Vascular System

Question 1

Arteries

Answer 1

efferent vessels of the cardiovascular system. they are vessels that carry blood away from the heart.

Question 2

veins

Answer 2

they are the afferent vessels. they carry blood back to the heart

Question 3

capillaries

Answer 3

microscopic, thin-walled vessels that connect the smallest arteries to smallest veins

Question 4

tunica intima/tunica interna

Answer 4

lines the inside of the vessels and is exposed to the blood. it consists of a simple squamous epithelium called the endothelium. the endothelium acts as selectively permeable barrier to materials entering of leaving the bloodstream. it normally repels blood cells and platelets so that they flow freely without sticking to the vessel wall.

Question 5

tunica media

Answer 5

the middle layer. is usually the thickets. consists of smooth muscle, collagen, and in some cases, elastic tissue. it strengthens the vessels and prevents blood pressure from rupturing them, and it provides vasomotion, changes in the diameter of a blood vessel.

• vasoconstriction or vasodilation
• arteries have thicker tunica media

Question 6

tunica externa/tunica adventitia

Answer 6

outermost layer. it consists of loose connective tissue that often merges with the neighboring blood vessels, nerves, and other organs.

Question 7

Arteries

Answer 7

are sometimes called the resistance vessels of the cardiovascular system because they have a relatively strong, resilient tissue structure that resists high blood pressure.

Question 8

Conducting (elastic or large) arteries

Answer 8

the biggest arteries. The aorta, common carotid and subclavian arteries, pulmonary trunk, and common iliac arteries are examples of conducting arteries.

Question 9

major systemic arteries

Answer 9

supplies oxygen and nutrients to all organs

Question 10

Ascending aorta

Answer 10

rises for about 5cm above the left ventricle. Its only branches are the coronary arteries, which arise behind two cusps of the aortic valve. They are the origins of coronary circulation. Right and left coronary arteries supply the heart.

Question 11

Aortic arch

Answer 11

curves to the left like an inverted U superior to the heart. it gives off three major arteries in this order: the brachiocephalic trunk, left common carotid artery, and left subclavian artery.

Question 12

brachiocephalic trunk

Answer 12

• right common carotid supplying right side of head

- right subclavian supplying right shoulder and upper limb

Question 13

left common carotid artery

Answer 13

supplying left side of head

Question 14

left subclavian artery

Answer 14

supplying shoulder and upper limb

Question 15

descending aorta

Answer 15

passes downward posterior to the heart, at first to the left of the vertebral column and then anterior to it, through the thoracic and abdominal cavities. It is called the thoracic aorta above the diaphragm and the abdominal aorta below the diaphragm.

Question 16

common carotid arteries

Answer 16

have the most extensive distribution of all the head-neck arteries. Near the laryngeal prominence (Adam’s Apple), each common carotid branches into external and internal carotid artery.

Question 17

external carotid artery

Answer 17

ascends the side of the head external to the cranium and supplies most external head structures

Question 18

pulmonary circulation

Answer 18

pulmonary trunk to pulmonary arteries to lungs. lobal branches for each lobe (3 right, 2 left)

-pulmonary veins return to left atrium. increased O2 and reduced CO2 levels

Question 19

aneurysm

Answer 19

weak point in an artery or the heart wall.

• forms a thin-walled, bulging sac that pulsates with each heartbeat and may rupture at any time
• most common sites: abdominal aorta, renal arteries, and arterial circle at the base of the brain
• can cause pain by putting pressure on other structures
• can rupture causing hemorrhage
• result from congenital weakness of the blood vessels or result of trauma or bacterial infections such as syphilis

Question 20

dissecting aneurysm

Answer 20

blood accumulates between the tunics of the artery and separates them, usually because of degeneration of the tunica media

Question 21

what is the most common cause of aneurysm?

Answer 21

the combination of atherosclerosis and hypertension

Question 22

arterial sense organs

Answer 22

sensory structures in the walls of certain vessels that monitor blood pressure and chemistry.
-transmit information to brainstem that serves to regulate heart rate, vasomotion, and respiration

Question 23

carotid sinuses

Answer 23

• baroreceptors (pressure sensors)
• in walls of internal carotid artery
• monitors blood pressure - signaling brainstem
• decreased heart rate and vessels dilation in response to high blood pressure

Question 24

carotid bodies

Answer 24

• chemoreceptors
• oval bodies near branch of common carotids
• monitor blood chemistry
• mainly transmit signals to the brainstem respiratory centers
• adjust respiratory rate to stabilize pH, CO2, and O2

