exchange

Question 18

examples of capillaries

Answer 18

Present throughout the body, especially in the tissues like muscles, lungs, and kidneys

Question 19

structure and function of venules

Answer 19

Venules: are small veins formed by the convergence of capillaries, thinner walls than veins, small amount of smooth muscle and elastic fibers. Thin Tunica median, and less developed tunica externa. They collect deoxygenated blood from the capillaries and work to return it to the heart, and serve as a transition point between the capillaries and larger veins

Question 20

structure and function of veins

Answer 20

Veins: larger vessels with wide lumen, relatively thin walls, thin tunica media, prominent tunica externa, has valves to prevent backflow of blood. It has smooth muscles in the media, and collagen and elastic in the externa. Carry deoxygenated blood back to the heart, have wide lumen to hold a large volume of blood, rely on skeletal muscle contraction and valves to facilitate the return of blood to the heart
- veins are termed the blood reservoir because they hold around 65% of all blood capacity and help blood to get back to the heart

Question 21

examples of veins

Answer 21

Superior and inferior vena cava, jugular veins, femoral veins

Question 22

vasoconstriction

Answer 22

Constriction – reduces blood supply to the skin, can be in response to cold
- when the blood vessel narrows

Question 23

vasodilation

Answer 23

Dilation – increases blood supply to the skin, is when muscles around the vessels relax, can be in response to hot temperatures
- when the blood vessel widens

Question 24

continuous capillaries

Answer 24

Continuous capillaries: The walls are continuous and made up of endothelial cells that are tightly joined by tight junctions. The basement membrane is also continuous and intact. These capillaries have small intercellular clefts (gaps) that allow for the passage of small molecules like glucose, ions, and gases. Function in exchange of small molecules and gases but prevent movement of larger molecules, have tight junctions to limit permeability and what exits the cell. Mostly in the tissue, including the muscles, skin, lungs, and brain
- often have associated pericytes

Question 25

fenestrated capillaries

Answer 25

Fenestrated capillaries: the endothelial cells have pores (fenestrae) in their walls, which make these capillaries more permeable than continuous capillaries. These pores are often covered by a thing diaphragm but still allow for the passage of larger molecules. They are adapted for more rapid movement or larger molecules. - often found in areas that need rapid absorption and filtration like the kidneys, small intestine, endocrine glands

Question 26

sinusoidal discontinuous capillaries

Answer 26

Sinusoidal discontinuous capillaries: These have larger gaps between the endothelial cells and a discontinuous basement membrane. This allows for the passage of large molecules, including blood cells, across the capillary walls. The lumen of sinusoidal capillaries is often wider than that of continuous or fenestrated capillaries. Are specialized for the exchange of large molecules and cells (blood cells and proteins), are vital for the immune responses and blood cell formation. Are found in many specialized organs like the spleen, liver, bone marrow, and certain lymphoid tissues. - this is where it is easiest for things to slide through because not only are the walls thin, but there is also minimal pressure so it is easy for things to go through

Question 27

Describe how muscular compression and the respiratory pump aid venous return.

Answer 27

Muscular compression, also known as the "skeletal muscle pump," and the respiratory pump both work together to facilitate venous return by squeezing veins, increasing pressure within them, and pushing blood towards the heart, primarily through the action of surrounding muscles contracting and the pressure changes in the thoracic cavity during breathing, respectively; with the help of one-way valves in veins preventing backflow

Question 28

Explain the mechanisms of capillary exchange of gases, nutrients, and wastes.

Answer 28

Capillary exchange refers to the process by which gases, nutrients, and wastes are exchanged between the blood and the tissues across the walls of capillaries. This process occurs via several mechanisms, depending on the size, solubility, and concentration gradients of the substances being exchanged. diffusion filtration reabsorption transcytosis

Question 29

diffusion in muscular compression and the respiratory pump aiding in venous return

Answer 29

Diffusion – the primary process for exchange where substances move from areas of higher concentration to lower concentration. Oxygen will go from capillaries to interstitial fluid to tissues. Carbon dioxide will go from the tissues to the capillaries to the lungs for exhalation. Nutrients like glucose and amino acids diffuse from the blood to the tissues.

