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Anatomy > (LESSON 16) Blood Vessels > Flashcards

(LESSON 16) Blood Vessels Flashcards

1
Q

Structure of Arteries, Veins, and Capillaries

Image

A
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2
Q

Lumen

A

the central blood-filled space of the blood vessel

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3
Q

Tunica Intima

A

innermost tunic of a vessel wall in intimate contact with the blood in the lumen.

  • Internal layer of simple squamos epithelium
    • Forms a smooth surface that minimizes friction of blood flow
  • Subendothelial layer lies just external to endothelium
    • In vessels larger than 1mm in diameter
    • Loose connective tissue
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4
Q

Tunica Media

A
  • Middle tunic
  • consists primarily of circular smooth muscles fibers with circular sheets of elastin and collagen fibrils between
  • Thicker in arteries than veins
  • Maintains blood pressue
  • Vasoconstriction**​
    • ​Contraction of the smooth muscle cells with decreases the diameter of the vessel
  • Vasodilation
    • ​Relaxation of the muscle cells that increases vessel diameter
  • Both activities are regulated by vasometer nerve fibers.
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5
Q

Tunica Externa

A
  • The outermost layer of the vessel wall
  • a layer of connective tissue that contains many collagen and elastic fibers
  • fibers run longitudinally
  • protects the vessel, strengthens wall, anchors vessel to surrounding structures
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6
Q

Arteries

A
  • Vessels that carry blood away from the heart.
  • In systemic circuit blood is oxygen-rich
  • in pulmonary circuit blood is oxygen-poor
  • Blood proceeds from elastic arteries to muscular arteries, to arterioles
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7
Q

Elastic arteries

A
  • the largest arteries near the heart. ie aorta and major branches
  • from 2.5 cm to 1 cm in diameter
  • AKA conducting arteries
  • High elastin content dampens the surges of blood pressure
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8
Q

Muscular Arteries

A
  • AKA distributing arteries
  • Distal to elastic arteries
  • supply groups of organs, individual organs, and parts of organs
  • Constitute most of the named arteries
  • 1cm-0.3mm in diameter
  • thicker tunica media can regulate the amount of blood going to certain organs, according to needs
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9
Q

Arterioles

A
  • Smallest arteries
  • 0.3mm-10wm? in diameter
  • contain only 1-2 layers of smooth muscle cells
  • Nervous system and local factors determine diameter
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10
Q

Capillaries

A
  • The smallest bust most important blood vessels
    • 8-10wm in diameter
    • Renew surrounding tissue fluid of all body cells with oxygen and nutirents
    • remove CO2 and Nitrogenous waste
  • Just large enough to allow erythrocytes to pass through in single file
  • composed of one layer of endothelial cells surrounded by a basement membrane (tunica intima)
  • Some capillaries perform site-specific functions
    • Lungs: oxygen enters blood through capillaries
    • Small intestine: receive digestive nutrients
    • endocrine glands: pick up hormones
    • Kidneys: remove nitrogenous waste
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11
Q

Capillary Bed

A
  • A network of the body’s smallest vessels
  • run through almost all tissue, especially loose connective tissue
  • When precapillary sphincters relax, blood fills the true capillaries
  • when sphinctes contract, they force most blood to flow straight from metarterioles to thoroughfare channels, bypassing the true capillaries
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12
Q

Metarteriole

A

A vessel that is structurally intermediate between an arteriole and a capillary-from which branch true capillaries.

Terminal arteriole-metarteriole-thoroughfare channel-postcapillary venule

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13
Q

Thoroughfare channel

A

A vessel structurally intermediate between a capillary and a venule. True capillaries merge into this, which then join the venule

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14
Q

Precapillary sphincters

A
  • Smooth muscle that wraps around the root of each true capillary where it leaves the metarteriole.
  • regulates bood flow to surrounding tissue according to needs for oxygen and nutrients.
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15
Q

Structure of Capillries Cut in Cross section

image

A

A. Continuous Capillary

B. Fenestrated Capillary

C. Sinusoidal Capillary

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16
Q

Intercellular Clefts

A
  • Gaps of unjoined membrane
  • small molecules exit and enter cavity here
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17
Q

Pericyte

A
  • spider shaped cells that strengthen and stabilize capillary
  • Thin processes form a network that is widely spaced to not interfere with spillary permeability
  • External to endothelial cells
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18
Q

Continous VS Fenestrated Capillaries

A

Fenestrated: Have pores (fenestrations) spanning the endothelial cells. Occur only in areas of exceptionally high rates of exchange between blood and surrounding tissue fluid.

  • small intestine, kidneys, synovial membrane of joints.

