Exam 1: Blood Vessels Flashcards Preview

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Flashcards in Exam 1: Blood Vessels Deck (56)
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1
Q

Major Types of Blood Vessels

A
  1. arteries
    - — branch into smaller and smaller structures
    - — carry blood away from the heart
  2. veins
    - — merge into larger and larger vessels
    - — carry blood back to the heart
  3. capillaries
    - — smallest vessels
    - — directly serve the needs of the tissues
2
Q

Arterioles

A
  • vessels smaller than the arteries

- carry blood directly into the capillary beds

3
Q

Venules

A
  • vessels smaller than the veins

- carry blood directly away from the capillary beds

4
Q

Layers/Tunics of Blood Vessels

A
  • from interior to exterior
    1. Tunica Interna/Intima
    2. Tunica Media
    3. Tunica Externa
5
Q

Lumen

A
  • the blood containing space in the middle of a vessel
6
Q

Tunica Interna/Intima

A
  • simple squamous cell epithelium and associated connective tissue
  • this epithelium is continuous with the endocardium of the heart
7
Q

Tunica Media

A
  • mostly circularly arranged
  • smooth muscle cells and sheets of elastin
  • smooth muscle is innervated by sympathetic nerve fibers
  • — allows for vasoconstriction and vasodilation to maintain blood pressure
8
Q

Tunica Externa

A
  • aka tunica adventitia
  • made up of collagen fibers to protect the vessel
  • the very largest vessels have tiny blood vessels within the tunica externa
  • — vasa vasorum
9
Q

Arteries: the aorta and its major branches

A
  • the large arteries near the heart
  • — have the largest lumens
  • — have the most elastin
  • — allows these vessels to expand and withstand large differences in pressure
10
Q

Arteries: as you get farther and farther from the heart….

A
  • arteries divide into smaller and smaller branches
  • greater amounts of smooth muscle
  • less elastin
  • larger arterioles: all three tunics
  • smaller arterioles: a layer of smooth muscle around an epithelial lining
11
Q

Capillaries: Tunics and diameter

A
  • smallest blood vessels
  • only a tunica interna
  • — epithelium and basement membrane
  • RBCs pass through capillaries in single file
  • — diameter is only one cell thick
12
Q

Capillaries: Molecule Exchange

A
  • oxy, nutrients, and hormones are exchanged with the tissues
  • some epithelial cells are continuous
  • — tight junctions
  • some are leaky
  • — pores in the epithelium and an incomplete basement membrane
  • — allows large molecules and WBCs to pass through the walls
13
Q

Capillary Beds

A
  • interweaving network of capillaries
  • two types of vessels: metarteriole and true capillaries
  • capillary sphincter
14
Q

Metarteriole

A
  • found in capillary beds

- thoroughfare channel which connects the arteriole and the venule at opposite ends of the bed

15
Q

Capillary Sphincter

A
  • found in capillary beds
  • a cuff of smooth muscle fibers
  • surrounds the root of each true capillary and acts as a valve to regulate blood flow
  • when the sphincters are closed, the blood is shunted through the metarteriole
16
Q

Small Venules

A
  • closer to capillary bed
  • collect blood from capillaries
  • very porous, allowing fluid and WBC’s to pass through easily
  • consist mostly of epithelium
17
Q

Larger Venules

A
  • farther from the capillary beds

- a few layers of smooth muscle and a thin tunica externa

18
Q

Veins

A
  • venules join to form veins
  • the same three distinct tunics as the arteries
  • — but have thinner walls with less smooth muscle and elastin
  • larger lumens than arteries
  • tunica externa is the largest of the layers
19
Q

How much of the body’s blood supply is found in the veins at any one time?

