-LESSON 4THE CARDIO RESPIRATORY SYSTEM
• CARDIO
• THE HEART
• RESPIRATORY
• THE LUNGS
• CARDIO-VASCULAR
• HEART AND BLOOD VESSELS
• THE HEART CONSISTS
OF FOUR CHAMBERS:
• TWO ATRIA
• UPPER PART OF HEART
• RECEIVE BLOOD FROM
BODY AND LUNGS
• TWO VENTRICLES
• LOWER PART OF HEART
• DELIVER BLOOD TO BODY
AND LUNGS
•
MYOCARDIUM
•
THICK MUSCULAR WALLS
SURROUNDING THE
CHAMBERS
• THE RIGHT ATRIUM RECEIVES DEOXYGENATED BLOOD FROM
THE BODY VIA THE LARGE VEINS
• THESE VEINS ARE CALLED THE SUPERIOR (UPPER) AND
INFERIOR (LOWER) VENA CAVA
• ONCE THE DEOXYGENATED BLOOD IS COLLECTED, THE
ATRIUM DELIVERS IT TO THE RIGHT VENTRICLE
• THE LEFT ATRIUM RECEIVES THE NEWLY OXYGENATED BLOOD
FROM THE LUNGS VIA THE PULMONARY VEINS
• THE PULMONARY VEINS ARE THE ONLY VEINS IN THE BODY
WHICH CARRY OXYGENATED BLOOD...ALL THE OTHER VEINS
CARRY DEOXYGENATED BLOOD
• ONCE THE LEFT ATRIUM IS FULL, THE BLOOD IS DELIVERED TO
THE LEFT VENTRICLE
• THE OXYGENATED BLOOD IS THEN PUMPED AROUND THE
BODY VIA THE AORTA
• THE LEFT VENTRICLE IS RESPONSIBLE FOR SUPPLYING THE
WHOLE BODY WITH OXYGENATED BLOOD
• CONSEQUENTLY, THE MUSCULAR WALLS OF THE LEFT
VENTRICLE ARE MUCH THICKER, ALLOWING MUCH FORCEFUL
CONTRACTIONS
• CARDIOVASCULAR SYSTEM CONSISTS OF:
• THE HEART
• THE PUMP WHICH CIRCULATES THE BLOOD
• THE BLOOD
• PUMPED BY THE HEART TO CIRCULATE AROUND BODY
• THE BLOOD VESSELS
• NETWORK OF VESSELS CALLED ARTERIES, VEINS AND CAPILLARIES
• THE CARDIAC CYCLE IS THE PROCESS THAT OCCURS DURING
ONE BEAT OF THE HEART
• THE HEART BEAT CAN BE BROKEN DOWN INTO TWO PARTS:
• SYSTOLE
• THE CONTRACTION PHASE WHERE A VOLUME OF BLOOD IS PUMPED
INTO THE ARTERIES TO THE LUNGS AND BODY
• DIASTOLE
• THE RELAXATION PHASE WHERE THE BLOOD FLOWS INTO THE HEART
VIA THE VEINS
• THIS CYCLE KEEPS THE BLOOD MOVING CONTINUALLY
THROUGH THE HEART AND BLOOD VESSELS
• A HEALTHY ADULT HAS A RESTING HEART RATE OF BETWEEN
60-80 BEARTS PER MINUTE (BPM)
• A WELL CONDITIONED INDIVIDUAL MAY HAVE A RESTING
HEART RATE AS LOW AS 30-50 BPM
• RESTING HEART RATE INCREASES WITH AGE
• LIKE ALL OTHER SKELETAL MUSCLE, THE HEART HAS THE
ABILITY TO GET STRONGER, IN PARTICULAR THE WALLS OF
THE LEFT VENTRICLE WILL INCREASE IN SIZE – CARDIAC
HYPERTROPHY
• THE STROKE VOLUME IS THE AMOUNT OF BLOOD PER BEAT
