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The Heart
Circulatory System
Ms. Lowrie
Advanced Biology 11
7.5 – The Mammalian Heart

Muscular pump

In circulatory system
Technically:
 Two parallel pumps


Synchronized
Separated by a thick
wall of muscle

Septum
Two Pumps
Left Side


Left atrium & ventricle
Systemic circulation:



Receives oxygenated
blood from lungs
Sends to body tissues
and cells
Think: BODY!
Right Side


Right atrium &
ventricle
Pulmonary circulation:

Receives deoxygenated
blood from body
Sends to lungs

Think: LUNGS!

Heart Chambers

Four chambers or “rooms”


Two atria and two ventricles
Atria



Thin walls
Receive blood
from veins
Pump blood to
ventricles

Ventricles



Thick walls
Receive blood from atria
Pump blood out of heart

To body or lungs
Blood Flow in Heart
Into heart
Like the alphabet …
Atria
A comes before V
Ventricles
Leaves heart
The heart has valves too!?

Just like veins!

Prevents backflow of blood

Atrioventricular (AV):


Between artia & ventricles
Semilunar:

Between ventricles & arteries
Major Veins & Arteries

Vena cava are VeINs
 Come INto heart
from body

Aorta is an Artery
 Go Away from
heart to body

Superior vena cava

Aorta


From upper body
Inferior vena cava



From lower body
Descending aorta


To upper body
To lower body
Coronary arteries

Supply heart with
oxygen and nutrients
Label Heart Diagram (pg 257)
(from
upper
body)
(to upper body)
L pulmonary vein
semilunar
AV
R atrium
semilunar
AV
(from lower
body)
(to lower body)
Task

Use notes & pages 256–258 & 261–262

Answer:



A: Practice Questions: #1-4 (pg 258)
B: Practice Questions: #2, 3 (pg 263)
C: Section Questions: # 1, 5 & 6 (pg 263)
Questions?
Blood Flow in the Heart
Grab blue & red colouring
utensils!
7.6 – Setting the Heart’s Tempo

Cardiac muscle is different from skeletal
muscles

Composed of myogenic muscle

Muscles that contract without external nerve
stimulation
The Heart’s Tempo

“Node” = bundle of specialized nerves

Sinoatrial (SA) node



Located where vena cava enter right atrium
Acts as pacemaker
Sends nerve impulse
to AV node

Atria contract
The Heart’s Tempo (cont.)

Atrioventricular (AV) node


Located at AV valve in right atrium
Sends nerve impulse through septum to
ventricles
Through Purkinje fibres
 Ventricles contract

Heart Rate & Communication

Controlled by autonomic nervous system

Sympathetic nervous system:

Increases rate under stress


Prepares for increased energy demands
Parasympathetic nervous system:


Decreases rate after stress
Controls rate during rest
Electrocardiogram (ECG)

Electrical impulses displayed on a graph
P wave = atrial contraction
 QRS wave = ventricular
contraction
 T wave = ventricular
recovery
 Flat lines = @ rest

Abnormal ECG

What has gone wrong?
normal ECG
7.7 – Heart Sounds

lubb-dubb caused by heart valves closing

Diastole (relaxation):




Atria fill with blood & contract
AV valves open
Blood enters ventricles & contract
AV valves close


lubb
Blood pushed into
arteries through
semilunar valves
Heart Sounds

Systole (contraction):



Ventricles relax & increase in volume
Blood drawn toward ventricles from arteries
Semilunar valves close


dubb
Blood stays in arteries
7.8 – Blood Pressure

Measured by a sphygmomanometer

“Blood pressure cuff”
Blood Pressure (cont.)

Measures 2 pressures:



When ventricles contract (systolic)
When ventricles relax (diastolic)
Normal blood pressure = 120/80


Systolic = 120mm Hg
Diastolic = 80mm Hg
Blood Pressure Can Change

Varies by artery

Decreases with distance from ventricles
Blood Pressure Regulation
1.
Cardiac output

2.
Any increase = increase blood pressure
Arteriolar resistance

Arteriole diameter:


Constriction (more blood in artery)
 Increase blood pressure
Dilation (less blood in artery)
 Decrease blood pressure
Blood Pressure Regulation
(cont.)

If CO2 & lactic acid build-up


Anaerobic respiration
Smooth muscles relax

Arterioles dilate

Delivers more oxygen
to tissues

Homeostasis!
Blood Pressure Problems
If too low:
 Reduces capacity to
move blood


Circulation problems
Adjustment:

Sympathetic (speed up) increased


Cardiac output increased
Arterioles constrict

Decrease outflow from arteries
Blood Pressure Problems
If too high:
 Can weaken artery


May rupture vessel
Adjustment:


Sympathetic (speed up) decreased
Parasympathetic (slow down) increased


Cardiac output decreased
Arterioles dilate

Increase outflow from arteries
Concept Map
Use terms:
1.
2.
3.
4.
5.
Capillaries
Diastolic
Heart
Pulmonary artery
Pulmonary vein
6.
7.
8.
9.
Sphygmomanometer
Systolic
Vein
Vena cava
Any Questions???