人類生理學/細胞生理學

細胞結構與功能

什麼是細胞？

細胞是生命的結構與功能基本單位。所有生命都由細胞構成：細菌、原生生物、真菌、植物以及動物都是。有些生物僅由一個細胞構成（像是細菌、原生生物）。不過動物（像是人類）則是由多個細胞構成。一個成年人的身體是由約一百兆個細胞所構成！每個細胞要維持功能，會需要一些基本需求，器官的系統很大一部份的建立在如何提供數以億記的細胞這些需求（像是氧氣、食物、排除廢物……等）。

人體中大約有兩百多種不同的細胞。當許多相似功能的細胞聚在一起，我們稱為組織（tissue），像是肌肉組織、神經組織……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.

詞彙表

主動運輸（Active Transport）

一種物質逆著化學梯度，跨細胞膜的運動。需要消耗能量

三磷酸腺苷（Adenosine Triphosphate，ATP）

細胞能量的來源

整體流動（Bulk Flow）

物質對應外力，往同一方向所產生的集體流動

細胞（Cells）

組成生物的基本單位

細胞膜（Cell Membrane）

細胞的外膜，有時候也叫做質膜（plasma membrane）

細胞質（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.

細胞骨架（Cytoskeleton）

由絲狀蛋白質構成，協助細胞維持形狀以及細胞移動內容物

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.

內分泌細胞（Endocrine cells）

類似外分泌細胞（exocrine cells），不過內分泌細胞是將產物分泌於體內

內吞（Endocytosis）

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

內質網（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

表皮細胞（Epithelial Cells）

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

外分泌細胞（Exocrine Cells）

透過導管將產物分泌於體外，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

促進擴散（Facilitated Diffusion）

the diffusion of solutes through channel proteins in the plasma membrane

高基氏體（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

溶體（Lysosomes）

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

微絲（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

粒線體（Mitochondria）

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

細胞核（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

滲透（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.

被動運輸（Passive Transport）

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

過氧化體（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.

胞飲作用（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).

受體介導的內吞作用（Receptor-mediated Endocytosis）

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

紅血球（Red Blood Cells，erythrocytes）

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

核醣體（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

簡單擴散（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