Lecture 8 - Cardiovascular System Flashcards
What is the function of the Cardiovascular system impacted by
Endocrine System
Nervous system
Kidneys
What are the 2 loops in the cardiovascular system
Systemic
Pulmonary
What does the systemic loop do
carries blood to from the heart to themajor parts of the body and back to the heart
Blood leaves the left ventricle via the aorta
Branches to form systemic arteries
Branch to form the microcirculation: Arterioles, capillaries, venules
What do the venules that form veins ultimately form
Inferior Vena Cava - Collects blood from below heart
Superior Vena Cava - Collects blood from above the heart
What is the job of the Pulmonary loop
carries oxygen-poor blood to the lungs and
back to the heart.
Blood leaves right ventricle: pulmonary trunk
Dividing into pulmonary arteries – take blood to both lung
What are the 5 types of blood vessels
Arteries
Arterioles
Capillaries
Venules
Veins
What is the exception to the rule “arteries carry oxygenated blood and veins carry deoxygenated blood”
the pulmonary arteries
- carry deoxygenated blood to the lungs
- here they collect oxygenated blood and
- the pulmonary veins carry oxygenated blood to the heart
What is the pressure in a blood vessel
Pressure is the force exerted and we measure this in mm Hg
What is flow in blood vessels
Flow is the volume moved and it is measured in mL/min
What is the resistance in a blood vessel
Resistance is how difficult it is for blood to flow between two points at any given
pressure difference
What are 3 things that contribute to the resistance in blood vessels
Blood viscosity
Total Blood Vessel length
Blood Vessel diameter
Where are elastic/conduit arteries located
These vessels are near the heart and carry blood for
circulation eg. the aorta
What are some features elastic/conduit arteries
Large lumen vessels (low resistance) that contain more elastin
than the muscular arteries.
Allows them to be “pressure reservoirs”
‒ expand and contract (recoil) as blood is ejected by the
heart. This allows blood flow to be continuous.
What are muscular arteries and their key traits
These arteries deliver blood to specific organs (mesenteric artery, renal artery etc.).
They have proportionally the most smooth muscle and are very active in vasoconstriction.
These arteries can play a large role in the regulation of blood pressure
What is compliance
how easily a structure stretches
What are some factors affecting pressure in an elastic container
How much water you put in it
How easily the walls of the balloon (eg.) can stretch
What is systolic blood pressure
Maximal arterial pressure reached during peak ventricular ejection
What is diastolic blood pressure
Minimal arterial pressure reached just before ventricular ejection
What is pulse pressure
Difference between systolic and diastolic pressure
What is intrinsic tone
Arterioles have basal level of contraction
How is smooth muscle regulated
Autonomically by local or extrinsic control
How does the dilation/contraction of arterioles affect minute-to-minute blood flow
If they contract, blood flow is diverted away from their tissues
If they Dilate, then blood flow to the tissue increases
What is an example of local control of resistance
Response to local metabolic or local blood flow changes
eg.Blood flow increases to an organ due to an increase in metabolism (eg. exercising skeletal muscle)
Response to injury - local inflammation Is characterised by increased blood flow
What are some examples of extrinsic control of resistance
Hormones
Sympathetic nerves
What does Epinephrine do
vasodilates or constricts
depending on the tissue
What does angiotensin II do
Constricts most arterioles
What does Vasopressin do
Constricts most arterioles
What is the affect of symapthetic nerves on arterioles
Always some sympathetic tone, this can be
reduced resulting in vasodilation, by
withdrawing sympathetic activity
What are the 3 types of capillary
Continuous capillary: found in skin, muscle, most
common kind have tight junctions.
Fenestrated capillary: more permeable —
intestines, hormone-producing tissues, kidneys,
etc.
Sinusoidal capillary: only one with an incomplete
basement membrane; these are found in the liver,
bone marrow and lymphoid tissues.
