Vascular Flashcards
Name the 3 layers of the blood vessels
Tunica externa
Tunica media
Tunica intima
Tunica externa
outer connective tissue layer
Tunica media
smooth muscle
contractile
varying amount of elastic fibres in medium and large arteries
Tunica intima
Inner endothelial lining
What is the glycocalyx?
A negatively charged sugar barrier that coats the endothelium
What can damage the glycocalyx? (5)
Ischemia
Hyperglycaemia
Hypervolemia
Systemic inflammation
Hypertension
The glycocalyx protects the endothelium from… (2)
- Mechanical shear stress of blood flow
- Oxidative stress by scavenging free radicals
Endothelium
Smooth inner vessel wall lining
Function of large elastic arteries
substantial amounts of elastic fibres in the tunica media,
- allowing expansion and recoil during the normal cardiac cycle.
- Helps maintain a constant flow of blood during diastole
Examples of large elastic arteries
aorta and brachiocephalic trunk
Function of medium muscular arteries
tunica media contains mostly smooth muscle fibres
- can regulate their diameter and control the flow of blood to different parts of the body
Examples of medium muscular arteries
femoral, axillary and radial arteries
Function of small arteries and arterioles
- control the filling of the capillaries (control conduits) and
- directly contribute to the arterial pressure in the vascular system.
fenestrations (e.g. in capillaries)
minute pores
Are valves in arteries and veins?
No. Just veins
Which layer of the large veins is the thickest layer of smooth muscle?
Tunica externa
Examples of large veins
superior vena cava
inferior vena cava
portal vein
What is unique about the passage from gut to liver?
No artery
Portal vein carries deoxygenated blood
Blood high in nutrients
Examples of small and medium veins
superficial veins in upper and lower limbs
deeper veins of the leg and forearm
~ 84% of the entire blood volume of the body is in what system?
systemic circulation
~ 16% of blood volume is in what 2 organs?
heart and lungs
What important function of the circulatory system occurs in the capillaries?
diffusion of substances back and forth between the blood and tissues
Principles of circulatory system (3)
- Blood flows to tissues where it is needed
- Cardiac output is sum of all local tissue flows
- Arterial pressure regulation is generally independent of either local blood flow or cardiac output control
Which organ plays a major role in pressure control over long periods? How does it do this? (2)
Kidney
secreting pressure-controlling hormones
regulating blood volume
How does the circulatory system adjust for certain parts of the body requiring more blood flow than others for a certain task? (2)
Active tissue has increased blood flow compare to at rest
Microvessels dilate/constrict to control local blood flow
What system controls arterial BP?
Circulatory System
Explain the neural signalling steps in the circulatory system to raise pressure to normal (3)
- increases force of heart pumping
- causes contraction of large venous reservoirs to provide more blood to heart
- causes generalised constriction of arterioles so more blood accumulates in larger arteries to increase arterial pressure
What is a key difference between the blood travelling in the pulmonary and systemic circuit systems?
Pulmonary: Oxygenated blood in Veins, Deoxygenated blood in Arteries
Systemic: Oxygenated blood in Arteries, Deoxygenated blood in Veins
What happens in the capillaries in the lungs?
Gas exchange
Anterior
Front
Posterior
Back
Superior
Higher
Inferior
Lower
Median Line
imaginary line down centre of body
Proximal
Close to median line
Distal
Further from median line
What is the purpose of systemic veins?
Carry deoxygenated blood to Right Atrium via superior and inferior vena cava vessels
What is the purpose of systemic capillaries?
Exchange of gas & nutrients
Explain the pathway of the aorta as it leave the heart. (4)
- Aorta ascends towards the right from the left ventricle
- Curves posteriorly and to the left
- Continues downwards, posterior to the heart and anterior to the spinal cord
- Passes through the diaphragm (aortic hiatus) into the abdomen
Name the 3 branches that arise from the superior border of the arch of the aorta, and where they supply blood to.
