05 The Circulatory System Flashcards
Explain and give examples of anastomoses, collaterals, and and arteries
Anastomosis is the connection of arteries without a capillary network between them. This provides an alternative route for blood flow which is called collaterals. An advantage is that this can provide blood supply to cells distal to an arterial occlusion. However disadvantage is that it can bleed from both sides when cut. Examples include scalp, circle of Willis in the brain, limb joints
End arteries involve only arterial blood supply to a particular area. Therefore occlusion can result in infarction of the area. This leads to irreversible cell damage dude to a lack of oxygen due to loss of blood supply. Examples include digits of the hand, coronary artery in the heart and central artery of retina(eye).
Explain the parts and branches of the aorta
- aorta has 4 parts
- ascending aorta
- 2 branches- right and left coronary arteries supplying blood to the brain - arch of the aorta
- 3 branches: brachiocephalic, left common carotid, left subclavian
- brachiocephalic bifurcated into right common carotid and right subclavian
- right subclavian>right axillary>right brachial> bifurcated at the elbow joint into the right radial and right ulnar arteries - thoracic descending aorta which has multiple branches
- abdominal aorta
- 3 unpaired midline arteries and 3 paired bilateral arteries
Describe carotid bifurcation.
The common carotid bifurcated into the external carotid (slighy anterior and with many mini branches) and internal carotid (which goes straight into the cranial cavity and has no branches).
Explain where is the carotid sinus and it’s function
The carotid sinus is the most proximal, usually dilated part of the internal carotid artery. It lies on the superior border of the thyroid cartilage. It is innervated by the glosspharyngeal nerve(9th carnival nerve) and helps detect changes in arterial blood pressure.
Explain what is the carotid body and its function
The carotid body detects blood has levels and ph. It is also innervated by the glossopharyngeal nerve.
Describe the two arteries carry blood supply to the brain
- Internal carotid artery- travels straight into the cranial cavity to supply the brain through the carotid canal
- Vertebral artery - branches from the subclavian artery, travels through the vertebral foraminae of the cervical vertebrae, then through the foreamen magnum to supply the brain
There, they anastomose together
Explain what is the blood brain barrier
The blood brain barrier is essentially tight junctions between brain capillary endothelial cells. Astrocyte processes surround the brain Capillaries. This helps to prevent the diffusion of some substances.
Describe the branches of the thoracic aorta
The thoracic aorta includes
- bilateral posterior intercostal arteries which supply the chest wall
- Anterior surface Arteries
- Bronchial arteries(lung)
- Oseophaghal arteries
- Mediastinal arteries
- Pericardial arteries
- Phrenic arteries (diaphragm)
Describe the branches of the abdominal aorta
- 3 unpaired arteries in the anterior surface
- 3 bilateral paired arteries on the lateral surface
- This aorta bifurcates into the common iliac arteries at L4 which supply the pelvis, perineum and lower limbs. The common iliac arteries further bifurcate into the internal iliac arteries which supply the pelvis and perineum and the external iliac arteries which supply the lower limb.
Name and give the location of the peripheral pulses
Neck
- carotid pulse
>present at bifurcation of the common carotid
> posterior at level of the thyroid cartilage
Upper limb
- brachial pulse
> anterior to the elbow join
- radial pulse
> on the radial side of the volar aspect of wrist
Lower limb
- femoral pulse
> at the femoral artery against the hip bone
> midpoint of groin
- popliteal pulse
> posterior to the knee joint
- posterior tibial pulse
> posterior to the medial malleolus of tibia
- dorsalis pedis pulse
> on the dorsum of the foot
Define the different venous systems, ‘Superficial and Deep’, ‘Systemic and Portal’
The body has Two sets of veins - superficial and deep veins
Superficial veins
- are smaller
- run in the superficial fascia
- drain into deep veins
- patterns show great anatomical variation
- upper limb superficial veins are often used to take a sample of venous blood
Deep veins
- are larger
- run deep to deep fascia
- and into body cavities
- less variation in their pattern
The body has two main venous systems - hepatic portal venous system and systemic venous system
The hepatic portal venous system drains blood from the absorptive parts of the GI tract and associated organs to the liver for ‘cleaning’
The systemic venous systems drains blood from all other organs and tissues to the superior or inferior vena cavae
Describe the function and basic anatomy of the lymphatic system
The lymphatic system is part of the immune system. Lymphatic capillaries collect tissue fluid which is called lymph once inside the lymphatic capillaries which join together to form lymphatic vessels. The lymphatics carry lymph to the lymph nodes which contain white blood cells to filter fluid and fight infection.
Lymph is drained into The Central veins at the root of the neck at the venous angles. The upper right part of the body drains into the right venous angle via the lymphatic duct while the rest of the body drains into the left venous angle via the thoracic duct.
Describe the clinical importance of the lymphatic system
Clinicians need to know the anatomical route of the lymph drainage towards the right lymphatic duct or thoracic duct.
This will help them to assess whether the lymph nodes along the route have been involved in any disease process affecting the organ or tissue being investigated.
Normal lymph nodes cannot be palpated.
Lymph nodes fighting infection or affected by a spreading cancer will enlarge and can then be palpated or seen during imaging.
Define the Circulatory system, systemic and pulmonary circulations and the great vessels
Circulatory system consists of the cardiovascular system and lymphatic system.
The cardiovascular system involved the systemic and pulmonary circulation.
The great vessels are directly connected to the heart chambers and they include the superior and inferior vena cava, aorta, pulmonary trunk and pulmonary veins.
How is venous blood pumped back to the heart if blood flow in veins is non-pulsatile
Venous blood is pumped back to the heart by
- skeletal muscle contractions in the limbs
- helped by venous valves which Ensure Uni directional flow back to the heart
- pressure changes in the chest cavity due to breathing movements also help to push blood back to the heart
