Blood Vessel Functions

• Blood vessels are critical for overall health and wellness.
• They deliver oxygen and nutrients, regulate blood pressure, facilitate substance exchange, redistribute blood, and regulate temperature.

Functions of Blood Vessels

• Delivery System: Transports oxygen, nutrients, hormones, and water to cells and collects waste.
• Regulation of Blood Pressure: Maintains blood pressure levels.
• Exchange of Nutrients and Waste: Capillaries facilitate exchange between blood and tissues.
• Blood Redistribution: Adjusts blood distribution based on the body's needs.
• Temperature Regulation: Helps dissipate or conserve heat.

Blood Vessels as a Delivery System

• Carries oxygen, hormones, nutrients, and water from the heart to cells.
• Collects metabolic waste products from cells for excretion via organs like the kidneys.

Regulation of Blood Pressure

• Blood pressure is the force exerted by blood against vessel walls.
• Systolic Pressure: Highest pressure during heartbeats (systole).
• Diastolic Pressure: Lowest pressure between heartbeats (diastole).
• Pulse Pressure: Difference between systolic and diastolic pressures.

Normal vs. Abnormal Blood Pressure

• Normal Adult Blood Pressure: Systolic below 120 mm Hg and diastolic below 80 mm Hg.
• Hypotension: Abnormally low blood pressure.
• Hypertension: Elevated blood pressure, posing health risks.

Factors Determining Blood Pressure

• Cardiac Output: The volume of blood pumped per minute, influencing blood pressure.
• Vasodilation: Relaxing of arteriolar smooth muscles, increasing vessel diameter.
• Vasoconstriction: Contracting of arteriolar smooth muscles, decreasing vessel diameter.

Mechanisms for Blood Pressure Regulation

• Rapidly Acting Mechanisms: Baroreceptor Reflex: Sensory receptors send nerve signals to the brain, adjusting heart rate and vessel dilation.
• Slower-Acting Mechanisms: Hormonal mechanisms play a key role.
• Renin-Angiotensin-Aldosterone System (RAAS): Regulates blood volume and systemic vascular resistance.
• Antidiuretic Hormone (ADH): Promotes water retention in kidneys, affecting blood volume.
• Atrial and Brain Natriuretic Peptides: Lower blood pressure by causing vasodilation and increasing sodium and water excretion.

Capillaries: The Exchange Vessels

• Designed for the exchange of nutrients and waste between blood and cells via diffusion, filtration, and osmosis.
• Capillary Forces: Facilitate the movement of substances across capillary walls.

Blood Redistribution

• Dynamically redistributes blood to meet metabolic demands of different tissues, such as increased blood flow to muscles during exercise which decreases blood flow to non-essential areas.

Temperature Regulation

• Dissipates Heat: Through vasodilation, especially in the skin, to release excess body heat.
• Conserves Heat: Through vasoconstriction to minimize heat loss in cold environments.