Brachiocephalic artery: right arm and the right side of the head
Divides into right subclavian artery (extends under the clavicle to supply the right upper extremity) and right common carotid artery (supplies right side of neck, head and brain)
Left subclavian artery: left upper extremity
Left common carotid artery: left side of neck and head
List 5 paired arteries - right and left branches - of the abdominal aorta, and what they supply blood to
- Phrenic arteries: diaphragm
- Suprarenal arteries - adrenal glands
- Renal arteries - kidneys
4.Ovarian arteries / testicular arteries: sex glands - Lumber arteries (4 pairs) extend into the musculature of the abdominal wall
List 3 unpaired branches of the abdominal aorta that supply abdominal viscera, and what they supply blood to
- Coeliac trunk: subdivides into
- left gastric artery (stomach);
- splenic artery (spleen) and
- hepatic artery (liver) - Superior mesenteric artery: small intestine & proximal large bowel
- Inferior mesenteric artery: distal large intestine
What parts of the body does the thoracic aorta supply? (3)
- Chest wall
- Oesophagus
- Bronchi & Respiratory tree
Name the 4 parts of the aorta and its branches
- Ascending aorta
- Aortic arch
- Thoracic aorta
- Abdominal aorta
What is the longest section of the aorta?
Abdominal aorta
Explain the branches of the abdominal artery. (5)
- 2 common Iliac arteries: internal (urinary bladder, rectum, and reproductive organs)& external (lower extremities)
- Femoral artery (thight)
- Popliteal artery (knee)
4.Posterior & anterior tibial - Dorsalis pedis (foot)
The carotid artery branches into external and internal carotid arteries. Where do these arteries supply blood to?
Internal carotid: thyroid gland, neck, head
External carotid: eye, superior brain, head
Name where blood is supplied to and list the branches of the subclavian artery (2.1.4)
arm and hand
- subclavian artery > vertebral artery (posterior part of brain)
- subclavian artery
> axillary artery (armpit)
> brachial artery (arm)
> radial artery (thumbside of forearm and wrist)
> ulnar artery (medial side of hand)
Anastomoses
Connection between 2 blood vessels
Arterial anastomoses
Allows blood to be supplied to vital organs by more than one route
Examples of anastomoses (4)
- Circle of Willis: blood supplied by two internal carotid arteries and from the basilar artery (supplies the brain)
- Superficial palmar arch: in the hands and fingers, union of radial and ulnar arteries
- Mesenteric arches: union of vessels that supply the intestinal tract
- Arterial arches: union of tibial artery branches in the foot
Name the superficial veins of the proximal limbs (3)
- Cephalic veins
- Basilic veins
- Medial cubital veins
(arms)
Name the superficial veins of the lower limbs (1)
Saphenous veins
Give the purpose of the jugular veins
2 jugular veins on each side of the neck - drain the tissues supplied by carotid arteries, empty into the subclavian vein
Superior Vena Cava (2)
Union of left & right brachiocephalic veins: drain head, neck, and upper extremities
Unpaired azygos vein: drains chest wall
Inferior Vena Cava. Paired veins and unpaired veins pathways.
2 common iliac veins:
Paired veins:
- Iliac veins (near the groin),
- 4 pairs of lumber veins (from the dorsal trunk and spinal cord), testicular / ovarian veins,
- renal (kidneys)
- supernal veins (adrenal glands),
- hepatic veins (liver)
Unpaired veins: drain the spleen, parts of the intestine empty into the hepatic portal vein
Venous Sinus
group of sinuses or blood channels that drains deoxygenated venous blood circulating from the cranial cavity
Name sinuses that form part of the venous sinus (5)
- coronary sinus: drains blood from heart wall
- cavernous cranial sinus: drains blood from opthalmic veins
- petrosal sinuses: drains blood into jugular veins
- superior sagittal sinus: located in midline above the brain and in the fissure between the two cerebral hemispheres
- lateral/transverse sinuses: large spaces between the layers of the dura mater
Confluence of sinuses
- connecting point of the superior sagittal sinus, straight sinus, and occipital sinus
- drains venous blood from brain into transverse sinuses
What type of vein does not carry blood directly back to the heart?
