Week 8 - CV Blood Vessels, Pressure & Flow

Question 1

What are the five main types of blood vessels?

Answer 1

arteries, arterioles, capillaries, venules, and veins

Question 2

What do arteries do?

Answer 2

They carry blood away from the heart to other organs

Question 3

What do veins do?

Answer 3

They convey blood from the tissues back to the heart

Question 4

What are smaller arteries called?

Answer 4

arterioles

Question 5

What do arterioles is do when they enter a tissue?

Answer 5

They branch into tiny vessel is called capillaries

Question 6

What do capillaries do?

Answer 6

allow for the exchange substances between the blood and body tissues

Question 7

What are Venules?

Answer 7

When groups of capillaries in the tissue reunite to form a small veins these are called venules

Question 8

What are the three layers that make up the wall of a blood vessel?

Answer 8

Tunica interna, tunica media, tunica externa

Question 9

How can you recognise the type and function of a blood vessel?

Answer 9

The type and function of a blood vessel vary based on the three layers that make up the wall of the blood vessel

Question 10

What is the tunica interna?

Answer 10

It is the interior lining of a blood vessel and is in direct contact with the blood as it flows through the lumen. It’s innermost layer is called endothelium

Question 11

What does the endothelium of the tunica interna do?

Answer 11

Facilitate efficient bloodflow by reducing surface fiction

Question 12

What does the basement membrane, and the outermost part of the tunica interna, the internal elastic lamina do?

Answer 12

The basement membrane anchors the endothelium to the underlying connective tissue. The internal elastic lamina (which looks like Swiss cheese), facilitate diffusion of materials through the tunica interna to the thicker tunica media

Question 13

What does the tunica media do?

Answer 13

It regulates the diameter of the loom. Decrease in the diameter is called vasoconstriction and increase in diameter is called vasodilaton. It therefore helps to regulate blood flow and blood pressure

Question 14

What is a vascular spasm?

Answer 14

It is the contraction of smooth muscle when a small artery or arteriole is damaged

Question 15

What blood vessel layer has the most variations and what difference does this make?

Answer 15

Tunica medica, and this results in it performing a variety of functions

Question 16

What is the tunica externa and what is it made out of?

Answer 16

It is the outer covering of a blood vessel and is made up of elastic and collagen fibres.

Question 17

What does the tunica externa do?

Answer 17

It to rest anchors the vessels to surrounding tissues but it also supplies the vessels with blood and nerves. The small vessels that supply blood to the tissue of the vessels are called vasa vasorum

Question 18

Describe the structure of an artery

Answer 18

It has the three layers of a typical blood vessel, but the tunica media is muscular and elastic. This allows it to stretch easily or expand without tearing in response to a small increase in pressure

Question 19

What are the largest arteries is in the body and describe their structure and their function?

Answer 19

The elastic arteries are the largest arteries in the body. They have the largest diameter but there vessel walls are relatively thin compare to the overall size of the vessel. They help propel blood onwards.

Question 20

Why are elastic arteries called conducting arteries and where would you find them?

Answer 20

Because they conduct blood from the heart to medium-sized more muscular arteries. They include the two major trunks that exit the heart the aorta and the pulmonary trunk, along with a aorta’s major initial branches such is the common carotid and common iliac arteries

Question 21

Describe the structure of muscular arteries and what they do

Answer 21

They are medium-sized arteries, and contain more smooth muscle and fewer and elastic fibres and elastic arteries, combined with being relatively thick they are capable of great vasoconstriction and vasodilation to adjust the rate of blood flow

Question 22

Why are muscular arteries known as distributing arteries?

Answer 22

Because they ultimately distribute blood to each of the various organs

Question 23

What is vascular tone?

Answer 23

It is the ability of the muscular arteries to contract and maintain a state of partial contraction helping maintain vessel pressure and efficient blood flow

Question 24

What are anastomoses?

Answer 24

Anastomoses is when the union of the branches of two or more arteries supply the same body region. It can also occur between veins and between arterioles and venules

Question 25

What are arteries that do not anastomose called?

Answer 25

End arteries

Question 26

What are arterioles?

