人类生理学/细胞生理学

细胞结构与功能

什么是细胞？

细胞是生命的结构与功能基本单位。所有生命都由细胞构成：细菌、原生生物、真菌、植物以及动物都是。有些生物仅由一个细胞构成（像是细菌、原生生物）。不过动物（像是人类）则是由多个细胞构成。一个成年人的身体是由约一百兆个细胞所构成！每个细胞要维持功能，会需要一些基本需求，器官的系统很大一部分的建立在如何提供数以亿记的细胞这些需求（像是氧气、食物、排除废物……等）。

人体中大约有两百多种不同的细胞。当许多相似功能的细胞聚在一起，我们称为组织（tissue），像是肌肉组织、神经组织……等等。 There are about 200 different kinds of specialized cells in the human body. When many identical cells are organized together it is called a tissue (such as muscle tissue, nervous tissue, etc). Various tissues organized together for a common purpose are called organs (e.g. the stomach is an organ, and so is the skin, the brain, and the uterus).

Ideas about cell structure have changed considerably over the years. Early biologists saw cells as simple membranous sacs containing fluid and a few floating particles. Today's biologists know that cells are inconceivably more complex than this. Therefore, a strong knowledge of the various cellular organelles and their functions is important to any physiologist. If a person's cells are healthy, then that person is healthy. All physiological processes, disease, growth and development can be described at the cellular level.

词汇表

主动运输（Active Transport）

一种物质逆着化学梯度，跨细胞膜的运动。需要消耗能量

三磷酸腺苷（Adenosine Triphosphate，ATP）

细胞能量的来源

整体流动（Bulk Flow）

物质对应外力，往同一方向所产生的集体流动

细胞（Cells）

组成生物的基本单位

细胞膜（Cell Membrane）

细胞的外膜，有时候也叫做质膜（plasma membrane）

细胞质（Cytoplasm）

a water-like substance that fills cells. The cytoplasm consists of cytosol and the cellular organelles, except the cell nucleus. The cytosol is made up of water, salts, organic molecules and many enzymes that catalyze reactions. The cytoplasm holds all of the cellular organelles outside of the nucleus, maintains the shape and consistency of the cell, and serves as a storage place for chemical substances.

细胞骨架（Cytoskeleton）

由丝状蛋白质构成，协助细胞维持形状以及细胞移动内容物

透析（Dialysis）

the diffusion of solutes across a selectively permeable membrane. Most commonly heard of when a patient has had renal failure. In medicine, dialysis is a type of renal replacement therapy which is used to provide an artificial replacement for lost kidney function due to renal failure. It is a life support treatment and does not treat any kidney diseases.

内分泌细胞（Endocrine cells）

类似外分泌细胞（exocrine cells），不过内分泌细胞是将产物分泌于体内

内吞（Endocytosis）

the capture of a substance outside the cell when the plasma membrane merges to engulf it

内质网（Endoplasmic Reticulum，ER）

organelle that play an important role in making proteins and shuttling cellular products; also involved in metabolisms of fats, and the production of various materials

表皮细胞（Epithelial Cells）

cells that aid in secretion, absorption, protection, trans-cellular transport, sensation detection, and selective permeability

外分泌细胞（Exocrine Cells）

透过导管将产物分泌于体外，像是汗腺、唾液腺或者消化器官

胞吐作用（Exocytosis）

the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell

促进扩散（Facilitated Diffusion）

the diffusion of solutes through channel proteins in the plasma membrane

高基氏体（Golgi Apparatus）

"packages" cellular products in sacs called vesicles so that the products can cross the cell membrane and exit the cell

糖酵解（Glycolysis）

process in which sugars (glucose) are converted to acid

溶体（Lysosomes）

sac-like compartments that contain a number of powerful degradative enzymes

微丝（Microfilaments）

provide mechanical support for the cell, determine the cell shape, and in some cases enable cell movements

微管（Microtubules）

function as the framework along which organelles and vesicles move within a cell

粒线体（Mitochondria）

the organelles that function as the cell "powerhouse", generating ATP

细胞核（Nucleus）

controls the cell; houses the genetic material

胞器（Organelles）

bodies embedded in the cytoplasm that serve to physically separate the various metabolic activities that occur within cells

渗透（Osmosis）

the diffusion of water molecules across a selectively permeable membrane from an area of high solute concentration to an area of low solute concentration.

被动运输（Passive Transport）

the movement of substances down a concentration gradient and does not require energy use

过氧化体（Peroxisomes）

organelles in which oxygen is used to oxidize substances, breaking down lipids and detoxifying certain chemicals

胞噬作用（Phagocytosis）

a form of endocytosis wherein large particles are enveloped by the cell membrane of a (usually larger) cell and internalized to form a phagosome, or "food vacuole." In animals, phagocytosis is performed by specialized cells called phagocytes, which serve to remove foreign bodies and thus fight infection. In vertebrates, these include larger macrophages and smaller granulocytes, types of blood cells. Bacteria, dead tissue cells, and small mineral particles are all examples of objects that may be phagocytosed.

胞饮作用（Pinocytosis）

also called cellular drinking, is a form of endocytosis, a process in which small particles are taken in by a cell by splitting into smaller particles. The particles then form small vesicles which subsequently fuse with lysosomes to hydrolyze, or to break down, the particles. This process requires adenosine triphosphate (ATP).

受体介导的内吞作用（Receptor-mediated Endocytosis）

occurs when specific molecules in the fluid surrounding the cell bind to specialized receptors in the plasma membrane

红血球（Red Blood Cells，erythrocytes）

cells that collect oxygen in the lungs and deliver it through the blood to the body tissues

核糖体（Ribosomes）

play an active role in the complex process of protein synthesis, where they serve as the structures that facilitate the joining of amino acids

简单扩散（Simple Diffusion）

the net movement of substances from an area of higher concentration to an area of lower concentration

液泡（Vacuoles）

spaces in the cytoplasm that sometimes serve to carry materials to the cell membrane for discharge to the outside of the cell

白血球（White Blood Cells，leukocytes）

produced in the bone marrow and help the body to fight infectious disease and foreign objects in the immune system