Blood Vessels Flashcards
What are the layers of a blood vessel
What does the lumen of blood vessels contain
Blood
What does the tunica intima of blood vessels contain
Endothelial/Epithelial cells + basement membrane
Supporting connective tissue
Internal elastic lamina
(remember that this is the basic structure of like everything - epithelia, basement membrane, connective tissue)
Epithelial cells of blood vessels
Simple squamous (like capillary; diffusion doesn’t really occur though so there are just more cells outside it)
What does the tunica media contain
Smooth muscle (and elastin)
External elastic lamina
What is the role of the tunica media
Like a thick wall around the vessel that stops the pressure and beating from being dissipated throughout the circulatory system
Tunica Adventitia/Externa
Just a thick wall of supporting connective tissue around blood vessels
Where do cells of the blood vessel get their oxygenation and nutrients from
Blood diffusing from the lumen, or from vasa vasorum in thick blood vessels
Vasa vasorum
Blood vessels that supply blood to the outer cells in thick blood vessels
Vasculature of the vasculature
Think coronary arteris
Structure and function differences between veins and arteries
Arteries have a larger tunica media to allow them to channel that pressurised pumping mechanism
Diameter of arterial lumen is smaller than that of the vein
Veins have generally thin walls and thick lumen**
Elastic Arteries
Arteries near the heart that contain much more elastic tissue in the tunica media than muscular arteries, allowing them to maintain a mostly constant pressure despite the continuous beating of the heart
Layers of the heart vessels
Endocardium (tunica intima); simple squamous epithelium, basement membrane, loose connective tissue
Myocardium (tunica media); cardiac muscle, suppolied by coronary vessels (vasa vasorum)
Epicardium (tunica adventitia/externa); Connective tissue bordered by simple squamous epithelium which forms the visceral pericardium
Main difference in myocardium and tunica media
Myocardium is made of cardiac muscle while the tunica media is made of smooth muscle
When are venous valves needed
Valves are generally not needed in the head and neck as the blood returns through gravity
It is generally needed in the limbs though to fight gravity
How do valves and the muscle pump of veins work
How does blood in vessels flow in the middle versus the edges and how does the surface of the endothelium facilitate this
It moves faster in the middle than it does on the edges - laminar flow
Non-stick surface of endothelium facilitates this
Where can turbulent blood flow occur and what is its effects
Where blood vessels turn at a sharp angle and blood pressure is raised
It eventually damages the endothelium, exposing blood to collagen in connective tissue and other factors that clot blood
Thrombus vs embolism
A thrombus is a blood clot that stays there while an embolism is a clot that travels
Myocardial infarction
Heart muscle doesn’t get enough oxygen; heart attack
Usually caused by ischaemia of coronary arteries
What are symptoms caused by hypertension
Damage to small and large blood vessels
- Atherosclerosis
- Arteriosclerosis
- Aortic dissection
- Abdominal aortic aneurysm
Damage to kidneys, CNS, heart, eyes
RCTs show BP reduction works to reduce stroke, MI, heart failure
10/5mmHg reduction in BP causes
- 40% less stroke
- 15% less CHD
- 21% less CV deaths
- 13% less Total mortality
Atheroma and layers affected
Type of atheroclerosis - Thickening of walls in large and medium sized arteries
Occurs in high pressure systems (arterial not venous)
Initially disease of tunica intima, later affects media
Describe the ubiquity of atheroma
Atheroma is ubiquitous, very mild in young people though and worsens with age
Risk Factors for Atheroma
A - Arterial Hypertension T - Tobacco H - Hereditary E - Endocrine (Diabetes, Hypothyroidism) R - Reduced Physical Activity O - Obesity M - Male sex A - Age
Common sites of atheroma
Aorta, Coronary , Carotid, Cerebral, Renal, Iliac, Femoral and Popliteal Arteries, Major Intestinal Arteries
Recognisable stages of Atheroma development (naked eye)
- Fatty streak (Barely visible)
- Lipid plaque (smooth, yellow, raised)
- Fibrolipid plaque (hard, white)
- Complicated Atheroma
Fats/Lipids, Fibre, ATHEROMA (BITCH)
idk this mneumonic works for me, don’t ask me to try explain it
How do lipids enter the tunica intima in the case of an atheroma
Through a damaged endothelium
What happens to form a fatty streak during atheroma development
High amounts of LDL cholesterol damages the endothelium and manages to slip into the cells and make a raised fatty streak
Macrophages try to phagocytose them but cannot break them down; thus they release cytokines causing inflammation and recruiting fibriblasts to build something around it (with collagen)
How does a lipid plaque form during atheroma development
More and more macrophages trying to deal with more and more LDL-C; builds up and forms a bump
Fibroblasts lay down some collagen and harden the plaque; the LDL and plaque also begins to dig into the tunica media
How does the fibrolipid plaque form during atheroma development
Collagen is laid down around it making a harder and bigger bulge/plaque which projects into the lumen and tunica media
Due to the T media projection, vessel loses elasticity as elastin and muscle is lost to collagen
Complications of atheroma
- It can be so big that such little lumen is left and ischaemia occurs
- Wall is so weakened so a rupture is caused
- Thrombus is formed on top, further contributing to narrowing which can cause an embolism elsewhere
3 Risk factors of thrombus formation
Stasis of blood flow
Endothelial Injury
Hypercoagulbility
What are arterioles and venules
Smallest vessels in arterial/venous systems
Role of arterioles during High BP
They constrict a bit and help reduce the impact of the high BP on cells
Pathology of arterioles
If they have to continuously contract during hypertension, their muscles will thicken (hypertrophy)
Causes arteriolosclerosis
These become overtaken with collagen as this strengthens the walls, but they can then no longer effectively control blood flow through altering diameter
(Affects total peripheral resistence)
Deep vein thrombosis
Pathology of veins
Starts with the stasis of blood at valves (especially lower limbs)
The clot begins to expand upwards then breaks off and travels around the system - gets stuck in lungs’ small capillaries causing pulmonary embolism
How to detect DVT (deep vein thrombosis)
Ultrasound the veins and D-Dimer blood test (D-Dimer is a product of fibrin breakdown)
