Cardiovascular system Flashcards by Ravi Jalif

What is the pulmonary circulation?

Oxygen depleted blood
Passes from heart to lungs
Returns oxygenated blood to heart

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What is the systemic circulation?

Oxygen rich blood
Passes from heart to rest of body
Returns deoxygenated blood to heart

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What is the mediastinum?

A membranous partition between two body cavities or two parts of an organ, especially that between the lungs

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What is the structure of the heart wall?

Fibrous layer
Pericardium - parietal, cavity, visceral
Myocardium
Endocardium

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What does the ductus venosus do?

Shunts a portion of the left umbilical vein bloos flow directly to the IVC, thus allowing oxygenated blood from the placenta to bypass the liver

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What is the foramen ovale?

A small hole located in the septum, it is an anatomic adaptation in the foetus to allow oxygenated blood coming from the umbilical vein via the inferior vena cava to bypass the pulmonary circulation

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What does the ductus arteriosus do?

Blood vessel connecting the main pulmonary artery to the proximal descending aorta. Allows most the blood from the right ventricle to bypass the foetus’ fluid-filled non-functioning lungs.

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What is the fossa ovalis?

Depression in right atrium, remnant of foramen ovale

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Where are the pulmonary arteries located?

Right side of the heart, they carry deoxygenated blood from the heart to the lungs

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What do the papillary muscles and chordae tendineae do?

Once the AV valves close the muscles contract and tendinaeae tighten preventing valve flaps from everting into atria during ventricular contraction

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What is endocarditis?

Infection of the endocardium

Most common is subacute bacterial endocarditis (SBE) - caused by Strep viridans or staph aureus

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What is atrial fibrillation?

Rapid, irregular contraction of different parts of the atria

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What is ventricular fibrillation?

Rapid, irregular contraction of the ventricles

Most disorganised form of dysrhythmia, and leads to cardiac arrest

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What is the purpose of recoil in the arterial system?

To maintain arterial blood pressure during diastole

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What are the 3 layers of the arterial system?

Tunica intima
Tunica media
Tunica adventitia

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What are the different types of arteries and where are they found?

Elastic - aorta, pulmonary, common carotid, subclavian
Muscular - radial, femoral, coronary and cerebral
Arterioles - terminal branches supplying capillary bed

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What are the characteristics of the venous system?

Low pressure
Passive movement down pressure gradient
Negative pressure in chest on inspiration
Contains valves in lower limb veins

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What is normal arterial blood pressure?

120 - systolic

80 - diastolic

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What are the four main control systems involved in cardiovascular control?

Arterial blood pressure
Cardiac output (stroke volume and HR)
The local circulation and blood
Extracellular fluid volume

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What is the nerve that carries information from the carotid sinus to the brain?

Glossopharyngeal (hering branch)

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What is the nerve that carries information from the aortic arch to the brain?

Vagus nerve

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Where are the CVS baroreceptors located?

Carotid sinus and aortic arch - respond to stretching
Carotid more important - more sensitive (60-180)
Input to Nucleus tractus solitari

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What is the response to a decrease in arterial pressure?

Decrease in arterial baroreceptors firing

Increase SNS outflow to heart/arterioles/veins
Decrease PNS outflow to heart

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What does the alpha2 subsection of the NTS do?

Inhibits Bulbar circulatory centres

Activates Vagal nucleus

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What does the beta1 section of the NTS do?

Activates bulbar circulatory centres | Inhibits vagal nucleus

What does the bulbar circulatory centres do?

Releases noradrenaline - acts on alpha and beta 1 receptors - Increases peripheral resistance - Increases CO

What does the vagal nucleus do?

Releases ACh - acts on M2 receptor | - Decreases CO

How to control arteriolar radius?

Alpha 1 - CONSTRICT Beta 2 - DILATE K+ - DILATE Acetlycholine muscarinic - DILATE

What is an example of local control of BP?

Adenosine produced by metabolsing tissue Blood gases - hyperventilation and rebreathing Nicorandil - opens ATP sensitive potassium channels

What is capillary fluid shift?

