Organisation of the Body
Help!
|
|
||||
|---|---|---|---|---|---|
| Functions of vessels | Oxygen delivery
CO2 removal
Nutrient delivery
Waste removal
Delivery of hormones
Regulate blood flow
Specialised functions
🗑
|
||||
| Components of circulatory system | Heart
Arteries
Capillaries
Venins
Lymphatic system - collects lymph and delivers it back
🗑
|
||||
| Macrovasculature | Vessels > 0.1 mm in diameter
Arteries
Veins
🗑
|
||||
| Microvasculature | Vessels < 0.1 mm
Arterioles
Capillaries
Venules
🗑
|
||||
| Pulmonary circuit | Carries blood to and from the lungs
🗑
|
||||
| Systemic circuit | Distributes blood to and from all organs and tissues of the body
🗑
|
||||
| Portal system | Blood carried from one site to another without directly involving the heart
Hepatic portal system - gastrointestinal to liver
Hypothalamic pituitary portal system - hypothalamus to anterior pituitary
🗑
|
||||
| Arteries | Thick walled vessels
Transport blood away from the heart
Branch into smaller and smaller vessels - arterioles
Usually round in histological sections
🗑
|
||||
| Capillaries | Thin walled vessels
Form capillary beds where substances passed between blood and tissues
Usually collapsed
🗑
|
||||
| Veins | Drain capillary beds - venules
From larger and larger vessels returning blood to heart
Also have valves
🗑
|
||||
| Components of vessel walls | Endothelium
Muscular tissue
Elastic tissue
Connective tissue
🗑
|
||||
| Tunics | Layers of vessel walls
Tunica intime - endothelium
Tunica media - muscle or elastic
Tunica adventitia - connective tissue
🗑
|
||||
| Tunica intima | Innermost layer
Composed if a single layer of flattened squamous epithelial cells and basal lamina
Sub endothelial tissue
Internal elastic lamina
Acts as a principle barrier to plasma from exiting lumen
🗑
|
||||
| Tunica media | Composed mostly of smooth muscle cells orientated concentrically around the lumen
replaced by elastic in elastic arteries
External elastic lamina
🗑
|
||||
| Tunica adventitia | Outermost layer composed mainly of fibroelastic connective tissue arranged longitudinally with adipose tissue
🗑
|
||||
| Internal elastic lamina | A thin band of elastic fibres in tunica intima
Well developed in medium sized arteries
With fenestrations that allow substances to diffuse between lumen and deeper regions of arterial walls to nourish these cells
🗑
|
||||
| External elastic lamina | Another band of elastic fibres in outermost layer of tunica media
Not distinguishable in all arteries
🗑
|
||||
| Endothelium | Smooth surface - orientated along line of flow
Regulates clotting and vascular tone and flow
Secretes collagen, lamin, endothelin, NO and VWF
Also posses bound enzymes ACE and ACE2 to control BP
🗑
|
||||
| Von Willebrand disease | Genetic disease where VWF is not produced
Problems with blood clotting
VWF normally binds to factor VIII which gets degraded in absence
🗑
|
||||
| Angiotensin Converting Enzyme | ACE is a central component of the RAS system
Predominantly in lung but is fairly ubiquitous
Controls BP - converts angiotensin I to active vasoconstrictor Angiotensin II which increases BP
🗑
|
||||
| ACE2 | Lowers BP by catalysing hydrolysis of Angiotensin II into Angiotensin 1-7 a vasodilator
Counteracts ACE - disruption in balance leads to unregulated BP
🗑
|
||||
| ACE inhibitors and ARBs | Lowers arteriolar resistance and increase venous capacity
Lowers BP
Used widely for treatment of CVD
🗑
|
||||
| ACE2 in Covid | Binds to ACE 2 - promotes internalisation of viral receptor and virus downregulating ACE2 impacting BP
Knocking down ACE2 or introducing sACE2 could reduce entry of covid to cells
But would affect BP control
🗑
|
||||
| Protective role of tunica media | Concentric cell layers of smooth muscle, elastic fibres, Type III collagen and proteoglycans
Collagen provides restraint - absence leads to aneurysm and EDS type IV (mutation in COL3A1 gene)
Larger arteries have larger external lamina
🗑
|
||||
| Composition of tunica adventitia | Fibroblasts
Type I collagen
Elastic fibres
Small blood vessels
Adipose tissue
🗑
|
||||
| Vasa Vasorum | Blood supply of the walls of larger arteries - too large for diffusion
Small arteries enter vessel walls and branch
Serve cells located in tunic media and adventitia with blood
Prevalent in veins as venous blood contains less oxygen and nutrients
🗑
|
||||
| Classification of arteries | Elastic - conducting
Muscular - distributing
Arterioles
🗑
|
||||
| Elastic arteries | Walls of pulmonary arteries and aorta have to withstand most pressure and changes in pressure
Walls have a thick layer of elastic tissue for this - appear yellow