Answer 26

They are microscopic vessels that regulate the flow of blood into the capillaries network of the bodies tissues

Question 27

What is the terminal end of the Arteriole called

Answer 27

It is called the metarteriole and tapers towards the capillary junction

Question 28

What does the distal most muscle cell form and what does it do?

Answer 28

It forms the pre-capillary sphincter, which monitors the blood flow into the capillaries

Question 29

What two things can alter the diameter arterioles and what roll do they play?

Answer 29

Sympathetic nerve supply along with the actions of local chemical mediators can alter the diameter of a Arteriole and thus vary the rate of bloodflow and resistance through these vessels. Arterioles play a key role in regulating blood flow from artilleries into capillaries by regulating resistance the opposition to blood flow due to friction between blood and the walls of blood vessels

Question 30

What are capillaries?

Answer 30

They are the smallest of blood vessels and form a U-turn that connects arterial outflow to the Venus return

Question 31

Why are capillaries known as exchange vessels?

Answer 31

Because their primary function is the exchange of substances between the blood and the interstitial fluid

Question 32

What is micro circulation?

Answer 32

The flow of blood from arteriole through capillaries and into a post capillary venule

Question 33

Where do you find capillaries and how do they vary based on the location?

Answer 33

And they are found near almost every cell in the body, the body tissues with high metabolic requirements such as muscles and the brain have extensive capillaries networks. They are absent in a few tissues, for example Lens of the eye and cartilage

Question 34

How does the structure of capillaries help their function?

Answer 34

They lack both a tunica media and the tunica external and are composed of only a single layer of endothelial cells. Helping their function as exchange vessels.

Question 35

How does capillary blood flow vary based on the metabolic needs of the tissue?

Answer 35

When metabolic need a low blood flows through only a small part of the capillary network however when the tissues active such as contracting muscle, the entire capillary network fills with blood

Question 36

What is the capillary bed?

Answer 36

A network of 10 to 100 capillaries the rise from a single metarteriole

Question 37

What is vaso motion?

Answer 37

Intermittent blood flow through capillaries

Question 38

What is a thoroughfare channel?

Answer 38

The distal end of an arterial which has no smooth muscle is called a thoroughfare channel and provide a direct route for blood from a Arteriole to venule thus bypassing capillaries

Question 39

What’s the difference between continuous capillaries and fenestrated capillaries?

Answer 39

Most capillaries are continuous capillaries, in which the plasma membrane and endothelial cells forms a continuous tube and is interrupted only by intercellular clefts, gaps between neighbouring endothelial cells. Fenestrated capillaries are found in places like the kidneys, the plasma membranes of the endothelial cells in thes plasma membranes of these capillaries have many fenestrations (Small pores rest, holes)

Question 40

What are Sinusoids and what do they do?

Answer 40

They are capillaries but wider and more winding than most. There endothelial cells have unusually large fenestrations. As well as having an incomplete or absent basement membrane sinusoids have very large intercellular clefts that allow proteins and in some cases even blood cells to pass from tissue into the bloodstream

Question 41

What is a portal system?

Answer 41

It is when blood pass it is when blood passes from one capillary network into another through vein call the portal vein

Question 42

What do venules do?

Answer 42

They drain the capillary blood and again the return flow of blood back towards the heart

Question 43

What are post capillary venules and what do they do?

Answer 43

They receive blood from capillaries. They are the smallest venules and very porous and function as significant signs of exchange nutrient and wastes and for this reason form part of the microcirculatory exchange unit along with the capillaries

Question 44

What do post capillary venues become? And what’s the difference?

Answer 44

They become muscular venules which have thicker walls which prevent Exchange with the interstitial fluid

Question 45

The poster pillory and muscular venues are the most distensible element of the vascular system. So what?

Answer 45

It allows them to expand and service excellent reservoirs for accumulating large volumes of blood

Question 46

How are veins different to arteries?

Answer 46

The lumen is larger, they are distensible enough to adapt variations in the volume and pressure blood passing through them but they are not designed to withstand high pressure and the tunica interna is thinner. They are more numerous than Artery is, some are paired and they accompany medium to small size muscular arteries often within the limbs. The subcutaneous layer deep to the skin is another source the veins

Question 47

How are superficial and deep veins related?

