Cardio Flashcards
(36 cards)
Blood is —% cellular and —% plasma
45% cellular and 55% plasma
What is blood plasma made up of?
Water and proteins (eg albumin, coag factors, immunoglobulins)
Definition of haematocrit
The percentage of RBCs in the cellular component of blood
RBC: site of production, life span and regulatory hormone
- Adults- bone marrow of axial skeleton
- Children- All bones
- Foetus- liver, spleen & yolk sac
- life span: 120 days
- regulated by erythropoeitin (prod by kidney and liver)
Platelets: site of production, life span and regulatory hormone
- Derived from megakaryocytes in bone marrow
- 7-10 days
- Thrombopoietin (prod by liver and kidneys)
Neutrophils: features, function, life span, prevalence
- Multi-lobed nucleus
- Early phagocytosis of a pathogen
Involved in acute inflammation - ~10 hours
- 40-60% of leukocytes
Eosinophils: features, function, life span, prevalence
- Bi-lobed nucleus, very eosinophilic (Pink), “Lozenge-shaped nucleus”, distinctive granules
- Combat parasites & involved in allergies
Neutralises histamine (antagonist to basophils & mast cells) - 8-12 hours
- 1% of leukocytes
Basophils: features, function, life span, prevalence
- Bi-lobed nucleus, very prominent dark blue granules of histamine
- Involved in allergic reaction & inflammation
Histamine (antagonist to eosinophils) - 8-12 hours
- 0.5% of leukocytes
Monocytes/ Macrophages: features, function, life span, prevalence
- Reniform (kidney bean-shaped) nucleus
- Monocytes differentiate into macrophages which then become tissue-resident
Major phagocytotic role
Can become antigen-presenting cells - 8-12 hours
- 2-10% of leukocytes
Lymphocytes: features, function, life span, prevalence
- ”Fried egg appearance”, can be B or T lymphocytes
- B lymphocytes > Plasma cells/ memory cells & produce antibodies
T lymphocytes > Thelper (CD4 & CD8), Tcytoxic (Tkiller), Tsuppressor - 8-12 hours
- 20-40% of leukocytes
3 main coagulation mechanisms
- Vascular constriction
- Platelet plug formation
- Clot formation
Cardiac Output definition
The amount of blood ejected by each ventricle per minute. CO = SV * HR. ~5-6 L/min
Stroke Volume definition
The volume of blood ejected by each ventricle with each beat ~70 mL
End-Diastolic Volume definition
Volume of blood in each ventricle at the end of diastole ~130 mL
Ejection Fraction
Percentage of end-diastolic volume ejected with each beat. SV/EDV. 65%.
End-systolic volume definition
Volume of blood remaining in each ventricle at the end of systole ~50 mL.
Factors affecting Cardiac Output
- Exercise
- Emotions
- Pregnancy
- Posture
- Sweating
- Age
- Gender
3 factors affecting stroke volume
- end-diastolic volume (preload)
- myocardial contractility
- afterload
Describe Frank-Starling Law
- Within PHYSIOLOGICAL LIMITS, the force of contraction is directly proportional to initial length of muscle fiber
- Increased EDV=Increased fiber length=Increases force of contraction=Increases stroke volume=Increases cardiac output
Describe effect of myocardial contractility on stroke volume
- More ventricular muscle mass=increased contractility=increased stroke volume (Athletes)
- Sympathetic stimulation increases ventricular contractility
- Hormones- catecholamines, acetylcholine, thyroxine
- Drugs/ chemicals- caffeine, digitalis
Afterload definition
Force against which ventricles contract/eject (peripheral resistance)
Describe effect of afterload on stroke volume
- peripheral resistance depends on vessel diameter and blood viscocity
- vasoconstriction/ increased viscosity = increased peripheral resistance = decreased SV (and vice versa)
Why doesn’t increased HR always increase CO?
- In tachycardia, duration of diastole SHORTENS, meaning ventricles have less time to be filled= EDV decreases/does not increases as much AS EXPECTED
- Conversely in bradycardia, diastole prolongs= EDV does not decrease as much AS EXPECTED= compensates to maintain CO
What is the primary pacemaker and its rate of discharge?
SA node = primary pacemaker (60-100/min)
