Download Heart

CIRCULATORY SYSTEM
Protists, Sponges, Cnidarians: no circulatory system
Small-bodied, submerged in water
Use simple diffusion for gas exchange
Open circulatory systems:
Organs submersed in pool of blood: blood sinus
Simple tubular heart
E.g., gastropod mollusks, arthropods
Closed circulatory systems:
Organs imbedded in network of fine vessels
Capillary bed
Blood cells always contained within vessels
E.g., earthworms, vertebrates
Hearts
Arteries:
Carry blood
Away from heart
Veins:
Carry blood
toward heart
Capillaries:
Gas
exchange
Closed systems can have high blood pressure
Enables faster delivery of O2 and nutrients
Hence, enables more active life:
Gastropod mollusks - snails – open system
Cephalopod mollusks – octopuses - closed
Mammal/bird circulatory system
pulmonary
atria
ventricles
Double circuit:
septum
Pulmonary (lung), & Systemic (body)
4-chambered heart
systemic
2 atria & 2 ventricles
Oxygen-rich & O-poor blood completely isolated
Septum separates ventricles
Oxygen-rich vs. O–poor blood
Fish heart
2-chambered
Amphibian heart
3-chambered
Circulation
Distinguish between:
1) Pulmonary/systemic
2) Venous/arterial
3) O-rich/O-poor
Internal anatomy of the mammalian heart
vena cava
(from systemic)
semilunar
valve
right atrium
right
ventricle
aortic arch
(to systemic)
pulmonary
artery
pulmonary
vein
left atrium
atrioventricular
valves
left
ventricle
septum
Physiology of the mammalian heart
Heart contraction:
Nerve nodes within heart initiate muscle contraction
Nerve pulse is electrical
Brain hormones only influence
Atria first
Atrio-ventricular
node
Then ventricles
Contracts from top to bottom
Sino-atrial
node
Heartbeat cycle
Systole: contraction phase
systole
1) Atria contract
Blood forced into ventricles
2) Ventricles contract
AV valves forced shut
“Lub” of lub-dub sound
Blood forced into arteries
Diastole: relaxation phase
diastole
3) Ventricles relax
Semilunar valves close
from arterial pressure
“dub” of “lub-dub”
Blood enters ventricles
from atria
Diastolic pressure: the
pressure in blood vessels
when the heart is relaxed
Blood pressure drops at capillaries
EKG (ECG): Electrocardiogram
Graph of electrical activity of heart
1) P-wave
Contraction of atria
2) QRS-complex
Relaxation of atria
Contraction of ventricles
3) T-wave
Relaxation of ventricles
Seconds
Healthy heart:
Correct & consistent timing
Correct & consistent amplitude
Heart attack
See lab manual for risk factors
Coronary artery
Supplies O2 &
nutrients to heart
Atherosclerosis:
Accumulation of lipids in blood vessels
Especially Low Density (LD) cholesterol
Measuring blood pressure
1.
2.
3.
4.
5.
Close valve gently
Inflate cuff to 140
Have stethoscope in place
Open valve SLIGHTLY, until needle starts to move
Observe where needle begins to pulse
Should also hear pulse at this time
This is systolic pressure
6. Watch for the needle to quit pulsing
Pulse sound should also go away
This is diastolic pressure
Blood pressure = systolic / diastolic
Normal = ~120/80
Heart dissection
sulcus (fat)
lies over septum
right ventricle
(thin wall)
left ventricle
(thick wall)
plane of
dissection
aortic
semilunar
valve
right
ventricle
left atrium
atrioventricular
valve
left
ventricle