Human Biology Chapter 2

Cells

Is the fundamental structural, functional, and biological unit of all known living oraganisms.

What are cells made up of

cell membrane, cytoplasm, cytosol, cytoskeleton, inclusions, nucleolus, ribosomes, and Golgi body/apparatus.

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Cell membrane

thin, flexible barrier around a cell; regulates what enters and leaves the cell

Cytosol

Liquid portion of cytoplasm

Cytoskelton

Internal scaffolding of protein fibres within the cytoplasm.

Organelles

structures suspended in the cytoplasm that carry out particular functions

Inclusions

chemical substances inside a cell, in the form of granules or droplets.

Nucleus

An organelle in a cell that contains DNA

nuclear membrane

a membrane that separates the nucleus of a cell from the cytoplasm.

Nuclear pores

small holes in the nuclear membrane, allowing material to enter and leave the nucleus

Ribosomes

They are very small, spherical organelles at the ribosomes, and amino acids are joined together to make proteins. They may be free in the cytoplasm

Endoplasmic Reticulum

a network of membranes forming channels through the cytoplasm of a cell; it is used for storage, support, synthesis and transport within the cell.

Golgi Body (Apparatus)

packaging, processing, and secreting of proteins

Lysosomes

An organelle containing digestive enzymes

Mitochondria

Powerhouse of the cell, an organelle that is the site of ATP (energy) production

Cillia

*Tiny hairlike extensions* that move together in a sweeping motion

Flagella

A long, whip-like filament that helps in cell motility. Many bacteria are flagellated, and sperm are flagellated.

What does the cytoplasm consist of?

Microtubules: fine tubes that help maintain the shape of the cell and hold the organelles in place.

Microfilaments: protein fibres that move materials around the cytoplasm or move the whole cell.

The structure of the cell membrane

lipid bilayer of phospholipids and proteins

Functions of the cell membrane

Physical barrier: the membrane separates the cytoplasm from the extracellular fluid around the cell.

Regulates passage of materials: controls the movement of materials into and out of the cell.

Sensitive to changes: Is the first part of the cell affected by any changes in the extracellular fluid.

Supports the cell: the internal part of the membrane is attached to the microfilaments of the cell's cytoskeleton, giving support to the whole. cell and adjacent cells.

Transport across the cell membrane

Cell membranes are described as differentially permeable, semipermeable and selectively permeable. This means that they allow certain ions and molecules to pass through, but restrict the movement of others. Materials pass through a cell membrane in different ways.

passive process: do not use energy

active process: use the cells energy

simple diffusion

the process of substances moving along the concentration gradient In a solution or across a semi permeable membrane, without the use of membrane protiens

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Concentration

A measurement of the number of particles in a given volume

Concentration Gradient

difference in the concentration of a substance, often between the inside and outside of the cell.

Osmosis

Diffusion of water through a selectively permeable membrane from an area of high concentration to an area of low concentration.

facilitated transport

Proteins in the cell membrane that allow molecules to be transported across the cell membrane. These proteins are channel proteins, which form protein channels, and carrier proteins, which allow carrier-mediated transport.

channel proteins

a protein that allows the transport of specific substances across a cell membrane

protein channel

A pathway through a protein in the cell membrane that allows the passage of substances across the membrane

carrier proteins

a protein that carries substances from one side of the membrane to the other

Carrier mediated transport

Transport of ions or molecules across a cell membrane by special carrier proteins

vescicular transport

The transport of materials into or out of a cell membrane

Endocytosis

process by which a cell takes material into the cell by the infolding of the cell membrane

Exocytosis

The process by which the content of the vesicles of the cells is pushed out through the cell membrane

What types of transport require energy and those that do not

Active: active transport, vescicular (endocytosis and exocytosis)

Passive: Simple diffusion, Osmosis, and Facilitated transport

Hypertonic

This solution has a higher solute concentration than the cell. Water moves out of the cell by osmosis, causing the cell to shrink.

Hypotonic

This solution has a lower solute concentration than the cell. Water moves into the cell causing it to swell

Cell Size

Small cells have a higher surface-area-to-volume ratio

Tissue

group of cells that are similar in structure and function

Epithelium

Tissue that forms the outer part of the skin and that lines hollow organs and ducts; a covering tissue

connective tissue

Tissue providing support for the body organs

Muscle fibers

Long Cylindrical Cells that make up skeletal muscle

skeletal muscle

muscle attached to bones, under voluntary control, is also called a striated muscle

Smooth muscle

Involuntary muscles are found inside many internal organs of the body, also called the non-striated muscle

Cardiac muscle

the muscle that forms the wall of the heart

nervous tissue

Tissue made up of nerve tissues

oragans

A group of tissues that work together to perform a specific function

Systems

groups of organs working together to perform complex functions

Organism

A living thing