Download Human Circulatory System

BILL
The Circulatory System
Blood Flow
Heart
Blood Pressure
Blood Flow
Lymphatic System
Respiratory System
The Heart
About the size of your fist
 Pump that forces blood through vessels
with regular contractions
 Pericardium – outside tough protective
covering of the heart

The Heart
4 chambers of the heart
 Atria (2) – upper chambers, thin walled
chambers that collect blood from moving in
from veins
 Ventricles (2) – lower chambers, thick
muscular walls that build up enough
pressure to pump blood to lungs/body

The Heart

Septum – separates L and R side of the
heart and prevents mixing of oxygen rich
(L side) and oxygen poor (R side) blood
The Heart
Blood flow in heart controlled by 4
valves
 Atrioventricular Valves (2) – allow blood
from atria to ventricles

 R Side – Tricuspid Valve (3 flaps)
 L Side – Bicuspid Valve (2 flaps) or Mitral
Valve

Semilunar Valves (2) – allow blood to
move from ventricle to pulmonary artery,
or from ventricle to aorta
The Heart
Blood Vessels
Pulmonary Arteries – carries blood from
right ventricle to lungs
 Pulmonary Veins – carries blood from
lungs to left atria
 Aorta – carries blood from left ventricle
to the rest of the body
 Superior/Inferior vena cava – veins that
carry blood from the body back to the
right atria

Blood Flow through Heart
The Heart – Blood Flow
Pair of side-by-side pumps each
consisting of two chambers
 Two possible routes

 Pulmonary circulation – blood flow from right
side of heart to lungs and back
 Systemic Circulation – blood flow from left
side of heart to body cells and back
Blood Flow through Heart
Pulmonary Circulation
Oxygen poor blood collects in right atrium,
and flows through right AV valve into the
right ventricle
 Once ventricle full, in begins to contract,
causing:

 Right AV valve closes to prevent backflow
 Blood pressure increases inside right ventricle,
opening right semilunar valve
 Blood is pumped through pulmonary artery to
lungs to gain oxygen and back to heart into left
atrium
Blood Flow through Heart
Systemic Circulation
Blood flows from lungs to the let atrium
through the left AV valve into ventricle
 Once ventricle fills, it begins to contract
causing:

 Closure of left AV valve to prevent backflow
 Increase in blood pressure inside ventricle,
opening left semilunar valve
 Blood pumps into aorta, leaving the heart
and traveling to the body
Circulation
Right and left sides of heart act in
unison
 Both atria contract at same time, both
ventricles contract at same time
 Closing of the valves causes “lub dub”
sound of heart beat

Heart Rate – “lub-dub” sound of heart valve
opening and closing (can be heard with a stethoscope)

Myogenic Muscle
Contraction –
spontaneous
contraction/relaxation of
cardiac muscle without
nervous system control

Diastole – relaxed heart
Systole – contraction of
the heart

Sinoatrial (SA) Node (“Pacemaker”)
Specialized group of
cells in R atria that
produce small
electrical current ,
signaling for the
atria to contract and
keeps contracting
(recorded on an ECG
– Electrocardiogram)
Atrioventricular Node (AV node)


Specialized mass of
tissue that receives
signals from SA
node and sends the
signal for ventricular
contraction
Occurs roughy 0.1
seconds after signal
is received
Heart Rate Control
During Exercise, heart rate increases
due to increased demand for
oxygen/removal of CO2
 As CO2 levels rise, area in brain called
the Medulla senses increase and sends
a signal to SA node through the cranial
nerve, called a cardiac nerve, to
increase in HR
 HR increases the rate of contractions

Heart Rate Control
As CO2 levels decrease after exercise,
Medulla senses decrease and sends a
signal to SA node through the cranial
nerve, called vagus nerve, to decrease
HR
 SA node returns to normal pace of
contractions

Heart Rate Control - Chemicals
Heart rate is also influenced by
chemicals
 During periods of excitement/stress,
adrenal glands secrete adrenaline
 Causes SA node to fire more frequently
and increase heart rate

Blood Pressure

Pulse – alternate expansion (high
pressure) and relaxation (low pressure)
of an artery
Blood Pressure
Normal Resting Blood Pressure –
120/80 (systolic/diastolic)
 When ventricles contract – high blood
volume into arteries (high pressure)
 When heart is relaxed, less volume in
arteries so pressure decreses

BILL

Explain how the heart beats? (5 marks)