Question 25

aortic bodies

Answer 25

-chemoreceptors • one to three in walls of aortic arch • same function as carotid bodies

Question 26

capillaries

Answer 26

site where nutrients, wastes, and hormones pass between the blood and tissue fluid through the walls of the vessels (exchange vessels) - the 'business end' of the cardiovascular system - composed of endothelium and basal lamina - absent or scarce in tendons, ligaments, epithelia, cornea and lens of the eye

Question 27

capillary exchange

Answer 27

- two way movement of fluid across capillary walls (water, oxygen, glucose, amino acids, lipids, minerals, antibodies, hormones, wastes, cardon dioxide, ammonia) - only through capillary walls are exchanges made between the blood and surrounding tissues - mechanisms involved: diffusion, transcytosis

Question 28

what is the most important form of capillary exchange?

Answer 28

diffusion | -large particles-proteins, held back (aka blood colloid osmotic pressure!)

Question 29

Transcytosis

Answer 29

- endothelial cells pick up material on one side of the plasma membrane by pinocytosis or receptor-mediated endocytosis, transport vesicles across cell, and discharge material on other side by exocytosis - important for fatty acids, albumin and some hormones (insulin)

Question 30

Capillary Beds

Answer 30

- capillaries organized into networks called capillary beds (usually supplied by a single metarteriole) - thoroughfare channel: metarteriole that continues through capillary bed to venule - precapillary sphincters control which beds are well perfused - three-fourths of the bodies capillaries are shut down at a given time

Question 31

capillary bed sphincters open

Answer 31

-when sphincters open: capillaries are well perfused with blood and engage in exchanges with the tissue fluid

Question 32

capillary bed sphincters closed

Answer 32

- when sphincters closed: blood bypasses the capillaries. flows through thoroughfare channel to venule - when the sphincters are closed, little to no blood flow occurs (skeletal muscles at rest)

Question 33

pulmonary capillaries near alveoli

Answer 33

- basketlike capillary beds surround alveoli | - exchange of gases with air and blood at alveoli

Question 34

Capillary Filtration and Reabsorption

Answer 34

-think principles behind osmosis and hydrostatic pressure (physical forces exerted by liquids) - two forces: 1. blood hydrostatic pressure drives fluid out of capillary (high on arterial end of capillary, low on venous end) 2. colloid osmotic pressure (COP) draws fluid into capillary (results from plasma proteins (albumin) - more in blood. oncontic pressure: net COP (blood COP-tissue COP) - capillaries reabsorb about 85% of the fluid they filter - other 15% is absorbed by the lymphatic system and returned to the blood

Question 35

edema

Answer 35

the accumulation of excess fluid in a tissue. occurs when fluid filters into a tissue faster than it is absorbed.

Question 36

three primary causes of edema?

Answer 36

- increased capillary filtration (kidney failure, histamine release, old age, poor venous return) - reduced capillary absorption (hypoproteinemia, liver disease, dietary protein deficiency) - obstructed lymphatic drainage (surgical removal of lymph nodes)

Question 37

Veins

Answer 37

(Capacitance Vessels) -greater capacity for blood containment than arteries • thinner walls, flaccid, less muscular and elastic tissue • collapse when empty, expand easily • have steady blood flow • merge to form larger veins • subjected to relatively low blood pressure – remains 10 mm Hg with little fluctuation

Question 38

Varicose Veins

Answer 38

• Blood pools in the lower legs in people who stand for long periods – Valves pull apart – Blood backflows and further distends the vessels – Hereditary weakness, obesity, and pregnancy also promote problems

Question 39

Superficial Veins of Head and Neck

Answer 39

* internal jugular vein receives most of the blood from the brain * branches of external jugular vein drain the external structures of the head * upper limb is drained by subclavian vein

Question 40

Great Saphenous Vein

Answer 40

* Longest vein in the body * Often times used for surgeries such as coronary bypass * Be aware of surgeries in the lower leg!

