Basic Biomedical Sciences I Case three: Path of the Heart

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Basic Biomedical Sciences I Case three: Path of the Heart ARTERIES

A series of vessels that transport blood away from the heart by branching into vessels of smaller and smaller diameter, eventually branching into capillaries to supply all regions of the body with oxygenated blood.

Have smaller diameter than their venous counterparts.

Are thick-walled and under high pressure.

The blood volume contained in arteries is called the stressed volume.

LAYERS OF THE ARTERY

Tunica Intima

The innermost layer made up of:

Endothelium.

Tunica Media.

The thickest layer of the vessel wall.

Composed of mostly helically arranged smooth muscle cells.

Interspersed within the layers of smooth muscles are some elastic fibers, type two collagen, and proteoglycans.

External elastic lamina is present in larger muscular arteries which is more delicate than the internal elastic lamina and separates the tunica media from the overlying tunica adventitia.

Capillaries and postcapillary venules do not have a tunica media, in these small vessels pericytes replace the tunica media.

Tunica Adventitia.

The outermost layer of the blood vessel wall, blends into the surrounding connective tissue.

Composed mostly of fibroblasts, type one collagen fibers and longitudinally oriented elastic fibers.

The muscular and elastic layers are not well developed but the connective tissue components are more pronounced than in arteries.

The thickest layer is the tunica adventitia and in large veins, this layer contain many elastic fibers, abundant collagen fibers, and vasa vasorum whereas the inferior vena cava has longitudinally arranged smooth muscle cells in its adventitia.

Veins with little or no smooth muscle in their walls are found in the retina, meninges, placenta, and penis.

Have valves (medium vein) that function to prevent backflow of blood.

STRUCTURAL CHARACTERISTICS OF THE VASCULAR SYSTEM AND THEIR FUNCTIONAL SIGNIFICANCE CAPACITIES, PERCENTAGE DISTRIBUTION OF BLOOD IN THE VASCULAR TREE

Capacitance (Compliance).

VELOCITY OF BLOOD FLOW AND CROSS-SECTIONAL AREA

Blood flow:

RESISTANCE

Resistance in Parallel or Series:

Series Resistance.

DIFFERENCE BETWEEN LAMINAR AND TURBULENT FLOW

Turbulent Flow.

CAUSES OF TURBULENT BLOOD FLOW

FACTORS AFFECTING TURBULENT FLOW

REYNOLD'S EQUATION

FLOW CONTINUITY EQUATION

BERNOULLI'S PRINCIPLE

Clinical Significance:

LAW OF LAPLACE

Clinical Significance:

MECHANISM OF CRITICAL CLOSING PRESSURE IN BLOOD VESSELS AND THE FACTORS AFFECTING IT

Overview

The document provides a comprehensive overview of the cardiovascular system's structure and dynamics, focusing on blood vessels' anatomical features, the principles governing blood flow, and factors affecting vascular resistance. It serves as an educational resource for understanding cardiovascular physiology.

Key Points

1Arteries transport oxygenated blood away from the heart under high pressure
2The structure of blood vessels includes three layers: tunica intima, tunica media, and tunica adventitia
3Blood flow velocity is higher in larger blood vessels and decreases in smaller ones for optimized nutrient exchange
4Turbulent flow occurs under certain conditions, affecting blood circulation and pressure dynamics
5Reynolds number helps predict whether blood flow will be laminar or turbulent based on vessel characteristics.

Details

Category: Biology and Natural Sciences

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