PUMPED OUT BY THE HEART
• AT REST, STROKE VOLUME IS APPROXIMATELY 70-80
MILLILITRES (ML) PER BEAT
• IN A WELL-TRAINED INDIVIDUAL, STROKE VOLUME AT REST IS
100-110 ML PER BEAT
• DURING ACTIVITY STROKE VOLUME CAN BE AS HIGH AS
200ML PER BEAT
• CARDIAC OUTPUT IS THE AMOUNT OF BLOOD PUMPED OUT BY
THE HEART IN ONE MINUTE
• WHEN EXERCISING CARDIAC OUTPUT MUST INCREASE TO MEET
THE BODY’S EXTRA DEMAND FOR OXYGEN
• CARDIAC OUTPUT FORMULA:
CARDIAC OUTPUT = STROKE VOLUME X HEART RATE
• IF AN AVERAGE STROKE VOLUME IS 71ML, AND AN AVERAGE
RESTING HEART RATE IS 70 BPM THEN:
• CARDIAC OUTPUT = 71ML X 70 BPM = 4970 ML PER MIN
• APPROXIMATELY 5LTRS OF BLOOD
• A REGULAR EXERCISER WITH A HEART RATE OF 50 BPM AND
A STROKE VOLUME OF 100ML:
• CARDIAC OUTPUT = 100ML X 50 BPM = 5000 ML PER MIN
• A REGULAR EXERCISER CAN MAINTAIN CARDIAC OUTPUT
WITH FEWER HEART BEATS
• PARTICIPATION IN REGULAR ENDURANCE EXERCISES:
• ...DECREASES THE RESTING HEART RATE
• ...INCREASES THE STROKE VOLUME
• ...ALLOWING THE HEART TO WORK LESS STRENUOUSLY AND
MORE EFFICIENTLY
• BLOOD PRESSURE IS THE AMOUNT OF PRESSURE EXERTED ON
THE WALLS OF BLOOD VESSELS AS BLOOD MOVES
THROUGH THEM
• VITAL TO CIRCULATE BLOOD, FORCING IT THROUGH TINY
CAPILLARIES, AND ENABLING IT TO MOVE UPWARDS
AGAINST GRAVITY
• BLOOD PRESSURE IS GIVEN AS TWO READINGS:
• SYSTOLIC PRESSURE / DIASTOLIC PRESSURE
• HEART PUMPING BLOOD / HEART RELAXING
• BLOOD PRESSURE IS GIVEN IN MILLIMETRES OF MERCURY
• EG. 120/80 mmHg IS A TYPICAL READING OF BLOOD
PRESSURE
• BLOOD PRESSURE IS CONSTANTLY CHANGING TO MEET THE
BODY’S NEEDS
• INDREASES DURING EXERCISE
• DECREASES DURING REST
• THE VASCULAR SYSTEM IS
COMPOSED BY THE BLOOD
VESSELS AND THE HEART
• IT TRANSPORTS AND EXCHANGES
PRODUCTS BETWEEN THE BLOOD
AND THE TISSUES
• THIS PROCESS TAKES PLACE IN
THE CAPILLARIES
• A MIXTURE OF BLOOD CELLS CARRIED IN A LIQUID CALLED
PLASMA
• TWO TYPES OF BLOOD CELLS:
RED BLOOD CELLS TRANSPORT OXYGEN
WHITE BLOOD CELLS HELP WITH THE IMMUNE SYSTEM
BLOOD ALSO CARRIES NUTRIENTS, HORMONES AND MEDICINES
• THE ARTERIES CARRY BLOOD AWAY FROM THE HEART TO THE
BODY
• ARTERIES PROGRESSIVELY REDUCE IN SIZE, BECOMING
ARTERIOLES AND CAPILLARIES AS THEY REACH THE TISSUES
