organ system

Examples of organ system in the following topics:

• Plant Tissues and Organ Systems

• Levels of Organization

  • Living organisms are made up of four levels of organization: cells, tissues, organs, and organ systems.
  • Using the circulatory system as an example, a cell in this system is a red blood cell, the heart's cardiac muscle is a tissue, an organ is the heart itself, and the organ system is the circulatory system.
  • An organism is made up of four levels of organization: cells, tissues, organs, and organ systems.
  • While most organ systems control a few specific physiological processes, some processes are more complex and require multiple organ systems to work together.
  • An organism contains organ systems made up of organs that consist of tissues, which are in turn made up of cells.

• Tissues in Levels of Organization

  • The next level is the organ system level.
  • Many organs working together to accomplish a common purpose create an organ system.
  • For example, the heart and the blood vessels of the cardiovascular system circulate blood and transport oxygen and nutrients to all the body cells.
  • Organs that fulfill related functions are called organ systems.
  • An organism is made up of interconnected organ systems.

• Organization of the Nervous System

  • A nervous system is what allows us to react to the changing environment around us.
  • The nervous system is an organ system that coordinates our actions by transmitting signals between different parts of our bodies.
  • The central nervous system (CNS) is composed of the brain, spinal cord, and retina.
  • Along with neurons, the nervous system relies on the function of other specialized cells called glial cells, or glia, that provide structural and metabolic support to the nervous system.
  • Gross organization of the nervous system, with the peripheral nervous system, the spinal, and the cortical levels.

• Overview of the Musculoskeletal System

  • The musculoskeletal system is an organ system that enables an organism to move, support itself, and maintain stability during locomotion.
  • The musculoskeletal system (also known as the locomotor system) is an organ system that gives animals (including humans) the ability to move, using the muscular and skeletal systems.
  • The musculoskeletal system is made up of the body's bones (the skeleton), muscles, cartilage, tendons, ligaments, joints, and other connective tissue that supports and binds tissues and organs together.
  • Its primary functions include supporting the body, allowing motion, and protecting vital organs.
  • The skeletal portion of the system serves as the main storage system for calcium and phosphorus.

• Structure of the Lymphatic System

  • The lymphatic system consists of lymphatic vessels and associated lymphoid organs.
  • The lymphatic vessels are the lymphatic system equivalent to the blood vessels of the circulatory system and drains fluid from the circulatory system.
  • Lymphatic organs are the site of many important functions for the immune system.
  • Lymphoid tissue is found in many organs, particularly the lymph nodes, as well as in the lymphoid follicles in the pharynx, such as the tonsils.
  • Describe how the lymphatic system consists of lymphatic vessels and associated lymphoid organs

• Parasympathetic Responses

  • The parasympathetic nervous system regulates organ and gland function during rest and is considered a slowly activated, dampening system.
  • The autonomic nervous system (ANS, or visceral nervous system, or involuntary nervous system) is the part of the peripheral nervous system that acts as a control system, functioning largely below the level of consciousness and controlling visceral functions.
  • The ANS is responsible for regulation of internal organs and glands, which occurs unconsciously.
  • The sympathetic nervous system can be considered a quick response, mobilizing system; and the parasympathetic a more slowly activated dampening system.
  • The postganglionic nerve then releases ACh to stimulate the muscarinic receptors of the target organ.

• Circumventricular Organs

  • Circumventricular organs (CVOs) are positioned at distinct sites around the margin of the ventricular system of the brain.
  • As a result, neurons located in circumventricular organs can directly sense the concentrations of various compounds, particularly peptide hormones, in the bloodstream without the need for specialized transport systems that move those compounds across the blood-brain barrier.
  • Therefore, they provide direct information to the autonomic nervous system from the systemic circulation.
  • These organs include:
  • The secretory organs are responsible for secreting hormones and glycoproteins into the peripheral vascular system using feedback from both the brain environment and external stimuli.

• The Role of the Circulatory System

  • The circulatory system can be thought of as a highway system that runs throughout the body .
  • At the core of the human circulatory system is the heart .
  • Gas exchange is one essential function of the circulatory system.
  • A circulatory system is not needed in organisms with no specialized respiratory organs, such as unicellular organisms, because oxygen and carbon dioxide diffuse directly between their body tissues and the external environment.
  • However, in organisms that possess lungs and gills, oxygen must be transported from these specialized respiratory organs to the body tissues via a circulatory system.

• Open and Closed Circulatory Systems

  • In all vertebrate organisms, as well as some invertebrates, this is a closed-loop system in which the blood is not moving freely in a cavity.
  • In contrast to a closed system, arthropods (including insects, crustaceans, and most mollusks) have an open circulatory system.
  • As the heart beats and the animal moves, the hemolymph circulates around the organs within the body cavity, reentering the heart through openings called ostia (singular: ostium).
  • An open circulatory system does not use as much energy to operate and maintain as a closed system; however, there is a trade-off with the amount of blood that can be moved to metabolically-active organs and tissues that require high levels of oxygen.
  • Arthropods, such as this bee and most mollusks, have open circulatory systems.