Continuous: No pores. More common, occuring in most organs of the body

  • Skeletal muscle, skin, and central nervous system
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19
Q

Routes of capillary permeability

A
  1. Direct diffusion through endothelial cell membrane
    • C02/Oxygen
  2. intercellular clefts
    • most exchange of small molecues
  3. pinocytotic vesicles that invaginate from plasma membrane and migrate across the endothelial cell.
    • transport dissolved gases, nutrients, and waste
  4. Fenestrations in fenestrated capillaries
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20
Q

Low Permeability: Blood-Brain Barrier

A
  • Complete tight junctions
  • no fenestrations or intercellular clefts
  • vital molecules for the brain are ushered through endothelial cells.
  • CO2, Oxygen, and some anesthetics may also diffuse unhindered
  • Prolonged emotional stress can cause tight junctions in brain to open, allowing toxic substances through
    • Gulf War Syndrome
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21
Q

Sinusoids

or

Sinusoidal Capillaries

A
  • Wide, leaky capillaries
  • Twisted course and large diameter ensure that blood slows to allow time for many exchanges to occur
  • Occur with extensive exchange of large materials
    • proteins
    • cells
  • Occur in
    • Bone Marrow
    • spleen
  • Usually fenestrated
  • fewer cell junctions
  • in some, intercellular clefts are wide open
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22
Q

Veins

A
  • The blood vessels that conduct blood from capillaries toward the heart.
  • Systemic circuit: carry oxygen-poor blood
  • Pulmonary circuit: carry oxygen rich blood returning from lungs
  • Blood pressure much lower than in arteries
    • blood pressure declines substantially passing through arterioles/cap. beds
    • Walls of veins are much thinner
  • At any time veins hold 65% of body’s blood
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23
Q

Venules

A
  • The smallest veins
  • 8-100wm in diameter
  • Join to form veins
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24
Q

Postcapillary venules

A
  • The smallest venules
  • consist of endothelium on which lie pericytes
  • Function like capillaries
    • during inflammatory responses more fluid and leukocytes leave the circulation through these than through capillaries

*

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25
Q

Valves

A
  • Prevent backflow of blood away from the heart
  • Counteracts low venous blood pressure
  • Each has several cusps formed by tunica intima
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26
Q

Mechanisms that counteract low venous blood pressure

A
  • Valves
  • normal movement of the body ensures blood moves only in the proper direction
  • skeletal muscular pump
    • contracting muscles press against thin-walled veins, propelling blood toward the heart (image)
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27
Q

Varicose Veins

A
  • Valves in vein weaken and fail
  • Vein twists and swells with pooled blood
  • Factors:
    • Hereditary
    • Obesity
    • Pregnancy
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28
Q

Hemorrhoids

A

varicosities of the anal canal

29
Q

Vascular Anastomoses

A
  • The interconnected or united vessels
  • provide alternate pathways (collateral channels) for blood to reach certain regions
  • occur around joints
  • more often in veins than arteries
30
Q

Vasa Vasorum

A
  • Little vessels that nourish living cells in blood vessels
31
Q

Atherosclerosis

A
  • Aorta and coronary arteries are the vessels most affected by this degenerative disease, but all arteries are susceptible
  • The following typifies the sequence of events leading to atherosclerosis
    • damage to intima (can be caused by chemicals, virus, stress, etc.)
    • injured tissue releases growth factors
    • sequesters and oxidizes LDLs
    • attracts monocytes to the area
    • monocytes migrate beneath intima
    • monocytes become macrophages which become foam cells
    • other molecules congregate creating plaques
32
Q

Lymphatic System

A
  • Main Function is to return excess tissue fluid back to the vascular system
  • Protexts our bodies from foreign organisms by fighting infection and conferring immunity to disease.
  • Components
    • lymphocytes
    • lymphoid tissue
    • lymphoid organs
      • spleen
      • lymph nodes
      • thymus
33
Q

Lymphatic Vessels

A
  • Collect excess tissue fluid from the loose connective tissue around blood capillaries
  • Return it to blood stream
  • Also returns leaked blood proteins back into the blood stream
34
Q

Lymph

A
  • Clear Water
  • the fluid inside of lymphatic vessels
  • Only flows towards the heart
35
Q

Edema

A
  • When a body region swells with excess tissue fluid due to blockage of lymphatic vessels
  • Can go away with exercise to area.
  • bouncing and wiggling while sitting actually performs important function of moving lymph up legs.
36
Q

Lymphatic Capillaries

A
  • Highly permeable vessels that collect the excess tissue fluid
  • located near blood capillaries in loose connective tissue
  • Single layer of endothelial cells
37
Q

Lymphatic Collecting Vessels

A
  • where lymph goes after lymphatic capillaries
  • accompany blood vessels
  • Narrow and delicate. Not seen in dissecting.
  • Same tunics as blood vessels (intima, media, externa) but much thinner
  • Superficial lymphatic collecting vessels in skin travel with superficial veins
  • Deep lymphatic collecting vessels of trunk and digestive viscera travel with deep arteries.
38
Q

Lacteals

A

A unique set of lymphatic capillaries.