A
  • 2/3
20
Q

Blood Pressure in the Veins

A
  • is low
  • because the effects of ventricular contraction are not present
  • to prevent backflow, veins have valves formed from folds in the tunica interna
  • — valves are most abundant in the extremities where the upward flow of blood is opposed by gravity
21
Q

Venous Sinuses

A
  • specialized, flattened veins with thin walls

- supported by surrounding tissue

22
Q

Varicose Veins

A
  • veins that are dilated due to stretched walls and incompetent valves
  • often occurs if there is a restriction hindering the return flow of blood to the heart
  • superficial veins receive little support from underlying tissues
  • — often in the legs
23
Q

Anastomoses

A
  • formed when veins or arteries unite
  • arterial anastomoses provide alternative routes for blood to reach an area
  • venous anastomoses are more common
24
Q

Blood Flow

A
  • the volume of blood flowing through a vessel in a specific time
  • measured in ml/min
  • in order for blood to flow, there must be a difference in pressure
  • Flow = change in pressure / resistance
25
Q

Blood Pressure

A
  • the force per unit area exerted by the blood on the vessel wall
  • measured in mmHg
  • systemic blood pressure is highest in the aorta and zero in the right atrium
26
Q

Resistance

A
  • the opposition to flow (friction)

- function of blood viscosity, vessel length, and vessel diameter

27
Q

Arterial Blood Pressure

A
  • a function of the elasticity of the arteries and the amount of blood being pumped through them at any one time
28
Q

Pulse pressure

A
  • the difference between the systolic and diastolic pressure
  • systolic pressure occurs bc of ventricular contraction
  • diastolic pressure occurs bc of ventricular relaxation
29
Q

Control of Blood Pressure

A
  • neural controls
  • hormones
  • kidneys
30
Q

Neural Controls of Blood Pressure

A
  • responds to the demands of various organs by altering blood distribution
  • maintains adequate pressure by altering blood vessel diameter
  • — regulated by sympathetic neurons in the medulla oblongata
  • — baroreceptors
  • — chemoreceptors
  • higher brain centers also effect blood pressure
  • — hypothalamus
31
Q

Baroreceptors

A
  • pressure sensor
  • neural receptors located in the aortic arch and carotid sinuses
  • — sinuses: dilations in the internal carotid arteries
  • vessel is stretched (ex: by high blood pressure) –> baroreceptors initiate a reflex arc to the medulla –> vasodilation –> decrease in blood pressure
32
Q

Chemoreceptors

A

detect sharp drops in O2 and increases in CO2 –> vasoconstriction –> increase in blood pressure –> speeds the return of blood to the heart and lungs (which can balance the O2/CO2 ratios)

33
Q

Hormonal control of blood pressure

A
  • adrenal hormones, ADH, NO
  • inflammatory chemicals
  • — histamine= vasodialator
  • regulate blood volume
  • vasoconstriction
34
Q

Kidneys help control blood pressure

A
  • Rises in blood pressure also induce the kidneys to remove fluid from circulation
  • blood pressure declines, the kidneys release renin resulting in an increase in angiotensin II, a potent vasoconstrictor.
35
Q

Hypertension

A
  • high blood pressure
  • major cause of heart failure, vascular disease, renal failure, and stroke
  • the heart must work harder to counteract hypertension –> weakening of the heart
  • primary or secondary hypertension
36
Q

Primary Hypertension

A
  • no known cause
  • about 90% of cases
  • diet, obesity, age, race, heredity, stress, and smoking may all play a part
37
Q

Secondary Hypertension

A
  • due to an identifiable disorder

- ex: kidney disease or a hormonal disorder

38
Q

Tissue Perfusion

A
  • blood flow through the body tissues
39
Q

Circulatory Shock

A
  • inadequate perfusion of the tissues
  • hypovolemic shock
  • – most common type
  • – loss of blood volume
  • vascular shock: a significant drop in blood pressure due to extreme vasodilation
  • cardiogenic shock: pumping of the heart fail to provide enough circulation to the tissues
40
Q