• THE PRESSURE WITHIN THE LARGE ARTERIES IS VERY HIGH
• THIS DIMINISHES AS THE ARTERIES GET SMALLER AND MOVE
FURTHER AWAY FROM THE HEART
• THIS HIGH PRESSURE ENSURES THAT THE BLOOD DOES NOT
GRAVITATE TO THE LOWER PARTS OF THE BODY
• BLOOD PRESSURE ENABLES BLOOD TO GO UP TO THE BRAIN
AND SUPPLY IT WITH NUTRIENTS
• VEINS CARRY BLOOD UNDER LOW PRESSURE FROM
CAPILLARIES BACK TO THE HEART VIA VENULES AND VEINS
• VENOUS RETURN
• THE AMOUNT OF BLOOD THAT IS RETURNED TO THE HEART BY VEINS
• THE HEART PUMPS THE BLOOD WHICH IT RECEIVES
• IF VENOUS RETURN DECREASES, THE HEART CONTRACTS LESS
FORCEFULLY AND BLOOD PRESSURE DECREASES
• CAPILLARIES CARRY BLOOD
FROM ARTERIOLES TO VENULES
• THE EXCHANGE OF MATERIALS
BETWEEN THE TISSUES AND
THE BLOOD TAKES PLACE IN
THE CAPILLARIES
• THIS PROCESS IS CALLED
DIFFUSION
• ARTERIES – THICK MUSCULAR WALLS, MADE UP OF SMOOTH
MUSCLE, WHICH ASSISTS BLOOD PRESSURE
• VEINS – THIN FIBROUS WALLS, MADE UP OF SMOOTH
MUSCLE, WITH ONE-WAY VALVES AT REGULAR INTERVALS
• CAPILLARIES – WALLS ARE ONLY ONE CELL THICK
• WITH AGE THE INNER WALLS BLOOD VESSELS BECOME LESS
ELASTIC AND THEREFORE LESS EFFICIENT
• THE MOVEMENT OF MOLECULES FROM AN AREA OF
GREATER CONCENTRATION TO AN AREA OF LESSER
CONCENTRATION
• GASES SUCH AS OXYGEN AND CARBON DIOXIDE ARE
MOVED VIA DIFFUSION
• BLOOD FLOWS TO THE LUNGS WITH A LOW CONCENTRATION
OF OXYGEN AND A HIGH CONCENTRATION OF CARBON
DIOXIDE
• OXYGEN IS DIFFUSED INTO THE CAPILLARIES AND CARBON
DIOXIDE DIFFUSES OUT OF THE CAPILLARY AND INTO THE
LUNGS
• IN BOTH CASES GASES MOVE FROM WHERE THERE IS MORE TO
WHERE THERE IS LESS
• DIFFUSION
THAT OCCURS
IN THE
EXCHANGE OF
GASES
(OXYGEN AND
CARBON
DIOXIDE)
WITHIN THE
LUNGS
• DIFFUSION TAKES PLACE WITHIN THE CAPILLARIES
• OXYGEN IN BLOOD IS BROUGHT FROM THE LUNGS TO THE
MUSCLES
• OXYGEN DIFFUSES FROM THE BLOOD (HIGH
CONCENTRATION) TO THE TISSUES (LOW CONCENTRATION)
• SIMULTANEOUSLY CARBON DIOXIDE DIFFUSES FROM THE
TISSUES (HIGH CONCENTRATION) TO THE BLOOD (LOW
CONCENTRATION)
• CARBON DIOXIDE IS THEN BROUGHT BACK TO THE LUNGS
TO BE EXHALED
• THE VASCULAR SYSTEM HAS TWO MAJOR PATHWAYS:
• PULMONARY CIRCULATION
• LUNGS
• SYSTEMIC CIRCULATION
• BODY
• THE FLOW OF
BLOOD FROM
THE RIGHT SIDE
OF THE HEART
TO THE LUNGS,
RETURNING TO