Hepatic vein
Lymph is propelled by: (3)
- Activity of adjacent skeletal muscles
- Tissue pressure
- Contraction of the lymph vessels
lymphatic system
lymphatic vessels form extensive and complex inter-connected network of channels that merge to form 2 large systems that drain into the arteries
lymphatic vessels
collect fluid lost from vascular capillary beds during nutrient exchange processes and deliver it back to venous side of vascular system
lymph nodes
small encapsulated structures that interrupt course of lymphatic vessels and contain elements of body’s defence system - detect and defend against foreign antigens carried in lymph
List the 3 major functions of the CV system
Transport: respiration gases, nutrients, wastes
Regulation: hormone transport & thermoregulation
Protection: clotting and immune cell transport
blood components (2)
Formed elements: erythrocytes (red blood cells), leukocytes (white blood cells) and platelets
Plasma
Cardiac Output
Blood pumped out of heart in one minute
Results of peripheral vascular dysfunction (5)
Reduced Blood Flow
Delayed Wound Healing
Cold and Discolored Extremities
Increased Risk of Ulcers and Tissue Damage
Higher Risk of Amputation
Types of stroke (2)
Atherosclerotic
Hemorrhagic
Which layer of the blood vessels is composed of connective tissue?
tunica externa
Which layer of the blood vessels is composed primarily of smooth muscle cells?
tunica media
Name the 3 parts of the tunica interna
- An inner endothelium
- The basement membrane
- A layer of elastic fibers (elastin)
Vascular compliance
Vascular compliance (capacitance) refers to the total quantity of blood (volume) which can be stored in a given portion of the circulation for each mmHg pressure rise.
C = V ^ / P ^
Venous Return is aided by: (3)
Sympathetic innervation
Skeletal muscle pump
Negative intrathoracic pressure
Venous return
Amount of blood coming from venous system back to RA
Endothelial Cells
specialized cells that line the interior surface of blood vessels, creating a barrier between circulating blood and the vessel wall.
Important functions of endothelial cells (3)
regulate:
- blood flow,
- blood pressure, and
- blood clotting.
What is the benefit of signalling molecules (e.g. NO) produced by endothelial cells? (2)
control vasodilation and help keep blood vessels flexible
Capillary hydrostatic pressure
outward force which drives nutrients and drives oxygen to the tissues where they are needed
Osmotic pressure
due to proteins in the blood, mainly albumin
What happens to pressure in the capillaries when blood moves through?
Osmotic pressure > hydrostatic pressure
Capillary exchange involves: (2)
Net filtration & net absorption
Relationship between capillary hydrostatic pressure & osmotic pressure
Absorption in capillaries
osmotic pressure pulls water, waste products, and carbon dioxide back into the capillaries from the tissues
Filtration in capillaries
Filtration begins when blood enters the capillaries, and the higher blood pressure pushes water, oxygen, and small solutes out of the capillaries into the surrounding tissues through tiny gaps between endothelial cells
How is fluid homeostasis maintained in the capillaries
Balance between net filtration and net absorption ensures tissues receive nutrients and O2, while waste and excess fluid removed
Functions of capillaries (3)
- Exchange of gases and nutrients
- Regulation of blood flow
- Connection between arteries and veins
What forces are involved in the net filtration pressure? (4)
- capillary pressure
- interstitial pressure
- capillary plasma colloid osmotic pressure
- interstitial fluid colloid osmotic pressure
What type of blood vessel has the largest pressure?
Large arteries
What type of blood vessel has the smallest pressure?
Large veins, especially systemic
What type of blood vessel is referred to as a resistance vessel? How does this type of blood vessel control blood pressure?
Small arteries and arterioles
Constriction/dilation
What benefits do the elasticity of the large arteries provide? (2)
Absorb pressure waves (avoids damage to vessel walls)
Dampening pulsatile flow (elastic recoil during diastole pushes blood forward, smoothing out pulsatile flow)
is more blood pumped during diastole or systole? Why?
Diastole (>60%)
Propulsion of blood forward after vessel pumped up during systole
What is blood pressure?
force of blood pushing against the walls of your blood vessels
Vasospasm
Narrowing of the arteries caused by a persistent contraction of the blood vessels - reduction in blood flow
As blood volume increases, what happens to blood pressure?
Increases
Importance of blood pressure
delivering oxygen and nutrients to your body’s cells and organs
Explain the 2 numbers in blood pressure measurement
systole: 1st/top number, heart beats (contracts)
diastole: 2nd/bottom number, heart relaxes
Name 3 BP regulators
Baroreflex
Atrial stretch receptors
Renal control of BP
Explain baroreceptors
Mechanoreceptors: stretch receptors
Sensors responsible for maintaining BP within narrow limits
Arterial BP is affect by…? (3)
Blood volume
Total peripheral resistance (TPR)
Cardiac rate
Baroreflex to orthostatic hypotension (4)
- decreased venous return
- decreased EDV
- decreased SV
- decreased cardiac output
How do kidneys adjust fluid excretion based on BP?