What is angiogenesis
Capillaries develop and grow (through muscle adaptation or tumours)
What does VEGF do
Increase endothelial growth - released by vascular endothelial cells
What is a precapillary sphincter
The site at which a capillary
exits from a metarteriole is
surrounded by a ring of
smooth muscle,
In some tissues, what does blood enter through to reach the capillaries
metarterioles
How does the slow forward movement of blood through the capillaries help the human body
maximises the
time for substance exchange across the
capillary wall
What are the major functions of veins
Act as low pressure conduits returning blood to the heart
Peripheral venous pressure
What are the factors determining venous pressure
Amount of blood in veins
Compliance of walls
What is the pressure in the veins
(10-15mmHG)
(Right atrium is 0 - creates pressure differential drawing blood up)
What is the pericardium
Muscular sack enclosing heart
What is the Epicardium
Fixes inner layer of pericardium to the heart
What is the myocardium
Muscular wall of the heart formed from cardiac muscle cell (hypertrophic cardiomyopathy)
What is the atrioventricular system
Muscular wall separating the ventricles
What do the Atrioventricular valves do
Permit flow from atrium to ventricle but not backward
What is hypertrophic cardiomyopathy
Disease in which the heart muscle becomes thickened
Where is the pulmonary semi lunar valve
Blood from right ventricle to pulmonary trunk
Where is the aortic semi-lunar valve
Blood from left ventricle to aorta
What are chordae tendinae
fasten
AV valves to the papillary
muscles
What are Papillary muscles
Do not
open or close the AV
valves, but limit
movement to prevent
backward flow of blood. (pressure changes do)
Why does cardiac muscle have large mitochondria
produce the energy
needed and prevent the heart
from fatiguing.
What do cardiac muscle cells do
Branching cells with gap junctions that are critical
to the hearts ability to be
electrically stimulated.
What are node cells (cardiac muscle)
have the ability
to stimulate their own action
potentials. This is called
automaticity or auto-
rhythmicity (“pacemarker
potential”, constant rhythm of
electrical activity)
How does the sympathetic nervous system innervate the heart
innervates the entire heart muscle and node cells
and release norepinephrine (increases heart rate)
How does the parasympathetic nervous system innervate the heart
innervates the node cells and release
primarily acetylcholine (slows down heart rate)
What is the depolarisation ordering
Sinoatrial node - Atrial muscle cell - atrioventricular node - Bundle of His - left and Right bundle branches - L and R Purkinje fibres - Ventricular muscle cells
How does the wave of depolarisation from the SA node travel
Through the internodal pathway (via gap junctions) to the atrioventricular node
Signal is delayed 0.1s to allow atria to contract and totally fill ventricles
What is the QRS complex a result of
The ventricular depolarisation and precedes ventricular contraction
What is the P wave (ECG)
Result of depolarisation wave from the SA node to the AV node. Atria contract
0.1 second after P wave starts.
What is a T wave (ECG)
caused by ventricular depolarisation
What is cardiac output
amount of blood pumped out of each ventricle in one minute
What is stroke volume
Stroke volume is the difference between end diastolic volume and the end systolic volume
How do you calculate Cardiac output
CO = HR (bpm) x Stroke Volume
How do you calculate Stroke volume
SV = End Diastolic Volume - End systolic volume
What is the Frank Starling mechanism
the ventricle contracts more forcefully during systole when it has been filled to a greater degree during diastole
What is contractility
The strength of a contraction at any given end-diastolic volume
(increased by Norepinephrine, adrenaline or plasma epinephrine)
How do you calculate mean arterial pressure
MAP = Diastolic pressure + 1/3 (Systolic pressure − diastolic pressure)
What is mean arterial pressure dependant on
Mean arterial pressure = Cardiac Output × Total Peripheral Resistance
What do arterial baroreceptors respond to
Changes in arterial pressure - degree of stretching is directly proportional to blood pressure
what are baroreceptors controlled by
Medulla oblongata
What does increased firing of baroreceptors lead to
LOWER sympathetic outflow to heart, arterioles,
veins and an HIGHER parasympathetic outflow to heart
How do you treat hypertension
Diuretics
beta blockers
Calcium channel blockers
ACE inhibitors
What do the intra-renal baroreceptors do
detect changes in stretching with due
to lower blood volume which stimulates an increase
in the production of renin
Where are Angiotensin-converting enzymes (ACEs) found
Endothelial cells
What is aldosterone
slow-acting steroid hormone that
stimulates sodium reabsorption by kidney tubules
What is vasopressin (anti-diuretic)
rapid-
acting peptide produced by the pituitary gland
which stimulates water reabsorption
What does Atrial Natriuretic Peptide (ANP) do
- Inhibits sodium reabsorption by kidney tubular cells
- Acts on renal blood vessels to increase filtration rate
causing sodium excretion - Inhibits the action of aldosterone
Independent learning task - 367-370
