Cardiovascular #2 Flashcards Preview

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Flashcards in Cardiovascular #2 Deck (74)
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1
Q

3 Layers of a blood vessel

A

1) Tunica Interna aka Tunica Intima - adjacent to lumen
2) Tunica Media - middle layer (includes smooth muscle and elastic fibers)
3) Tunica Externa - adjacent to surround tissue

2
Q

Elasticity of Arteries

A
  • The walls of the arteries are elastic
  • Allows them to absorb the pressure created by ventricles of the heart
  • Creates a pressure resevoir
3
Q

Which anatomy of the artery regulates its diameter?

A

Smooth muscles of the Tunica media

4
Q

Effects of elastic expansion and recoil or the aorta and its branches

A
  • Maintains steady flow of blood during diastole
  • Smooths out pressure fluctuations
  • ↓ stress on small arteries
5
Q

2 Types of Arteries

A

1) Elastic or Conducting Arteries

2) Muscular or Distributing Arteries

6
Q

Characteristics of Elastic Arteries

A
  • Large diameter
  • More elastic fibers
  • Less smooth muscle
  • Function as pressure reservoirs
7
Q

Characteristics of Muscular Arteries

A
  • Medium diameter
  • Fewer elastic fibers
  • More smooth muscle
  • Distribute blood to various parts of the body
8
Q

Anastamosies

A
  • Union of the branches of 2 or more arteries supplying the same region of the body
  • Provides an alternate route for blood flow
9
Q

End Arteries

A

Arteries that do not form an anastomosis

10
Q

What happens if an End Artery gets blocked

A

Blood cannot get to that part of the body and necrosis can occur

11
Q

3 Arterial Sense Organs

A

1) Carotid Sinuses
2) Carotid Bodies
3) Aortic Bodies

12
Q

Carotid Sinuses

A
  • Baroreceptor (sensitive to pressure ∆ )
  • Located in internal carotid artery
  • Monitors BP and signals brainstem ↓ HR and dilate vessels
13
Q

Carotid Bodies

A
  • Oval bodies near carotids (cluster of chemoreceptors)
    monitor blood chemistry
  • Adjust respiratory rate to stabilize pH, CO2, and O2
14
Q

Aortic Bodies

A
  • In walls of aorta (cluster of chemoreceptors)
    monitor blood chemistry
  • Adjust respiratory rate to stabilize pH, CO2, and O2
15
Q

Capillaries

A
  • Microscopic vessels that connect arterioles & venules
  • Walls made of single layer of cells and a basement membrane
  • Thin walls permit the exchange of nutrients & wastes
16
Q

Capillary Bed Routes

A

1) Most Common Route - heart&raquo_space;> arteries&raquo_space;> arterioles&raquo_space;> capillaries&raquo_space;> venules&raquo_space;> veins
2) Portal System - Blood flows through two consecutive capillary networks before returning to heart:
- Hypothalamus/pituitary
- Kidneys
- Hepatic Portal System between intestines - liver

17
Q

3 Types of blood vessel anastomoses

A

1) Arteriovenous Shunt - artery flows directly into vein
2) Venous Anastamoses- most common, blockage less serious
3) Arterial Anastomoses- colateral circulation (coronary)

18
Q

Continous Capillaries found in ___?

A

Most tissues

19
Q

Fenestrated Capillaries found in ____?

A

Kidneys, small intestine, choroid plexus, ciliary bodies (eyes)

20
Q

Sinusoid Capillaries found in _____?

A

Liver, bone marrow and spleen

21
Q

3 method by which substances cross capillary walls

A
  • Diffusion
  • Transcytosis
  • Bulk flow
22
Q

Examples of substances that cross capillary walls by diffusion?

A

1) Oxygen
2) Carbon dioxide
3) Glucose
4) Amino acids
5) Some hormones

23
Q

Examples of substances that cross capillary walls by transcytosis

A
  • Large lipid-insoluble molecules (like insulin) cross capillary walls in vesicles via transcytosis
24
Q
  • Examples of substances that cross capillary walls by Bulk Flow
  • Characteristics of Bulk Flow
A
  • Large numbers of ions, molecules, or particles in a fluid move together in the same direction
  • Passive process
  • Occurs from an area of high pressure to low pressure
  • Continues as long as a pressure difference exists
  • Regulates volumes of blood and interstitial fluid
25
Q

Filtration

A
  • Pressure-driven movement of fluid and solutes from blood capillaries into interstitial fluid
  • i.e. Blood hydrostatic pressure (BHP) and interstitial fluid osmotic pressure (IFOP)
26
Q

Reabsorption

A
  • Pressure-driven movement of fluid and solutes from interstitial fluid into blood capillaries
  • i.e. Interstitial fluid hydrostatic pressure (IFHP) and blood colloid osmotic pressure (BCOP)
27
Q

Causes of Edema

A

1) ↑ Capillary Filtration

2) ↓ Capillary Reabsorption

28
Q

3 causes of ↑ Capillary Filtration

A

1) Poor venous return (i.e. CHF and pulmonary edema, insufficient muscular activity)
2) Kidney failure (water retention, hypertension)
3) Histamine makes capillaries more permeable

