Download Transport in Human

Cardiovascular system
Learning objectives I
To outline the cardiovascular system;
To state the general properties of
cardiac muscle;
To describe the conducting system of
the heart;
To describe the cardiac action potentials;
Learning objectives II
To describe cardiac cycle;
To define cardiac output and blood pressure;
To describe the structure of blood vessels;
To identify the control of cardiac function and
blood circulation;
To state the composition of blood;
To describe the relation between blood and
lymph.
Transport in Human
The necessity:
far distance
high metabolic rate
slow diffusion
small surface area
for material
exchange
The circulatory system in
Human
Transport medium:
blood
Pumping device: heart
One- way flow: valves
Way for the exchange
of materials: capillary
network
Plasma
~ pale yellow, alkaline, 90% water, 10%
solid materials
Plasma protein: fibrinogen, globulin,
prothrombin & albumen
Carbohydrates & fats
Inorganic ions : Fe, Ca, K, Mg & Na
Nitrogen: urea, uric acid
Others: O2. CO2 & antitoxins
Erythrocytes(Red blood
cell)
5,000,000 RBC /mm3
Female has less RBC than male
No nucleus in matured RBC
Tiny biconcave disc
Million hemoglobin/ RBC
Production: Fetus  liver; Adult  bone
marrow
Life span: 4 months
Destruction: liver, spleen & bone marrow
Leukocytes(White blood
cell)
Colorless or transparent
Amoeboid in shape
1-2, or more distinct nuclei
5000- 10000 WBC/ mm3
5 main classes of leukocytes:
Neutrophils, eosinophils, basophils,
monocytes & lymphocytes
Platelets
250,000 blood platelets / mm3
Small colorless fragments
No nucleus
Produced in bone marrow
Life span: 10 days
Function of platelets
Stimulate contraction of injured vessels
 prevent blood loss
Adhere to one another plug the
wound
Formation of thromboplastin main
step of blood clotting
Hemophilia ~ / plateletexcessive bleeding
Hemorrhage ~ vit. K bleeding
Function of blood
Transportation ~ gas,
food, wastes, heat,
hormones & metabolites
Homeostasis ~ water
balance, acid- base
balance
Defense ~ blood
clotting, phagocytosis &
immune response
Structure of heart
Pericardium
~ double-layer sac surrounding the heart;
~ fluid fills the sac to reduce friction.
Heart chambers
~ right atrium
~ right ventricle
~ left atrium
~ left ventricle
Atrium
Upper chambers
Thin wall
Smaller than the ventricles
Receive blood from the veins
Push blood into ventricles
Ventricles
Lower chambers
Thicker muscle wall
Pump blood out of the heart to he lungs
or around the whole body.
The muscular wall of the left ventricle is
thicker than that of the right ventricle
Heart valves
Allow one-way flow of the blood.
Closure of the heart valves results in
heart beat sound “Lup dup”
Tricuspid valve: between RA & RV
Biscuspid valve: between LA & LV
Semi-lunar valve: at the base of
pulmonary artery & the aorta
Coronary system
Coronary artery
~ branches from aorta
~ supplies oxygen and nutrients to the
heart muscle
Coronary vein
~ drains deoxygenated blood from the
cardiac muscle into RA
Heart beat
Heart beats automatically i.e. it does
not depend on impulses from the
nervous system.
Contraction is generated within the
muscle itself.
Pacemaker (SA node) is the origin of
stimulus(cardiac action potential) for
heart muscle contraction.
Important !
SA node initiates the
heart beat, but the
rate at which it
beats can be varied
by stimulation from
the nervous system.
Spread of cardiac impulses
SA node