BP high: increase urine output to lower volume
BP low: retains fluid
What 2 factors determine blood flow in a vessel?
Pressure difference
Vascular resistance
What is the flow in a vessel if the pressure at both ends of a vessel is 100 mm Hg and the vascular resistance is 15mmHg/L/min?
0 (no pressure difference)
What factors affect vascular resistance? (3)
vessel diameter
blood viscosity
vessel length
What is the relationship between conductance and resistance?
Inversely proportional
Vessel conductance
Blood flow through a vessel for a given pressure change
What property of blood affects the viscosity?
Number of red blood cells in blood
RBCs have mass, exert drag against adjacent cells
(e.g. milkshake vs coke example)
myogenic responses
smooth muscle in vessel walls contracts or relaxes in response to pressure changes
metabolic response
changes in local levels of oxygen, carbon dioxide, and other metabolites cause vessels to dilate or constrict
What is the purpose of autoregulation?
- Ensure that tissues receive a constant supply of oxygen and nutrients, especially during fluctuations in blood pressure or changes in metabolic demand
-Protects against hypotensive ischaemia
When is long-term control of blood flow important?
when the metabolic demands of a tissue change
What is the principle function of long-term control of blood flow?
manipulate vasculature (angiogenesis)
Mechanisms involved in resting vasomotor tone (4)
Baseline activity
Norepinephrine release
BP regualtion
Quick adjustments
When activated, the vasomotor centre…?
Increases sympathetic output, leading to the release of norepinephrine from postganglionic neuron
Vasomotor centre (2)
coordinates autonomic nervous system responses to maintain blood pressure and regulate blood flow by controlling the diameter of blood vessels
Difference between thrombosis and embolism
Thrombosis = attached
Embolism = dislodged
stenosis
narrowing
aneurysm
abnormal bulge or ballooning in the wall of a blood vessel
Endothelium Activators (7)
- Immune cytokines and/or bacterial products activate inflammatory response
- Viruses
- Haemodynamic stress
- Lipid products (atherosclerosis)
- Glycation end products (e.g. diabetes)
- Complement components
- Hypoxia
Congenital Variants in vascular anatomy (4)
Developmental / berry aneurysm
Arteriovenous fistulas
Fibromuscular dysplasia
Anomalous coronary artery origin
What do endothelial cells play an obligatory role in modulating ? (4)
- Vascular tone and permeability
- Angiogenesis
- Mediating haemostasis
- Mediating inflammatory & reparative responses to local injury
Endothelium dysfunction (2)
- Proinflammatory & prothrombogenic phenotype
- Intimal thickening – vascular SMC thickening
Causes of endothelial dysfunction
Haemodynamic disturbances
Hypercholesterolemia
Inflammation
Risks associated with hypotension
inadequate organ perfusion may lead to hypoxia & tissue death
Risks associated with hypertension
can cause end-organ damage, major risk factor for atherosclerosis
Normal BP range
90/60mmHg to 120/80mmHg
Normal BP for elderly (>80)
under 150/90mmHg
Normal BP for diabetics
140/80mmHg
Hardening of arteries - physical & mechanical (2)
arterial wall thickening
loss of elasticity
4 general patterns of artery hardening
- Arteriosclerosis
- Monkeberg medical sclerosis
- Fibromuscular intimal hyperplasia
- Atherosclerosis
Most common cause of PAD?
Peripheral atherosclerosis
plaque
regional thickening of vessel wall
most common location for PAD
femoral popliteal segment
Right Ankle-Brachial Index (ABI)
Highest pressure in right foot / Highest pressure in both arms
What does PAD < 0.3 indicate?
Ischameia
What does PAD >1.4 indicate?
calcification/vessel hardening
Borderline Blockage in peripheral arteries (ABI)
0.9-0.99
What happens to ABI post-exercise?
Drops
Raynaud Phenomenon
Intrinsic hyperreactivity of medial SMCs
Most commonly affects extremities
In response to cold / emotion
Pulmonary Embolism
Thrombi dislodge and embolise (move) to the lungs
