Circulation

1
Circulation

• Biology 11
• S. MacInnes

2
Interesting Facts

• A heart beats about 100,000 times a day and 35
  million times a year.
• In one day, the heart pumps nearly 7200 litres of
  blood. In a 70-year lifetime, it pumps about 185
  million gallons.
• An aorta is almost the diameter of a garden hose,
  but it takes ten capillaries to equal the
  diameter of a strand of human hair.
• There are 100,000 km of blood vessels in each
  human!
• In ancient times, the heart was given special
  importance. The Chinese considered that happiness
  originated in the heart, and the Egyptians
  considered the heart to be the source of
  intelligence and emotion.
• Heart cells can beat on their own without
  intervention from the brain.
• No cell in your body is further away than 2 cells
  from a blood vessel
• You have 96,000 km of blood vessels to sustain
  your 100 trillion cells
• Your heart is no larger than the size of your
  fist with a mass of about 300 g
• Your heart beats about 70 times a min from the
  day you are born until you die
• If you could stretch out all your blood vessels
  there is enough to go around the world twice.

3
THINK!

• Small unicellular organisms do not need a
  circulatory system. Why do larger organisms need
  one?
• HINT Think surface volume ratio.

4
The Importance of Circulation

• Unicellular organisms do not need any specialized
  system to transport nutrients, wastes and gases.
• The cells of unicellular and simple multicellular
  organisms are never far away from the organisms
  surroundings (from where nutrients, gases, etc.
  come from)
• The cells of larger organisms are too far away
  for such substances to diffuse to/from all cells.
  Therefore, a specialized transport system is
  required.

5
Transport in AnimalsOpen vs. Closed Systems

• Most animals have evolved specialized systems to
  transport gases, nutrients and metabolic wastes.
• These systems in animals have two essential
  parts
• 1. circulatory fluid (blood)
• 2. a pump (heart or other muscular structure)
• Some animals have blood vessels (optional)
• if vessels are present ? closed transport
  system.
• if absent ? an open transport system

6
Transport in Animals- Open Systems

• Open System Ex grasshopper
• not true circulatory systems
• from the action of muscular movements, the blood
  circulates into open spaces and surrounding
  organs. Blood bathes cells directly in order for
  transport of nutrients etc.
• openings in the heart allow blood to enter.
• the blood carries mainly food nutrients and
  metabolic wastes.
• not very efficient movement of blood is slow and
  under low pressure.
• in insects, the blood does not carry oxygen.
  There is a separate tubular system for this.
• wing movement (muscles) of flying insects speeds
  up blood flow.

7
Transport in Animals- Closed Systems

• only closed transport systems ? true circulatory
  systems. Blood is contained within blood vessels.
• closed systems can be simple or complex.
• efficient.
• ex. An earthworms transport system represents
  the most basic of true circulatory systems
• muscle movement from locomotion (movement) helps
  to keep blood flowing.
• earthworms have five pairs of pumps, aortic
  arches (simple hearts)
• flow of blood in earthworm
• pump contracts ? blood pumped into a ventral
  (belly side) blood vessel ? blood flows into
  dorsal (back side) blood vessel ? blood returns
  to heart
• blood can only move in one direction.

8

• Closed system

• Open system

9
Earthworms Five Hearts
10
The Human Circulatory System
11
Purpose of the Circulatory system

• Transport!
• To bring oxygen and nutrients to the cells
• To take away wastes (For ex CO2) from the cells
• To facilitate the immune system

12
Components of The Human Circulatory System

• Heart, blood vessels, blood

13
...Components of The Human Circulatory System

• Blood Vessels
• arteries
• take blood from heart.
• not always rich in O2.
• size 25 mm (aorta) to 0.5 mm.
• branch into smaller arteries called arterioles (lt
  0.5 mm). arterioles contain smooth muscle that
  regulates blood pressure.
• elastic in nature. they stretch and bulge
  when heart pumps blood through ? feel your pulse!

14

• Blood Vessels
• veins
• take blood to heart
• not always low in O2
• branch into smaller veins called venules
• the lumens (openings) are larger than that of
  arteries but walls are thinner.
• depend on contraction of surrounding muscle to
  move blood.
• contain valves ? prevent backflow of blood.

