Summary
Summary of Cardiac Physiology
- Course
- HUB2021S
- Institution
- University Of Cape Town (UCT)
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Cardiac PhysiologyCARDIAC PHYSIOLOGY.................................................................................................................................. 1
THE BLOOD................................................................................................................................................... 2
FUNCTION............................................................................................................................................................2
COMPOSITION.......................................................................................................................................................2
Erythrocytes (Red Blood Cells):.......................................................................................................................3
Blood Plasma:.................................................................................................................................................3
The Buffy Coat................................................................................................................................................4
Leukocytes:.....................................................................................................................................................4
Platelets:.........................................................................................................................................................5
Maintenance of normal blood O2 levels:.......................................................................................................5
HEMATOPOIESIS....................................................................................................................................................5
HEMOSTASIS.........................................................................................................................................................6
THE HEART.................................................................................................................................................... 7
ANATOMY OF THE HEART........................................................................................................................................7
Size, Location, and orientation:......................................................................................................................7
Pericardium....................................................................................................................................................7
Heart Wall......................................................................................................................................................8
Chambers........................................................................................................................................................8
Pulmonary circulation.....................................................................................................................................8
Systemic circulation:.......................................................................................................................................9
Valves:............................................................................................................................................................9
Coronary Circulation.....................................................................................................................................10
PHYSIOLOGY OF THE HEART...................................................................................................................................10
Cardiac Cycles...............................................................................................................................................10
Heart Sounds................................................................................................................................................11
Electrical Activity..........................................................................................................................................11
Electrocardiogram........................................................................................................................................13
......................................................................................................................................................................13
THE VESSELS............................................................................................................................................... 14
ANATOMY OF VESSELS..........................................................................................................................................14
Walls of arteries and veins...........................................................................................................................14
Arteries.........................................................................................................................................................14
Capillaries.....................................................................................................................................................15
Venous circuit...............................................................................................................................................16
PHYSIOLOGY OF CIRCULATION: BLOOD PRESSURE.......................................................................................................17
Arterial Pulse:...............................................................................................................................................17
Blood pressure..............................................................................................................................................17
Regulation of blood pressure:......................................................................................................................17
Control of stroke volume:.......................................................................................................................................17
Control of heart rate:..............................................................................................................................................18
Control of peripheral resistances:...........................................................................................................................18
Hypertension vs hypotension:.................................................................................................................................20
, Cardiac Physiology
Circulatory system
Cardiovascular system + Lymphatic system
Heart: a transport system Lymphatic vessels
Vessels: the delivery route Lymphoid tissues
Blood: the transport medium
The Blood
Function
1. Transportation:
o Respiratory substances essential for metabolism (O2, CO2 etc.)
o Nutritive – carries products of digestion to cells and liver
o Excretory – Metabolic waste carried in blood
2. Regulation:
o Hormonal – carries hormones from site of origin to distant target organs
o Temperature – can be regulated by diversion of blood from deeper to more
superficial cutaneous vessels and vice versa.
Diversion of blood from superficial to deeper vessels will help keep
the body warm when environmental temperature is low (That’s why
you go blue).
3. Protection:
o Clotting – protects from blood loss
o Immunity – protects from foreign microbes etc.
Composition
- Sticky opaque fluid
- Metallic and salty taste
- Color: Scarlet (oxygen rich) to dark red (oxygen poor)
- pH: 7.35-7.45
- Temp: 38 degrees Celsius (slightly higher than body temp)
- Represents 8% of body weight (
o 5-6L in men, 4-5L in females)
- Contains both cellular and liquid components
- Living cells suspended in a non-living fluid matrix (the plasma)
- Can be separated into layers by centrifugation
, Cardiac Physiology
Erythrocytes (Red Blood Cells):
- Heavier ‘red’ substances at the bottom of centrifugation.
- ±45% of total volume of blood
- Hematocrit: percentage of erythrocytes in blood volume
o In healthy male = 47% ± 5%, in female = 42% ± 5%.
- Lifespan: ±120 days
- Flattened, bi-concave disc of ±7 μm in diameter, 2.2 μm thick
o Important because diameter of vessel must be at least 7 μm thick for
erythrocyte to travel through
- Mature erythrocyte has no nuclei and no mitochondria
- Erythropoietin: Hormone released from kidney that stims erythrocyte production
(erythropoiesis)
- Hemoglobin:
o Gives erythrocyte red color
o ±65% of iron supply in body is in hemoglobin
- Transferrin: Because iron is toxic it is transported via this transporter protein.
- Anemia (‘lacking blood’): Condition where blood has abnormally low O2 carrying
capacity.
o Could be due to lack of erythrocytes
o …or low hemoglobin content (could result from inadequate intake of Fe
containing foods, or because of impaired Fe absorption)
o …or from abnormal hemoglobin (genetic origin)
- Thalassemia: Disease where 1 globin chain in hemoglobin is absent/faulty resulting
in hemoglobin not being able to carry enough O2
Blood Plasma:
- Lighter plasma at the top of centrifugation
- ±55% of total volume of blood
- Contains all the proteins in the blood (8% plasma volume)
- 90% water
- Albumin:
o 60% of the plasma proteins
o Produced in liver
o Carry certain mols through circulation (i.e. major protein contributing to
plasma osmotic balance)
- Globulins ( ∝ , β , γ ):
o 36% of all plasma proteins
o Produced in liver
o Transport lipids & fat soluble vitamins
o γ functions in immunity
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