Circulation Flashcards
What is the circulation network composed of
The heart- which is a centralised pump
Blood vessels
Blood
What are the 2 seperate circulation loops
The pulmonary circulation
The systemic circulation
What is the function of the pulmonary circulation
The pulmonary circulation transports blood from the heart to the lungs to become oxygenated then back to the heart
What is a similarity of both the pulmonary circulation and systemic circulation
They both begin at the heart
What is the hierarchy in the systemic circulation
Heart
Arteries
Arterioles
Capillaries
Gas exchange occurs at the tissues and becomes deoxygenated
Venules
Veins
Heart
What is transported in the blood via the circulatory system
Hormones
Gases
Nutrients
Waste
Electrolytes
Give a brief overview of the structures that blood passes through in the pulmonary circulation
Superior and inferior vena cava
Right atrium
Right ventricle
Right and left pulmonary artery
Capillaries of the lung
Pulmonary veins
Left atrium
Left ventricle
Aorta
Give a brief overview of the structures the blood passes through in the systemic circulation
Left atrium
Left ventricle
Aorta and main branches- braceocephalic, left common carotid, left subclavien
Capillaries
Veins
Inferior and superior vena cava
Give a brief overview of the structures in the coronary circulation
Ascending aorta
Right coronary artery
Right marginal branch + posterior interventricular artery + left coronary artery
Anterior interventricular branch
Circumflex artery
How does blood from the coronary circulation get back to the right atrium
Via the coronary sinus
When does blood from the right artium flow into the right ventricle
During diastole
What valve sits between the right atrium and right ventricle
The tricuspid valve
What happens to the blood in the right ventricle during systole
The right ventricle contracts pushing blood into the conus arteriousus at the base of the pulmonary trunk
What does contraction of the right ventricle cause to happen
The tricuspid valve closes to prevent back flow into the right atrium
When does the pulmonary valve close and what does it prevent
During diastole which prevents back flow of blood into the right ventricle
When does newly oxygenated blood pass into the left atrium
During diastole
During diastole blood passes from the left atrium to the left ventricle by passing through which valve
The mitral valve
During systole the left ventricle contracts pushing blood where
Into the aorta through the aortic valve
When does the mitral valve close
The mitral valve closes when the left ventricle contracts pushing blood up into the aorta to prevent back flow
When does the aortic valve close
During diastole to prevent back flow into the left ventricle
Where do the left and right coronary arteries branch from
The ascending aorta
The arch of the aorta has 3 main branches what are they
Braceocephalic trunk
Left common carotid
Left subclavien
What do the 3 main branches that branch from the arch of the aorta supply
The head, neck and upper limbs
What does the arch of the aorta become
The arch of the aorta becomes the descending aorta which travels down through the thorax giving off many branches to supply structures in the thorax
From the throax where does the aorta go
It passes through the diaphragm
At what level does the aorta pass through the diaphragm
T12
What aperture does the aorta pass through in the diaphragm
The aortic hiatus
When the aorta enters the abdomen what does it become
The abdominal aorta
What are the branches that come off the abdominal aorta
The coeliac trunk
Superior mesenteric artery
Inferior mesenteric artery
When the abdominal aorta terminates what does it become
Bifurcates into the common iliac arteries which supply the pelvic cavity and the lower limbs
Describe the corse of the coronary circulation
The left and right coronary branches from the ascending aorta immediately above the aortic valve.
The right coronary goes to the right and gives 2 branches the right marginal artery which runs along the right border and the posterior descending artery which runs along the interventricular septum along the base of the heart.
The left coronary goes left and splits into the anterior descending which runs along the anterior of the interventricular septum and the circumflex artery.
