Studied by 42 people
Does the CV system help regulate temperature?
Yes
What are the components of the CV system
Heart Blood vessels Blood
What are the 5 divisions of the CV system?
Systemic, Pulmonary, Cerebral, Coronary, Portal
The coeliac trunk (abdo aorta) branches into the
common hepatic artery and splenic arteryT
The common hepatic artery and splenic artery supply what with blood?
Most of the organs
Venous blood is passed from where to where
capillary bed to abdominal part of the digestive system
How many times a day does the heart beat?
100,000
How far does blood travel approximately?
12,000 miles
What shape is the heart?
A hollow cone shape
Where does the heart live?
MediastinumA
At what angle does the heart lie?
Oblique
How tall is the typical adult heart?
12.5cm (base-apex)
How much does the average female heart weigh?
225-300gH
How much does the average male heart weigh?
300-350g
In what cavity is the heart found?
Thoracic
Where does the base of the heart sit?
Posterior to sternum at 3rd costal cartilage
How many chambers are there in the heart?
4
What are the 2 top chambers of the heart called?
atria
What are the two bottom chambers of the heart
ventricles
Which set of chambers has larger muscle?
Ventricles
What is the biggest heart chamber?
Left Ventricle (LV)
What ensures there is no backflow of blood
Valves
What are the valves called?
Tricuspid Pulmonary Mitral Aortic
What prevents the heart from turning inside out?
Tendinae and papillar muscle
What are the layers of the heart?
Pericardium Epicardium Myocardium Endocardium
What are some characteristics of the pericardium
Fibrous sac Outer surface Adheres to diaphragm Prevents over distension
How much space is in the pericardial cavity
15-50ml
Properties of epicardium
thin and transparent
The Myocardium is a muscle
True
Where is the myocardium the thickest?
around the left ventricle
Cardiac myocytes are interconnected by
intercalated discs
How does the myocardium contract?
Impulses that spread from cell to cellIf
If the myocardium impulses aren't strong, does the heart still contract?
No
Do the atria and ventricles conduct impulses?
no
The endocardium is
the inner layer, continuous with valves and blood vessels
What are 4 characteristics of cardiac cells?
Automaticity Excitability Conductivity Contractivity
How is cardiac output calculated?
Stroke volume (SR) x Heart Rate (HR)
If SV = 70, and HR = 72. What is the cardiac output?
5,040ml
The Frank-Starling law refers to
Ability of heart to change its force of contraction
The frank starling law allows for stroke volume to respond to changes in
venous return
What nervous system does the heart respond to?
autonomic nervous system
The state of relaxation in cardiac muscle is known as
refractory period
What is the conduction systems order?
SA Node AV Node Bundle of HIS R/L bundle branches Purkinje fibres
The SA node is a group of
specialised cells
The SA Node can be found
R atrium, near opening of superior vena cava
What is the firing rate of the SA node
60-100BPM
What does the cardiac cycle start with?
SA Node
Can the SA node be sped up or down?
Yes
What is the AV nodes natural rate?
40-60BPM
Where is the AV node located?
Above divide between atria and ventricles on septal wall
If the SA node fails, what steps in?
AV Node
The AV is influenced by the ANS
true
The bundle of his runs
from AV node to lie within ventricular septum
Purkinje fibres spread from base of septum into
myocardium of ventricles
The purkinje fibre rate is
20-40bpm
A P wave represents
Atrial contraction SA Node firing off
PR interval represents
AV holding onto SA node. Can be 1st degree heart block
QRS =
Ventricle contraction
T wave=
Repolarisation
What can alter the hearts rate of contraction
sympathetic and parasympathetic nerves
What role does the vagus nerve have in parasympathetic response
slow the heart down and reduce force of contraction
The sympathetic nerve increases
irritability of myocardium and produce premature ventricular contractions
What are some impulses on heart rate
Higher centres (emotions) Respiration (deeper) Baroreceptors in carotid stimulus Anoxia Temperature rise Endocrine activity
What are the types of blood vessels?
Arteries, Arterioles, Capillaries, Venules, Veins
How many layers does an artery have?
3
What is the middle arterial layer called?
Tunica media
The tunica media is
smooth muscle and elastic connective tissue
The external arterial tissue is called
tunica adventitia
The internal arterial tissue is called
tunica intima
Large arterioles are similar to
arteries
As arterioles reduce in size they have
layer of endothelium and few scattered muscles
Arterioles regulate
blood flow to the capillaries
Similarities between arterioles + arteries
Thick walled Large amount of elastic fibres Allows stretch during systole Allows recoil They act as a control valve for blood entering the capillaries
How many capillaries do we have
10 billion
Lipid soluble diffuse through
capillaries
Water soluble materials leave and enter via
pores
When capillaries unite they form
venules
Venules lead to veins which
return blood to the heart
Venules and veins are
distensible collapsible capable of enlarging and storing large quantities
What is the makeup of blood?
45% formed elements 55% plasma
Average blood volume for a male is
6L
Average blood volume for a female is
5L
adult SV is
70ml/kg
paed SV is
80ml/kg
What are some functions of blood
Transport O2 and CO2 Carry nutrients Movement of hormones Regulates pH WBC fight infection Protection via clots
The average blood pH is between
7.35-7.45
Platelets are replaced....
Continuously
How long do platelets live for?
9-12 days
What shape are platelets when they aren't active
disc shaped
When platelets are active they are
Spherical and spikey
Where are platelet reserves stored?
In the spleen
Note 
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