Anatomy CVS 2 Flashcards
Describe the structure of blood vessels in the terms of layers
Tunica externa, media and intima (from out to in)
What is the tunica intima made up from?
Epithelium, connective tissue and BM
What is the tunica externa made up from?
Fibrous connective tissue
WHat is the tunica media made up from?
Muscle and elastic tissue
Compare the diameter and thickness of the arteries with vein
include the media and adventita
Arteries smaller diameter than accompanying vein
Arteries thicker wall than accompanying vein
Arteries thick media thin adventitia
Veins thin media thick adventitia
Which vessel has the largest total cross sectional area?
Capillaries
Describe elastic arteries and give examples
Elastic – large conducting – eg: aorta, common carotid,
pulmonary
Describe the muscular arteries
Muscular – distributing arteries – eg: coronary arteries, radial, femoral
Describe the arterioles arteries
terminal branches which supply blood to capillary bed
Name the 3 different types of arteries?
Elastic, muscular and arterioles
Describe the histology of elastic arteries
Can see elastic fibres ( blue) that are wavy obscuring th emuscle in the T media
Doesnt have IEL and OEL
Describe the muscular arteries histology
Thick T media has smooth muscle cells
No elastic laminae between muscle cells in T. media
Has IEL and OEL
Where is the elastic lamina in muscular arteries?
Elastic fibres are concentrated in 2 well defined sheets called the internal elastic lamina (IEL) just under epithelium
Where do you see the external/outer elastic lamina in muscular arteries?
and the thin external/outer elastic lamina (OEL) between T.media & T. adventitia
Describe the histology behind arterioles
The smaller muscular arteries gradually change histologically to become arterioles
No IEL
Only 1-2 layers of smooth muscle in T. media
No T. adventitia
Has nerves around it to control the diameter
What can arterioles control and how?
Rich sympathetic nerve innervation
Control blood flow to capillary beds (local)
Control blood pressure (systemic)
Describe the shape and histology of capillaries
Capillaries tiny and consist of single squamous epithelial cells turned initself
Therefore very thin walled
T. intima only – endothelium on BM
No T. media
No T. adventitia
Can have Pericytes
What is Pericytes?
incomplete layer of cells surrounding basement membrane – have contractile properties which help control flow of blood in the capillaries.
Is BP high or low in capillaries?
Average diameter – 4-15µ
Sum of diameters of all capillaries in body > diameter of aorta. Therefore blood pressure in capillaries is LOW!
Describe the 3 types of capillary
Continuous - complete basal lamina
Fenestrated - compelte basal lamina and fenestrated endothelial lining
Discontinuous - fenestrated endothelial lining and incompelte basal lamina
Describe the structure of continuous capillary and where it can be found
Can control what is exchanged
Material must pass through cell, or between cell (junctions can control)
Selective transport mechanisms
Eg. in muscle
Describe the structure of fenestrated capillary and where it can be found
Have fenestrations (or pores)
Fenestrations up to 100μm
With or without protein diaphragms
Diaphragms filter molecules by MW &/or charge
Eg. endocrine glands, kidney renal corpuscle
Describe the structure of discontinous capillary and where it can be found
Gaps between endothelial cells (and basement membrane)
Allow free passage of fluid and cells
Eg. liver, spleen, bone marrow
What do the capillary bed and ateriovenous shunts allow? And give example
Bypasses capillary beds eg: skin for thermoregulation
Describe the structure of veins and its histology
Structure: T.intima is thin IEL and OEL thin or absent T.media v thin or absent T adventitia - collagenous tissue
Valves – to prevent back flow = endothelial projections into lumen
Whats the differene between superficial and deep veins
Differences most obvious in lower limb
Superficial
Thick walled
No surrounding support
Deep
Thin walled
Surrounding support from deep fascia and muscles
Describe the lympathic system and its function
Drains tissue fluid lost from blood capillaries
Where are the nodes found for the lymphatic system?
Nodes found alongside major veins and around origins of major arteries
Where specifically is the lympathic clinically important in?
Tumor cell metastases
Describe the histology and structure behind lymph capillaries?
Blind-ended capillaries
Lined by very thin endothelium
No fenestrations
Absent / rudimentary basal lamina
Lumen maintained at –ve hydrostatic pressure
Anchoring filaments – fine collagenous filaments link endothelial cell to surrounding tissue keeping lumen open
No red blood cells in lumen
Whats the main key difference between lymph capillaries vs venules?
Presence of blood cells
- should have NO blood cells
What is the nerve supply of skin?
ONLY sympathetic
What is the nerve supply of the heart?
Sympathetic + parasympathetic