THE LEFT SIDE
OF THE HEART
• RIGHT VENTRICLE PUMPS DEOXYGENATED BLOOD VIA
THE PULMONARY ARTERIES TO THE LUNGS
• PULMONARY DIFFUSION TAKES PLACE IN THE LUNGS
• CARBON DIOXIDE IS EXHALED, OXYGEN IS INHALED
• THE EXCHANGE TAKES PLACE VIA THE PULMONARY
CAPILLARIES
• THE CAPILLARIES UNITE TO FORM VENULES WHICH LEAD
TO VEINS
• THESE VEINS FORM THE TWO LARGER PULMONARY
VEINS COMING FROM BOTH LUNGS
• THEY RETURN OXYGENATED BLOOD TO THE LEFT ATRIUM
OF THE HEART
• THE FLOW
OF BLOOD
FROM THE
LEFT SIDE OF
THE HEART
TO THE BODY
AND THEN
BACK TO THE
RIGHT SIDE
OF THE
HEART
• LEFT VENTRICLE PUMPS BLOOD VIA THE AORTA INTO
THE ARTERIES
• THE ARTERIES REDUCE IN SIZE TO FORM ARTERIOLES
• ARTERIOLES THEN FORM CAPILLARY NETWORKS
THROUGHOUT THE BODY
• CAPILLARIES MERGE TO FORM VENULES
• VENULES THEN FORM VEINS WHICH FINALLY FORM
THE TWO LARGER VEINS:
• SUPERIOR AND INFERIOR VENA CAVA
• THEY RETURN BLOOD TO THE RIGHT ATRIUM OF THE
HEART
• THE RESPIRATORY SYSTEM IS RESPONSIBLE FOR THE
MOVEMENT OF AIR IN AND OUT OF THE LUNGS...BREATHING
• THE EXCHANGE OF OXYGEN AND CARBON DIOXIDE OCCURS
IN THE LUNGS
• ALL OUR CELLS NEED OXYGEN:
• TO CARRY OUT CELL RESPIRATION TO PRODUCE ENERGY (ATP)
• TO ELIMINATE WASTE PRODUCTS SUCH AS CARBON DIOXIDE
• OXYGEN COMES FROM AIR WE BREATHE
• PURE DRY AIR CONTAINS:
• 78% NITROGEN... 21% OXYGEN... TRACES OF OTHER GASES
• NORMAL AIR USUALLY CONTAINS WATER VAPOUR, DUST
POLLEN, GERMS, POISONOUS GASES AND OTHER
POLLUTANTS
• CARBON DIOXIDE CONTENT IS NEARER TO 0.04%
• AIR ENTERS THE RESPIRATORY SYSTEM VIA THE NOSE
OR MOUTH
• NASAL BREATHING IS PREFERABLE BECAUSE AIR IS WARMED
AND FILTERED IN THE NASAL CAVITIES
• FROM THE NOSE, AIR PASSES FROM THE PHARYNX OR
THROAT
• THIS LIES BEHIND THE NOSE AND MOUTH WHERE BOTH
CAVITIES OPEN INTO IT
• FROM THE PHARYNX AIR GOES TO THE LARYNX
• OFTEN CALLED THE VOICE BOX
• THE CAVITY OF THE LARYNX IS SEPARATED FROM THE
PHARYNX BY A FLAP CALLED THE EPIGLOTTIS
• THIS FLAP PREVENTS FOOD FROM ENTERING THE TRACHEA
(WINDPIPE) AND THE LUNGS
• THE TRACHEA IS CYLINDRICAL AND APPROXIMATELY
10-13CM IN LENGTH
• IT IS KEPT OPEN BY RINGS OF CARTILAGE THROUGHOUT
ITS LENGTH
• AT THE LOWER END THE TRACHEA DIVIDES INTO
TWO BRONCHI
• ONE BRONCHUS LEADS TO EACH LUNG
