Cardiovascular System Flashcards
What are the three principal components of the cardiovascular circulatory system?
Heart, Blood and Blood Vessels
What is the function of the cardiovascular system impacted by?
The Endocrine system, nervous system and kidneys
What is haematocrit?
Percent of blood volume that is erythrocytes
what is bulk flow?
Rapid flow of blood throughout the body
What are the two ‘loops’ of the cardiovascular system?
- Systemic
- Pulmonary
What does the systemic loop of the cardiovascular system do?
Carries blood from the left ventricle via the aorta, systemic arteries and then microcirculation to the major parts of the body and back to the heart by the vena cava
What does the pulmonary loop of the cardiovascular system do?
Carries oxygen poor blood from the right ventricle via the pulmonary trunk, splitting into the pulmonary arteries
Describe the pathway that blood goes from leaving the heart via the systemic loop, coming back to the heart, then leaving via the pulmonary loop and back
- Left Ventricle
- Aorta
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
- Vena Cava
- Right Atrium
- Right Ventricle
- Pulmonary Trunk
- Pulmonary Arteries
- Pulmonary Arterioles
- Pulmonary Capillaries
- Pulmonary Venules
- Pulmonary Veins
- Left Atrium
What is blood pressure measured in?
mm Hg
What is blood flow measured in?
mL/min
What is resistance, and what is its relationship to blood flow?
Resistance is the measure of friction that impedes flow. Has a negative proportional relationship with flow
What three things contribute to resistance?
- Blood viscosity
- Total blood vessel length
- Blood vessel diameter
what factors affect blood pressure
Volume of blood
Compliance of blood vessels
What is the maximal arterial pressure reached during peak ventricular ejection referred to as?
Systolic Blood pressure
What is the minimal arterial pressure reached just before ventricular ejection referred to as?
Diastolic blood pressure
What is the term used to describe the difference between Systolic and diastolic bp?
Pulse pressure
What is the function of arterioles regulated by?
Neural, hormonal and local chemicals
what are the two functions of arterioles?
- Constriction, to divert blood away from tissues
- Dilation, to increase blood flow to tissues
What changes are detected locally to cause active hyperaemia in an organ?
- Decreased O2 and increased CO2
- Increased K+
- Inreased NO2
- Increased H+
- Increased Adenosine
What is reactive hyperaemia?
Huge increase in blood flow after complete occlusion
What hormones are responsible for extrinsic control of arteriole resistance?
Epinephrine (dilates or constricts) Angiotensin II (constricts) Vasopressin (constricts)
What extrinsic factors apart from hormones can affect arteriole resistance?
Sympathetic nervous system action
What are the three types of capillary?
- Continuous
- Fenestrated
- Sinsuoidal
What are continuous capillaries?
- Found in skin and muscle.
- Most common
- Have tight junctions
What are fenestrated capillaries?
More permeable, found in intestines and hormone producing tissues
What are sinusoidal capillaries?
Incomplete basement membrane, Found in liver, bone marrow and lymphoid tissue
What is the process of capillary growth called?
Angiogenesis
What are the endothelial cells of the capillary wall separated by?
Water filled Intercellular clefts
What does blood enter capillaries via?
Metarterioles?
What is at the boundary between metarterioles and capillaries?
Precapillary sphincters
What is a benefit of the slow movement of blood through the capillaries?
Maximises time for substance exchange
What are the three mechanisms allowing substance exchange between the plasma and ISF?
- Diffusion
- Vesicle transport
- Bulk flow
What are the two major functions of veins?
- Serve as low pressure conduits to return blood to heart
- Maintain peripheral venous pressure
What are the factors determining venous pressure?
- Amount of blood in veins
- Compliance of walls
What three mechanisms propagate blood flow through the veins?
- Norepinephrine facilitated smooth muscle contraction
- skeletal muscle pump
- respiratory pump
What does the sympathetic nervous system innverate in the cardiac cycle, and via what neurotransmitter?
Entire heart muscle and node cells, via norepinephrine
What does the parasympathetic nervous stem innverate in the cardiac cycle, and via what neurotransmitter?
The node cells, via acetylcholine
Explain the pathway that an action potential takes in the cardiac cycle, starting at the Sinoatrial Node
- SA Node
- Atrial muscle
- AV Node
- Bundle of HIS
- Left/Right bundle branch
- Left/right Purkinje fibres
- Ventricular muscle cells
What type of ion channels cause depolarisation of myocardial cells?
Voltage Gated L-type CA2+ channels
