6. Cardiovascular System - Part 2 Flashcards
Describe the difference between the ‘systemic circulation’ and ‘pulmonary circulation’.
There are the two types of circulation in the body
Systemic circulation:
BLOOD FROM THE HEART is distributed AROUND THE BODY before RETURNING TO THE HEART
Pulmonary circulation: BLOOD FROM THE HEART is distributed TO THE LUNGS before RETURNING TO THE HEART
What is meant by hepatic first pass
This describes the blood flow from the digestive system to the liver via the portal vein where we basically drain all of the contents of the digestive system and process them through the liver
Name the three layers of the blood vessel wall
(From the outside in)
Tunica Externa
Tunica Media
Tunica Intima
The same three layers exist in arteries, arterials, veins and venules but in different thicknesses. Capillaries only have a single layer which is tunica intima.
Think of it like a garden hose where the outer layer is TUNICA EXTERNA, the middle layer of plastic is TUNICA MEDIA and the inner layer is TUNICA INTIMA. Inside that is the water running through the hose which is the blood.
How do veins prevent the backflow of blood
They have valves that prevent the blood from going backwards
What type of blood vessel plays a key role in regulating blood pressure?
Arterioles. They are more muscular and under high pressure are better able to regulate blood pressure.
Name the four heart chambers in order of flow
There are four cavities in the heart through which the blood flows one chamber at a time starting at the right and moving to the left.
RIGHT ATRIUM to RIGHT VENTRICLE to LUNGS to LEFT ATRIUM to LEFT VENTRICLE.
The Atria are the arrival or receiving chambers of the heart (think atrium/entrance hall) , receiving venous blood. The atria pump blood into the ventricles
What vessel between the heart and the lungs carries deoxygenated blood?
Pulmonary artery
Where is the pulmonary valve located
The right Ventricle pumps blood into the lungs through the pulmonary valve into the pulmonary trunk which divides into the left and right pulmonary arteries.
So the pulmonary valve is located between the right ventricle and the pulmonary arteries
Is the right or left ventricle thicker? Why is one side thicker?
The left ventricle is thicker @ 10-15mm. This is because when it contracts it needs to pump the blood around the entire body. The right ventricle only needs to pump blood to the lungs so not as much force/pressure/muscle needed
Does the left atrium contain oxygenated or deoxygenated blood
Oxygenated
Label the hearts conductive system
The conductive system are the nerve structures that signal to the heart when the heart muscle needs to contract. Without the conductor system the heart can’t contract.
SA Node: Contraction of
Sino Atrial Node in the right atrial wall is the pacemaker of the heart. It sets the rate and the rhythm for the rest of the conductive system. It initiates the conduction system, sending a signal to the ….
AV Node: Signals are gathered
Atrial ventricular node which is between the atrium and the ventricles in the bottom right of the interatrial septum is the relay station gathering electrical signals.
Bundle of His: Through the Bundle of His
These signals from the AV node ascend through the bundle of his conducting from the Atria to the ventricles.
Right and left bundle branches: Impulse enters right and left bundles
The Bundle of His separates into the right and left bundle branches and spread out heading down towards the apex of the heart right at the bottom.
Purkinje fibres: Ventricular contraction
Purkinje fibres are where the bundle branches terminate. They conduct the nerve impulse from the apex of the heart up the sides of the heart branching out into the purkinje fibres.
Describe in specific detail the conduction system in the heart, commencing with the sinoatrial node (include all key structures and their functions).
WE know the heart is a muscle pumping blood through the chambers and out of the ventricles but something needs to tell the heart when to contract and in what order to do it. It is a very fast wave and it must be done in a specific order.
The conductive system of the heart are the nerve structure that signal to the heart when the heart muscle needs to contract. Without the conductive system the heart cannot contract.
- Sinoatrial Node (SA Node) CONTRACTION OF ATRIA
SA NODE is located in the right atrium. This ‘PACEMAKER OF THE HEART’ initiates cardiac contraction and sets the rate. Nerve impulses from the SA node causes Atrial contraction - Atrioventricular Node (AV Node) – SIGNALS ARE GATHERED
Located between the atrium (atrio) and the ventricles (ventricular). Bottom right of the interatrial septum.
