The Circulatory System Lecture Flashcards

Introduction to the Circulatory System

General Definition: The circulatory system acts as an internal road network, linking all parts of the body together.
System Type: It is described as a closed system.
Road Network Metaphor:
- Highways: Represented by arteries and veins.
- Main Roads: Represented by arterioles and venules.
- Streets: Represented by capillaries.
Major Functions:
- Supply food, oxygen, and hormones to the cells of the body.
- Produce and supply antibodies.
- Remove waste products from cells.
- Control body temperature.
Significance: A healthy circulatory system is essential for life.

Anatomy of the Heart

Physical Characteristics:
- A triangular organ.
- The size of a closed fist.
Structural Layers (Muscle Composition): The heart is a muscle made up of three distinct layers:
1. Pericardium
2. Myocardium
3. Endocardium
Location:
- Situated between the lungs in the lower portion of the mediastinum.
- The apex (the lower edge of the heart) lies on the diaphragm.

Internal Structure and Phases of the Heart

Chambers of the Heart: The interior is divided into four chambers:
- Two Upper Chambers (Atria): Consists of the right and left atrium. These function by receiving blood from either the body or the lungs.
- Two Lower Chambers (Ventricles): Consists of the right and left ventricles. These function by discharging blood to either the body or the lungs.
Functional Phases:
- Systole: The phase where the heart is at work; it involves contracting and pushing blood out of the left ventricle.
- Diastole: The phase when the heart relaxes or rests; during this time, the chambers fill with blood.
Valves of the Heart: One-way flow of blood is maintained by four valves that prevent blood from flowing back into the various chambers:
- Atrioventricular valves: Includes the tricuspid valve and the mitral valve.
- Semilunar valves: Includes the pulmonary valve and the aortic valve.

Blood Flow and Circulation Routes

General Principle: Blood circulation is the flow of blood through all vessels arranged in a complete circuit or circular pattern.
Path of Blood Flow Through the Heart:
1. The right atrium receives deoxygenated blood from the body via major veins: the superior and inferior vena cava.
2. When the right ventricle is filled, blood is pumped to the lungs for gaseous exchange via the pulmonary artery (this constitutes the pulmonary circuit), where $CO_2$ is removed and $O_2$ is taken in.
3. The left atrium receives oxygenated blood from the lungs via the pulmonary veins.
4. When the left ventricle is filled, blood is pumped to the organs and tissues of the body via the aorta (this constitutes the systemic circuit).
Pulmonary Circulation:
- Carries blood to and from the lungs.
- Arteries deliver deoxygenated blood to the lungs for gas exchange.
- Path: Right ventricle $\rightarrow$ pulmonary arteries $\rightarrow$ lungs $\rightarrow$ pulmonary veins $\rightarrow$ left atrium.
Systemic Circulation:
- Carries blood throughout the remainder of the body.
- Path: Left ventricle $\rightarrow$ aorta $\rightarrow$ smaller arteries $\rightarrow$ arterioles $\rightarrow$ capillaries $\rightarrow$ venules $\rightarrow$ venae cavae $\rightarrow$ right atrium.

Blood Supply to the Heart Muscle (Coronary Circulation)

Requirement: As a muscle, the heart itself requires oxygen and nutrients for fuel.
Coronary Circulation: The heart's own dedicated blood supply.
- Oxygen-rich and nutrient-rich blood flows to the cardiac myocardium through the right and left coronary arteries.
- Deoxygenated blood is returned to the right atrium through the cardiac veins.
Clinical Implications:
- Myocardial Infarction (MI): Commonly known as a heart attack, caused by a blockage of blood flow through the coronary arteries.
- Coronary Bypass Surgery: A common treatment for individuals suffering from severely restricted blood flow in the coronary arteries.

