Blood Vessels and Lymphatics Flashcards
What are the features of tunica interna/intima
Its lines by simple sqaumous epithelium known as the endothelium.
The endothelium releases the hormone endothelins which can cause constriction of smooth muscle, increasing blood pressure.
Beneath endothelium is a basement membrane/basal lamina that binds the endothelium to connective tissue.
In arteries - layer of elastic fibers called internal elastic membrane (allows streching whilst keeping structure)
Describe the features of tunica media
Composed of concentric circles of smooth muscle cells, elastic fibres that support muscle cells. Contraction of the muscles causes vasoconstriction (increases peripheral resistance and increases blood pressure) Relaxation of the muscles causes vasodilation
Features of tunica externa/adventitia
A layer of connective tissue made of collagen fibers. Thickest tunica in veins and can be thicker than the tunica media in some larger arteries.
Describe the functions of muscular arteries
They have a thick tunica media layer meaning they can control the distribution of blood flow to regions and organs (constricting or relaxing as needed to regulate flow if needed)
They can contract to prevent haemorrhages or accomodate an increase in diameter
The subclavian artery changes name as it moves down the upper limb, name these
Becomes the axillary then brachial and then will branch into ulnar and radial (all artery)
Name the arterial anastomosis in the hands and what they allow for?
There is the deep palmar arch and the superficial arch both of which are derived from the radial and ulnar arteries. Arterial anastomosis ensures blood flow to the hand even if an artery becomes cut off my movement. Every joint have anastomoses around them.
Name the large arteries in the abdomen
Descending thoracic aorta, abdominal aorta and the common iliac artery
Describe the position of the femoral artery, vein and nerve.
The femoral artery lies with its vein medially and nerve laterally (importance of locations for when inserting cannulas)
Name the major arteries in the thigh
The common iliac, external iliac, internal iliac common femoral, profunda femoris, superficial femoral and popliteal
Name the major arteries of the leg and the main artery of the foot
Anterior tibial, tibio-peroneal/fibular trunk, peroneal and posterior tibial. Foot - Dorsalis pedis
What are arterioles, metarterioles and capillaries
Arterioles- arteries less than 0.5mm in diameter
Metarterioles - same diameter as capillaries but with one layer of smooth muscles
Capillaries - tubes of endothelium, no smooth muscle
Describe the features of capillaries
Endothelium cells supported on a basal lamina (basement membrane)
Form networks called capillary beds
Allow exchange of oxygen and CO2, nutrients and hormones.
VERY small diameter (7 or 9 micrometers), Unable to contract because of the lack of muscle
The basal lamina splits to enclose pericytes (myoepithelial cells) these look after endothelium.
What regulates blood flow through a capillary bed?
Pre-capillary sphincter
Name the two main capillaries
1 - continuous capillary (most common)
2- Fenestrated capillary, contains fenestrae/pores that permit the exchange of larger molecules so they are found in the intestine, choroid plexus (cells that produce cerebrospinal fluid), endocrine glands and kidneys
What prevents the back flow of blood through through a vein
Valve leaflets, they close when the blood pressure proximal is greater than distal to them thus preventing back flow.
What are venae comitantes
The veins that accompany smaller arteries. They are all wrapped in a vascular sheath, the pulsing of the artery aids venous returns to the heart.
Name the two superficial veins in the lower limb
The great saphenous vein (long) and the small saphenous vein (short.)
Deep and superficial veins connected by?
Perforating veins.
What is venous flow?
The flow between superficial and deep veins, is due to valves in perforating veins, incompetency of these veins can lead to varicose veins which is where there is too much blood in the superficial veins.
How is blood pumped up to the heart?
Muscle contraction, arterial pulsation and negative intrathoracic pressure
Upper limb superficial veins used for phlebotomy
Cephalic, Basilic and median cubital veins.
Must avoid the brachial artery and median nerve posteriorly
Name some large veins
Inferior vena cave, Superior vena cava, Azygous vein (which drains into the SVC) and the hepatic portal vein which drains all the blood from the GI tract and spleen and joins the ICV
What do vaso vasorum do?
Supply larger veins with a blood supply
Describe the basics of the lymphatic system
It is part of the immune system formed by the tonsils, spleen, lymph nodes, thymus and intestinal wall.
It helps veins remove interstitial fluid, otherwise the body would become very swollen with the volume of interstitial fluid.
Lymphatic capillaries do what?
Absorb interstitial fluid and drain it into lymph nodes (contains a lot of immune cells so when there is an infection, the lymph nodes swell. Therefore you can detect where an infection is coming from due which lymph nodes are inflamed)
Superficial/deep lymph nodes relate to what?
veins and arteries respectably.
What is metastasis
Where malignant cells detach from a primary tumour and travel along the lymphatic system and until they reach a lymph node where they can give rise to a secondary tumour.
Name the three superficial lymph node collections
1) Superficial inguinal (alongside the great saphenous vein and inferior to the inguinal ligament, drain to the deep inguinal nodes)
2) Deep inguinal (below the femoral vein)
3) Axillary (lateral/deep/medial to the pectoralis minor)
4) Superficial cervical (under jaw, over parotid, behind ear; occuipital)
5) Deep cervical (along side the jugular vein) Can communicate with axillary and thoracic nodes.
How does lymph enter the bloodstream?
Enters at the subclavian vein via the thoracic duct
What is lymph?
Interstitial fluid in lymph vessels
