The Cardiovascular System Flashcards
Describe the structural arrangement of the walls of the heart and pericardium
- Heart -
3 layers:
-Endocardium (inner layer - epithelium) -Myocardium (middle layer - cardiac muscle)
-Epicardium (outer layer - visceral pericardium. - Pericardium -
‘Sack’ that contains the heart.
Consists of: - Fibrous Pericardium (inelastic sac of fence connective tissue that wraps around heart)
- Serous Pericardium (two layers: paretial and visceral - separated by pericardial cavity which contains serious fluid)
Describe the location of the heart
- Located slightly to he left (2/3) of midline of ribs
- Between 2nd and 5th ribs
- Protected by sternum and ribs
Describe the structural and functional characteristics of the cardiac muscle and the cardiac conducting muscle.
- The Cardiac Muscle -
Forms a branching network of cells which are interconnected by interlaced discs which contain gap junctions. Allow ion transport between cells and promotes coordination contraction. - The Cardiac Conducting Muscle -
Coordinates heart contraction and consists of non-contractile cells that initiate electrical impulses.
Consists of the: sinoatrial (SA) node, atrioventricular (AV) node, AV bundle (of his), right and left bundle branches and purkinge fibres.
Distinguish between pulmonary and systemic circulation
- SYSTEMIC CIRCULATION -
- Delivers blood rich in O2 to most body tissues
- Leaves from left side and returns to right side
- Blood returns low in O2
- Forms an extensive network
- PULMONARY CIRCULATION -
- Delivers blood low in O2 to the lungs
- Leaves from right side, returns to left side
- Blood returns high in O2
- Low pressure system
Discuss how and why the foetal circulation differs from adult circulation
- Foetus receives O2 and nutrients from placenta via the unbiblical cord and needs to bypass the lungs (don’t want foetus to start breathing)
- Ductus Venosus connects the umbilical vein inferior vena cava
- Foramen ovale connects right as left atria
- Ductus arteriosus connects pulmonary artery to arch of aorta
Define the term blood pressure
- The force that the blood exerts on the walls of the blood vessels
What is the different between systolic and diastolic blood pressure?
SYSTOLIC BLOOD PRESSURE (SBP)
- Maximum pressure when ventricles contract
- ~120mmHg
DIASTOLIC BLOOD PRESSURE (DBP)
- Maximum pressure when ventricles relax
- ~80mmHg
Explain pulse pressure and mean arterial pressure (MAP)
PULSE PRESSURE
- SBP minus DBP = ~40mmHg
MEAN ARTERIAL PRESSURE
- DBP and one third of pulse pressure
- 80 + 40/3 = ~93mmHg
What is stroke volume? (SV)
- Volume of blood ejected per best
- ~ 70ml/beat EDV minus ESV
Describe End Diastolic Volume (EDV) and End Systolic Volume (ESV)?
EDV- Amount of blood in the ventricles at the end of diastole - before contraction
~ 130ml
ESC - Amount of blood in the ventricles at the end of systole after contraction
~ 60ml
What is cardiac output (CO)
- The volume of blood expelled by the heart in one minute
- Stroke Volume x Heart Rage
70ml/beat x 75 beats/min - CO = ~5,250ml/min
What is Total Peripheral Resistance (TPR)?
- The pressure in the peripheral vessels, resists flow and changes often according to need.
What is Heart Rate (HR)?
- How fast the heart beats
- ~120bpm newborn, ~64-80bpm in young adults
- Rises with age
What factors affect cardiac output (CO)
- Degree of stretch of myocytes (preload)
- Forcefulness of contraction (contractility)
- Pressure required to eject blood (after load)
What factors affect blood pressure?
- Local control (autoregulation, metabolites and vasoactive chemicals)
- Short-term Mechanisms (neural control, vasomotor centre, cardiac accelerator, cardiac inhibitor centre)