The circulatory system
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The Circulatory System. A closed system of the heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate to all parts of the body The functions of the cardiovascular system To deliver oxygen and nutrients to cells and tissues

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The Circulatory System

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The circulatory system

The Circulatory System

  • A closed system of the heart and blood vessels

    • The heart pumps blood

    • Blood vessels allow blood to circulate to all parts of the body

  • The functions of the cardiovascular system

    • To deliver oxygen and nutrients to cells and tissues

    • To remove carbon dioxide and other waste products from cells and tissues


The circulatory system

Superior

vena cava

Aorta

Parietal

pleura (cut)

Pulmonary

trunk

Left lung

Pericardium

(cut)

Apex of

heart

Diaphragm

(c)

Figure 11.1c


The circulatory system

Left common carotid artery

Brachiocephalic trunk

Left subclavian artery

Superior vena cava

Aortic arch

Right pulmonary artery

Ligamentum arteriosum

Ascending aorta

Left pulmonary artery

Pulmonary trunk

Left pulmonary veins

Left atrium

Right pulmonary

veins

Auricle of left atrium

Right atrium

Circumflex artery

Right coronary artery

in coronary sulcus (right

atrioventricular groove)

Left coronary artery in

coronary sulcus (left

atrioventricular groove)

Anterior cardiac vein

Left ventricle

Right ventricle

Great cardiac vein

Marginal artery

Anterior interventricular

artery (in anterior

interventricular sulcus)

Small cardiac vein

Inferior vena cava

Apex

(a)

Figure 11.3a


Open vs closed circulation

Open vs. closed circulation

  • Arthropods have open system

  • Humans have closed system


Systemic circulation

Systemic Circulation

  • Left atria to Aorta to arteries to arterioles to capillaries for gas/nutrient exchange

  • De-oxygenated blood travels through venules to veins to superior/inferior vena cava to right atrium of heart.

  • Superior and inferior vena cava feed the rt. Atrium.


Pulmonary circulation

Pulmonary Circulation

  • Blood moves from rt. Atrium to rt. Ventricle through the tricuspid valve.

  • Blood is pumped from the rt. Ventricle through the pulmonary semilunar valve to the pulmonary (trunk) artery to the lungs

  • Gas exchange occurs in alveoli


The circulatory system

Superior vena cava

Aorta

Left pulmonary artery

Right pulmonary artery

Left atrium

Right atrium

Left pulmonary veins

Right pulmonary

veins

Pulmonary semilunar valve

Left atrioventricular valve

(bicuspid valve)

Fossa ovalis

Aortic semilunar valve

Right atrioventricular

valve (tricuspid valve)

Left ventricle

Right ventricle

Chordae tendineae

Interventricular septum

Inferior vena cava

Myocardium

Visceral pericardium

(b) Frontal section showing interior chambers and valves.

Figure 11.3b


The circulatory system

Capillary beds

of lungs where

gas exchange

occurs

Pulmonary Circuit

Pulmonary

arteries

Pulmonary

veins

Venae

cavae

Aorta and

branches

Left

atrium

Left

ventricle

Right

atrium

Heart

Right

ventricle

Systemic Circuit

Capillary

beds of all

body tissues

where gas

exchange

occurs

KEY:

Oxygen-rich,

CO2-poor blood

Oxygen-poor,

CO2-rich blood

Figure 11.4


Thermoregulation

Thermoregulation

  • Characterizes human homeostasis

  • Endothermic animals regulate body temperature

  • Arteries carry warm blood from core to body, veins carry cold blood from body.

  • The vessels run next to each other – counter-current exchange


Heart cycle

Heart Cycle

  • 72 beats per min.

  • Beat begins in the right atrium at the sinoatrial node (“pacemaker”)

  • Then to the atrioventricular node

  • Then to the bundle of His and Purkinje Fibers in the ventricles causing contractions

  • Systole – during contraction

  • Diastole - relaxation


The circulatory system

Superior

vena cava

Sinoatrial (SA)

node (pacemaker)

Left atrium

Atrioventricular

(AV) node

Atrioventricular

(AV) bundle

(bundle of His)

Right atrium

Bundle branches

Purkinje fibers

Interventricular

septum

Purkinje fibers

Figure 11.7


Contents of blood

Contents of Blood

  • Plasma and cells

  • 3 types of cells

  • Red blood cells – erythrocytes – carry oxygen

  • White blood cells – leukocytes – fight infection

  • Platelets – clotting cells


Clotting

Clotting

  • When a blood vessel is damaged, the platelets stick to the vessel wall and send signals

  • Platlets release protein clotting factors that signal a series of reactions

  • Prothrobin activator converts prothrombin to thrombin

  • Thrombin converts fibrinogen to fibrin threads – this strengthens the clot and stops bleeding


The circulatory system

1

Step Vascular spasms occur.

  • Smooth muscle contracts, causing

    vasoconstriction.

Figure 10.6, step 1


The circulatory system

2

Step Platelet plug forms.

  • Injury to lining of vessel exposes collagen fibers;

  • platelets adhere.

Collagen

fibers

  • Platelets release chemicals that make nearby

  • platelets sticky; platelet plug forms.

Platelets

Figure 10.6, step 2


The circulatory system

3

Step Coagulation events occur.

• Clotting factors present in plasma and releasedby injured tissue cells interact with Ca2+ to formthrombin, the enzyme that catalyzes joining offibrinogen molecules in plasma to fibrin.

Fibrin

• Fibrin forms a mesh that traps red blood cells

and platelets, forming the clot.

Figure 10.6, step 3


Bone marrow

Bone marrow

  • This is where the blood is made

  • Located in the center of bone


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