Further from the heart amount of elastin decreases and media becomes more muscular
🗑
|
||||
| Muscular arteries | Include most vessels arising from aorta
Muscle tone maintains pressure
Some have 3-4 layers of SM while some have up to 40
Tunica intima is thinner and internal elastic lamina more prominent
Allow selective distribution of blood
🗑
|
||||
| Atherosclerosis | A chronic disease with thickening, hardening, loss of elasticity and occlusion of arteries
Impaired circulation and ischemia leading to heart attack and stroke
Develops with age, hypertension, diabetes, smoking and high LDL
🗑
|
||||
| Atherosclerosis affects large vessels | Artery wall thickens as a result of accumulation of fatty materials
Promoted by LDL which carry cholesterol to tissues
Macrophages injects LDL cholesterol turning into foam cells and plaques develop
🗑
|
||||
| Cholesterol | Modified steroid in membranes
Precursor for steroids, bile acids and Vit D
Produced by liver - statins block this
Transported by lipoproteins - HDL and LDL
🗑
|
||||
| Role of LDL and HDL | LDL transports cholesterol to cells and tissues
HDL reduces, reuses and recycles LDL cholesterol by transporting it to the liver to be reprocessed
High HDL correlated with better health outcomes
Low HDL associated with atheromatous disease
🗑
|
||||
| Development of Atherosclerosis | Initiates with endothelial damage - endothelium adhesion molecules capture leukocytes
LDL invades and becomes oxidised
Macrophages take up LDL - accumulations of cholesterol engorged macrophages form foam cells - fibrous plaques develop and rupture
🗑
|
||||
| Result of plaques | Fatty material develops on walls
Thickens, hardens and blocks arteries
Platelet aggregation and clot formation
Predisposes to narrowing, clot formation and weakness
Calcification at the outer base
🗑
|
||||
| Coronary Heart Disease | Nutrients and oxygen for heart muscle not provided
Heart attack
Chest pain, angina, shortness of breath, sweating, left back and arm pain, dizziness
Most common risk factors are smoking, family history, hypertension, obesity, diabetes
🗑
|
||||
| Ischemic stroke | When a blood vessel supplying brain becomes blocked
Thrombosis - obstruction by locally forming clot
Embolism - obstruction by an embolus formed elsewhere e.g. pulmonary embolism where pulmonary artery is blocked
🗑
|
||||
| Haemorrhagic stroke | When a blood vessel bursts leaking blood into the brain
🗑
|
||||
| Results of ischemic stroke | Shortage of blood supply results in shortage of oxygen, glucose and other blood borne fules
Results in tissue
🗑
|
||||
| Treatment of Ischemic stroke | Timely diagnosis and treatment are critical as damage evolves rapidly over firsts few hours
First goal of acute ischaemic stroke treatment is to restore blood flow by dissolving the clot
Thrombolysis - TSA needs to be injected in first 4.5 hours
🗑
|
||||
| Thrombectomy | Putting thin tube into patients blood vessel in periphery and feeding it up to clot in brain
A wire mesh is wrapped around the clot and it is pulled out
Restores normal blood flow to brain if done in first 6 hours
Costs around £12000
🗑
|
||||
| Anuerysm | A sac like dilation in the wall of a vessel
Risk factors; atherosclerosis, hypertension, Marfan syndrome, EDS, Syphilis
Vessel wall is damaged and ruptures easily
Massive blood loss or death - Abdominal Aorta Anuerysm
🗑
|
||||
| Gangrene | Results when tissue becomes necrotic due to reduced blood supply
Caused by blood vessel disease precipitated by infection, diabetes, atherosclerosis, surgery
Reduced blood supply leads to cell death
Treatment - surgical debridement
🗑
|
||||
| General scheme if microvasculature | Discontinuous smooth muscle cells - surround arterioles and small veins
Pericytes support these vessels and can differentiate into fibroblasts, smooth muscle cells or macrophages
🗑
|
||||
| Pericytes | Multitasking cells with plasticity and a range of activities
Support blood vessels - promote vessel stabilization
Regulate vascular tone and tissue perfusion
Act as macrophages
Key in wound healing -loss leads to hyper dilated and haemorrhagic vessels
🗑
|
||||
| Angiogenesis | A normal and vital process in growth/development, wound healing and granulation tissue
Also a fundamental step in transition of tumours from dormant to maligant
A target for combatting tumour progression
🗑
|
||||
| Arterioles | Arteries with a diameter of <0.1mm
Width of wall equal to diameter of vessel
One or two layers of SM
Peripheral resistance vessel - controls arterial blood pressure
Controls distribution of blood to whole capillary beds
Controlled by SNS
🗑
|
||||
| Pre-capillary sphincters | A ring of muscle surrounding a blood vessel at the junction between an arterioles and a capillary
