Blood Vessels & Lymphics Flashcards
Name the vessels that transport deoxygenated blood
Pulmonary Artery
Vena Cava
Hepatic Vein
What are the different types of blood vessel ?
Elastic Arteries
Muscular Arteries
Arterioles
Capillaries
Venules
Medium veins
Large veins
Tunica intima structure
Endothelium
Internal elastic layer (in larger arteries)
Describe the endothelium of the tunica intima
Lined with simple squamous epithelium (endothelium)
Deep to the endothelium is the basement membrane
Tunica media structure
Concentric layers of smooth muscle & elastic fibres
External elastic membrane
Contains sympathetic vasomotor nerve fibres
Tunica externa structure
Collagen fibres - Primarily type 1
Vasa vasorum
What are the layers that form arteries and veins?
(Endothelium)
Tunica interna
Tunica media
Tunica externa
Capillary structure
Basement membrane
Endothelial Cells
Tunica intima function
Creates the lumen
Tunica media function
Involved in vasoconstriction/dilation and controls blood pressure/flow.
Tunica externa function
Contains nerves and vasa vasorum
What is the tunica intima lined with ?
Simple squamous epithelium called the endothelium.
How does the tunica intima in arteries vary from that of veins ?
In arteries, the tunica intima contains an internal elastic membrane at the boundary which provides additional support.
How does the structure of arteries and veins differ ?
Arteries have a thicker tunica media and their tunica intima contains an internal elastic membrane.
What does vasoconstriction do to the lumen size ?
Decreases lumen size
What does vasodilation do to the lumen size ?
Relaxation, so lumen size widens
What is the thickest tunica in veins ?
Tunica externa
What is the thickest tunica in arteries ?
Tunica media
What is vasa vasorum ?
A network of small blood vessels in the largest vessels.
Where are the vasa vasorum found ?
Brach profusely in the externa and outer part of media.
What is the function of the vasa vasorum ?
Nourishes the outer layers and responds to nutrient need.
Where are elastic arteries found ?
Near the heart. They are large thick walled arteries.
What is a feature of elastic arteries ?
Large lumen, low resistance.
Expand during systole and recoil during diastole.
Name some arteries
Internal carotid a.
External carotid a.
Common carotid a.
Right Subclavian a.
Brachiocephalic trunk
Structure of muscular arteries
Have more smooth muscle and less elastic tissue than elastic arteries, in the tunica media.
What is the function of muscular arteries ?
More active in vasoconstriction :
Regulates blood flow
Controls distribution of blood to tissues
Ischaemic meaning
Inadequate blood supply (circulation) to a local area due to blockage of the blood vessels supplying the area.
Name the 5 upper limb arteries, starting from top to bottom.
Subclavian a.
Axillary a.
Brachial a.
Radial a.
Ulnar a.
What arches are derived from the radial and ulnar arteries ?
Deep & Superficial palmar arches
What is the function of arterial anastomosis ?
Ensures blood supply to the hand and fingers in any position of the upper limb.
Do joints have anastomoses around them ?
Yes ! All joints have anastomoses around them.
What is positioned around the femoral artery ?
The femoral vein lies medially, and the femoral nerve lies laterally, with the ferry artery in the middle.
Name the 7 lower limb arteries, from top to bottom.
Aorta
Common, internal, external iliac
Common, deep, superficial femoral
Popliteal
Anterior, posterior tibial
Tibio-peroneal trunk
Peroneal (fibular)
What is the structure of smaller arterioles ?
Tunica media (smooth muscle cells)
Basal lamina
Endothelium
What is the structure of larger arterioles ?
They have the 3 tunics
What happens when arterioles constrict ?
There is an increase in resistance.
The controls the blood flow into capillary beds and blood pressure within tissues.
Metarteriole
Capillary bed end of arteriole
What do pre-capillary junctions contain ?
Sphincters control blood flow within the tissues.
What is the structure of capillaries ?
Endothelial cells supported on a basal lamina.
They form a network called a capillary bed.
What occurs at a capillary bed ?
Exchange of O2, CO2, nutrients, hormones between cells/interstitial fluid and blood via :
- Active transport
- Passive transport
What are the 3 types of capillaries ?