The posterior descending artery joins with the left anterior descending artery at the apex of the heart
What is the venous drainage of the heart
The coronary sinus
The coronary sinus drains which main veins
The great cardiac vein
The middle cardiac vein
The small cardiac vein
What is the portal system
The portal system is a a network of veins that drains the deoxygenated blood from the abdomen
The veins of the portal system directs blood to which organ
The liver
Why is blood from the abdomen directed to the liver before going back to the heart
The blood goes to the liver to be filters so the body is able to use the nutrients in the blood
What does the splenic vein drain
The spleen, the pancreas, the stomach
What does the superior and inferior mesenteric veins drain
They drain everything from the jejunum to the upper rectum
What 2 veins join to form the hepatic portal vein
The superior mesenteric vein and the splenic vein
What is the role of arteries
They carry blood away from the heart towards peripheral tissues
What are characteristics of arteries
They have thick walls and narrow lumens which means they can resists high pressure from the blood been forced out of the heart
Arteries goes through a process of segmentation
What does this mean
Arteries go through a process of segmentation which means they decrease in diameter and the wall becomes thicker with each division
What are conducting arteries
They carry blood directly from the heart and main branches, they have a high degree of elasticity and so can withstand the high pressure
What are the distributing arteries
The distributing arteries are arteries which transport the blood to the specific organ systems, these have a high muscular component
What are arterioles
They are small in size and are muscular resistant so they only cope with low pressure blood
How many layers do artery walls have
3 layers
What are the 3 layers of the artery walls
The tunica intima
The tunica media
The tunica externa
What is the tunica intima made up of
Basement membrane
Endothelium
Internal elastic lamina
Subendothelial
What is the tunica media made up of
Smooth muscle
External elastic lamina
What are examples of conducting arteries
Aorta and its major branches
What is the role of arterioles
They connect vessels between muscular arteries and capillary beds.
They can also control the blood from into capillaries via the contraction of the smooth muscle
What are capillaries
They are the vessels closes to the target organ and act as a barrier between the blood and the interstitial fluid
What is a characteristic of capillaries
They have a marrow lumen which is just wide enough for the largest blood cell to fit through
What are venules
They are formed when 2 or more capillaries converge
What are veins
They are formed by the union of muscular venules
What are some characteristics of veins
They have a thin wall and large lumen with small amounts of muscle due to the blood is under low pressure
They have distensible walls meaning they can expand to accommodate large volumes of blood
What do peripheral veins contain
They contain valves which prevent back flow
Which veins do not contain valves
Veins within the abdomen
What is anastomoses
They are formed by 2 arteries connecting with each other
Which does anastomoses allow
Allows for continuous blood supply
If an artery becomes blocked blood flow is still able to continue why is this possible
This is possible due to the anastomosis of an artery with am adjacent artery
What is mean by direct anastomosis and give an example
2 arteries join
Eg- redial and ulnar arteries via the palmar arteries
What is meant by convergence anastomosis and give an example
2 arteries join to form one single artery
Eg- when vertebral arteries join to form basilar artery
What is meant by transverse anastomosis and give and example
This is when a small artery connects 2 large arteries
Eg- anterior communicating artery connects the left and right anterior cerebral arteries
What is meant by arteriosvenous anatamosis and give an example of where this could happen
The direct connection between a small artery and small vein
Eg- in the nose or ear
What is a portacaval anastomosis and give an example where this could happen
This is the connection between systematic artery and the portal veins
Eg- oesophagus or rectum
Why are circulatory shunts needed in a foetus
They are required to bypass the liver and non-functioning lungs
What are the 2 shunts that are used to bypass the lungs
The foramen ovale
Ductus arteriosus
Where can the foramen ovale found
It is found between the left and right atria
What happens to blood if it does pass through the foamen ovale
Blood enters the right ventricle and goes through the ductus arteriosus
What does the ductus arteriosus connect
It connects the pulmonary trunk to the distal aorta
What triggers the foramen ovale to close
This closes due to the baby taking its first breath when been born causing the pulmonary resistance to fall as the pressure within the left atrium becomes higher in the right atrium so blood can no longer flow through the foramen ovale so this closes the shunt and will have completely fused by the age of 1
What causes the ductus arteriosus to close
This closes when the muscular wall contracts.
This is mediated by bradykinin
What is the remnant of the foramen ovale
The fossa ovalis
What is the remnant of the ductus arteriosus
The ligamentum arteriosum
What is the remnant of the ductus venousus
The ligament venosum
What is the remnant of the umbilical vein
The ligament teres
How are blood vessels formed in the embryo
On day 17 blood islands in the extraembroynic mesoderm which are a core of hemoblasts surrounded by endothelial cells
How many days after fertilisation does vasculogenesis commence
Day 18
What is the difference between vasculogenesis and angiogenesis
Vasculogenesis is the development of blood vessels from in situ differentiating angioblasts
Angiogenesis is the sprouting of capillaries from pre-existing vessels
What drives embryonic vessel development
Angiogenic growth factors
Eg- vascular endothelial growth factor, angiopoietin 1 and 2
Repulsive signals
Eg- plexin/semaphorin signalling, ephrin