Answer 47

Superficial veins form small connections anastomoses, with the deep veins the travel between the skeletal muscles allowing communication between the deep and superficial flow of blood

Question 48

What is the colour of venous blood?

Answer 48

Venous blood is a deep dark red, but superficial veins can appear blue because they are thin walls and the tissues of the skin absorb the red light wavelengths, align the blue like to pass through the surface to our eyes

Question 49

How is blood distributed?

Answer 49

At rest about 64% is systemic veins and venues, systemic arteries and arterioles hold about 13% of the blood volume, systemic capillaries about 7% pulmonary blood vessels about 9% and the heart about seven percent

Question 50

What are the three basic mechanisms by which substances into and leave capillaries?

Answer 50

Diffusion, trans-cytosis, and bulk flow

Question 51

What is diffusion?

Answer 51

It is the most important method of capillaries exchange. Because oxygen and nutrients are normally present in higher concentrations in blood, they defuse down the concentration gradient into interstitial fluid, and then into body cells. Carbon dioxide and other wastes release by body cells are present in higher concentrations in interstitial fluid so they defuse into blood.

Question 52

How does diffusion happen?

Answer 52

Substances in blood or interstitial fluid and cross the walls of the capillary by diffusing through inter cellular clefts or fenestrations or by diffusing through the endothelial cells

Question 53

What is the blood brain barrier and is applied parts of the brain?

Answer 53

The capillaries in most parts of the brain are very tight and Laura only a few substances to move across their walls. However there are certain areas like the hypothalamus and pituitary gland where capillary exchange happens more freely

Question 54

What is trans-cytosis?

Answer 54

It is when substances in blood plasma become enclosed within tiny pinocytic vesicles that first enter endothelial cells by endocytosis, then move across the cell and exit on the other side by exocytosis. This method of transport is important mainly for large, lipid-insoluble molecules that cannot cross capillary walls in any other way. For example, the hormone insulin

Question 55

What is bulk flow (filtration and reabsorption)?

Answer 55

occurs from an area of higher pressure to an area of lower pressure, but substances move at rates far greater than can be accounted for by diffusion alone.

Question 56

What is diffusion more important for and bulk flow more important for?

Answer 56

Diffusion is more important for solute exchange between blood and interstitial fluid, but bulk flow is more important for regulation of the relative volumes of blood and interstitial fluid

Question 57

What’s the difference between filtrating and reabsorption?

Answer 57

Pressure-driven movement of fluid and solutes from blood capillaries into interstitial fluid is called filtration . Pressure-driven movement from interstitial fluid into blood capillaries is called reabsorpti

Question 58

What pressures promote filtration and reabsorption?

Answer 58

blood hydrostatic pressure (BHP), interstitial fluid hydrostatic pressure (IFHP), blood colloid osmotic pressure (BCOP) and interstitial fluid osmotic pressure (IFOP) promote filtration. The balance of these pressures, called net filtration pressure (NFP) , determines whether the volumes of blood and interstitial fluid remain steady or change.

Question 59

What is the difference between blood hydrostatic pressure (BHP) and interstitial fluid hydrostatic pressure (IFHP) ?

Answer 59

BHP ‘pushes’ fluid out of capillaries into interstitial fluid. The opposing pressure of the interstitial fluid, called interstitial fluid hydrostatic pressure (IFHP) , ‘pushes’ fluid from interstitial spaces back into capillaries.

Question 60

What is the difference between blood colloid osmotic pressure (BCOP) and interstitial fluid osmotic pressure (IFOP) ?

Answer 60

The effect of BCOP is to ‘pull’ fluid from interstitial spaces into capillaries. Opposing BCOP is interstitial fluid osmotic pressure (IFOP) , which ‘pulls’ fluid out of capillaries into interstitial fluid.

Question 61

What is Starling’s law of capillaries?

Answer 61

That volume of fluid and solutes reabsorbed normally is almost as large as the volume filtered.