Look at the veins on this guy!
15
Valves in veins prevent backflow...
16
When the valves of the veins are leaky varicose
veins!
17

• Blood Vessels
• Capillaries
• tiny blood vessels. about 0.008 mm in diameter.
  just wide enough for one red blood cell to pass
  through.
• one cell thick makes exchange of materials
  between blood and body cells easy.
• connect arterioles and venuoles
• the total length of all the capillaries in your
  body is 1000s of kilometres. total surface area
  is nearly 6000 m2. why?
• penetrate almost every tissue in the body.

18
(No Transcript)
19
Comparison of Blood Vessels
20
Blood Vessels of a Fetal Pig
21
Components of The Human Circulatory System

• The Heart
• two atria (right and left) (singular atrium)
• two ventricles (right and left)
• Has valves to prevent backflow

22
Label your diagram!
17
1a
15
2a
7
8b
8a
9a
9b
10
10
11
3
12
4
13
5
14
2b
16
6
1b
20
23

• very cool heart videos

24
(No Transcript)
25
Circulatory Routes of the Human Cardiovascular
System

• The CV system is a closed, one-way system (blood
  only flows in one direction)
• Blood flows in two distinct circuits
• pulmonary circuit
• path of blood
• right side the heart ? lungs (blood picks up O2
  and gets rid of CO2) ? left side of heart.
• systemic circuit
• path of blood
• left side of the heart ? tissues in the body to
  deliver O2, nutrients, get pick up wastes ? right
  side of heart.

26
Valves of the Heart

• TWO kinds Atrio-ventricular and Semilunar
• Atrio-Ventricular (AV) Valves
• each is located between an atrium and a ventricle
• when the ventricles contract, these valves
  prevent blood from flowing from the ventricles
  back into the atria
• tricuspid valve
• has three cusps or flaps that open and close.
• between right atria and right ventricle
• bicuspid (mitral) valve
• has two cusps or flaps that
• open and close.
• (AKA mitral valve)
• between left atria and left
• ventricle

27
...Valves of the Heart

• Semilunar Valves
• located in the two major arteries as they leave
  the heart
• prevent blood flow back into the ventricles
• each have a crescent or half-moon shape
• pulmonary valve
• leads to the pulmonary artery
• between right ventricle and pulmonary artery
• aortic valve
• leads to the aorta
• between left ventricle and aorta
• Cool fact Ever listen to your heart beat? It
  makes a lub-dub sound. As your ventricles
  contract, your AV valves close preventing
  backflow into atria ? lub. When your ventricles
  relax, the semilunar valves close preventing
  backflow ? dub
• animation valves in action

28
Heart Valve Pics
29
CV Word Scramble

• Several structures of the circulatory system are
  listed below. Unscramble the terms to describe
  the flow of blood through the body. Start with
  "blood from the body". Present your answer as a
  flow chart-style graphic organizer.
• Blood from the body
• bicuspid valve
• Superior vena cava
• carbon dioxide
• right ventricle
• Inferior vena cava
• pulmonary valve
• Left ventricle
• oxygen
• body
• Left atrium
• Pulmonary artery
• Tricuspid valve
• Pulmonary veins
• lungs
• Aortic valve
• carbon dioxide

30
CV Word Scramble Answers!

• Blood from the body
• Superior vena cava Inferior vena cava
• Right atrium
• Tricuspid valve
• right ventricle
• pulmonary valve
• Pulmonary artery
• lungs
• Dump carbon dioxide
• Pick up oxygen
• Pulmonary veins
• Left atrium
• Bicuspid valve
• Left ventricle
• Aortic valve
• Aorta
• body
• Pick up carbon dioxide
• Dump oxygen

31
Locating Heart Sounds with a Stethoscope
32
Conduction System of the Heart

• cardiac muscle can contract without external
  nerve stimulation (i.e. messages from the brain).
  The heart can continue to beat for a short time
  once removed from the body
• the hearts tempo is set by the sinoatrial node
  (SA node) a bundle of specialized nerves. It is
  often referred to as the pacemaker. Its tempo is
  set to about 70 bpm (beats per minute).
• the autonomic (automatic) nervous system
  regulates heart rate but does not initiate
  contraction (the SA node does). It speeds
  up/slows down the SA node as needed.

