Lecture Notes: Organs - Structure and Function

Amelia Roses (UNC2021-5678) Bachelor of Science in Nursing LECTURE NOTES: ORGANS - STRUCTURE AND FUNCTION Definition of Organ: An organ is a group of tissues that work together to perform more complex functions. These tissues collaborate to ensure the organ can carry out specific tasks within the body. In biology and anatomy, understanding the concept of organs is fundamental to comprehending how the human body functions as a cohesive unit. Organs are integral parts of biological systems, composed of different types of tissues that work together to perform specific and complex tasks. This lecture will delve into the structure and function of major organs in the human body, exploring how they contribute to overall health and homeostasis. We will examine the composition of organs, the roles they play in bodily systems, and their interdependence to maintain life. Structure of Organs Tissues that Make Up Organs • Epithelial Tissue: Covers the surfaces of organs and body cavities, protects from external environments, and is involved in absorption, secretion, and excretion. • Connective Tissue: Provides support and structure for organs, and connects various tissues. Examples include bone, blood, and adipose tissue. • Muscle Tissue: Specialized for contraction and generating movement. There are three types: skeletal muscle, cardiac muscle, and smooth muscle. • Nervous Tissue: Receives stimuli and conducts nerve impulses. It consists of neurons and glial cells. Functions of Major Organs in the Body Heart • Structure: Composed of four chambers (two atria and two ventricles) and lined by three layers (epicardium, myocardium, endocardium). • Function: Pumps blood throughout the body, delivering oxygen and nutrients, and transporting waste products for excretion. Lungs • Structure: Consist of bronchi, bronchioles, and alveoli. Covered by the pleura. • Function: Gas exchange (oxygen and carbon dioxide) between the air and blood through the alveoli. Liver • Structure: Has right and left lobes, covered by a fibrous capsule, and consists of hepatocytes. • Function: Metabolizes nutrients, detoxifies harmful substances, produces bile, stores glycogen, and synthesizes plasma proteins. Kidneys • Structure: Composed of cortex and medulla, and functional units called nephrons. • Function: Filter blood to form urine, regulate fluid and electrolyte balance, and produce hormones (renin, erythropoietin). Brain • Structure: Consists of the cerebrum, cerebellum, and brainstem. Covered by meninges and protected by the skull. • Function: Central control of body activities, including sensory perception, motor function, cognition, emotions, and homeostasis regulation. Stomach • Structure: Composed of the fundus, body, and antrum, with layers of mucosa, submucosa, muscularis, and serosa. • Function: Mechanical and chemical digestion of food, production of gastric acid and digestive enzymes, and partial absorption of nutrients. Interaction of Organs within Body Systems Organs do not function in isolation but interact within integrated body systems, such as: • Cardiovascular System: Involves the heart and blood vessels for blood transport. • Respiratory System: Involves the lungs and airways for gas exchange. • Digestive System: Involves the mouth, stomach, intestines, liver, and pancreas for digestion and absorption of food. • Excretory System: Involves the kidneys and urinary tract for elimination of metabolic waste. • Nervous System: Involves the brain, spinal cord, and nerves for coordination and control of body functions. Conclusion Organs are essential units in the body composed of various tissues working together to perform specific functions. Understanding the structure and function of major organs provides a foundational knowledge critical for studying how the human body operates as a whole.