  • Located in vili of small intestine
  • Absorb digestive fats from intestine
  • chyle: Lymph that becomes milky white from fats and is carried to blood stream
39
Q

Areas absent of Lymphatic Capillaries

A
  • bone
  • teeth
  • bone marrow
  • entire CNS
    • excess tissue fluid here drains through the nervous system into the cerebrospinal fluid.
    • cerebrospinal fluid returns tissue fluid to blood at superior sagittal sinus
40
Q

Lymphangiography

A
  • Radiographic Process
  • Lymph Valves bulge at the base creating a distinctive appearance
  • vessels are injected with radiopaque dye
  • the distinctive appearance allows phyisicians to recognize vessels on X-Ray film
41
Q

Lymphatic Valves

A
  • Vessels are not connected to heart so fluid flows under low pressure
  • For this reason Lymphatic collecting vessels contain more valves than do veins
  • Valves direct flow of lymph
42
Q

Mechanisms that aid the flow of lymph

A
  • Contracting skeletal muscles
  • pulsations of nearby arteries
  • muscular tunica media contracts
  • normal movement of limbs and trunk

*Despite these mechanisms, propulsion is sporadic and slow. This explains while people who stand on their feet at work a long time can develop severe edema around ankles by the end of the workday.

43
Q

Lymph Nodes

A
  • Bean shaped organs situated along lymphatic collecting vessels
  • cleanse the lymph of pathogens
  • These are not glands
  • 500 in the body
  • 1 to 25mm in diameter
  • Large clusters of nodes in these areas:
    • cervical
    • axillary
    • inguinal
44
Q

Cervial Nodes

A

Superficial, along jugular veins and carotid arteries, and receive lymph from head and neck

45
Q

Axillary Nodes

A

in the armpit

46
Q

Inguinal Nodes

A

In the superior thigh, filter from upper and lower limbs respectively.

47
Q

Tracheobronchial Nodes and other nodes in the mediastinum

A

Recieve lymph from the thoracic viscera

48
Q

Aortic Nodes

A

deep nodes along the abdominal aorta. filter lymph from posterior abdominal wall

49
Q

iliac nodes

A

Deep nodes along the iliac arteries. filter lymph from pelvic organs and the lower limbs.

50
Q

Structure of a lymph node

image

A
51
Q

Capsule

A

dense connective tissue that surrounds node

52
Q

trabeculae

A

fibrous strands that extend inward from the capsule to divide the node into compartments

53
Q

afferent lymphatic vessels

A

convex aspect of the node through which lymph enters the node

54
Q

hilium

A

indented region through which lymph exits node and passes through efferent lymphatic vessels.

55
Q

lymph sinuses

A

large sinuses within the node between the afferent and efferent vessels.

  • Subscapular
  • cortical
  • medullary
56
Q

Reticular tissue in human lymph node

image

A
57
Q

Lymph Trunks

A
  • after leaving nodes, the largest lymphatic collecting vessels converge
  • Drain large areas of the body
  • large enough to be found by a skilled dissector
58
Q

Five Major Lymph Trunks

A

From inferior to superior

  1. Lumbar Trunks
  2. Intestinal Trunk
  3. Bronchiomediastinal Trunks
  4. Subclavian Trunks
  5. Jugular Trunks
59
Q

Lymph Ducts

A
  • Trunks drain into ducts
  • Largest lymphatic vessels
  • Some individuals have two, others just have one
60
Q

Thoracic Duct

A
  • Present in all individuals
  • Most inferior part (cisterna chyli) at union of lumbar and intestinal trunks
  • empty at junction of subclavian and internal jugular veins
  • Drains 3/4 of the body:
    • head
    • neck
    • thorax
    • left upper limb
    • entire lower half of body
61
Q

Right lymphatic duct

A
  • 20% of people have it
  • when present this empties into the neck
  • drained by right jugular, subclavian, and bronchimediastinal trunks
  • More common these trunks open independently into the neck veins
62
Q

Lymph Organs

A
  1. Thymus
  2. Lymph Nodes
  3. Spleen
  4. Tonsils
63
Q

Thymus

A
  • Infants and children require greater activity of this gland than adults.
  • hormone production
  • activation of T-lymphocytes
  • thymic lobules
  • cortex and medulla
  • atrophies with age
64
Q

Spleen

A
  • largest lymphoid organ
  • immune response, blood cleaner, erythrocyte producer (fetus), and erythrocyte graveyard
    • red pulp (RBCs):
    • white pulp (WBCs)
65
Q

Valves are only found in

A

veins

66
Q

Tonsils

A

exterior surface is covered by squamous epithelium

67
Q

Elephantiasis

A
  • Wuchereria bancrofti is the parasitic culprit.
  • Edema is the consequence.
  • Inguinal lymph nodes are sites of blockage.
  • treated with antibiotics
68
Q

Crypts

A
  • Trap bacteria in tonsils
  • Trapped bacteria works its way through epithelium to underying lymphoid tissue
  • Lymphocytes are activated
  • Leads to infection to tonsils during early childhood
  • Also generates great variety of memory lymphocytes for long-term immunity.
69
Q
A

Anatomy (25 decks)

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