• EACH BRONCHUS DIVIDES INTO SMALLER BRONCHI
AND EVEN SMALLER BRONCHIOLES
• THE BRONCHIOLES TERMINATE IN CLUSTERS OF
ALVEOLI
• OFTEN CALLED THE AIR SACS
• GASEOUS EXCHANGE OCCURS IN THE ALVEOLI
• EXTREMELY SENSITIVE STRUCTURES IN THE YOUNG
• THE ALVEOLI (SINGULAR
ALVEOLUS) ARE THE
FUNCTIONAL UNIT OF
THE LUNGS
• THERE ARE MILLIONS OF
ALVEOLI IN THE LUNGS
• THEY ARE SURROUNDED
WITHIN A NETWORK OF
PULMONARY
CAPILLARIES WHERE
DIFFUSION TAKES PLACE
• CARBON DIOXIDE PASSES THROUGH THE CAPILLARY
WALLS INTO THE ALVEOLUS TO BE BREATHED OUT
• OXYGEN PASSES INTO THE CAPILLARIES FROM THE
ALVEOLUS
• OXYGINATED BLOOD IS COLLECTED INTO THE VEINS
AND RETURNED TO THE HEART THROUGH THE
PULMUNORY VEIN
• AGEING BRINGS A REDUCTION IN ALVEOLI
• BREATHING IS THE RESULT OF THE MOVEMENT OF
THE RIB CAGE AND THE CHANGES IN VOLUME AND
PRESSURE IN ALVEOLI
• THE MAIN RESPIRATORY MUSCLES ARE:
• THE DIAPHRAGM
• THE INTERNAL AND EXTERNAL INTERCOSTALS
• A DOME LIKE MUSCLE
SITUATED BELOW THE
LUNGS
• IT FLATTENS WHEN IT
CONTRACTS, INCREASING
THE CAPACITY OF THE
CHEST CAVITY
• THE CONTENTS OF THE
ABDOMEN ARE PUSHED
DOWNWARDS, CAUSING
A SLIGHT FORWARD
BULGE
• FOUND BETWEEN THE
RIBS
• THE EXTERNAL
INTERCOSTAL MUSCLES
PULL THE RIBS UPWARD
AND OUTWARD
• THE INTERNAL
INTERCOSTAL MUSCLES
PULL THE RIBS
DOWNWARD AND
INWARD
• INSPIRATION OR INHALATION OCCURS WHEN THE
DIAPHRAGM CONTRACTS AND MOVES
DOWNWARDS, EXPANDING THE CHEST CAVITY
• THE EXTERNAL INTERCOSTAL MUSCLES PULL THE RIBS
UP AND OUT
• THE ALVEOLI EXPAND WHILST AIR IS TAKEN INTO THE
LUNGS
• EXPIRATION OR EXHALATION OCCURS WHEN THE
DIAPHRAGM AND EXTERNAL INTERCOSTALS RELAX
• THE CHEST BECOMES SMALLER
• THE LUNGS ARE COMPRESSED BY THE ELASTIC
CONNECTIVE TISSUE COMPRESSING THE ALVEOLI
• AIR IS FORCED OUT
• THE CONTENT OF EXHALED AIR WILL CHANGE
ACCORDING TO THE REQUIREMENTS OF THE BODY
• OXYGEN LEVELS DROP AS BODY USES IT TO PRODUCE
ENERGY
• CARBON DIOXIDE INCREASES DUE TO THE PRODUCTION
OF CARBON DIOXIDE DURING AEROBIC ENERGY
PRODUCTION
• BREATHING IS PERFORMED CONTINUALLY AND
UNCONSCIOUSLY
• IT IS CONTROLLED BY THE RESPIRATORY CENTRE IN THE
BRAIN, WHICH RESPONDS VERY QUICKLY TO SLIGHT
CHANGES IN CARBON DIOXIDE CONCENTRATION IN THE
BLOOD
• LACK OF OXYGEN ALSO AFFECTS THE BREATHING RATE.
