MPharm Programme - Circulatory System

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Questions and Answers

What primary role does the heart serve in the circulatory system?

Regulates hormone levels in the body

Filters metabolic wastes from the blood

Pumps blood and generates cardiac output (correct)

Transports oxygen and nutrients to tissues

Which function of the circulatory system is responsible for transporting hormones?

Hormonal regulation (correct)

Homeostasis maintenance

Nutrient transport

Respiratory exchange

How does the circulatory system contribute to excretion?

By distributing nutrients to body tissues

By filtering blood through the heart

By removing excess oxygen from the blood

By carrying metabolic wastes to the kidneys (correct)

What is the primary role of blood vessels in the circulatory system?

To carry blood from the heart to all parts of the body Signup and view all the answers

Which substance is NOT primarily transported by the circulatory system for respiratory function?

Hormones Signup and view all the answers

Which of the following is NOT one of the major components of the circulatory system?

Kidneys Signup and view all the answers

What is the primary function of blood in the circulatory system?

Transport of oxygen and nutrients Signup and view all the answers

Which type of cardiac cell is responsible for conducting electrical impulses in the heart?

Pacemaker cells Signup and view all the answers

The regulation of cardiac output is influenced by what factors?

Heart rate and stroke volume Signup and view all the answers

Which segment of the vascular system is responsible for carrying oxygenated blood away from the heart?

Arteries Signup and view all the answers

Which cellular component of blood is primarily involved in the defense against infections?

White blood cells Signup and view all the answers

What is the role of platelets in the circulatory system?

Clotting blood Signup and view all the answers

Which of the following best describes the cardiac cycle?

The alternating phases of relaxation and contraction of cardiac muscle Signup and view all the answers

What is the primary function of the circulatory system in terms of temperature regulation?

It diverts blood to cool or warm the body. Signup and view all the answers

What percentage of blood volume is made up of plasma?

55% Signup and view all the answers

Which component of blood is responsible for mediating blood clotting?

Platelets Signup and view all the answers

Which element makes up the majority of the liquid composition of plasma?

Water Signup and view all the answers

Which of the following best describes the function of leukocytes in blood?

Protecting against pathogens Signup and view all the answers

What is the approximate total blood volume in an average adult female?

4-5 litres Signup and view all the answers

What percentage of blood consists of formed elements?

45% Signup and view all the answers

What type of blood cells are primarily responsible for gas transport?

Erythrocytes Signup and view all the answers

Which of these is NOT a component of plasma?

Platelets Signup and view all the answers

Which component of blood helps in transporting hormones?

Plasma Signup and view all the answers

Study Notes

MPharm Programme - Normal Systems - The Circulatory System

This lecture series is about the circulatory system
The circulatory system is broken into three basic components (Blood, The Heart, & Blood Vessels)
Blood is a transport medium carrying dissolved or suspended material (oxygen, carbon dioxide, nutrients, electrolytes, hormones, and metabolic wastes) over long distances in the body
The heart serves as a pump generating pressure and cardiac output, delivering blood to organs and tissues
Blood vessels form a conduit network distributing blood from the heart to all body parts and back to the heart
The circulatory system performs multiple functions, including:
- Transportation: of respiratory gases (oxygen and carbon dioxide), nutrients, and metabolic waste
- Regulation: of hormones, homeostasis (pH and electrolyte balance), and temperature
- Protection: through haemostasis (blood clotting) and immunity (leukocytes, cytokines, and complement)

Blood

Blood is a specialized liquid connective tissue, essential for short-range and long-range material transport between cells and the external environment
Total blood volume varies dependent on body size, fluid & electrolyte concentration and adipose tissue
Blood makes up 8% of body weight, with 5-6 liters in males and 4-5 liters in females
Blood composition consists of:
- Plasma (55%): A straw-colored liquid primarily composed of water (92%) and dissolved solutes (proteins, electrolytes, nutrients, hormones, and metabolic wastes)
- Formed or Cellular Elements (45%): Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)
Erythrocytes (red blood cells) are the most abundant and carry hemoglobin responsible for oxygen transport
Blood composition can be analyzed further using centrifugation; revealing the percentage of plasma, buffy coat, and erythrocytes after being withdrawn into a tube. This will indicate the relative concentration of formed elements present in the sample.

The Heart

A four-chambered muscular pump driving circulatory functions
Located in the mediastinum, between the sternum and the vertebrae
Surrounded by the pericardium, a double-layered membrane (visceral and parietal pericardium) with a lubricating fluid-filled cavity.
The heart pumps blood throughout the body, driving both pulmonary and systemic circulation pathways
Right side pumps deoxygenated blood to the lungs
Left side pumps oxygenated blood to the body

Vessels of the Heart

Great Cardiac Vessels: include the superior and inferior vena cavae, pulmonary artery, pulmonary veins, and aorta
Coronary Vessels: specialized vessels forming the coronary circulation, supplying blood to the cardiac muscle tissue. These vessels include the coronary arteries, coronary sinus, and various cardiac veins.

Cardiac Cells

Two main types
- Contractile cells - comprise 99% of heart cells, primarily responsible for the mechanical pumping action
- Electrical or Autorhythmic cells specialized for initiating and conducting action potentials (electrical impulses). The impulses activate contraction in the muscle cells. The electrical cells include the sinoatrial (SA) node, atrioventricular (AV) node, Bundle of His, and Purkinje fibers.
General Properties of Cardiac Cells:
- Resting Membrane Potential (RMP): Cell membrane at rest is polarized, inside being negative compared to the outside. Unequal distribution of ions across the cell membrane determines it.
- Excitability: Ability of heart cells to react to electrical stimuli by generating and propagating action potentials. The action potentials lead to contraction of the adjacent cardiac cells..
- Types of Action Potentials: Fast and slow. The differences are due to differences in voltage and time-dependent ion-channel opening/closing. The two types lead to differences in conduction characteristics.

Heart Valves

Four heart valves ensure unidirectional blood flow through the heart.
Atrioventricular (AV) valves include the tricuspid and bicuspid (mitral) valve, situated between the atria and ventricles; preventing backflow into the atria during ventricular contraction
Semilunar valves (Pulmonary and Aortic) are situated between the ventricles and their respective arteries; preventing backflow into the ventricles during ventricular relaxation.

The Heart Valves' Function

The heart valves ensure unidirectional blood flow through the heart.

Heart Wall Layers

The three distinct layers comprise;
- The innermost: Endocardium, lines the heart chambers; permitting efficient blood flow while preventing clotting.
- Myocardium, thick, middle layer of cardiac muscle tissue. It is mainly responsible for the heart's pumping function.
- Epicardium, the outermost layer, is a protective membrane covering the heart and embedding coronary blood vessels.

Components Summary

These components work in concert to allow constant blood flow and support all body functions.
Coordination of the system is crucial for maintaining homeostasis.
Irregularities or failures in any one of these components can lead to significant health issues.

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Description

This quiz covers the fundamentals of the circulatory system, including blood, the heart, and blood vessels. It outlines the system's essential functions such as transportation, regulation, and protection within the body. Test your understanding of how these components work together to maintain overall health.