Download - 20.1: The Circulatory System
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20.1: The Circulatory System
Section Objectives: Distinguish among the
various components of blood
Trace the route blood takes through the body and heart.
Explain how heart rate is controlled.
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Circulatory system
made up of 3 parts organ
heart tissues & cells
blood vessels arteries veins capillaries
blood red blood cells plasma
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Your Blood: Fluid Transport
Blood is a tissue of fluid & cells
transports O2 and nutrients to cells
takes away CO2 and other wastes
Aids in fighting disease
Helps maintain body temp.
Blood composition:Plasma: 55% (liquid part)Blood cells: 45% (red,
white, & platelets
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Blood Cell production ribs, vertebrae,
breastbone & pelvis
Stem cells “parent”
cells in bone marrow
differentiate into many different types of cells
white bloodcells
red bloodcells
white blood cells
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Red blood cells: Oxygen carriers
Bioconcave disc shaped, most numerous
No nucleus when mature, last 120 days
5-6 million RBC in drop of human blood
Produced in red marrow of long bones
contain hemoglobin Hemoglobin enables the
transport of O2
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Hemoglobin Protein which carries O2
250,000 hemoglobins in 1 red blood cell
O2
O2O2
O2
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White blood cells: Infection fighters Largest blood cell play a major role in
protecting your body from foreign substances.
White Blood Cells
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Platelets: Blood clotting Smallest (fragments) help blood clot after an
injury. Short-lived
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Blood vesselsarteries
arterioles
capillaries
venules
veins
artery
arteriolesvenules
veins
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Arteries: Built for their job
Arteries blood flows away from heart thicker walls
provide strength for high pressure pumping of blood
elastic & stretchable maintains blood
pressure even when heart relaxes
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Major arteries
pulmonaryartery
pulmonaryartery =to lungs
aortacarotid = to headto brain & left arm to right arm
coronary arteries
to body
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Veins: Built for their job Veins
blood returns back to heart thinner-walled
blood travels back to heart at low speed & pressure
why low pressure? far from heart
blood flows because muscles contract when we move squeeze blood through veins
valves in large veins in larger veins one-way valves
allow blood to flow only toward heart
Open valve
Blood flowstoward heart
Closed valve
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Major Veins
pulmonaryvein =
from lung
superiorvena cava = from upper body
pulmonaryvein = from lung
inferiorvena cava = from lower body
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Structure-function relationship Capillaries
very thin walls allows diffusion of
materials across capillary O2, CO2, H2O,
food, waste body cell
O2
food
waste
CO2
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Your Heart: The Vital Pump Atria: upper
chamber which receive blood that pump blood to
Ventricles: muscular walled chambers which pump blood from heart
leftatrium
rightatrium
leftventricleright
ventricle
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2 part system Circulation to lungs
blood gets O2 from lungs drops off CO2 to lungs brings O2-rich blood from
lungs to heart Circulation to body
pumps O2-rich blood to body picks up nutrients from
digestive system collects CO2 & cell wastes
Circulation of Blood
heart
lungs
body
Circulationto lungs
Circulationto body
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Blood’s path through the heart
1. vena cavae 2. right atrium 3. valve 4. right ventricle 5. valve 6. pulmonary artery (to
lungs) 7. pulmonary veins 8. left atrium 9. valve 10. left ventricle 11. valve 12. aorta largest blood
vessel in the body.
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Heartbeat regulation
surge of blood through an artery is called a pulse.
Pacemaker: initiates heartbeat generates an electrical impulse that spreads over both atria.
Sinoatrial node (Pacemaker
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Blood pressure the force that the blood exerts on the blood vessels. Blood pressure is measured as systolic (ventricles
contract) and diastolic (ventricles relax) pressures
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Control of the heart
A portion of the brain called the medulla oblongata regulates the rate of the pacemaker, speeding or slowing its nerve impulses.
If the heart beats too fast, the medulla oblongata, sends signals that slow the pacemaker.
If the heart slows down the medulla oblongata sends signals to speed up the pacemaker and increase the heart rate.
Medulla oblongata
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wastefood
Circulatory System & Homeostasis Homeostasis
keeping the internal environment of the body balanced
need to balance food & O2 in need to balance energy (ATP) production need to balance CO2 & waste out
Exercise heart beat faster
need more ATP bring in more O2 & food; remove more CO2 & waste out
Disease poor lung or heart function = heart beat faster
need to work harder to bring in O2 & food & remove wastes
O2
ATP
CO2
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Cardiovascular disease Atherosclerosis & Arteriosclerosis
deposits inside arteries (plaques) develop in inner wall of the arteries,
narrowing their channel increase blood pressure increase risk of heart attack, stroke, kidney
damage
normal artery hardening of arteries
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Cardiovascular healthbypass surgery
Risk Factors genetics diet
high animal fat exercise & lifestyle
smoking lack of exercise
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Women & Heart Disease
Heart disease is 3rd leading cause of death among women aged 25–44 years & 2nd leading cause of death among women aged 45–64 years.
Risk factorsSmokingLack of exercise
High fat dietOverweight
Death rates for heart disease per 100,000 women, 2002
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