It is a RELAY STATION. It gathers in the electrical signals and conducts them at a slightly slower rate to allow the atria to finish contracting. - Atrioventricular bundle (Bundle of His) – THROUGH BUNDLE OF HIS
The AV node gathers the electrical signals and sends them down through the middle of the heat through the Bundle of His. - Right and left bundle branches – IMPULSE ENTERS RIGHT AND LEFT BUNDLES
Now the electrical signals need to start going to the left and right side of the heart so the Bundle of His separates into the right and left bundle branches. They spread out and head down towards the apex of the heart at the bottom. - Purkinje Fibres - VENTRICULAR CONTRACTION
These are the terminal branches of the right and left branches.
The Purkinje fibres rapidly conduct the nerve impulse beginning at the apex of the heart spreading up the sides of the heart and this is when we get ventricular contraction forcing the blood upwards and out of the heart.
What is meant by autorhythmic
It refers to the heart regulating its own rhythm and rate
What is the term describing a pulse rate over 100 BPM?
Tachycardic
What is meant by systole? Does this represent the top or the bottom number when reading blood pressure.
Systole is the force of the hearts contraction and the amount of pressure that builds up in the blood vessels when the heart contracts. It is the top number on a blood pressure reading.
What is the effect of the sympathetic nervous system on heart rate and strength of contraction?
When in fight or flight, the heart rate goes up and contractions are stronger to allow more blood to pump through the body giving oxygen for action.
Outline the key steps in the formation of atherosclerosis. (need to know this perfectly)
1) Damage to the vascular endothelium wall (tunica intima) of the artery, creating inflammation
Damage can be from high blood pressure, high glucose, high insulin which is associated with high cholesterol, transfers, smoking, alcohol, sedentary lifestyle etc
2) LDL’s (cholesterol) deposit in the tunica intima to repair the damage but they become oxidised and therefore unstable and they attract white blood cells (macrophages) to help out.
3) Macrophages try to engulf and destroy LDL, the fatty material. But they have trouble and end up covering the whole area. This results in the creation of foam cells which are cells packed with fat.
At this point we have a bit of an issue and a bit of lump.
4) Vascular smooth muscles proliferate to try to stabilise
5) wrap around the foam cells to create a cap of plaque and separate it from the blood but in doing so for protective reasons it reduces the space for blood to flow.
Now we have a narrowed passage in the lumen
What are the risk factors for atherosclerosis
Sex and age (men > 45 years); Family history; Ethnicity – South Asian, African, Caribbean
Diet: High trans fats, insulin resistance; high refines sugar; obesity; alcohol; gut or oral dysbiosus
Lifestyle: stress, sedentary, smoking
What is the difference between a stroke and TIA (Transient Ischaemic Attack)
Both associated with Ischaemia (lack of blood supply) to part of the brain but symptoms of TIA does not long last long – Impaired function for no longer than 24 hours. Someone could have a TIA and not know.
What is the usual cause of a myocardial Infarction (aka heart attack)
Death of myocardial tissue due to ischaema (lack of blood supply) usually caused by a blockage of the coronary artery by a thrombus (clot).
List three symptoms of pericarditis.
Pericarditis is acute inflammation of the pericardium which is the outer layer of the heart. It is attached to the diaphragm so when breathing in and drawing the diagram into the abdomen you are pulling the pericardium sac which is inflamed and painful.
3 symptoms:
1) Chest pain: radiating to the back and relieved by sitting up and forward. Worsened by lying down or breathing deeply.
2) Dyspnoea: when reclining
3) Fever (because this is an infection generally)
Compare the main symptoms of left and right sided heart failure
Right:
* Systemic Oedema because right sided heart failure will affect the venous system leading to backflow and pooling of blood more broadly
* Ascites
* Portal hypertension due to backflow of blood into the portal vein
Left
* Pulmonary Oedema because blood backflow from left atrium into lungs
* Congestion bronchitis
* Cardia Asthma (with coughing often most severe at night)
Explain what is meant by an aneurysm.
Abnormal local dilations of the arteries due to weakness of the vessel wall (Often secondary to atherosclerosis)
Two common examples are:
Abdominal aortic aneurysm Where the abdominal aorta expands Leading to a tearing pulsating sensation of the abdomen and lower back
Berry aneurysm which manifest as a very bad explosive headache and may lead to a haemorrhage stroke
What are the major risk factors of a DVT?
- Lack of movement /inactivity- leads to reduced blood flow. Blood becomes stagnant and sits and pools. Hospital stays; long haul fights
- Varicose veins as this suggests that blood is not circulating well.
- Changes in blood composition making it more viscous such as severe dehydration, polycythemia, sticky platelets and the oral contraceptive pill.
- Damage to blood vessel wall
What are the common causes of haemorrhoids?