Aorta

A
  1. ascending: leaves the left ventricle and goes up
  2. aortic arch: bends sharply to the left
    - — three branches
  3. descending: runs inferiorly through the thoracic cavity
  4. abdominal aorta: the descending after it passes through the diaphragm
41
Q

Branches of the Aortic Arch

A
  1. Brachiocephalic
    - – branches into the right common carotid and the right subclavian arteries
  2. Left Common Carotid
  3. Left Subclavian
    - – from it, branches the right and left vertebral arteries which pass through the transverse foramina of the cervical vertebrae and supply part of the brain
42
Q

Branches of the Right/Left Common Carotid

A
  • each has two branches:
    1. internal carotids: which supply the brain and orbits
    2. external carotids: supply the head and neck
43
Q

Right and Left Axillary Arteries

A
  • pass through the axillae
  • right/left subclavian –> right/light axillary –> right/left brachial artery
  • -> right/left radial and ulnar arteries
44
Q

Abdominal Aorta Splits into…

A

abdominal aorta –> right/left common iliac –> right/left external iliacs which pass through the pelvis –> right/left femoral arteries –> right/left popliteal arteries which pass through the intercondylar notch of the femur –> anterior and posterior tibial arteries

  • posterior tibial passes posteriorly to the medial maleolus
  • anterior tibial –> dorsalis pedis artery in the dorsal foot
45
Q

Celiac Trunk

A
  • large, ventral, unpaired branch of the aorta
  • shortly after the aorta passes through the diaphragm
  • celiac –> left gastric, common hepatic, splenic arteries
46
Q

Superior and Inferior Mesenteric Arteries

A
  • two unpaired arteries that branch off the abdominal aorta
  • supply the small and large intestines
  • between them are the paired renal arteries and the paired testicular/ovarian arteries
47
Q

Deoxygenated blood leaves the right ventricle–>……..lungs

A

pulmonary trunk –> right and left pulmonary arteries –> right: three lobar arteries, left: two lobar arteries

48
Q

Pulse

A
  • when the left ventricle contracts, a pressure wave is sent along the elastic arteries through the arterial tree
  • can be felt by compressing an artery near the surface against deeper firmer tissue
  • heart rate = pulses per minute
  • can be taken at: radial, carotid, brachial, temporal, ulnar, femoral, popliteal, posterior tibal, dorsalis pedis
49
Q

Veins of the Forearm

A

radial + ulnar –> brachial

50
Q

Veins of the Upper Arm

A
  • brachial + basilic –> axillary
  • cephalic (lower and upper arm) + axillary –> subclavian
  • medial cubital vein: an anastomosis of the cubital region
  • — joins the cephalic and the basilic
51
Q

The subclavians are joined by….

A
  • subclavians + external jugulars (join first) + internal jugulars (join 2nd) –> brachiocephalic veins
  • right brachiocephalic + left brachiocephalic –> superior vena cava which enters the right atrium
52
Q

Veins of the Leg

A
  • anterior tibial vein + posterior tibial vein –> popliteal vein which crosses the back of the knee –> femoral vein
  • great saphenous vein: drains the foot and medially runs the length of the leg
  • — great saphenous + femoral –> external iliac
  • external iliac + internal iliac –> common iliac
  • right common iliac + left common iliac –> inferior vena cava
53
Q

Superior Mesenteric Vein

A
  • drains the entire small intestine
  • — rich with nutrients
  • superior menenteric + inferior mesenteric + splenic –> hepatic portal vein
54
Q

Hepatic portal Vein

A
  • enters the liver and branches again and again, eventually into small capillaries
  • after filtering through the liver, vessels merge into larger vessels –> right and left hepatic veins –> inferior vena cava
55
Q

Right and Left Renal Veins

A
  • drain the kidneys
56
Q

Right and Left Gonadal Vein

A
  • testicular or ovarian
  • right: enters the inferior vena cava directly
  • left: enters the left renal vein