This controls the movement of substances into and out of the cell. Nerve cells, or neurons, are one of the most numerous types of body cell. The nervous system contains billions of neurons, which collect and transmit information around the body. The adult brain alone may contain as many as 25 billion neurons. Cells come in different shapes and sizes, but all have features in common.
Most cells have a nucleus. The cytoplasm contains small structures called organelles. There are several types of organelle, each with a specific job. Mitochondria, for example, produce energy for the cell.
English Only. Image from Purves et al. Where there are no capillaries, the alveolar septum contains fibroblasts, collagen, elastic fibers, smooth muscle cells, and macrophages known as dust cells. This multidisciplinary review of signaling pathways that regulate circulatory and respiratory Animal organs are usually composed of more than one cell type.
Cells group together to form tissues, each with specific functions. Connective tissue is the most widespread; it separates and supports other tissues and organs, and includes cartilage and bone. Adipose tissue is packed with fat cells, which provide energy storage and insulation. Epithelial tissue protects and lines the surfaces of many body organs. Other types include muscle and nervous tissue. Tissues are grouped together in the body to form organs.
These include the brain, heart, lungs, kidneys, and liver. The sarcomere is the visible functional contractile unit within cardiac and skeletal muscle. The animation below shows the relative movement of the thick and thin filaments in the sarcomere if animation not playing reload page. Do not confuse these cardiac Purkinje fibres cells with neural Purkinje cells neurons located in the cerebellum. Adult Heart Conduction System.
Only the mitral and tricuspid valves, located between the atria and the ventricles, are connected to the cardiac wall by chord tendineae and papillary muscles.
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Embryonic Start. Animal Models. An organ system is made from a group of different organs, which all work together to do a particular job.
Here are some examples of organ systems:. Cells are organised into tissues, organs, systems and organisms. Cells, tissues, organs and systems Multicellular organisms are organised into increasingly complex parts. In order, from least complex to most complex: cells tissues organs organ systems organism Tissues Animal cells and plant cells can form tissues , such as muscle tissue in animals.
The volumes in this authoritative series present a multidisciplinary approach to modeling and simulation of flows in the cardiovascular and ventilatory systems. Cell and Tissue Organization in the Circulatory and Ventilatory Systems ( Biomathematical and Biomechanical Modeling of the Circulatory and Ventilatory .