### 1. Blood Pressure (BP) Fundamentals * **Definition:** Blood pressure is the measurement of the *force of blood pushing against blood vessel walls*. * **Measurement:** Measured in *millimeters of mercury (mmHg)*. * **Components of a BP Reading:** * **Systolic Blood Pressure (Top Number):** Measures pressure on artery walls *when the heart beats or contracts*. * **Diastolic Blood Pressure (Bottom Number):** Measures pressure on artery walls *between beats when the heart is relaxing*. * **Normal Blood Pressure:** Approximately *120/80 mmHg*. ### 2. Hypertension (High Blood Pressure) * **Definition:** A condition where blood pressure is *consistently higher than 140/90 mmHg*. * **Characteristics:** The blood pushes harder against artery walls, increasing strain on the cardiovascular system. * **Diagnosis:** Can be made if one or both readings (systolic or diastolic) are consistently high. * **Primary vs. Secondary:** * **Primary (Essential) Hypertension:** Has no identifiable cause and develops gradually over many years. * **Secondary Hypertension:** Caused by an underlying condition (e.g., kidney problems) and tends to appear suddenly. ### 3. Hypotension (Low Blood Pressure) * **Definition:** A condition in which the *force of blood pushing against the artery walls is too low*. * **Characteristics:** Generally defined as a blood pressure reading *lower than 90/60 mmHg*. * **Symptoms:** May include dizziness, fainting (syncope), blurred vision, and fatigue. * **Orthostatic Hypotension:** A sudden drop in blood pressure that occurs when a person stands up quickly. ### 4. Factors Regulating Blood Pressure Blood pressure is dynamically influenced by a combination of internal and external factors. #### 4.1. Controllable Risk Factors These are lifestyle and external factors that individuals can modify. * **Diet:** High *sodium* intake, diet low in *potassium*, and excess *saturated fat*. * **Physical Activity:** Lack of *regular exercise*. * **Weight:** Being *overweight or obese*. * **Stress:** High *stress levels* can lead to temporary increases. * **Sleep:** *Insufficient or poor quality sleep*. * **Medications:** Some medications, including cough and cold medicines, can interfere with BP control. #### 4.2. Uncontrollable Risk Factors These are inherent or pre-existing conditions that cannot be directly modified. * **Age:** The risk of high blood pressure increases with *aging*. * **Genetics:** *Family history* of hypertension can increase predisposition. * **Medical Conditions:** *Kidney disease*, *thyroid problems*, and *obstructive sleep apnea*. #### 4.3. Physiological Regulators (Other Factors) These are internal biological mechanisms that directly influence blood pressure. * **Baroreceptors:** *Sensory receptors* located in blood vessels that *monitor blood pressure*. They send signals to the brain to adjust *heart rate* and *blood vessel constriction*. * **Cardiac Output:** The *amount of blood pumped by the heart with each beat*. * **Total Peripheral Resistance:** The *resistance to blood flow in the blood vessels*, affected by *blood vessel diameter* and *blood viscosity*. * **Blood Volume:** The *total amount of blood circulating in the system*. ### 5. Protection and Prevention of Hypertension & Cardiac Problems (Lifestyle Modifications) Adopting a heart-healthy lifestyle is crucial for managing and preventing hypertension and associated cardiac issues. * **Heart-Healthy Diet:** Focus on fruits, vegetables, whole grains, and lean protein. Limit saturated and trans fats and reduce sodium intake. * **Regular Physical Activity:** Aim for at least 150 minutes of moderate-intensity or 75 minutes of vigorous activity per week. * **Maintain a Healthy Weight:** Calculate your *Body Mass Index (BMI)* to determine if you're at a healthy weight. * **Quit Smoking:** Smoking *damages blood vessels* and significantly increases the risk of heart attack and stroke. * **Manage Stress:** Use exercise, yoga, meditation, and ensure 7-9 hours of quality sleep. | Aspect | Hypertension (High BP) | Hypotension (Low BP) | Normal BP | | :------------ | :------------------------------------------------------- | :-------------------------------------------------- | :------------------------- | | **Definition** | Force against arterial walls is too high | Force against arterial walls is too low | Balanced force | | **Reading** | >140/90 mmHg | <90/60 mmHg | ~120/80 mmHg | | **Impact** | Increased risk of heart disease, stroke, kidney damage | Dizziness, fainting, inadequate organ perfusion | Optimal cardiovascular function |

2.18 Hypertension And Hypotension | Blood Circulatory System Of Man | Biology 12