CARDIOVASCULAR SYSTEM

The circulatory system

* Can be thought of as the transport system of the body
* A closed system consisting of the heart, blood vessels, and blood

Function of cardiovascular system

Deliver oxygen & nutrient-rich blood to body cells and remove carbon dioxide and waste

Location of heart

Located in the thoracic cavity between the lungs slightly to the left

Heart

A hollow, cone-shaped muscle about the size of a fist that is made up of **cardiac muscle**

Pericardium

A double serous membrane

Visceral pericardium (epicardium)

Next to heart

Parietal pericardium

Outside layer

Serous fluid

fills the space between the layers of pericardium

Heart Walls

Three layers

* Epicardium
* Myocardium
* Endocardium

Epicardium

–Outside layer

–This layer is the visceral pericardium

Myocardium

–Middle and thickest layer

–Mostly cardiac muscle

Endocardium

–Inner layer

–Made up of simple squamous epithelium

4 chambers of the heart

–Left & right atria – **receive blood**

–Left & right ventricles -**pump blood out**

Septum

Separates the chambers

Valves

* flaps of connective tissue between the atria and ventricles
* moves the blood through the heart in one direction

Open

Valves ___ as blood is pumped through

Chordae tendineae (“heart strings”)

Holds the valves in place

To prevent backflow

Valves are closed ____

Atrioventricular valves

– between atria and ventricles, open valves

–left atrium → bicuspid valve (mitral valve) → left ventricle

–right atria → tricuspid valve → right ventricle

Semilunar valves

**-** between ventricle and artery, closed valves

–right ventricle → pulmonary semilunar valve → pulmonary ARTERY

–left ventricle → aortic valve → aorta

Aorta

Blood leaves left ventricle towards body

Pulmonary arteries

Oxygen-poor blood leaves right ventricle towards lung

Vena cava

–Superior and inferior

–Blood from the body enters the right atrium

Pulmonary veins (4)

Oxygen-rich blood from lungs enters left atrium

Blood vessels

Tubes which transport  blood

Function of blood vessels

–Transport blood

–Carry out the exchange of gases and waste

–Regulate blood pressure

–Direct blood flow

Types of blood vessels

1. arteries
2. capillaries
3. veins
4. diaseases

Arteries

Thick walls blood vessels which carry oxygen-rich blood **away from the heart to the body.**

Aorta

Largest artery in the body

Capillaries

* Microscopic blood vessels which connect arteries and veins together
* Where exchange of oxygen, carbon dioxide, nutrients, and waste occur
* One cell layer thick

Veins

* Blood vessels which carry oxygen-poor blood from the body back to the heart.
* Thin walls
* Requires muscles to push blood back to the heart

Arteriosclerosis

–The hardening of the arteries due to the formation of scar tissue

–Leads to hypertension, heart attack, & stroke

Varicose Veins

Valves in the veins become weak leading to abnormal dilations in the superficial veins

Phlebitis

–Inflammation of a vein

–Very serious because it can lead to blood clots (thrombosis) and death

**Circulation**

* **the transportation of blood**
* **Movement of Blood Through Vessels** 

Arterial blood

**Most ____ is pumped by the heart**

**Milking action**

**Veins use the _____ of muscles to help move the blood**

**The goal of circulation of blood in the body**

1\.**Send oxygen-poor blood to the lungs to pick up oxygen and then**

2\.**To pump oxygen-rich blood from the heart to the body cells**

**Three circulation pathways**

1\.  **Pulmonary circulation**

2\.  **Systemic circulation**

3\.  **Coronary circulation**

**Pulmonary circulation**

**From heart to lungs**

**Systemic circulation**

**From heart to body**

**Coronary circulation**

**From heart to heart muscle**

Pulmonary Circulation

* **The flow of blood from the heart to the lungs**

**DEOXYGENATED BLOOD** **must have carbon dioxide removed, so it is sent to the lungs**

**Body cells > Veins > Vena cava (1)> R Atrium (2)> Tricuspid valve > R Ventricle > Pulmonary Semilunar valve> Pulmonary ARTERY (3) > Lungs**

Systemic Circulation

* **The flow of blood from the heart to the body Cells**

OXYGENATED BLOOD **coming back from the lungs is pumped to the body cells**

**Lungs > Pulmonary VEINS (4)> L Atrium > Bicuspid (mitral) valve > L Ventricle (5) > Aortic Valve > Aorta (6)> Arteries > Body cells**