Question 41

Principles of Blood Flow

Answer 41

• Important for delivery of nutrients and oxygen, and removal of metabolic wastes

Question 42

Hemodynamics

Answer 42

-physical principles of blood flow based on pressure and resistance • F is proportional to P/R, (F = flow, P = difference in pressure, R = resistance to flow) • the greater the pressure difference between two points, the greater the flow; the greater the resistance the less the flow

Question 43

Blood Pressure

Answer 43

• 2 pressures are recorded: 1. systolic pressure: peak arterial BP taken during ventricular contraction (ventricular systole) 2. diastolic pressure: minimum arterial BP taken during ventricular relaxation (diastole) between heart beats • normal value, young adult: 120/75 mm Hg

Question 44

Hypertension

Answer 44

• high blood pressure – chronic is resting BP > 140/90 – consequences • can weaken small arteries and cause aneurysms

Question 45

Hypotension

Answer 45

chronic low resting BP | – caused by blood loss, dehydration, anemia

Question 46

Vasomotion

Answer 46

• vasomotion is a quick and powerful way of altering blood pressure and flow • three ways of controlling vasomotion: – local control – neural control – hormonal control/chemical

Question 47

autoregulation

Answer 47

the ability of tissues to regulate their own blood supply – metabolic theory of autoregulation – if tissue is inadequately perfused, wastes accumulate stimulating vasodilation which increases perfusion

Question 48

vasoactive chemicals

Answer 48

substances secreted by platelets, endothelial cells, and perivascular tissue stimulate vasomotion – histamine, bradykinin, and prostaglandins stimulate vasodilation (inflammation)

Question 49

reactive hyperemia

Answer 49

(gua sha and cupping!) – if blood supply cut off then restored, flow increases above normal

Question 50

angiogenesis

Answer 50

growth of new blood vessels – occurs in regrowth of uterine lining, around coronary artery obstructions, in exercised muscle, and malignant tumors

Question 51

Neural Control of Blood Vessels

Answer 51

Autonomic nervous systems (and some CNS) • Vasomotor center of medulla oblongata exerts sympathetic control over blood vessels throughout the body – stimulates most vessels to constrict, but dilates vessels in skeletal and cardiac muscle to meet demands of exercise • precapillary sphincters respond only to local and hormonal control due to lack of innervation – vasomotor center is the integrating center for three autonomic reflexes • Baroreflexes-in carotid sinus/regulates BP via medulla • chemoreflexes-sensitive to pH, O2 and CO2 • medullary ischemic reflex-sens. to insufficient profusion (shock) • Consider Raynaud’s disease – sympathetic NS, hypoglycemia…

Question 52

Hormonal Control of Blood Pressure: angiotensin II

Answer 52

potent vasoconstrictor | – raises blood pressure

Question 53

Hormonal Control of Blood Pressure: aldosterone

Answer 53

promotes Na+ and water retention by kidneys | – increases blood volume and pressure

Question 54

Hormonal Control of Blood Pressure: atrial natriuretic peptide

Answer 54

increases urinary sodium excretion – reduces blood volume and promotes vasodilation – lowers blood pressure

Question 55

Hormonal Control of Blood Pressure: ADH

Answer 55

promotes water retention and raises BP | – pathologically high concentrations - vasoconstrictor

Question 56

Hormonal Control of Blood Pressure: epinephrine and norepinephrine effects

Answer 56

– most blood vessels • binds to adrenergic receptors – vasoconstriction (GI) – skeletal and cardiac muscle blood vessels • binds to adrenergic receptors - vasodilation

Question 57

Routing of Blood Flow

Answer 57

• localized vasoconstriction – if a specific artery constricts, the pressure downstream drops, pressure upstream rises – enables routing blood to different organs as needed • examples – vigorous exercise dilates arteries in lungs, heart and muscles • vasoconstriction occurs in kidneys and digestive tract – dozing in armchair after big meal • vasoconstriction in lower limbs raises BP above the limbs redirecting blood to intestinal arteries

Question 58

Blood Flow in Response to Needs

Answer 58

arterioles shift blood flow with changing priorities

Question 59

Mechanisms of Venous Return

Answer 59

– Cardiac hydrostatic pressure moves blood – Skeletal muscle pump in the limbs • contracting muscle squeezed out of the compressedpart of the vein ``` – Thoracic (respiratory) pump • inhalation - thoracic cavity expands and thoracic pressure decreases, abdominal pressure increases forcing blood upward – central venous pressure fluctuates • 2mm Hg- inhalation, 6mm Hg-exhalation • blood flows faster with inhalation ``` – cardiac suction of expanding atrial space

Question 60

transient ischemic attacks (TIAs )

Answer 60

brief episodes of cerebral ischemia - caused by spasms of diseased cerebral arteries - dizziness, loss of vision, weakness, paralysis, headache or aphasia - lasts from a moment to a few hours - often early warning of impending stroke

Question 61

stroke

Answer 61

cerebral vascular accident (CVA) – sudden death of brain tissue caused by ischemia • atherosclerosis, thrombosis, ruptured aneurysm – effects range from unnoticeable to fatal • blindness, paralysis, loss of sensation, loss of speech common – recovery depends on surrounding neurons, collateral circulation