Question 62

What’s the formula for that net filtrating pressure ( NFP)?

Answer 62

NFP = (BHP + IFOP) Pressures that promote filtration − (BCOP + IFHP) Pressures that promote reabsorption

Question 63

Where does filtration and reabsorption occur and what are their respective pressures?

Answer 63

at the arterial end of a capillary, there is a net outward pressure of 10 mmHg, and fluid moves out of the capillary into interstitial spaces (filtration). At the venous end of a capillary, the negative value ( − 9 mmHg) represents a net inward pressure , and fluid moves into the capillary from tissue spaces (reabsorption).

Question 64

What is bloodflow and total bloodflow?

Answer 64

Blood flow is the volume of blood that flows through any tissue in a given time period (in mL/min). Total blood flow is cardiac output (CO), the volume of blood that circulates through systemic (or pulmonary) blood vessels each minute.

Question 65

What is cardiac output and how is it calculated?

Answer 65

Cardiac output (CO) = heart rate (HR) x Stroke Volume (S V)

Question 66

What are the two main factors that affect have a cardiac output (CO) becomes distributed into circulatory roots and subsequently body tissues?

Answer 66

(1) the pressure difference that drives the blood flow through a tissue and (2) the resistance to blood flow in specific blood vessels. Blood flows from regions of higher pressure to regions of lower pressure; the greater the pressure difference, the greater the blood flow. But the higher the resistance, the smaller the blood flow.

Question 67

What is the difference between systolic blood pressure and diastolic blood pressure?

Answer 67

Systolic Pressure?
• Force of blood when ventricles contract, aorta stretches Diastolic Pressure?
• Force of blood when aortic SL valve closes, aorta recoils

Question 68

What happens to blood pressure as blood leaves the aorta?

Answer 68

As blood leaves the aorta and flows through the systemic circulation, its pressure falls progressively as the distance from the left ventricle increases. reaches 0 mmHg as blood flows into the right ventricle.

Question 69

What is mean arterial pressure (MAP) how is it calculated?

Answer 69

Mean arterial pressure (MAP) , the average blood pressure in arteries. It can be estimated as follows. MAP = diastolic BP + 1 ∕ 3 (systolic BP − diastolic BP) Thus, in a person whose BP is 110/70 mmHg, MAP is about 83 mmHg [70 + 1 ∕ 3(110 − 70)].

Question 70

How are MAP and CO related?

Answer 70

Another way to calculate cardiac output is to divide mean arterial pressure (MAP) by resistance (R): CO = MAP ÷ R. By rearranging the terms of this equation, you can see that MAP = CO × R. If cardiac output rises due to an increase in stroke volume or heart rate, then the mean arterial pressure rises as long as resistance remains steady. Likewise, a decrease in cardiac output causes a decrease in mean arterial pressure if resistance does not change.

Question 71

Vascular resistance is the opposition to bloodflow due to friction between blood and the walls of blood vessels. What does it depend upon?

Answer 71

Vascular resistance depends on (1) size of the blood vessel lumen, (2) blood viscosity, and (3) total blood vessel length.

Question 72

What is systemic vascular resistance where is it regulated and which blood vessel helps to control it?

Answer 72

Systemic vascular resistance (SVR) refers to all of the vascular resistances offered by systemic blood vessels. The main centre for regulation of SVR is the vasomotor centre in the brain stem. The smallest vessels (smallest diameter lumen) — arterioles, capillaries, and venules — contribute the most resistance. A major function of arterioles is to control SVR — and therefore blood pressure and blood flow to particular tissues — by changing their diameters. Arterioles need to vasodilate or vasoconstrict only slightly to have a large effect on SVR.

Question 73

What is Venus return and how does it happen?

Answer 73

Venous return, the volume of blood flowing back to the heart through the systemic veins, occurs due to the pressure generated by contractions of the heart’s left ventricle

Question 74

Apart from the heart what two other mechanisms pump blood from the lower body back to the heart??

Answer 74

(1) the skeletal muscle pump and (2) the respiratory pump. Both pumps depend on the presence of valves in veins.

Question 75

How does the respiratory pump help venous return from the lower body?

