Health Quiz: Managing Hypertension

Cardiovascular System Organization

• The central nervous system (CNS) includes the brain and spinal cord.
• The peripheral nervous system (PNS) encompasses everything else.
• Afferent pathways carry sensory information to the CNS.
• Efferent pathways carry signals from the brain to effectors.
• The autonomic system controls involuntary actions, broken down into the sympathetic (fight-or-flight) and parasympathetic (rest-and-digest) pathways.
• The somatic system controls voluntary actions.

Heart Structure and Function

• The heart is a pump, lying mostly on the left side of the chest cavity.
• It has four chambers: two atria and two ventricles.
• The right and left sides are separated by the intraventricular septum.
• Cardiac output is approximately 6000 liters per day.
• The myocardium is the muscle of the heart.
• Striated and involuntary cardiac muscle cells are connected by intercalated disks, allowing synchronized contractions.

Cardiac vs. Skeletal Muscle

• Both are striated.
• Cardiac muscle is involuntary; skeletal muscle is voluntary.
• Cardiac muscle responds to stretch/tension; skeletal muscle does.
• Cardiac muscle's intercalated disks allow electrical signals to spread quickly.

Ventricular Contraction and Relaxation

• Ventricular diastole is the relaxation phase, allowing ventricles to fill with blood.
• Ventricular systole is the contraction phase, pushing blood through the circulatory system.

Systemic Circulation

• Arteries carry blood away from the heart (mostly oxygenated).
• Pulmonary artery is an exception - carries deoxygenated blood to the lungs.
• Capillaries allow for the exchange of oxygen and nutrients.
• Veins carry oxygen poor blood back to the heart (mostly deoxygenated).
• Pulmonary veins carry oxygenated blood from the lungs back to the heart.

Blood Pressure and Related Factors

• Blood pressure (BP) is the force exerted by blood on vessel walls.
• BP is calculated as cardiac output multiplied by total peripheral resistance.
• Factors affecting BP include cardiac output, vessel elasticity, blood viscosity and vessel length.
• Uncontrolled high blood pressure (hypertension) can lead to serious health problems including heart attack, stroke, kidney failure and dementia.

Coronary Circulation

• The heart requires its own blood supply.
• Coronary arteries branch off the aorta and supply blood to the heart muscle. Blood flow occurs primarily during diastole (relaxation)
• Coronary heart blockage can result in a myocardial infarction (heart attack).

Oxygen Consumption and Regulation

• Myocardial oxygen consumption is significantly influenced by factors including exercise and heart rate.
• The acronym RPP stands for Rate Pressue Product - HR x SBP, used in the estimation of myocardial oxygen consumption.

Cardiovascular Regulation and Integration

• The heart has an intrinsic rhythm generated by the sinoatrial (SA) node, which serves as the pacemaker.
• The autonomic nervous system regulates heart rate.

Blood Composition and Other Info

• Blood is comprised of plasma (liquid portion) and formed elements (cells & platelets).
• About 55% of blood is plasma and 45% of blood is formed elements (RBCs, WBCs and platelets).
• Hemoglobin within red blood cells transports oxygen.
• Blood doping is a way athletes try to artificially increase RBC count.

Cardiovascular Control Center

• Located in the medulla of the brainstem
• Regulates heart rate and output, blood vessel diameter etc. via autonomic nervous system.