Continuous
Fenestrated
Sinusoid
What is the most common type of capillary ?
Continuous
Where are continuous capillaries found ?
Skin, Muscle, Lungs, CNS
What capillary bed type is least permeable ?
Continuous capillaries
Where are fenestrated capillaries found ?
Kidneys, Small intestines and areas of hormone secretion.
This is due to them having large pores for active filtration.
Which capillary bed type is most permeable ?
Sinusoid
Which capillary type is least common ?
Sinusoid
Where are sinusoid capillaries found ?
Liver, Bone Marrow, Spleen
What types of molecules pass through sinusoid capillaries ?
Large molecules and cells
How are venules formed ?
Capillaries unite to form venules
How are veins formed ?
Venules unite to form veins
How is the structure of veins different from arteries ?
The walls of veins are thinner, and lumen diameter greater than corresponding arteries.
In veins how much muscle does the tunica media have ?
Little muscle
Which is the thickest layer of tunica is veins ?
Tunica externa
What is a key feature of venules/veins ?
They are extremely porous. White blood cells extravasate to sites of inflammation.
Where are valves formed from ?
The tunica intima
What do veins contain that prevents the back flow of blood ?
Valves
What are the types of lower limb veins ?
Deep veins
Superficial veins
Where do superficial veins lie ?
Immediately under the skin
Where do deep veins lie ?
They are situated deeply and have the same names as the arteries. e.g. femoral vein.
They accompany limb arteries.
Name 2 examples of superficial veins in the lower limbs
Great saphenous
Small saphenous
How are deep and superficial veins connected ?
Via PERFORATING veins
Blood flow is from superficial to deep due to valves in perforating veins.
What is the result of incompetency of valves ?
Varicose veins
Examples of deep veins in the upper limbs from top to bottom
Subclavian vein
Axillary vein
Brachial vein splits off into :
Radial and Ulnar vein
Examples of superficial veins in the upper limbs
Cephalic vein
Basilic vein
Median cubital vein -connects the cephalic and basilic
Where does blood from the lower limbs, pelvic organs, kidneys and abdominal was drain into ?
The inferior vena cava
What is the function of the superior vena cava ?
It drains the venous blood of the head, neck and upper limbs into the right atrium.
Where does blood from components of the gastro-intestinal tract and spleen return to ?
It forms the hepatic portal vein, which takes venous blood through the liver before it then joins the IVC (inferior vena cava)
What is the function of the lymphatic system ?
It collects interstitial fluid lost from the vascular capillary beds and returns it to SYSTEMIC CIRCULATION
What is the lymphatic system part of ?
It is part of the immune system, containing T and B lymphocytes.
What does the lymphatic system consist of ?
Lymph vessels, Lymph nodes, Tonsils, Thymus, Spleen and Interstitial walls
What is the interstitial fluid called once it enters the lymph vessels ?
Lymph
What is the structure of lymph capillaries ?
They are thin walled, endothelial tubes, permeable to fluid and proteins.
What is lymph filtered by ?
Lymph nodes which are usually clustered at specific sites.
What does lymph return rely on ?
Similar mechanisms to venous return
What does the right lymphatic duct drain ?
The right side of the head/thorax and upper limb
What does the thoracic duct do ?
It drains the rest of the body
What is larger, the right lymphatic duct or the thoracic duct ?
The thoracic duct. It opens at the junction of the left subclavian / internal jugular veins.
What do lymph nodes contain ?
Lymphocytes
Inguinal lymph nodes
Drains lower limbs; buttock; external genitalia; lower back & abdominal wall
Axillary Lymph nodes
Drains upper limb; thoracic walls, plus upper abdominal walls above umbilicus and breast.
Cervical lymph nodes
Lie on either side of the neck.
Drains head and neck structures
Where does lymph drain back into ?
Lymph travels from :
Lymph glands —-> Larger lymphatic vessels that join up —-> Thoracic duct (at the base of the neck) —-> Lymph is drained back to blood circulation.
What is a disadvantage of the lymph system ?
Can be involved in the spread of cancer.
Metastasis
Malignant cells may become detached from a primary tumour and can be carried along lymph vessels until they reach a lymph node where they may give rise to a secondary tumour.
Edema
An excess of interstitial fluid, manifest as swelling