Chronic Constipation
Pregnancy
Chronic cough
portal hypertension
Obesity
Describe two possible complications of pericarditis?
Constrictive pericarditis - the sack should be nice and flexible to allow the heart to pump easily. This complication means it is thickened, scarred and fibrotic.
Cardiac tamponade - the pericardium is a serous membrane which means that it has two layers of membrane with fluid in between. Constructive pericarditis is where you have a pericardial effusion meaning a collection of fluid within the space between the serious membranes. The fluid can build up and limit space for the heart.
Describe the main role of capillaries.
There are three main types of blood vessels - arteries, veins and capillaries.
Capillaries are small blood vessels connecting arterials and venules.
They specialise in the EXCHANGE OF SUBSTANCES between blood and cells/tissues
What vessel between the heart and lungs carries deoxygenated blood.
This is the pulmonary artery. The exception to the ruke that arteries carry oxygenated blood. It carries deoxygenated blood away from the heart towards the lungs
With regards to blood vessels, complete the following table:
Direction/location?
Blood content?
Pressure?
Valves?
Direction/Location?
Arteries and arterioles carry blood AWAY from the heart
Veins and venules carry blood TOWARDS the heart
Blood content?
Arteries and arterioles have Oxygenated * blood
Veins and venules have Deoxygenated blood
Pressure?
Arteries and arterioles have high pressure because oxygen is demand all the time
Veins and venules low pressure because there is not the same urgency
Valves?
Arteries and arterioles - no valves
Veins and venules - valves prevent backflow of blood in a system that is slow and low in pressure
*In most cases arteries carry oxygen and veins carry carbon dioxide but not always. There are exceptions. The two main ones are pulmonary and umbilical arteries and veins
Describe how the structure of capillaries supports its main role.
Capillaries are made-up of a single layer of cells to ease exchange of substances.
It is only at the level of capillaries that we are exchanging substances. Arteries are too thick but we can’t go straight from arteries to capillaries so we have an intermediate level known as arterioles.
Which muscle type supports the return of venous blood to the heart?
SKELETAL MUSCLE. It’s contraction aids return of venous blood to the heart.
The pumping action of the HEART is also a major drive. The respiratory pump (DIAPHRAGM) also aids return
Where is most of the blood found in the body?
64% in the venous system – veins and venules
13% in arteriole system – arteries and arterioles
9% in pulmonary system (the network between the heart and lungs)
7% in capillaries
7% in the heart
Explain the role of the ‘portal vein’.
All of the blood that drains the digestive organs get funnelled into a system of veins and ultimately into one vein - the portal vein - which goes into the liver
So the vessel that carries the absorbed substances through the hepatic first pass is known as the portal vein.
Think of the portal like a gateway into the rest of your circulation. The liver then filters it. By the time the blood comes out of the liver and goes up to the heart it is filtered. If there was something in the gut that could be harmful it would be filtered out.
Explain how the following affects blood pressure:
a. Vasoconstriction
b. Vasodilation
a. Vasoconstriction increases blood pressure.
SYMPATHETIC NERVOUS SYSTEM. When stressed the sympathetic nervous system sends impulses to the arteries and arterials telling them to constrict. This INCREASES BLOOD PRESSURE.
b. Vasodilation reduces blood pressure as there is more area though which it can flow.
With regards to the heart complete the following:
Heart sits in the thoracic cavity within the thorax. It rests on the ………. near the midline of the thoracic cavity pointing ……….. The heart is covered anteriorly by the ………. and ribs 3-6. The apex of the heart is formed by the left ………. and lies in the ………. intercostal space.
Heart sits in the thoracic cavity within the thorax. It rests on the DIAPHRAGM near the midline of the thoracic cavity pointing LEFT. The heart is covered anteriorly by the STERNUM and ribs 3-6. The apex of the heart is formed by the left VENTRICLE and lies in the FIFTH intercostal space.
Name the three layers of the heart as well as their location, function and structure
Endocardium
Innermost layer of heart
Provides a SMOOTH LAYER for the heart chambers and covers heart valves
A LAYER OF ENDOTHELIUM overlying a thin layer of connective tissue
Myocardium
Middle layer of heart
Functions to PUMP blood out of the heart and lungs
Consists of CARDIAC MUSCLE and makes up 95% of the heart
Pericardium
Outer layer of heart
Functions to keep the heart in position within the thorax and allow FREE MOVEMENT during contractions
Thin double layered membrane made up of (i) a FIBROUS PERICARDIUM that attaches to the diaphragm and (ii) an inner SEROUS fluid PERICARDIUM
Name the heart layer that contains cardiac muscle.
