The Heart - Hrsbstaff.ednet.ns.ca
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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???