Question 30

filtration in muscular compression and the respiratory pump aiding in venous return

Answer 30

Filtration – the process by which fluids and small solutes move from the blood to the interstitial fluid. It is primarily in the arterial end of the capillaries where hydrostatic pressure is greater than osmotic pressure. Filtration helps to deliver oxygen, nutrients, and other small molecules to tissues.

Question 31

reabsorption in muscular compression and the respiratory pump aiding in venous return

Answer 31

Reabsorption – the process by which fluid and solutes are drawn back into capillaries from the interstitial fluid due to osmotic pressure. Typically, on the venous ends of the capillaries where osmotic pressure is greater than hydrostatic pressure. This pulls fluid and waste products back into the bloodstream. Works to prevent the loss of essential blood components and helps return excess fluid into circulation. Also for reabsorption of waste products from tissues which are then transported to organs like the kidneys for excretion.

Question 32

transcytosis in muscular compression and the respiratory pump aiding in venous return

Answer 32

Transcytosis - involves the active transport of large molecules across the endothelial cells of the capillaries. In this process, substances such as proteins or large lipid-soluble molecules are encapsulated in vesicles at one side of the endothelial cell and then transported across the cell to be released on the other side. Especially important for the exchange of larger molecules that cannot simply diffuse through. Plays a large role in the transport of hormones, antibodies, and lipid-soluble substances

Question 33

define anastomosis

Answer 33

Anastomosis – a interconnection between two structures (specifically between blood vessels)

Question 34

what is the functional significance of anastomosis

Answer 34

Significance - An anastomosis is a surgical connection between two structures. It usually means a connection that is created between tubular structures, such as blood vessels or loops of intestine. For example, when part of an intestine is surgically removed, the two remaining ends are sewn or stapled together (anastomosed). Provides an alternate route for blood if one direction is blocked or cut. Big in heart, brain, abdominal organs, and around the joints. Not around retina, spleen, and kidneys.

Question 35

the forces that create capillary filtration and reabsorption

Answer 35

Capillary filtration and reabsorption are primarily driven by two opposing forces: hydrostatic pressure which pushes fluid out of the capillary (filtration), and colloid osmotic pressure (oncotic pressure) which draws fluid back into the capillary (reabsorption); the balance between these forces determines the net movement of fluid across the capillary wall, with filtration dominating at the arterial end and reabsorption at the venous end of the capillary hydrostatic pressure colloid osmotic pressure

Question 36

hydrostatic pressure in the forces that create capillary filtration and reabsorption

Answer 36

Hydrostatic pressure - This is the pressure exerted by the fluid within the capillary, pushing against the capillary walls and tending to force fluid out into the interstitial space. At the arterial end of the capillary, where blood pressure is highest, hydrostatic pressure is greater, promoting filtration.

Question 37

colloid osmotic pressure in the forces that create capillary filtration and reabsorption

Answer 37

Colloid osmotic pressure - This pressure is created by the presence of large plasma proteins within the capillary, which draw water back into the capillary due to their high solute concentration. Since these proteins are largely unable to leave the capillary, their osmotic pull is constant, promoting reabsorption

Question 38

Explain how changes in net filtration pressure (NFP) can result in edema and how a functional lymphatic system normally prevents edema.

Answer 38

Edema occurs when there is an increase in net filtration pressure (NFP), causing excessive fluid to leak out of capillaries into the interstitial spaces, leading to tissue swelling; a healthy lymphatic system prevents edema by actively draining this excess fluid back into the bloodstream, maintaining fluid balance within tissues This means that if not enough fluid is taken out by the capillaries, an edema can occur which the lymphatic system gets rid of the wastes that cause this fluid build up thus helping prevent edema.