Myocardium
What is the aorta?
The main and largest artery in the body.
The left and right coronary arteries are the first branches of the aorta and supply the MYOCARDIUM with an abundance of oxygenated blood.
Describe specifically the flow of blood in the heart from entering via the right atrium to exiting via the aorta. Include all key structures and indicate if blood is oxygenated or deoxygenated.
DEOXYGENATED STAGES
1. DEOXYGENATED blood into RIGHT ATRIUM via SUPERIOR and INFERIOR VENA CAVA
2 RIGHT ATRIUM pumps blood into the RIGHT VENTRICLE through the TRICUSPID VALVE
3 RIGHT VENTRICLE contracts and pumps the DEOXYGENATED BLOOD up through the PULMONARY VALVE and into the PULMONARY TRUNK.
4 The ULMONARY TRUNK. divides into the LEFT and RIGHT PULMONARY ARTERIES.
5 Blood flows through the lungs. Gas exchange occurs
OXYGENATED STAGES
6 OXYGENATED BLOOD returns to the LEFT ATRIUM via the PULMONARY VEIN
7 The LEFT ATRIUM pumps the OXYGENATED blood through the BICUSPID/MITRAL VALVE into the LEFT VENTRICLE
8 LLEFT VENTRICLE contracts and pumps OXYGENATED BLOOD through the AORTIV VALVE into the ASCENDING AORTA
9 Some of the OXYGENATED BLOOD in the aorta flows into the CORONARY ARTERIES which carry blood to the heart wall
What vessel between the heart and lungs carries deoxygenated blood.
This is the pulmonary artery. The exception to the ruke that arteries carry oxygenated blood. It carries deoxygenated blood away from the heart towards the lungs
Describe how the structure of capillaries supports its main role.
Capillaries are made-up of a single layer of cells to ease exchange of substances.
It is only at the level of capillaries that we are exchanging substances. Arteries are too thick but we can’t go straight from arteries to capillaries so we have an intermediate level known as arterioles.
Describe the structure of the 3 layers of blood vessels
Tunica intima
Innermost layer of ENDOTHELIUM (endothelial tissue). Contains epithelium to PROTECT the vessel wall and functions to secrete chemicals.
This layer is in direct contact with blood and is well positioned to monitor and respond to changes
Tunica media
Layer of smooth muscle that controls blood vessel diameter.
In arteries and arterioles tunica media is the thickest layer. It is more muscular and under high pressure plays an important role in blood pressure regulation.
Capillaries do not have this layer
Tunica externa
Outermost layer. Made of ELASTIC AND COLLAGEN FIBRES. Contains nerves and small blood vessels. Capillaries do not have this layer
For veins and venules tunica externa is the largest because of the slow pace of veins it needs to stretch to allow pooling of blood.
Indicate which transport process supports capillary exchange of:
a. Gases
b. Nutrients
c. Water
a. Gases – Carbon Dioxide and Oxygen by DIFUSSION
b. Nutrients – Glucose, fats, vitamins, minerals etc by FACILITATED DIFUSSION and ACTIVE TRANSPORT
c. Water – OSMOSIS. This is a passive transport meaning no ATP is needed. Water is move down the concentration gradient.
Explain the role of the ‘portal vein’.
All of the blood that drains the digestive organs get funnelled into a system of veins and ultimately into one vein - the portal vein - which goes into the liver
So the vessel that carries the absorbed substances through the hepatic first pass is known as the portal vein.
Think of the portal like a gateway into the rest of your circulation. The liver then filters it. By the time the blood comes out of the liver and goes up to the heart it is filtered. If there was something in the gut that could be harmful it would be filtered out.
Explain how the following affects blood pressure:
a. Vasoconstriction
b. Vasodilation
a. Vasoconstriction increases blood pressure.
SYMPATHETIC NERVOUS SYSTEM. When stressed the sympathetic nervous system sends impulses to the arteries and arterials telling them to constrict. This INCREASES BLOOD PRESSURE.
b. Vasodilation reduces blood pressure as there is more area though which it can flow.
Which nervous system stimulates vasoconstriction?
Automatic nervous system which is made up of the sympathetic, parasympathetic and enteric nervous system. All the blood vessels except the capillaries contain smooth muscles which are influenced by the autonomic nervous system.
Is the sympathetic nervous that stimulates vasoconstriction