Blood Vessels and Blood Pressure

Arteries:
- Carry oxygenated blood (with the exception of the pulmonary artery, which carries deoxygenated blood).
- Distribute nutrients and gases.
- Facilitate blood movement under high pressure.
- Assist in maintaining arterial blood pressure.
Capillaries:
- Serve as exchange vessels for nutrients, wastes, and fluids.
Veins:
- Collect deoxygenated blood and return it to the heart (with the exception of the pulmonary vein, which returns oxygenated blood).
- Contain internal valves at various points to prevent the backflow of blood; these valves are pushed closed if blood flows back against them.
Major Arteries of the Human Body:
- Aortic arch
- Posterior tibial
- Radial
- Ulnar
Major Veins of the Human Body:
- Carotid vein
- Axillary vein
- Cephalic vein
- Femoral vein
Blood Pressure (BP):
- Defined as the measure of force exerted on arterial walls as blood is pumped from the heart.
- Gradient: Highest in the arteries and lowest in the veins.
- Normal Values: Blood pressure varies within a normal range; the normal average arterial blood pressure is $120/80$ .

Aging and Observations

Normal Changes with Aging:
- The heart pumps less efficiently.
- Decreased blood flow.
- Narrowed blood vessels.
Signs/Symptoms of Abnormal Changes (To be reported):
- Changes in pulse rate.
- Weakness or fatigue.
- Loss of ability to perform Activities of Daily Living (ADLs).
- Swelling of hands and feet.
- Pale or blue (cyanotic) hands, feet, or lips.
- Chest pain.
- Weight gain.
- Shortness of breath, changes in breathing patterns, or inability to catch breath.
- Severe headache.
- Inactivity (noted as a cause of circulatory problems).

Chronic Conditions and Care Guidelines

Hypertension (HTN) / High Blood Pressure:
- Causes: Atherosclerosis (hardening and narrowing of blood vessels), kidney disease, adrenal tumors, pregnancy, or certain medications.
- Symptoms: Headache, blurred vision, dizziness (though sometimes there are no noticeable symptoms).
- Care Guideline: Take blood pressure exactly as ordered.
Coronary Artery Disease (CAD):
- Cause: Vessels in coronary arteries narrow, reducing blood supply to the heart.
- Symptom: Angina pectoris (chest pain, pressure, or discomfort).
- Treatment: Nitroglycerin, a medication that relaxes coronary artery walls. It is available in tablet, patch, or spray form.
- Care Guideline: Nitroglycerin must be kept close by; notify the nurse if a nitroglycerin patch detaches.
Myocardial Infarction (Heart Attack):
- Cause: A block of blood flow to the heart muscle resulting in tissue death (which can be a large or small area).
- Risk: Can result in serious heart damage or death. (Refer to Chapter 7 for warning signs).
- Care Guideline: Encourage adherence to special diets and exercise programs; minimize stress.
Congestive Heart Failure (CHF):
- Cause: Failure of the heart muscle to pump effectively due to damage.
- Symptoms: Fatigue, rapid or irregular heartbeat, shortness of breath, dizziness, weakness, swelling (edema) of feet and ankles, increased urination at night (nocturia), and weight gain.
- Care Guidelines: Measure Intake and Output (I&O); weigh residents as instructed; apply elastic leg stockings; use extra pillows to assist with breathing.
Peripheral Vascular Disease (PVD):
- Cause: Fatty deposits in the blood vessels that harden.
- Symptoms: Cool extremities (legs, feet, arms, hands); ashen or blue nail beds/feet; swelling in hands and feet; ulcers of the legs and feet.
- Care: Anti-embolic stockings to prevent swelling and blood clots while aiding circulation.

Questions & Discussion

Workbook Study Tasks:
- Students are required to share answers with the class when prompted by the instructor.
- Chapter 9, Topic 5: Identify "Normal" versus "Signs/Symptoms" via multiple choice.
- Chapter 18, Topic 4:
  - Hypertension: Short Answers.
  - Coronary Artery Disease: True/False.
  - Congestive Heart Failure: Fill in the Blank.
  - Peripheral Vascular Disease: Multiple Choice.
Class Discussion Prompts:
- What are the three possible causes of Hypertension?
- Why is the treatment of hypertension important?
- What causes a Myocardial infarction?
- What causes a Congestive Heart failure?