Lecture on Animal Circulatory System

Components of the Circulatory System

• Circulatory Fluid: Blood or hemolymph
• Heart: Muscular pump that moves the circulatory fluid through the vessels
• Blood Vessels: Includes arteries, capillaries, and veins

Functions

• Transport substances between different parts of the body
• Maintain bodily functions by ensuring the circulation of nutrients, gases, and waste

Types of Circulatory Systems

Open Circulatory System

• Found in arthropods and some mollusks
• Heart pumps blood into open spaces where it bathes the cells
• Low pressure, slow blood movement

Closed Circulatory System

• Found in annelids, some mollusks, and vertebrates
• Heart pumps blood through a closed circuit of blood vessels
• High pressure, fast blood movement

Structure and Function of the Heart

• Four chambers in humans: two atria (receive blood) and two ventricles (pump blood)
• Automatically contracts and relaxes (autonomic)

Blood Vessels

• Arteries and Veins: Three layers of tissue
• Capillaries: Single layer of tissue; site of substance exchange

Blood Pressure

• Systolic Pressure: Pressure during heart contraction
• Diastolic Pressure: Pressure during heart relaxation
• Blood pressure measured in the arm artery

Blood Velocity

• Speed of blood flow depends on the vessel's diameter
• Changes with alterations in blood pressure

Capillary Exchange

• Tiny and numerous; facilitate exchange between blood and interstitial fluid
• Exchange of nutrients and waste occurs through capillary walls

Regulation of Circulatory Activity

• Controlled by the nervous and endocrine systems

Benefits of Regular Exercise on Circulatory Health

• Enlarges and strengthens the heart, increases cardiac output
• Improves the elasticity and function of blood vessels
• Increases blood volume and red cell count

Effects of Alcohol on Circulatory Health

• Increases heart rate and blood pressure
• Prolonged high blood pressure can damage the heart
• Impairs nervous system functioning

Causes of Circulatory System Diseases

• Genetic or congenital (e.g., heart defects)
• Lifestyle factors (e.g., diet, smoking)

Note: Regular exercise positively affects heart function and overall circulatory health, while excessive alcohol consumption can have detrimental effects.