Controlled by factors which reflect tissue metabolism
Can open and close a capillary - facilitates shunting
🗑
|
||||
| Types of capillary | Continuous
Fenestrated
Sinusoidal
🗑
|
||||
| Capillaries | 50 um length and 8-10 um diameter
Squamous epithelium
Pericytes along outside involved in regulation of blood flow
After injury pericytes may differentiate into endothelial cells
No smooth muscle or vasomotor activites
🗑
|
||||
| Continuous capillaries | Muscle, nervous and connective tissue where there is no protein passage
Have junctional complexes - tight control of trans-endothelial transport
Barriers e.g. blood brain barrier
Prevent passage of molecules
Substances moved by active transport
🗑
|
||||
| Fenestrated capillaries | Pores 60-80 nm in diameter
Pancreas, intestine, kidney and endocrine glands where there is no need for protein passage
Basement membrane in kidney specialised for filtration
Pores bridged by diaphragms
Permeable to small ions and other molecules
🗑
|
||||
| Sinusoidal capillaries | Large fenestrae without diaphragms permit enhanced exchange between blood and tissue
Bone marrow, liver, spleen, lymphoid organs and endocrine glands
Immune system - allows leukocytes to pass between tissues
Irregular channels - conform to structure
🗑
|
||||
| Bypassing of capillaries | Channels in vascular system which allow capillary beds to be bypassed
Common in the skin for thermoregulation
Common in gut to allow perfusion of liver when gut circulation is shut down during fight or flight
🗑
|
||||
| Anastomosis | Arterio-arterial e.g. circle of willis in brain
Veno-venous e.g. portacaval
Arterio-venous e.g. finger tips
Serve as back up routes for blood but can be pathogenic e.g. fistula
Can be induced surgically to bypass diseased vessel
🗑
|
||||
| Veins | Classified based on size
Low pressure - less muscle
Same 3 layers as arteries but less developed muscle and elastic layers
Connective tissue more pronounced
Tunica intima/media boundary less clear
Valves in medium veins
🗑
|
||||
| Small veins and venules | Blood goes from capillary beds to postcapillary venules
Walls similar to capillaries with thin endothelium surrounded by reticular fibres and pericytes
Site of migration of neutrophils, macrophages especially in inflammation - diapedesis
🗑
|
||||
| Medium veins | Less than 1 cm in diameter
Smooth muscle cells of tunica media loosely organised with collagen fibres and fibroblasts
Tunic adventitia thickest - composed of longitudinally arranged collagen bundles and elastic fibres
🗑
|
||||
| Large veins | Low pressure high capacitance allows large amounts of blood to be stored - 60% of total
Have valves to prevent backflow
Thin tunica media
Well developed smooth muscle
Well developed tunica adventitia
🗑
|
||||
| Varicose veins | Valves in veins no longer work properly allowing blood to move backwards
Results from loss of muscle tone, degeneration of vessel wall and vascular incompetence
May also occur in lower oesophagus = oesophagus varices
Terminus of anal canal
🗑
|
||||
| Deep vein thrombosis | Blood clots in veins most often occur in legs
Caused by; damage to lining of vein, clotting conditions e.g. factor V mutation, immobility and post surgery
Blood clot can break off and travel to lungs - pulmonary embolism
Treated by anticoagulants
🗑
|
||||
| Vasculitis | Arteries and veins affected
Though to be autoimmune inflammation of vessels
Can be a main feature or an accompanying symptom
Many symptoms
Treatment with immunosuppressants
🗑
|
||||
| Blood vessel specialisations | Blood brain barrier
Blood air barrier
Kidney filtration barrier
🗑
|
||||
| Blood brain barrier | Composed of tight junctions, astrocytes, pericytes and microglia
Prevent paracellular and transcellular diffusion
Dyes injected into the blood accumulate in organs but not the brain
Astrocytes have end feet which form part of the barrier
🗑
|
||||
| Blood air barrier | Gases diffuse via passive diffusion
Cytoplasm of alveolar cells, endothelial cells and fused basal laminae of these cells form the barrier
🗑
|
||||
| Kidney filtration barrier | Thin endothelium of capillary with fenestration
Specialised basal lamina
Podocytes - urinary capsule lining cells
Thin endothelial cells for filtration
Regulates filtration
🗑
|
Review the information in the table. When you are ready to quiz yourself you can hide individual columns or the entire table. Then you can click on the empty cells to reveal the answer. Try to recall what will be displayed before clicking the empty cell.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Created by:
12345678987654321000000
Popular Medical sets