33
Conduction System of the Heart

• Electrical Impulse in Heart
• SA node initiates cardiac cycle. It sends out an
  electrical impulse.
• electrical impulse spreads over both atria
  causing them to contract
• At the same time, it sends an impulse to the AV
  node
• impulse is slowly spread through AV node and then
  to the Bundle of His (atrioventricular bundle)
• impulse spreads through both sides of the septum
• impulse goes to Purkinje Fibres which stimulate
  contraction of ventricles!

34
ECG (Electrocardiogram)

• An ECG can be used to measure the electrical
  fields produced within the heart. Doctors can
  analyze such a ECG to diagnose heart problems.

P-wave Atrial contraction
T-wave Ventricles recover
QRS-wave Ventricular contraction
35
Regulation of Heart Rate Autonomic Nervous System
(ANS)

• Although the heart can beat without nervous
  intervention, heart rate must be regulated by the
  nervous system as conditions change
• The ANS is comprised of the sympathetic nervous
  system and the parasympathetic nervous system

ANS
Parasympathetic nervous system
Sympathetic nervous system
Stimulated by brain in times of stress. It makes
heart beat faster. Blood flow increases.
Stimulated by brain in times of relaxation. It
makes heart beat slower. Blood flow decreases.

• Tachycardia When Heart Rate gt 100 bpm. This can
  be caused by exercise or drugs such as caffeine
  or nicotine.

36
Regulation of Blood Flow

• The Autonomic nervous system (ANS) maintains
  homeostasis automatically.
• Precapillary sphincter muscles encircle
  arterioles before capillary beds. The ANS can
  regulate blood flow to tissues by sending a nerve
  impulse to these muscles causing them to contract
  or relax.
• Contraction of precapillary sphincter muscles ?
  vasoconstriction (less blood flow)
• relaxation of precapillary sphincter muscles ?
  vasodialation (more blood flow)

37
What is Blood Pressure?

• Blood pressure is the measure of force against
  the blood vessel walls.
• measured in the brachial artery (in upper arm).
  It is measured in the units mm Hg (millimetres
  of mercury).
• Blood pressure has two readings systole and
  diastole.

• systole blood pressure when the ventricles are
  contracting.
• diastole blood pressure when the ventricles are
  relaxed.
• blood pressure varies with age, health, exercise.
  A typical resting bp is 120/80 (read as 120 over
  80)

38
What is this called?
Sphygmomanometer
39
Regulation of Blood Pressure

• It is important to regulate blood pressure. Low
  blood pressure reduces blood flow. High blood
  pressure weakens arteries which may rupture.
  Consistently high blood pressure is called
  hypertension.
• bp is regulated by renal system (kidneys),
  nervous system, and by hormones. Together,
  physiological changes are made to raise or lower
  blood pressure.
• Special sensors called baroreceptors detect
  pressure change in the aorta and carotid artery
  (in neck). The baroreceptors send messages to
  medulla oblongata to increase/decrease.

regulation of blood pressure
40
Regulation of Blood Pressure
41
Regulation of Blood Pressure

• If blood pressure is LOW
• vasoconstriction smooth muscle around the blood
  vessels contracts, narrowing the lumen of the
  vessels ...bp ?
• blood volume blood volume ?blood pressure ?
• cardiac output Heart Rate (beats/min) and Stroke
  Volume (mL per beat) increase blood pressure ?
• If blood pressure is HIGH
• vasodilation smooth muscle around the blood
  vessels relaxes. the blood vessel opens up bp
  ?.
• blood volume blood volume ?blood pressure ?
• cardiac output Heart Rate and Stoke Volume ?
  blood pressure ?

measuring blood pressure
42
Regulation of Blood Pressure

• Cool facts
• Some people think a alcoholic drink will warm
  you up on a cold day. It actually cools you down!
  Alcohol causes vasodilation of blood vessels in
  skin. this ? blood flow to skinheat is lost!
• Alcohol makes some people congested! Blood
  vessels in nose dilate ? nasal passages close
  off.