The movement of fluid across the capillary membrane between the blood and the interstitial fluid compartment Caused by reduced proximal capillary hydrostatic pressure

When is blood pressure greatest and lowest?

Greatest on waking, lowest in sleep Increases in exercise, stress, sensory stimuli Hypertension > 90mmHg Diastolic

What is primary and secondary hypertension?

Symptomless Primary - Idiopathic (95%) Secondary - known cause (5%) - Renal hypertension, aortic coarctation, drug induced

What are treatments of hypertension?

Reduce HR - beta adrenoreceptor antagonists Reduce SV - beta antagonists, Calcium channel blockers Reduce TPR - alpha blockers Reduce volume - diuretics Central control systems - clonidine (alpha 2 agonist)

What are the types of blood vessels in the CVS?

``` Large arteries Arterioles Capillaries Veins Venules ```

What is the function of endothelial cells?

Local BP control - constrictors (endothelin), dilators (prostacyclin) Prevent platelet aggregation and blood clot formation (NO) Angiogenesis+vessel remodelling Permeability barrier

Where is smooth muscle found and what is its function?

In all BV's but capillaries | Determine vessel radius

What is found in the tunica intima?

Endoethilium Subendothelial layer Internal elastic lamina

What is found in the tunica media?

Smooth muscle, collagen and ground substance Elastin External elastic lamina

What is found in the tunica adventitia?

Mostly collagen fibres Elastic fibres not elastin Fibroblasts/Macrophages Vasa Vasorum

What is MAP?

Average pressure pushing blood round the system | MAP = DiastolicBP + 1/3PP

What is PP?

Difference between systolic and diastolic BPs

How much blood do the venules, veins and venae cavae carry?

70% - very distensible

How much blood do capillaries carry?

5% - make up 25,000 miles in total

What are the factors influencing transport within capillaries?

Blood in capillaries exert a pressure on capillary wall - hydrostatic pressure - OUT Plasma has intrinsic osmotic pressure due to plasma proteins - COLLOID pressure - IN

Which is higher pulmonary or systemic hydrostatic pressure?

Pulmonary hydrostatic pressure is much lower Colloid pressure is equivalent

What is an indication of heart failure to do with blood vessels?

In heart failure, capillary hydrostatic pressure increases, particularly in extremities

What is the condition where tissue fluid builds up in the tissue?

Oedema | Uses lymph capillaries and vessels to move this fluid back into blood

What is the other function of lymph apart from moving fluid from tissue to blood?

Moving absorbed fat into the circulation

How can you modify TPR and therefore MAP?

alpha-adrenoreceptor anatgonists - alpha1-selective - PRAZOSIN - decrease vasoconstrictor tone (post-synaptic), no direct change in HR or CO alpha2-selective - phentolamine - decrease vasoconstrictor tone (pre/post-synaptic) - not used therapeutically

What are local controls for arterioles?

Changes in O2 and Co2 can dilate arterioles Blocking blood flow temporarily induces hyperaemia Flow can be maintained by flow autoregulation

What is the P wave?

Atrial depolarisation

What is the QRS wave?

Ventricular depolarisation

What is the T wave?

Ventricular repolarisation

What is the P-R interval?

Delay through AV node

What is the S-T interval?

Plateau phase of AP

What are the 3 SA node AP phases?

Phase 0 - Calcium in Phase 3 - Potassium out Phase 4 - Calcium in and reduced potassium out

What triggers contraction in cardiac muscle?

Entrance of calcium ions | either from exterior of myocyte or from SR

What is sarcoplasmic reticulum?

Specialised ER - regulates calcium ion conc in cytoplasm of striated muscle cells

What node does the right vagus modulate?

What node does the left vagus modulate?

On an ECG what does the P wave represent?

P wave is a record of the electrical activity through the atria

On an ECG what does the QRS complex represent?

Movement of electrical impulses through the ventricles

On an ECG what does the ST segment represent?

When the ventricle is contracting but no electricity is flowing through it, usually appears as a straight level line between QRS and T wave.

On an ECG, what does the T wave represent?

When the lower heart chambers (ventricles) are resetting electrically and preparing for their next muscle contraction

Cardiovascular system Flashcards

(64 cards)