Answer 75

respiratory pump is also based on alternating compression and decompression of veins. During inhalation, the diaphragm moves downward, which causes a decrease in pressure in the thoracic cavity and an increase in pressure in the abdominal cavity. As a result, abdominal veins are compressed, and a greater volume of blood moves from the compressed abdominal veins into the decompressed thoracic veins and then into the right atrium.

Question 76

Why does the speed or velocity of bloodflow vary?

Answer 76

is inversely related to the cross-sectional area, thus, the velocity of blood flow decreases as blood flows from the aorta to arteries to arterioles to capillaries, and increases as it leaves capillaries and returns to the heart.

Question 77

What does the CV Ctr do?

Answer 77

cardiovascular (CV) centre in the medulla oblongata helps regulate heart rate and stroke volume. The CV centre also controls neural, hormonal feedback system that regulate blood pressure and blood flow to specific tissues.

Question 78

Where does the CV Centre receive its inputs from?

Answer 78

From higher brain regions and from sensory receptors

Question 79

What are the three types of sensory receptors?

Answer 79

Proprioceptor is that none of the movement of joints and muscles. Barrow receptors that monitor changes in pressure and stretch in the wall of blood vessels & chemo receptors monitor the concentration various chemicals in blood

Question 80

Where does the output from the cardiovascular centre go?

Answer 80

It flows along the sympathetic and parasympathetic neurons of the autonomic nervous system. These opposing forces, sympathetic (stimulatory) and parasympathetic (inhibitory) influences Control the heart

Question 81

What are the four hormones that regulate blood volume and pressure?

Answer 81

Renin– angiotensin– aldosterone (RAA) system. Epinephrine and norepinephrine. ADH. Atrial natriuretic peptide (ANP).

Question 82

How does the Renin– angiotensin– aldosterone (RAA) system affect blood pressure?

Answer 82

blood volume falls or blood flow to the kidneys decreases, juxtaglomerular cells in the kidneys secrete renin into the bloodstreamresulting in hormone angiotensin II which raises blood pressure in two ways. 1., angiotensin II is a potent vasoconstrictor; it raises blood pressure by increasing systemic vascular resistance. 2, it stimulates secretion of aldosterone , which increases reabsorption of sodium ions (Na + ) and water by the kidneys. The water reabsorption increases total blood volume, which increases blood pressure.

Question 83

How do Epinephrine and norepinephrine.regulate blood pressure?

Answer 83

In response to sympathetic stimulation, the adrenal medulla releases epinephrine and norepinephrine. These hormones increase cardiac output by increasing the rate and force of heart contractions. They also cause vasoconstriction of arterioles and veins in the skin and abdominal organs and vasodilation of arterioles in cardiac and skeletal muscle,

Question 84

How does ADH regulate blood pressure?

Answer 84

ADH causes vasoconstriction, which increases blood pressure. It also promotes movement of water from the lumen of kidney tubules into the bloodstream. This results in an increase in blood volume

Question 85

How does ANP regulate blood pressure?

Answer 85

atrial natriuretic peptide (ANP) lowers blood pressure by causing vasodilation and by promoting the loss of salt and water in the urine, which reduces blood volume.

Question 86

What is systemic circulation?

Answer 86

systemic circulation includes all arteries and arterioles that carry oxygenated blood from the left ventricle to systemic capillaries, plus the veins and venules that return deoxygenated blood to the right atrium after flowing through body organs. Blood leaving the aorta and flowing through the systemic arteries is a bright red colour. As it moves through capillaries, it loses some of its oxygen and picks up carbon dioxide, so that blood in systemic veins is dark red. All veins of the systemic circulation drain into the superior vena cava , inferior vena cava , or coronary sinus , which in turn empty into the right atrium.

Question 87

What is pulmonary circulation?

Answer 87

blood returns to the heart from the systemic route, it is pumped out of the right ventricle through the pulmonary circulation to the lungs . In capillaries of the air sacs (alveoli) of the lungs, the blood loses some of its carbon dioxide and takes on oxygen. Bright red again, it returns to the left atrium of the heart and reenters the systemic circulation