Blood

The only fluid tissue in the human body

5x

Blood is ___ thicker than water

Scarlet red

Oxygen-rich blood

Dull red

Oxygen-poor blood

Ph of blood

must remain between 7.35–7.45

Volume of blood

5-6 Liters or about 6 quarts/body

Composition of blood

1. Blood plasma
2. Erythrocytes – Red Blood Cells
3. Leukocytes – White Blood Cells
4. Platelets

Blood plasma

* Makes up 55% of blood
* Composed of 90% of water
* Contains nutrients, salts (metal ions), respiratory gases, hormones, proteins, waste products

Erythrocytes – Red Blood Cells

* The main function is to carry oxygen
* Biconcave disks
* Anucleate (no nucleus)
* Outnumber white blood cells 1000:1

250 million

**Each erythrocyte has ____ hemoglobin molecules**

Hemoglobin

–Iron-containing protein

–Binds strongly to oxygen

Leukocytes – White Blood Cells

Crucial in the body’s defense against disease

Platelets

* Small fragments produced from ruptured cells (megakaryocytes)
* Needed for the clotting process

Blood Disorders

1. Anemia
2. Sickle cell Anemia
3. Hemophilia

Anemia

* caused by low iron or hemoglobin

–Symptoms: fatigue, dizziness, headaches, shortness of breath

Sickle cell Anemia

* recessive genetic disorder

–Symptoms: fatigue, bone pain, ulcers, delayed growth, shortness of breath

Hemophilia

* recessive sex-linked bleeding disorder

–Blood lacks clotting factors

–Minor injuries can cause **uncontrolled bleeding**

Blood types

1. ABO blood types
2. Rh blood types

ABO blood types

There are 4 blood types, A, B, AB, and O, which are determined by **antigens** on our blood cells.

Antigens

substances that trigger an immune response.

Antigens present

* Type A blood have A antigens on their cells
* Type B has B antigens
* Type AB has both A and B antigens
* Type O has neither A nor B antigens

Parents

We inherit our blood type from our ____

Type O

most common in the United States (45% of the population).

Type AB

most rare (4% of the population)

Blood transfusions

can be done using the same blood type or another type that will not trigger an immune response

Type O

the universal donor

Type AB

the universal recipient

**Rh Blood Types**

A person will also have + or – for their Rh factor. 

Rh Factor

usually does not affect transfusions, but can **cause problems** for a pregnant woman and the fetus if they have a different Rh phenotype

Conduction System of the Heart

* Initiates, stimulates, and coordinates the contraction of the atria and ventricles

–Makes the heart an effective pump

2 types of Nodal tissue controls the heartbeat

SA (sinotrial) Node

AV (atriocentricular) Node

SA (sinoatrial) Node

* found in the right atrium

0\.85 seconds

SA (sinoatrial) Node Initiates the heartbeat every ____

Pacemaker

SA (sinoatrial) Node serves as the ___

4 steps to the conduction system of the heart

1. The ***SA node*** sends out an impulse causing the atria to contract.
2. The impulse reaches the ***AV nod*****e** and travels along the ***AV bundle****.*
3. The impulses travel throughout the ventricles to the ***Purkinje fibers***.
4. Ventricles contract.

The **SA node**

sends out an impulse causing the atria to contract.

The impulse

reaches the **AV node**  and travels along the **AV bundle**.

Purkinje fibers

The impulses travel throughout the ventricles to the **____**

Cardiac cycle

includes all the events that occur in one heartbeat

Heart beats

70x/minute

L & R atria

contract simultaneously

Relaxes

Atria ___- then L & R ventricles contract simultaneously

Systole

Contraction

Diastole

Relaxation

Atrial systole

– 0.15 sec

–Atria is systole (contracted) pumping blood into ventricles (diastole-relaxed)

Ventricle Systole

\- 0.30 sec

–Ventricle fills with blood and contracts pumping blood to the aorta and pulmonary arteries

Atrial & Ventricle Diastole –

\- 0.40 sec

–Both atria & ventricles are diastole (relaxed) as blood from the body fills the atria

Lup

closing of the bicuspid and tricuspid valve

Dup

closing of aortic and pulmonary valve

Heart Murmur

any of the heart valves do not close properly

**Electrocardiograms (EKG or ECG)**

**are used to measure the electrical rhythm of the heart’s contraction**

Arrhythmia

irregular heart beat

Tachycardia

= more than 100 beats/min

* Irregular contractions of the atria and/or ventricles due to chaotic electrical signals
* Result is lack of blood flow to heart
* Heart rate may be 100-175 bpm at ret

Bradycardia

= less than 60 beats/min

* Heart does not pump enough oxygen-rich blood

Pacemaker

**Used to maintain a consistent heart rate when the body’s natural pacemaker (SA node) is not properly functioning**

Vital signs

1. pulse
2. blood pressure