Circulatory System Chapter 42. Slide 2 of 20 Circulation – The basics 3 basic parts Blood – What type of tissue? Vessels – tubes for blood movement.

Circulatory System

Chapter 42

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Circulation – The basics

3 basic parts Blood – What type of tissue? Vessels – tubes for blood movement Heart – structure that pumps blood

2 Types of systems Open Circulatory System

Bloods contacts the organs directly Hemolymph – Combined blood & lymph Heart pumps hemolymph into sinuses (cavities) Arthropods & molluscs

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Closed Circulatory System

Blood is contained within vessels & pumped about the body by the heart

Blood is separate from the interstitial fluid

Annelids, cephalopods, & all vertebrates

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Blood Vessels

Arteries – Blood AWAY from the heart Contain significant amount of smooth muscle

Arterioles – smaller branches of arteries

Capillaries – microscopic vessels 1 cell thickness Site of diffusion (gas, fluids, etc.)

Veins – carry blood back TO the heart Valves prevent backflow

Venules – smaller branches of veins

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Cardiac Cycle Notes

Capillaries are for gas exchange

Arteries Capillaries Veins

Cardiac Cycle Always Atrium Ventricle

Atria – receive blood from body or lungs Ventricles – receive blood from atria, pump to body or

lungs

Right Atrium right ventricle lungs Lungs Left Atrium Left Ventricle Body From Body Veins Right Atrium

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Cardiac Cycle

Consists of a systole and diastole

Systole – contraction phase

Diastole – Relaxation phase

Heart Rate – rate of contractions per minute

Stroke volume – amount of blood pumped by the left ventricle during the systole

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Cardiac Valves

Atrioventricular valves – valve between atria & ventricles

Prevent backflow of blood into atria

Semilunar valves – Exit valves for ventricles Prevent backflow of blood into ventricles

AV valves close during Ventricular systole Usually OPEN

Semilunar valves close during Ventricular diastole Usually CLOSED

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Electrical Signal Transmission

Sinoatrial (SA) node – Pacemaker of the heart Located in the upper wall of the right atrium Sets the rate of cardiac muscle cell contraction

AV node – Delays signals from the SA node Located in the lower wall of right atrium Allows atria to completely empty before ventricles contra

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Cardiac (Heart) Rate

Affected by Sympathetic nerves – accelerate heart rate Parasympathetic nerves – decelerate heart rate

Body Temperature Increase Body temp 1°C 10 beats per minute Fever increase in pulse rate Exercise Rate increase

Hormones Epinephrine Increases heart rate

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Systemic Vascular Pressure

Blood pressure Typically taken at upper arm cuff Wrist monitors are not used for diagnostic purposes

2 Types of blood pressure are taken Systolic

Remember from cardiac cycle? Vascular pressure when heart has contracted

Diastolic Remember from cardiac cycle? Vascular pressure when heart is relaxed

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In a typical reading,-- 1st number is systolic (always larger)-- 2nd number is diastolic (always smaller)-- Extremely subjective measurement

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Lymphatic System

Returns lost fluid & proteins to the blood In the form of lymph

Along lymph vessels are lymph nodes Filter lymph Part of immune system

attack viruses and bacteria here Uses White Blood Cells (WBC)

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Blood

Plasma Mostly Water Ions, electrolytes, & plasma proteins Transports nutrients, gases, wastes, & hormones Oh yeah, and it carries Blood Cells

Cellular Constituents Red Blood Cells (RBC or erythrocytes)

Transports oxygen by hemoglobin White Blood Cells (WBC)

Part of immune system Platelets

Cellular fragments responsible for blood clotting

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Red Blood Cells (RBCs)

Biconcave discs Increased surface area enhances O2 transport 250 million molecules of hemoglobin in each RBC Each hemoglobin = up to 4 O2 molecules

Lack nuclei (more room for hemoglobin)

Lack Mitochondria (so oxygen carried is NOT consumed)

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