SENSORS IN THE LARGE BLOOD VESSEL IN THE NECK
DETECT LACK OF OXYGEN
• AT REST, THE BREATHING RATE IS NORMALLY ABOUT
12-14 BREATHS PER MINUTE
• THE AMOUNT OF AIR (TIDAL VOLUME) INVOLVED IN
ONE NORMAL INSPIRATION AND EXPIRATION IS
APPROXIMATELY 0.5 LTRS...
• ...MEANING 6-7 LTRS OF AIR PER MINUTE
• LUNG CAPACITY VARIES DEPENDING ON THE SIZE
AND AGE OF AN INDIVIDUAL
• TALLER PEOPLE TEND TO HAVE LARGER LUNGS
• AS WE AGE OUR LUNG CAPACITY REDUCES AS THE
LUNGS LOSE THEIR ELASTICITY
NOSE/MOUTH
OXYGEN IN
TISSUE
CAPILLARIES
ARTERIOLES/
ARTERIES
PHARYNX
TISSUE
DIFFUSION
LARYNX
VENULES/
VEINS
CARBON DIOXIDE OUT
VENA
CAVAE
ALVEOLI
BRONCHIOLES
RIGHT
ATRIUM
AORTA
PULMONARY CAPILLARIES
LEFT
VENTRICLE
LEFT
ATRIUM
PULMONARY ARTERY
PULMONARY
VEIN
TRACHEA
RIGHT
VENTRICLE
PULMONARY
CAPILLARIES
ALVEOLI
PULMONARY
DIFFUSION
• CHILDREN
• CHILDREN HAVE A DECREASED BLOOD VOLUME WHEN
COMPARED TO ADULTS
• THEIR HEART CHAMBERS ARE SMALLER AND LESS
POWERFUL THAN ADULTS’
• MAXIMUM HEART RATES ARE HIGHER, STROKE VOLUME IS
LESS
• THEY ARE LESS EFFICIENT AT PROCESSING OXYGEN AND
NEED HIGH UPTAKE OF OXYGEN FOR AEROBIC ACTIVITY
• PREGNANCY
SOME OF THE PREGNANCY RELATED CHANGES ARE:
• BLOOD VOLUME INCREASES BY APPROXIMATELY 30%
• BLOOD BECOMES MORE DILUTE WITH FEWER RED BLOOD CELLS
• STROKE VOLUME AND CARDIAC OUTPUT INCREASES
• RESTING HEART RATE INCREASES BY APPROXIMATELY 10-15 BPM
• VENOUS RETURN IS REDUCED CAUSE OF FOETUS PRESSING ON
BLOOD VESSELS AT PELVIC AREA
• PREGNANCY (CONT.)
• OXYGEN REQUIRED BY THE FOETUS INCREASES BY 20% FROM THE
18TH WEEK
• CARBON DIOXIDE RECEPTORS IN THE BRAIN BECOME MORE
SENSITIVE, RESULTING IN PREGNANT WOMEN BECOMING MORE
EASILY BREATHLESS
• THE DIAPHRAGM IS FORCED UP IN THE LATTER STAGES, REDUCING
TOTAL LUNG CAPACITY
• THE RIBS MOVE UP AND OUT BY 10-15CM TO ASSIST BREATHING
• SUPINE HYPOTENSIVE SYNDROME OCCURS WHEN LYING ON
BACK
• AGEING
• THE CARDIOVASCULAR SYSTEM SHOWS A DECLINE OF
30% FROM 30-70 YEARS OF AGE
• SOME OF THE CHANGES OCCUR DUE TO A LACK OF
ACTIVITY WHICH ACCOMPANIES AGE
• REGULAR EXERCISE CAN REDUCE THIS BY AS MUCH AS 50%
• AN ACTIVE 60 YEAR OLD CAN HAVE A MORE EFFICIENT
CARDIOVASCULAR SYSTEM THAN AN INACTIVE 25 YEAR
OLD