Cardiovascular overview 1 Flashcards
What is the function of the CV system?
Deliver oxygen, nutrients, hormones and enzymes to tissues
Remove waste products and heat
The thorax is bound by what landmarks?
Cranially - thoracic inlet
Dorsally - thoracic vertebrae
Ventrally - sternum
Caudally - diaphragm
How many thoracic vertebrae are in the dog? How many sternobrae?
13
8 - manubrium and xiphoid process
What lung lobes are found in the dog?
Left lung divided into cranial and caudal. Cranial lobe is further divided into cranial and caudal parts
Right lug is divided into 4 - cranial, middle, caudal and accessory
Which lung lobe does the horse lack?
Middle
What encapsulates the heart? What are the two layers of this and what is found between them?
Pericardium
Parietal and visceral layers
Serous fluid to allow movement
What layers does the heart wall consist of?
Endocardium
Myocardium
Epicaridum (confluent with visceral pericardium)
What is a pleura? What are the 2 types of pleura found in the thorax?
Serous membrane
Parietal
Visceral - lines lungs
What makes up the parietal pleura?
Diaphragmatic pleura
Costal pleura
Mediastinal pleura
What is the mediastinum and what does it do?
Central compartment of thoracic cavity, separates the lungs
What is within the mediastinum?
Heart and its vessels Oesophagus Trachea Phrenic and cardiac nerves Thoracic duct (lymphatic) Thumus Lymph nodes of central chest
What is hydrostatic pressure? What happens if hydrostatic pressure is higher in capillaries than it is in ISF?
The pressure exerted by a fluid on its container
Substance filtered out of the blood vessel into ISF
What is bulk flow?
The movement of fluid caused by differences in hydrostatic pressure
What is oncotic pressure?
Osmotic pressure exerted by proteins (mainly albumin)
What is perfusion pressure?
Pressure needed for blood to move through a vessel
What are the main phases of the cardiac cycle?
Diastole - filling of ventricles
Diastasis - initial filling has slowed down, before isovolumetric contraction
Systole - contraction and blood ejection from the heart
The visceral and parietal pleura form a potential space. What is it filled with? What does this do?
Serous fluid
Maintains negative pressure and eliminates friction
What is the equation for cardiac output? How does an increased heart rate affect CO?
Stroke volume X HR
Increases CO, however if too fast not enough time for diastole, reduced oxygen reaching tissues
What is contractility? What is a huge factor in this?
Ability of heart to contract
Calcium ions
End systolic ventricular volume (ESVV) is affected by what 2 factors?
Contractility
Afterload
End diastolic ventricular volume is affected by what 3 factors?
Preload
Diastolic filling time
Compliance
What is preload? What is it equal to?
Filling pressure of the ventricles
Arterial pressure
How is preload increased? (2 ways)
Reduce blood flow to non-essential tissues
Increasing blood volume
What is afterload?
Pressure heart is working against or vascular resistance
How is afterload increased (2 ways)?
When aortic pressure increased (e.g. aortic stenosis)
When vascular system resistance increased e.g. vasodilation
How does an increased afterload affect stroke volume and ESVV?
Decreases SV
Increases ESVV
What veins provide oxygenated blood to the foetus? Where does this blood drain into?
Umbilical veins in allantois
Drains into caudal VC then right atrium
What is the foramen ovale? What does it do?
What happens to it in a neonate?
Hole within interatrial septum
Allows oxygenated blood to pass from right to left atrium
Closes to form fossa ovalis
What is the ductus venosus?
Duct to bypass liver
What is the ductus arteriosus? What does it connect?
Duct to bypass lungs (allows small amount of blood flow for development)
Connects pulmonary artery to aorta
How does the foetus get nutrition?
Yolk sac, via vitelline veins
What cardiovascular changes happen at birth?
Umbilical arteries contract - stop blood flow to neonate and prevent haemorrhage when ruptures
First breath causes drop in resistance to pulmonary circulation and opens capillaries
Decreased right ventricular afterload, increased aortic pressure and left preload - cause septum primum to push against septum secondum and close foramen ovale
Smooth muscle of the ductus arteriosus constricts
What closes the ductus arteriosus and what does this become?
What would happen if the ductus arteriosus remained patent after birth?
Connective tissue closes it to become ligamentum arteriosum
Blood flow other way - too much preload
