Mammalian Circulatory System

Circulatory Systems

• There are both open and closed systems.– Insects have an open circulatory system (blood

leaves the heart and flows freely throughout the body)

– Mammals have a closed system (blood is at all times contained within a series of vessels)

• In the 17th century William Harvey established that we have a cyclic system (blood flows in one direction)

Circulatory Cycles

• There are 3 primary circulatory cycles:– Cardiac Cycle – the route of blood within the

heart– Pulmonary Cycle – the route of blood between

the heart and lungs– Systemic Cycle – the route of blood between the

heart and the body

Three key aspects of a closed system

• Vessels – to transport blood

• A pump (heart)- to move blood throughout the body

• A transport medium – a specialized fluid tissue to carry vital elements

Why do we need a transportation system?

• What does our transportation system have to do with maintaining homeostasis?

Blood Vessels

• Many of the names of vessels comes from the Latin or Greek names.

• Remember interest in the body has been since the dawn of time!!!

How blood is transported• Arteries:

– Carry blood away from the heart– Rigid/Elastic to take blood under

high pressure (from heart)• Capillaries:

– Very thin narrow where diffusion of gases and materials occurs

– opens and closes to regulate blood flow (e.g. stress, eating, etc...)

• Veins:– Loosen to expand more (controlled

by smooth muscles)– Store great quantities of blood

Keeping Blood Moving

• Veins posses one-way valves that keep blood moving in one direction.

• Muscle contractions squeeze the veins to force blood that can be under negative pressure to move towards the heart.

• Varicose Veins – prolonged periods of standing without leg contractions can increase the risk of developing faulty valves

Another Look at Blood Vessels

Important ones to note• Aorta – main artery from heart.• Mesenteric – digestive system• Renal – Kidney• Iliac – Hip/Pelvic• Hepatic – Liver• Inferior Vena Cava – blood to heart from lower• Superior Vena Cava – blood to heart from upper• Carotid Artery – neck vessel to brain.• Jugular vein – neck vessel from brain• Pulmonary – Lung• Cardiac - Heart

The Heart

The Heart

• Located within the thoracic cavity positioned more on the left side of the body

• The heart is protected by fat and a pericardium. (a bilayer tissue filled with fluid)

How Blood Circulates: The Heart

The Heart• Contraction of ventricles

– Larger of heart chambers – Takes blood in from the atria– Pumps blood out to the

lungs/body• Contraction of atria

– Smaller chambers– Takes blood in from

lungs/body– Pumps blood into the

ventricles• Coordinated beating of

atria then ventricles

Cardiac Cycle• Right Atria receives de-oxygenated blood

Returned from the body. Pumps it to:• Right ventricle - receives blood from R. atria

and pumps it out to the lungs for oxygen.• Tricuspid valve prevents back flow from

ventricle to atria. (Atrioventricular valve)

Cardiac Cycle cont.• Left Atria receives oxygenated blood from the Lungs

and pumps it to:• Left ventricle which then pumps it out to the body

(Leaving the heart).• Bicuspid valve prevents back flow from ventricle to

atria.• Semi-lunar valves prevent backflow between both

ventricles and their arteries

Coordination of the Beating• The Heart cells naturally

beat without conscious control.

• Specialized cells in the right atria called the SA Node (pacemaker) send an electric impulse to neighboring cells stimulating them to contract.

• The atria beat top-down.• The ventricles beat bottom-

up• Cardiac Cycle

• Without coordination of the electric signal, the heart cells would all beat randomly (fibrillation)

- These nerve impulses are detectable using an electrocardiogram (ECG) See Fig 9.19 pg 317

- Drug overdoses, electric shock, or other damage can trigger random fibrillations. This would need ro be corrected by providing a strong electrical current directly to the heart. AKA De-fibrillation.

Heart Regulators, Fitness and Disease

Regulation

• At rest the S-A node fires about 70 beats/min.• During activity, stress or fear, CO2 builds up in the

body becoming carbonic acid.• Sensory receptors transmit this to the medulla

oblongata (brain) and stimulate the release of noradrenaline

• Noradrenaline is a stimulant that causes the heart to beat faster.

Cool Down

• Once the stress is gone the heart is still pumping. heart rate = blood pressure.

• This pressure on the arteries triggers sensory receptors within the artery wall to send a signal to the medulla to release acetylcholine.

• Acetylcholine slows heart rate back to normal levels

Cardiac Output and Fitness• Cardiac Output is the amount of blood pumped

by the heart in a time given time period. It provides a measure of blood pumped & amount of oxygen delivered to body.

• CO = stroke volume x heart rateStroke volume - amount of blood pumped out of the heart per beat.

• AVG (S.V. = 70 ml) x ( H.R. = 70 b/m) = 4900 ml/min. ***~5 L in body***

Ailments and Diseases

• Poor fitness decreases the distensibility (stretchiness) of the ventricles. ( Stoke vol.)

