A&P 4

Cardiovascular system

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