Kin human systems chap 2

Cytology

The study of cells

Micrometer

measurement for human cell

Contrast

what needs to be added to specimen to see through microscope

Covering

Epithelial cells form a sheet to cover surfaces and protect outer surface of body

Lining

Epithelial cells line the internal surfaces of organs and regulate nutrient movement into body tissues.

Storage

Some body cells, hepatocytes and adipocytes, store nutrients or energy reserves for the body.

Movement

Muscle cells are composed of contractile proteins that cause the muscle to shorten, allowing movement to occur. Muscle cells move skeletal tissue and contract to pump blood through the heart and body.

Connection

Connective tissues helps to connect and support other tissues. such as collagen that forms ligaments that attach bone to bone.

Defense

Many cell types protect the body against pathogens or antigens (anything the body percieves as foreign).

Communication

Nerve cells (neurons) transmit nerve impulses from one part of the body to another. These impulses carry information between neurons within the nervous system and result in a muscle moving or a gland secreting.

Reproduction

Some cells function solely to produce new life. for example sperm and oocytes are specialized cells designed to join together to initiate the formation for a new individual. There are also other cells that divide to prove new cells that can specialize, such as cells within red bone marrow called stem cells.

Plasma Membrane

Sometimes called the cell membrane, forms the outer, limiting barrier separating the internal contents of the cells from the external environment.

Cholesterol

yellow clusters, a type of liqid called a steroid. It makes up about 20% of the plasma membrane lipids. It is scattered within the hydrophobic internal region of the phospholipid bilayer.

Glycolipids

Lipids with attached carbohydrate groups form about 5-10% of the membrane lipids. They are only on the outer layer of the membrane. The carbohydrate portion of the molecule (glycocalyx) allows the cell to cell recognition, adhesion, and communications.

Proteins

In addition to lipids, half the plasma membrane by weight is made of Proteins. Diverse molecules composed of smaller amino acids. There are Integral and peripheral proteins.

Phospholipids

Most the membrane is made up of phospholipids, seen here in purple circles. the basic structure of the plasma membrane is called the phospholipid bilayer. This layer keeps the intracellular fluid within the cell and the extracellular fluid outside.

Glycoprotein

Another integral protein to the phospholipid bilayer. Glycoproteins are integral proteins with attached carbohydrate groups. Carbohydrates will attach to glycoproteins as well as the glycolipids.

Lipids

A compound that are insoluble to water (fats,oils,and steroids) that insolubility of the lipids within the plasma membrane ensures the membrane with not dissolve when in contact with water. The main 3 lipids are phospholipids, Cholesterol, and glycolipids.

Cytoplasm

A general term for for all cellular contents located between the plasma membrane and nucleus. Made up of, Cytosol, Inclusions, and Organelles.

Cytosol

sometimes referred to as intracellular fluid, it is the syrup like fluid of the cytoplasm. It high water content and contains many dissolved solutes.

Inclusions

The cytosol of some cells contains inclusions. this is a large group of chemical substances that the cell stores temporarily. One example is melanian, a stored pigmant in some skin, hair, and eye cells.

Organelles

Means “little organs” are complex, organized structures with unique characteristic shapes. Collectively, the function of all organelles are essential or normal cellular structure and activities. Tiny structures that perform specific cellular functions.

Endoplasmic reticulum (ER)

An extensive intracellular membrane network through the cytoplasm ER is composed of two distinct regions, smooth ER and rough ER. 

Smooth ER

continuous with the rough ER, the walls do not have ribosomes attached to the membrane.  Smooth ER synthesizes, transports, and stores lipids, metabolizes carbohydrates, and detoxifies drugs, alcohol and poisons. the liver contains abundant amounts of smooth ER.

Rough ER

produces, transports, and store proteins associated with a membrane.  It consists of parallel membranes enclosing spaces called cisternae. Ribosomes attach to the sides of the membrane and they synthesize proteins. The amount of rough ER  is greater in cells producing large amounts of proteins for secretion such as pancreas. 

Golgi Apparataus

It is a center for modifying, packaging, and sorting materials that arrive from the rough ER in the transport vesicles.  The golgi apparatus is especially extensive and active in cells specialized for secretion.

Lysosomes

Membrane sacs formed by the golgi apparatus. Lysosomes contain enzymes used by the cell to digest waste products and ingested macromolecules. these enzymes break down proteins, fats, polysaccharides, and nucleic acids into smaller molecules. Think of them as the "garbagemen" of the cell.

Peroxisomes

These small sacs are formed by pinching off vesicles from the rough ER.  They use oxygen to catalytically detoxify specific harmful substances produced by the cell or in the cell. these are most abundant in the liver cells, where they break down fatty acids to detoxify some toxic materials, such as alcohol, that are absorbed in the gastrointestinal tract. 

Mitochondria

Double membrained structures that are involved in producing large amounts of cell's energy (ATP).  Mitochondria are the powerhouse of the cell. The internal structure of the mitochondria contains crests and a matrix to increase the surface are exposed to internal fluid contents. Cells requiring more energy require more mitochondira, for example muscle cells with high energy usage. 

Ribosomes

Small, dense granules responsible for protein production. When they float freely in the cytosol they are called Free ribosomes, those that are attached to the rough ER are called bound ribosomes.

Cytoskeleton

Composed of protein subunits organized either as filaments or hollow tubes. 

-microfilament

-Intermediate filament

-Microtuble

Centriole and Centrosome

closely adjacent to the nucleus in most cells is a spherical structure called centrosome.  The centrosome is a matrix of microtubules that support growth and elongation of the microtubule and provide support in cell division. A pair of centrioles perpendicular to one another make up the centrosome. 

Cilia and Flagella

Cilia and flagella are projections extending from a cell. They are composed of cytoplasm and supportive microtubules enclosed by plasma membrane. Cilia are found in large numbers on cell surfaces exposed to the external environment (such as respiratory pathways).  Flagella are similar to cilia, however usually appear alone to move or propel a cell.  The only human flagellum is the sperm.

Nucleus

The Control center of the cell. It controls protein synthesis and directs the functional and structural characteristics of the cell.

Nuclear Envelope

separates the cytoplasm from the nucleoplasm, and controls transport of material in and out of the nucleus via the nuclear pores. 

Nucleoplasm

fluid within the nucleus

Nucleolus

Made up of RNA, enzymes, and proteins.  Responsible for making the subunits of ribosomes, where when transported to the cytoplasm go on to form a complete ribosome. Not all cells have a nucleoli, typically reserved for the cells requiring a lot of protein production.