29
Q

Causes of ↓ Capillary Reabsorption

A

Hypoproteinemia, cirrhosis, famine, burns, kidney disease

Obstructed lymphatic drainage

30
Q

Consequences of Edema

A

1) Tissue necrosis - oxygen delivery and waste removal impaired
2) Pulmonary edema - suffocation
3) Cerebral edema - headaches, nausea, seizures and coma
4) Circulatory shock - excess fluid in tissue spaces causes low blood volume and low BP

31
Q

Veins

A

1) Have lower BP: 10mmHg with little fluctuation
2) Thinner walls, less muscular and elastic tissue
3) Expand easily and have high capacitance
4) Have valves - aid skeletal muscles in upward blood flow

32
Q

Venules

A
  • More porous than capillaries

- Muscular venules have tunica media

33
Q

Venous Sinuses

A
  • Veins with thin walls, large lumens, no smooth muscle
34
Q

Veins compared to Arteries

A
  • Veins have a thinner tunica interna and media
  • Veins have thicker tunica externa
  • Veins have less elastic tissue and less smooth muscle than arteries
35
Q

Venous Return is assisted by

A
  • One-Way Valves
  • Respiratory pump
  • Skeletal muscle pump
  • Gravity (for head and neck)
  • Cardiac suction of expanding atrial space
36
Q

Effects of Inhalation on Respiratory Pump

A
  • ↑ Blood flow to thoracic veins
  • ↓ Thoracic pressure
  • Blood moves superiorly
  • ↑ intra-abdominal pressure
37
Q

Effects of Exhalation on Respiratory Pump

A
  • ↑ Blood flow into heart and abdominal veins
  • ↑ Thoracic pressure
  • Diaphragm relaxes
  • ↓ intra-abdominal pressure
38
Q

At rest, where is the largest portion of the blood located?

A

In the systemic veins and venules (the blood reservoir)

39
Q

Blood Flow vs Perfusion

A

Blood Flow - Volume of blood flowing through a tissue in a given time (ml/min)
Perfusion - Rate of blood flow per given mass of tissue (ml/min/100g)

40
Q

Poiseuille’s Law

A
F =  (πr^4ΔP)/8ηl; where
F = flow in L/s
η = viscosity in Pa/s
r = radius of tube in meters
l = length of tube in meters
41
Q

Calculate Cardiac Output

A
  • CO = HR × SV

- CO = MAP ÷ resistance (R)

42
Q

Mean Arterial Pressure (MAP)

A
  • Measurements taken at intervals of cardiac cycle
  • Best estimate: diastolic pressure + (1/3 of pulse pressure)
  • Varies with gravity: ex: standing: 62 – head; 180 - ankle
43
Q

What determines BP

A
  • CO
  • Blood Volume
  • Vascular resistance
44
Q

BP changes with distances

A

BP highest near left ventricle and lowers as it moves away i.e. highest near aorta and lowest vena cava

45
Q

Vascular Resistance

A

The opposition to blood flow due to friction between blood and the walls of blood vessels

46
Q

Vascular Resistance depends on which 3 things?

A
  • Size of the blood vessel lumen
  • Blood viscosity
  • Total blood vessel length
47
Q

Regulation of BP and flow

A

1) Local control - Autoregulation
2) Neural control - Vasomotor Center in Medulla Oblongata
3) Hormonal control - RAAS, ANP, ADH, Epi

48
Q

Metabolic theory of Autoregulation

A

Tissue inadequately perfused results in wastes accumulating, which = vasodilation

49
Q

Vasoactive chemicals’ role in auto regulation of BP

A

Substances that stimulate vasomotion. i.e. histamine and bradykinin

50
Q

What is Reactive Hyperemia

A

Transient increase in organ blood flow that occurs following a brief period of ischemia (e.g., arterial occlusion)

51
Q

What is Angiogenesis

A

Growth of new blood vessels. i.e. regrowth of uterine lining, around obstructions, exercise, malignant tumors

52
Q

3 Autonomic Reflexes involved in the neural control of BP

A
  • Baroreflexes
  • Chemoreflexes
  • Medullary ischemic reflex
53
Q

Baroreflex

A
  • Changes in BP detected by stretch receptors baroreceptors
  • ↓ in BP = ↑in HR, contractility and vasoconstriction
  • Acute HTN = opposite response
  • Inhibited by inhalation anesthetics
54
Q

Baroreceptor Locations

A

Located in large arteries above heart:

1) Aortic arch
2) Aortic sinuses (behind aortic valve cusps)
3) Carotid sinus (base of each internal carotid artery)

55
Q

Chemoreceptors

A
  • Sensors that detect changes in CO2, O2, and pH
  • Located in aortic arch, external carotids and subclavian arteries
  • Primary role - adjust respiration
  • Secondary role - vasomotor
  • Inibited by inhalation anesthesia
56
Q

Physiological factors that stimulate chemoreceptors?

