circulatory system

Question 1

Describe the heart and position

Answer 1

The Heart
•Hollow coned shaped muscular organ -approximately size of the owners fist
•It lies in the thoracic cavity, obliquely in the mediastinum, behind the sternum.
•2/3 lies to the left of the midline,
•Base above, apex below, resting on the diaphragm.

Question 2

Three layers of the walls of The Heart

Answer 2

Three layers of the walls of The Heart

• Pericardium – fibrous outer sac –2 layers
• Myocardium – muscle layer, thickest in the left ventricle, has its own intrinsic stimulus, coronary arteries found here
• Endocardium – smooth inner lining continuous with blood vessels

Question 3

Pericardium

Answer 3

Pericardium
•Consists of two sacs
–an outer fibrous sac (Fibrous pericardium)
–a double inner layer of serous membrane

• The outer layer of serous membrane, called the parietal pericardium adheres to the outer fibrous pericardium
• The innermost layer of serous membrane, called the visceral pericardium adheres to the myocardium

Question 4

Myocardium

Answer 4

Myocardium
Is the muscle layer of the heart. It is thickest around the left ventricle and has a unique characteristic, called Automaticity.
This means the heart can contract without an outside stimulus

Question 5

Endocardium

Answer 5

Endocardium
The innermost lining of the heart and its valves, it is composed of endothelium, providing a smooth lining and preventing local blood clotting

Question 6

Three main components of the circulatory system

Answer 6

Three Main Components

• The heart
• Blood vessels
• Blood

Question 7

Heart chambers

Answer 7

Heart Chambers
Four chambers

• Left and right atria
• Left and right ventricles
• Left and Right sides are divided by muscular partition called the septum

Question 8

Heart valves

Answer 8

Heart Valves
Four valves:

• Pulmonary valve
• Aortic valve

•Two atrioventricular valves
–Right or tricuspid valve
–Left or mitral valve

Question 9

Pulmonary & Systemic circulation

Answer 9

Pulmonary & Systemic Circulation

• Pulmonary – involves pumping deoxygenated blood to the lungs and returning re-oxygenated blood to the heart
• Systemic – involves circulating oxygenated blood throughout the body to the tissues and returning deoxygenated blood to the heart

Question 10

Types of blood Vessel

Answer 10

The heart pumps blood into vessels that vary in structure, size, and function, and there are several types:
• arteries
• arterioles
• capillaries
• venules
• veins

Question 11

Structure of Blood Vessels

Answer 11

Structure of Blood Vessels
All vessels are structured in three layers:

• Tunica Adventicia (Outer fibrous sheath)
• Tunica Media (middle layer of muscle and elastic tissue)
• Tunica Intima (Inner layer of smooth endothelium)

Question 12

Portal circulation

Answer 12

Portal Circulation
•A branch of the systemic circulation
•Carries blood to and from the liver
•Hepatic artery supplies oxygenated blood
•Hepatic portal vein carries blood rich in nutrients from the digestive tract to the liver
•Hepatic Veins carry deoxygenated blood from Liver to Inferior Vena Cava

Question 13

Spleen

Answer 13

Spleen
•Lies in the left hypochondrial region of the abdominal cavity, between fundus of the stomach and the diaphragm

• Size varies but usually approx. 12cm long, 7cm wide and 2.5cm thick
• Weighs approx. 200g

Question 14

Function of the spleen

Answer 14

Functions of the Spleen

• Produce new white blood cells
• Store red blood cells
• Destroy old red blood cells

Question 15

Composition of blood

Answer 15

Composition of Blood
Blood is composed of 55% liquid, 45% solids and contains four main elements:

• Plasma (Liquid)
• Red cells (erythrocytes)
• White cells (leukocytes)
• Platelets (thrombocytes)

Question 16

Principle functions of blood

Answer 16

Principle Functions of Blood
•Carry oxygen and carbon dioxide

• Carry nutrients and water
• Carry waste products to excretory organs
• Distribute secretion of glands (Enzymes and hormones)

Protect the body from infection

• Distribute heat
• Seal wounds by clotting