Atrial muscle

AV node

Bundle of His

All parts of ventricle
Characteristics of cardiac
muscle
Long refractive period ~ avoid fatigue
No tetanus or oxygen debt ~ avoid
fatigue
Highly vascularized ~ adequate
nutrients & oxygen
Characteristics of cardiac cycle
Pressure in Left ventricle > Pressure in
Right ventricle thicker muscle wall of
left ventricle
Length of cardiac cycle is varied at
different state, but during exercise, less
time is consumed.
Cardiac cycle
Sequence of events taking place in one
heartbeat:
~ Atrial systole (contraction of atrium)
~ Ventricular systole (contraction of
ventricles)
~ Diastole ( both atrium and ventricles
relax)
Heart sound
1st heart sound “Lup”:
~ closure of tricuspid & bicuspid valves
~ low pitched, not very loud, long
duration
2nd hear sound “Dup”
~ closure of semi-luna valves
~ high pitches, louder, short duration
Control of heart beat I
Cardiac pacemaker ( SA node)
~ nerve innervated the heart only
regulate the rate of heart beat but not
initiation of heart beat
Cardiac output
~ CO = Heart Rate x Stroke Volume
Control of heart beat II
Nervous regulation
~ Parasympathetic nerve
Cardio-inhibitor center  vagus nerve 
acetycholine  SA node  slow down heart
beat
~ Sympathetic nerve
Cardio-accelerator center  accelerator nerve 
noradrenaline  SA node   heart beat
Control of heart beat III
Hormonal control
~ Adrenaline   heart beat
Others
~  pH   Heart beat
~  temperature   Heart beat
Blood vessels
Artery
~ elastic artery
~ muscular artery
~ arterioles
Vein
~venules
Capillary
Artery
Thick muscular wall
Small lumen
Much elastic tissue
Blood under high pressure
Oxygenated blood except in pulmonary
artery
Elastic artery, muscular artery, arterioles
Capillary
No muscle & elastic
tissue
Links arteries to vein
Blood change from
oxygenated to
deoxygenated
Vein
Thin muscular wall
Little elastic tissue
Large lumen
Presence of valves
Deoxygenated
except in pulmonary
vein
Blood under low
pressure
Blood flow in arteries
Left ventricle contract

Push blood through aorta

Ventricles relax & semi- lunar valve close

Elastic aorta recoils

Muscular wall contracts & push blood to adjacent part
of aorta
Blood flow in veins
I.
Contraction of skeletal muscle
~ many veins are lying between large
skeletal muscle;
~ muscles contract and squeeze the
blood to flow forward in the vein.
Blood flow in veins
II. Inspiration movement
Inspiration

ICM & diaphragm contract

Enlarge thoracic cavity & pressure

-ve pressure suck blood towards the heart
Blood flow in veins
III. Remaining blood pressure
~ blood pressure in the vein is not zero;
~ the remaining blood pressure pushes
blood back to the heart.
Material exchange
 Matter out:
O2, glucose, amino
acid, fatty acid,
hormones, water &
inorganic ions
 Matter in:
CO2, ammonia, lactic
acids
Variation in blood pressure
Blood pressure in
Arteries> Arterioles> Venules & vein >
capillaries
Variation on permeability of
blood vessels
Permeability of
Capillaries > arteries, arterioles, venules
& veins
Variation in total sectional
area
Capillaries have the largest total section
area.
This makes sure the blood staying in
the tissue area longer, so promote
material exchange.
Variation in velocity
Velocity in
arteries > veins > capillaries
Blood circulation in the body
Mammalian double circulation
Coronary circulation
Portal circulation
Renal system
Double circulation
Pulmonary circulation
~ circulation of deoxygenated blood from RV to
lungs and oxygenated blood return to RA;
~ a short cycle
Systemic circulation
~ circulation of oxygenated blood from RV to
other parts of the body and the
deoxygenated blood returns to RA;
~ a long cycle.
Coronary circulation
Right & left coronary arteries: supply
oxygenated blood to heart muscle;
Coronary vein drains deoxygenated
blood into RA.
Portal circulation
It is characterized by having a vein with
capillaries at both of its ends.
The capillary network at both ends of
the portal vessel promote rapid and
efficient loading and unloading
substances.
e.g. hepatic portal vein
Renal system
Kidney receives urea-rich oxygenated
blood via renal artery;
Kidney drains urea-free deoxygenated
blood through renal vein;
Lymphatic circulation system
Lymph
~ Fluid leaks out from
the capillaries due to
filtration
~ Similar composition
as plasma except:
protein
WBC
No RBC
Lymph vessels
Blind ending
Present everywhere
Thin wall, no valves
Lymph flow: adjacent
skeletal muscle &
breathing motion of
chest
Lymph flows back to
blood via: Right
lymphatic duct &
thoracic duct
Lymph nodes
Swelling along lymph
vessels at interval
Conspicuous in armpits,
angle of the jaw & groin
As filters for lymph 
prevent foreign particles
from entering the
bloodstream
Function of Lymphatic system
Bridge for the exchange of materials
Collects excess tissue fluid back to the
blood circulation
Transport oil soluble substances
Filters the lymph
Produce lymphocytes