• Septum defect - heart chamber between the ventricles fails to close at birth causing “Blue-babies”. (low oxygen)

• Heart Murmur - one or more heart valves does not open/close restricting the smooth flow of blood in the heart.

Tricuspid valve with a faulty valve door.

The Lymphatic SystemThe Other Transport System

• The Lymphatic system is the network of glands and vessels throughout the body that transports a near colourless fluid called Lymph.

• This vascular system (not found in all animals) helps in immunity and maintaining osmotic balance.

• It is transported throughout the body using muscle contractions and one-way valves, like blood in veins.

Works with Cardiovascular System• Some plasma that

escapes the capillaries to bath the body cells does not re-enter the capillaries. This fluid is absorbed into the lymphatic system and returned to the cardiovascular system through ducts near the heart.

Immunity support

• The Lymphatic system also aids in transporting white blood cells that guard the body against infection.

• Lymphocytes (White Blood Cells) originate in the lymph nodes of the body. (Think swollen lumps in your throat when you are sick)

Blood Pressure

• Blood Pressure is described using two parts:– Systolic Pressure- is the highest pressure reached

during a ventricular contraction.– Diastolic Pressure- is the lowest pressure reached

just before the next ventricular contraction.– Blood Pressure is recorded in mmHg (mm

Mercury). Normal range equals 120/80 mmHg.

Hypertension• Hypertension is a chronically elevated high blood

pressure. It can be associated with a number of health problems.

• Any condition that increases the volume of blood or the rate of blood flow can lead to hypertension– Ex. High salt intake, high cholesterol, diet, age, fitness.

• http://health.howstuffworks.com/adam-200079.htm• http://www.healthcentral.com/high-blood-pressure/introduction-47-115.html

Arteriosclerosis &Atherosclerosis

Clots, Stroke, and Heart Attacks

Angioplasty

• A procedure used to open the artery lumen by compressing or removing a plaque deposit.

Coronary Bypass

• Coronary blockages can lead to major heart problems. The muscles of the heart need a constant supply of oxygen. During a bypass vessels are removed from another part of the body and are used to bypass the blockage.

• READ Pages 322-328

• Do #1, 2, 3 & 4

BloodTransport Medium

Function of BloodComposition of Blood

Blood Types

Function of Blood• Transport of:

OxygenCarbon Dioxide

Nutrients Wastes

• Immunity

Composition Of BloodBlood is a collection of cells

specialized to perform a particular task. Therefore it’s considered a tissue.

• 55 % Plasma- 45% Cells and Cell Parts

Plasma• composed of:

– clear golden fluid and water– dissolved substances– proteins (Fibrinogen & Globulin's)

• Has several functions:– Transports small molecules and ions– contains Fibrinogen involved in blood clotting– contains antibodies (globulin's) that are

involved in disease fighting

Blood Cells and Cell Parts

3 Cellular components to blood• Red Blood Cells• White Blood Cells • Blood Platelets

• Plasma:–Glucose, hormones,

etc. suspended in a viscous goo

• White Blood Cells:(leukocytes)–Protect the cells from

infection/invasion

• Platelets:–Clot the blood to prevent it from

spilling out when a rupture of the fluid conduit occurs

• Red Blood Cells:(erythrocytes)–Transport O2

–99% of all blood cells

Red Blood Cells• Also called Erythrocytes ~ 5 million/ml• Main function is to carry Oxygen• Structure:

– Mature cells have no nucleus and are disk shaped (to surface area & size)

– Cytoplasm contains a molecule called Hemoglobin• a iron containing molecule to carry oxygen• every R.B.C contains > 200 mil. hemoglobin

molecules

White Blood Cells• also called Leucocytes• Function: protect the body from infectionThere are Two main types of W.B.C. s• macrophages

–move out of the capillary and digest foreign materials by phagocytosis

• Lymphocytes–specialized antibodies that fight infection

Platelets

• Cell fragments• 250 million per cubic centimeter• Function: Trigger the Blood Clotting

Process

Blood Clotting• Broken or damaged blood vessels release

platelets.• Ruptured Platelets release chemicals that react

with plasma proteins to make thromboplastin. • Thromboplastin reacts with prothrombrin to

produce thrombrin (needs calcium)• Thrombrin causes fibrinogen molecules to join

together to form strands called Fibrin• Many strands of Fibrin form a mesh or clot that

stops the bleeding

Blood Clot

Blood Clotting

Review of Blood Components

Plasm a

M acrophages Lym phocytes

W hite B lood C ells(W.B.C)-Leucocytes

P late lets R ed B lood C ells (R .B .C )-Erththrocytes

B lood Cells and B lood Parts

B lood

Blood Problems

• Anemia - occurs when there is a shortage of hemoglobin ib blood

• Leukemia - Cancer of the white blood cells• A.I.D.S - the H.I.V. virus attacks and destroys

an important type of WBC• Sickle Cell Disease - abnormal hemoglobin

causes RBC s to have irregular shape

The END