Transcript Circulatory system - KCI-SBI3U

Circulatory
system
Components of a Circulatory System
Three fundamental features in all circulatory
systems:
1.A fluid that transports materials throughout
the body
2. A network of tubes in which the fluid
circulates
3.A pump that pushes the fluid through the
tubes
Functions of a circulatory system
• delivers oxygen, nutrients, and hormones
to cells
• carries metabolic wastes away from cells to
the lungs and kidneys
• Helps distribute heat to maintain constant
body temperature in warm-blooded animals
Why the need for circulation?
• Unicellular organisms (bacteria, sponge, algae) do not
have a circulatory system. Use surface for exchange
•In larger multicellular organisms, body cells cannot move
and do not come in contact with the external environment.
•A circulatory system develops as an evolutionary
adaptation
Open (circulatory) System
e.g. insect, crustaceans
no closed vessels - blood bathes the cells directly
No distinction between blood and interstitial (tissue) fluid
have one blood vessel that has chambers called sinuses
Hemolymph: mixture of blood and tissue fluids
Closed (circulatory) System
e.g. earthworms, frogs, birds, humans
 need faster blood flow to get O2 to all cells
blood contained in a network of true blood vessels
that separate blood from tissues and interstitial fluid
blood circulates in only one direction
Blood and its functions
Disturbing?
•
•
•
•
•
carry nutrients, O2, CO2
equalize body temperature
transport hormones & antibodies
helps clotting
removes wastes
Components of Blood
Blood
• average 4-5L in a human body
• Blood is a connective tissue
• When centrifuged, blood separates into two
major components:
• Plasma(55%)
• Formed elements (45%)
Blood’s components
1. Plasma
•Fluid part of the blood
–92% water
–1% ions (Ca 2+, Na+, K+, Cl-, etc.)
–7 % proteins (albumins, globulins, fibrinogen)
Serum = plasma –( fibrinogen +clotting factors)
2. Cellular components:
RBC, WBC, and platelets
To fill in the info on
slide 13-17; use
the provided
summary table on
Cellular
component of
blood.
Your table should
look like the page
on the right here
2. Cellular Components (previously called Formed elements)
Description
Red Blood
 tiny biconcave disks (135
Cell
RBC = 1mm). Biconcave
(erythrocytes shape increases surface area
Can fold to pass through
_)
99% of
narrow blood vessels
Cellular
Made from stem cells in
Components bone marrow
Lack mitochondria and
nuclei
Stored in spleen
Constantly being destroyed
and replaced (~120 days)
Function
Carry O2 & CO2
Have iron-containing
protein called
hemoglobin (~ 280 mill/1
RBC) specializing at
transporting O2
 1 hemoglobin can bind
4 O2
Thalassemias and
Anemia are conditions of
abnormal haemoglobin
and haemoglobin
shortage, respectively
2. Cellular Components of Blood (Cont)
White Blood Cell Produced in the bone
marrow
(Leucocytes)
Do have nuclei
5-9 mill./1cm3 of blood
Male 10% more WBC
than female
Many different types
1. Neutrophils
2. Basophils
3. Eosinophils
4. Lymphocytes
5. Monocytes
Pus
•
•
•
•
•
Defend against
diseases and infections
Function in allergic
reactions
Produce antibodies
stimulated by binding
of foreign particles
Phagocytize (i.e.
engulf) to destroy
invaders
Leukemia – cancer of
the wbc (wbc can’t
stop dividing)
Histology of WBC
WBC
2. Cellular Components of Blood (Cont)
Platelets
(thrombocytes)
Fragments of cells
1-3um; no nuclei
Break down after 710 days
How blood clots? https://www.youtube.com/watch?v=--bZUeb83uU
Let’s go to the ER: https://www.youtube.com/watch?v=cFmmmj6a2sY
Responsible for blood
clotting
Prevent excessive blood
loss
Hemophilia – Sex-linked
condition resulting in
excessive bleeding
The Heart
Atrium: heart
chamber that
receives blood
from the body
Ventricle: heart
chamber that
pumps blood to the
body
Septum (a wall of tissue)
Pathway of blood flow through the heart
Blood from upper body
Deoxygenated blood from
rest of body to right atrium
via superior and inferior vena
cava  right atrium  right
ventricle  pulmonary artery
 lung where blood picks up
O2  left atrium via
pulmonary veins  left
ventricle  oxygenated
blood left heart via aorta to
rest of the body
Blood from lower body
https://www.youtube.com/watch?v=KSbbDnbSEyM
Cardiac (heart) System
Circulates blood through
tissues of the heart.
Pulmonary (lung) System
Circulates blood from heart,
to lungs, & back to heart
Systemic System
Supplies nutrients, O2 to
body cells except for heart
and lungs
Also picks up CO2
Blood Vessels
Red – Arteries
(Oxygen rich blood)
Blue – Veins
(Oxygen poor blood)
The largest blood vessel has a diameter of 3 cm, the smallest between
5-10um
•Three major types of blood vessels: arteries, veins and capillaries
Arteries




carry blood away from heart
usually O2 rich (Except for pulmonary artery)
connective tissue and muscle - walls elastic and thick
Pre-capillary sphincters control blood flow
Arterioles = smaller arteries
Vasoconstriction:
Decreases arterioles’
diameters restricting
blood flow  prevent
heat loss to
environment
Vasodilation:
Increases arterioles’
diameters increasing
blood flow 
facilitates heat loss to
cool down
(Flushing)
Veins
 carry blood to the heart
 usually O2 poor (Except for
pulmonary vein)
 Thinner walls and not elastic as
arteries
 valves push blood towards heart
 smooth surface
Varicose vein:
Are veins that lose their elasticity
as we age
Leads to blood pooling in the legs
that results in bulging condition
When sitting or standing for a long
time
Blood flow in veins
 Less pressure than arteries
(A)Small muscles surrounding the veins contract and relax to
squeeze blood along the veins.
(B)One-way valves inside the veins prevent blood from
flowing backward due to the pull of gravity
Arteries and Veins
Capillaries
•Found in the muscles and lungs
•Thin, semi-permeable wall- only a
single cell layer thick
•Very narrow; blood cells move through
in single file
•Cover a large surface area: no body
cell is more than 2 cells away from a
capillary
•Movement of blood through capillaries
is controlled by pre-capillary sphincters
Capillaries in the hand can leak excess fluid
accumulates in the tissues due to an allergic
reaction
p490 Textbook
Veins
•Carries blood
towards the heart
•
•
Carries blood away from
the heart
Branch into arterioles
•
•
•
•
•
•
Small veins
Converge into veins
Small arteries
Branch into capillaries
Site of gas, nutrient and
waste exchange
Converge to form venules