SA node fires (electrical) signal throughout walls of atria to
begin cycle; causing atria to undergo systole; SA signal
reaches atrioventricular node; which spreads signal
throughout; causing ventricles to undergo systole;
atrioventricular valves slap shut; causing "lub" sound; after
ventricles are emptied semilunar valves close; causing "dub"
sound; atrioventricular valves open; ventricles begin diastole
and start filling; all four chambers are in diastole and filling;
when atria filled and ventricles 70% filled cycle has ended;
Closed System with Three Types
of Blood Vessels

Arteries

Veins

Capillaries
Arteries – carry blood Away from
the heart to organs and tissues
Thick, muscular, elastic walls
 Blood at High Pressure as it travels
through artery
 Branch off into smaller arterioles (the
smallest arteries) in tissues and organs

Capillaries – connect arteries to
veins
So small (1 cell thick), red blood cells
must go through single file
 Dissolved nutrients, wastes, oxygen, etc
exchanged between blood and body
cells as blood flows through capillaries

Veins – return blood to the heart
from the body organs and tissues
Thin and slightly elastic
for large diameters
because of low pressure
 Flap-like valves in veins
allow blood to flow in one
direction only (toward the
heart)
 Venules – smallest veins

Varicose Veins
Vein walls become
stretched and valves
do not work properly
causing blood to build
up in vein
Plasma – liquid part of blood
(nonliving)

Transports
nutrients, wastes,
Hormones, etc

Mostly water
(90%)
Red Blood Cells (RBCs) Erythrocytes

Red in color – hemoglobin

Transport dissolved substances
(oxygen, carbon dioxide, nutrients,
wastes, etc)

No nucleus
Red Blood Cells

Smaller than white blood cells

More numerous than white blood cells
(2-5 million per mm3 of blood)

Made by bone marrow and live for about
120 days
Red Blood Cell Disorders
Anemia – too few RBCs or insufficient
amount of hemoglobin causing body to
not receive enough oxygen
 Sickle Cell Anemia – caused by
abnormal shaped hemoglobin

White Blood Cells (WBCs) Leukocytes
AKA phagocytes and lymphocytes
 Colorless


Helps fight infection and protect the body
from disease causing organisms

Move on their own like amoebas
(pseudopods) and through circulatory
system
White Blood Cells

Have a nucleus

Larger than RBCs

Less numerous than RBCs (5,000-10,000)
– you have more WBCs in your body when
you have an infection and less when you
are healthy
White Blood Cells

Made by bone marrow and lymphatic
tissue

Leukemia – cancer of
cells that make WBCs
Platelets

Help to clot blood and begin the healing
process
Blood cell fragments
(250,000-500,000)
 Live for 7 days

Blood Clotting – platelets stick together
to damaged/torn area and seal the “leak”

If wound is more serious  clotting
process takes over
1. Platelets release thromboplastin (enzyme)
2. Thromboplastin converts prothrombin
(plasma protein) into thrombin
3. Thrombin converts fibrinoogen into fibrin
4. Fibrin forms a network of strands that trap
RBCs and platelets to form clot
5. Once the healing is complete, plasmin
(enzyme) dissolves the fibrin clot
Blood Clot
Clotting Problems

Hemophilia – hereditary disease with
inability to clot blood

Clotting when not needed  heart
attack or stroke
Blood – liquid tissue that
transport, regulates, and protects

Transports – oxygen, carbon dioxide,
nutrients, wastes, etc

Regulates – absorbs heat, maintains pH
and water balance, etc

Protects – defense against pathogens
BILL

Distinguish between the following: Red
Blood Cells, White Blood Cells, Platelets

RBCs – small cells with no nucleus, composed of
protein hemoglobin, transport dissolved nutrients
WBC – larger cells with a nucleus, help fight
infections in the body and protects body from
infectious diseases
Platelets – blood cell fragments help to clot blood
and begin healing process


Lymphatic System

Lymphatic system – a network of
vessels, nodes, and organs that collects
fluid that is lost by the blood and returns
it back to the circulatory system

Fluid that is lost is called lymph
Lymph Nodes

Lymph Nodes – act as filters, trapping
bacteria and other microorganisms that
cause disease

When there are large numbers of
microorganisms trapped in the lymph
nodes, they become enlarged (swollen)
Lymphatic System
As blood circulates, some blood leaks
into surrounding tissues
 This helps maintain movement of
nutrients and salts from the blood into
the tissues
 Between 3-4 liters of fluid leaks from the
circulatory system per day and if the
leaks go unchecked, the body would
swell
