Circulatory System. Figure 24.01 Transports materials throughout body: Nutrients Metabolic wastes Gases (O 2 & CO 2 ) Hormones [regulate body processes]

Circulatory System

Figure 24.01

Transports materials throughout body:

• Nutrients

• Metabolic wastes

• Gases (O2 & CO2)

• Hormones [regulate body processes]

• Antibodies

Circulatory System Function

Components of Circulatory System:

• Blood – transport medium; – consists of cells suspended in liquid

(plasma)• Heart

– Pumps the blood through the vessels• Blood vessels

– tubes that carry blood – including arteries, veins, capillaries

Components of Blood

Plasma: (yellowish), contains water, minerals, salts, proteins, vitamins, hormones, dissolved gases and fats

Red blood cells: carry oxygen

Contain hemoglobin – no nucleus

White blood cells: destroy pathogens (disease-causing organisms) bacteria, viruses

Platelets: important part in blood clotting

Accounts for ~ 7% body weight

Totals ~ 5 liters (a little over a gallon) in volume

Blood

The Heart

Double pumpRight side: pumps O2-poor blood to lungs

Left side: pumps O2-rich blood to body

Each side has 2 chambersAtria : upper, thin-walled chambers,

receive bloodVentricles: lower, thick-walled chambers ,

pump bloodSeptum: separates sides and prevents mixing

Heart

Four Chambers

Right Atrium

Right Ventricle

Left Atrium

Left Ventricle

Pumps Blood Through Vessels

Septum – divides ventricles

Blood Flow Through Heart1.Blood arrives in the atria of the heart

2. Blood flows from atria to ventricles

3. Blood leaves the heart from the ventricles

From the Body

From the Lungs

Blood Flow Through Heart

Valves keep the blood moving in one direction

Aortic Semilunar

Pulmonary Semilunar

Semilunars are found between ventricles and vessels

Blood Flow Through Heart

Valves keep the blood moving in one direction

Tricuspid Bicuspid or Mitral

Atrioventricular (cuspid) valves are between atria and ventricles

Circulatory System Pathways:

Three Branches:– Pulmonary circulation

heart – lungs – heart

– Systemic circulation heart – body – heart

– Coronary circulation heart – heart

Path of a Red Blood Cell

• Vena cava• Right Atrium

– Tricuspid valve

• Right Ventricle– Pulmonary semilunar

• Pulmonary trunk• Pulmonary arteries• Lungs

• Lungs• Pulmonary Veins• Left Atrium

– Bicuspid or Mitral

• Left Ventricle– Aortic semilunar

• Aorta• Body cells

Arteries, Capillaries, Veins

Blood Vessels

• Carry blood away from heart

• Thick-walled

• Elastic fibers

• Muscle layer

• Blood under high pressure

• Small arteries called arterioles

• Diameter can be regulated

Arteries

• Exchange materials with surrounding tissue cells

Capillaries

• Extremely narrow

• Only one cell thick

• Materials diffuse or actively transported through the lining

• All human cells less than 1 mm away from a capillary

All exchanges of materials occur through the capillaries

• Return blood to the heart

• Thin-walled and wider diameter than arteries

• Low pressure - further from heart

• Valves keep blood moving towards heart

• Small veins called venules

Veins

Blood Flow in Veins

• Blood pressure much reduced in veins

• Two ways to help blood get back to heart Skeletal muscles help force

blood back toward heart Reduced pressure in thoracic

cavity during inhalation

• Valves prevent backflow

Varicose VeinsVeins with defective

valves allow the blood to flow backward and pool inside the vein

Veins become enlarged or dilated to form varicose veins

Blood flows from Heart arteries arterioles capillaries venules veins heart

Major arteries and veins

Systemic Circulation

Aorta: largest artery brings blood from the heart (left ventricle) to the rest of the body

Inferior vena cava: vein brings blood from the legs and abdominal cavity to the heart (right atrium)

Superior vena cava: vein that brings blood from the head and the arms to the heart (right atrium)

Inferior Vena Cava

Aorta

Superior Vena Cava

Major arteries and veins

Pulmonary Circulation

Pulmonary arteries: bring blood from the heart (right ventricle) to the lungsOnly artery with low oxygen

Pulmonary veins: bring blood from the lungs to the heart (left atrium)Only vein with high oxygen

Pulmonary Artery Pulmonary

Vein

Major Arteries and Veins

Aorta

Pulmonary Arteries

Pulmonary TrunkPulmonary Veins

Inferior Vena Cava

Superior Vena Cava

Stages in the cardiac cycle

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superiorvena cava

rightatrium

inferiorvena cava

c.

aortapulmonaryarteries

atrioventricularvalves

b.

semilunarvalves

a.

pulmonaryvein

leftatrium

leftventricle

rightventricle

aorta

Atria contract –Atrial systole

Ventricles Contract – ventricular systole

Atria and Ventricles relax - diastole

Control of Heartbeat: The Pacemaker

Electrical impulse starts at the sino-atrial node and spreads across the atria, causing them to contract

Impulse transferred to atrio-ventricular node, spreads across ventricles, causing them to contract

Brain/nervous system- Monitor blood circulation- maintain constant blood

pressure- Send signals to heart, blood

vessels, endocrine glands

Red Bone Marrow- Site of new blood cell

manufacture

Supporting Organs

Supporting Organs

• Kidneys - Metabolic waste products

removed from blood - Balance of minerals and

fluids, pH, glucose• Spleen

- Breaks down and filters out old red blood cells

- Stores red blood cells- Recycles constituents,

such as iron

Spleen