Download Physiology, Health & Exercise

Lesson 2
Blood vessels
Cardiac cycle
Heart Sounds
1
Blood vessels
There are three types of blood vessels:
Arteries
Capillaries
Veins
2
Blood vessels
3
Arteries
Carry blood away from the heart
Thick muscular wall to withstand high
pressure of blood
Narrow lumen
Most collagen (tough fibrous protein)tough and durable
Elastic fibres and smooth muscle- allows
stretch & recoil
4
Arteries… cont
No valves
Branch into smaller and smaller vesselsarterioles
Contraction of smooth muscle of arterioles
allows blood to be diverted to different
parts of the body
e.g. fight or flight more blood to skeletal
muscles and less to digestive system
5
Arteries… cont
6
Capillaries
Tiny vessels- 1 cell thick wall 10mm in diameter
Exchange of nutrients and waste with tissues
occurs here
Extensive branching network (capillary bed)
throughout body tissues
Only certain capillary beds open at one time to
allow shunting of blood from one area to
another
7
Capillaries… cont
Most numerous type of blood vessel in the
body
Permeable walls
Carry blood at low pressure and low flow
rate
Reduces fluid loss through permeable
capillary walls
Allows sufficient time for exchange of
8
materials
Veins
Carry blood back to the heart
Thin muscular wall as blood at low
pressure
Wide lumen- reduces resistance to blood
flow
Less collagen, elastic fibres and smooth
muscle
10
Veins… cont
Have valves
Blood at low pressure- return blood
against gravity- so lie close to muscleswhen muscle contract they squeeze the
veins to temporarily increase the blood
pressure
11
Veins… cont
12
14
Describe three things that this graph shows.
Major Blood Vessels
NB heart muscle itself
is supplied with blood by
coronary arteries
16
Cardiac Cycle
A pattern of contraction (systole) and
relaxation (diastole) by heart in 1 heart
beat
Lasts about 0.8 seconds (based on heart
rate of 75bpm)
Chambers alternately contract and relax
Blood always flows towards low pressure
17
Cardiac Cycle…cont
3 phases to the cycle:
1. Atrial systole
2. Ventricular systole
3. Diastole
Decrease in
volume
Increase in
pressure
Blood forced
out
18
Atrial systole
 Blood flows into LA and RA under low
pressure
 LA & RA contract simultaneously
 AV (bicuspid & tricuspid) valves open
 Blood forced into LV & RV
 At this point LV & RV in diastole & SL
valves closed
19
Ventricular systole
0.1 secs later
AV (bicuspid & tricuspid) valves close
Blood forced into LV & RV which contract
& push blood through open SL valves to
arteries
 High pressure in ventricles




20
Diastole
 Atria & ventricles relax
 Elastic recoil of relaxing heart walls
lowers pressure in atria & ventricles
 Blood under high pressure in arteries
drawn back into heart from veins
21
Heart Sounds
 Lub dub
 Lub- closing of AV valves
 Dub- closing of SL valves
 Human heart sounds
 Feline heart sounds
23