A

Hypoxemia, hypercapnia and acidosis stimulate chemoreceptors, which stimulate vasomotor center to cause vasoconstriction, ↑ BP, ↑ lung perfusion and gas exchange

57
Q

Medullary Ischemic Reflex

A

Inadequate perfusion of brainstem

58
Q

Effects of Medullary Ischemic Reflex

A
  • Cardiac/vasomotor centers send sympathetic signals to heart & blood vessels
  • ↑ C.O. and causes widespread vasoconstriction
  • ↑ BP
59
Q

Hormonal Control of BP

A

1) Atrial Natriuretic Peptide (ANP) - ↑ Na excretion which ↓ BP
2) Antidiuretic Hormone (ADH) - ↑ water retention and vasoconstriction which leads to ↑ BP
3) EPI and NE - catecholamines released from adrenal medulla ↑ cardiac output & BP

60
Q

Where would you feel for the following pulses:

1) Superior Temporal Artery
2) Facial Artery
3) Common Carotid Artery
4) Brachial Artery
5) Femoral Artery
6) Popliteal Artery
7) Radial Artery
8) Dorsal Artery of Foot

A

1) Superior Temporal Artery - Medial to ear
2) Facial Artery - Mandible, on line with corners of mouth
3) Common Carotid Artery - Lateral to larynx (voice box)
4) Brachial Artery - Medial side of biceps brachia muscle
5) Femoral Artery - Inferior to inguinal ligament
6) Popliteal Artery - Posterior to knee
7) Radial Artery - Lateral aspect of wrist
8) Dorsal Artery of Foot - Superior to instep of foot

61
Q

Valsalva Maneuver

A
  • Forced expiration against closed glottis
  • Mediated by baroreceptors -> CN. IX and X
  • Vasomotor Center (Medulla)
  • ↓SNS, ↑ PSNS
  • ↑ intrathoracic pressure = ↓ venous return = ↓ CO
62
Q

Ocularcardiac Reflex

A
  • Aka Aschner phenomenon

- Traction on extraocular muscle (esp. medial rectus), conjunctiva or orbital structures = ↓ BP and HR

63
Q

Besides traction of extra ocular muscle, 3 things that could cause stimulation of ocular cardiac reflex

A
  • Retrobulbar block
  • Ocular trauma
  • Pressure on remaining tissue post enucleation
64
Q

How do you reverse the Oculocardiac Reflex?

A

Vagal response antagonized by anticholinergics like atropine and glycopyrrolate

65
Q

Celiac Reflex

A
  • Caused by traction on mesentery, gallbladder, or other structures in thorax or abd. cavity during surgery and pneumoperitoneum
  • Causes Bradycardia, Apnea, Hypotension
  • Resolved by removing initiating stimulus
  • Vagal response antagonized by anticholinergics like atropine and glycopyrrolate
66
Q

Bainbridge Reflex

A
  • Atrial stretch reflex
  • ↑ in HR due to an ↑ in CVP
  • Stretch receptors in RA, Vena caval jct. & Pulmonary veins
  • Sense ↑ venous return to heart
  • ↓ ADH, ↑ SNS, ANP
67
Q

Cushing Reflex

A
  • Response to CNS ischemia secondary to ↑ ICP
  • Causes ↑ Vasoconstriction
  • If MAP < 50%, vasomotor area becomes ischemic
    Maximal stim. of Vasomotor ctr. Occurs
  • Results in Cushing’s Triad: HTN, bradycardia, Irreg. Resp.
  • Triad indicates sustained ↑ ICP prior to herniation/death
68
Q

Define Shock

A

Shock is an inadequate CO that results in failure of the CV system to meet the metabolic demands of body cells

69
Q

5 Types of Shock

A

1) Hypovolemic
2) Neurogenic (from ↓ vasomotor tone)
3) Cardiogenic (Acute MI)
4) Vascular (normal vol. w/ ↑ vasodilation i.e. anaphylactic or septic shock
5) Obstructive (PE , Cardiac Tamponade)

70
Q

Homeostatic Responses to Shock

A
  • Activation of the RAAS
  • Secretion of ADH
  • Activation of the SNS
  • Release of local vasodilators
71
Q

SxS of Shock

A

1) Same as dramatic decrease in BP
2) Clammy, cool, pale skin
3) Tachycardia, weak but rapid pulse
4) Sweating
5) Hypotension (SBP <90 mmHg)
6) Altered mental status
7) ↓ urinary output
8) Thirst
9) Acidosis

72
Q

Responses to Hypovolemic Shock

A
  • ↑ Renin
  • ↑ ADH
  • ↑ Epi
73
Q

Compensated Shock

A

Homeostatic mechanisms bring about recovery

BP triggers baroreflex and production of angiotensin II, both stimulate vasoconstriction

74
Q

What are the 3 life-threatening positive feedback loops of Decompensated Shock

A

1) ↓ CO = myocardial ischemia and infarction = ↓ CO
2) slow circulation = disseminated intravascular coagulation = slow circulation
3) ischemia and acidosis of brainstem = ↓ vasomotor tone, vasodilation = ↓ CO = ischemia and acidosis of brainstem