CELLS, TISSUES & ORGANS

CELLS Nucleus The basic functional unit of body structure is the cell. Cells require food, H2O, and O2 to live and perform their functions. Each cell has the same basic parts, however, their size, shape and function may vary. Each cell has 3 main parts Nucleus This is the control centre of the cell and contains the DNA (deoxyribonucleic acid). DNA contains the “blueprints” for building the whole human body, specifically proteins. DNA is also necessary for cell reproduction.

CELLS The nucleus contains 3 regions: Nuclear membrane – a double membrane barrier that is selectively permeable. The nuclear membrane encloses a jelly like substance called nucleoplasm which contain the nucleoli and chromatin. Nucleoli– this where ribosomes are made. Ribosomes are the sites for protein synthesis Chromatin – a loose network of bumpy threads that form chromosomes. Each cell has 46 chromosomes that contain genes. Genes control the physical and chemical traits that are inherited from parents.

CELLS Cytoplasm ORGANELLES the cytoplasm is outside of the nucleus and inside the plasma membrane, it contains many smaller structures that perform cell functions including the organelles. ORGANELLES Organelles are little organs, each performing their own function within the cell. Ribosomes – tiny, dark, round bodies made of protein. They are the sites of protein synthesis Endoplasmic reticulum (ER)– is a network within the cell. A system of fluid filled tubules that make up half the cells membranes. They carry substances from one part of the cell to another. There is Rough ER and Smooth ER

CELLS Golgi Apparatus – looks like a stack of flattened membranous sacs. It is the “traffic director” for cellular proteins. Its main function is to modify and package proteins. Lysosomes – The cells “demolition site”. They digest non-useable cell structures and foreign substances. Peroxisomes – membranous sacs that detoxify harmful or poisonous substances. Their most important is to disarm free radicals (highly reactive chemicals) Mitochondria – sausage shaped. The “powerhouse” of the cell. They are responsible for producing/supplying energy to the cell

CELLS The Plasma Membrane Cytoskeleton – The cell’s “bones and muscles”. It gives the cell shape Centrioles – The paired centrioles are rod shaped bodies. They move substances along the cell surface using cilia. The Plasma Membrane A fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment.

CELLS PLASMA MEMBRANE NUCLEUS CYTOPLASM Nuclear membrane Nucleoli Chromatin CYTOPLASM Ribosomes Endoplasmic reticulum Golgi apparatus Lysosomes Peroxisomes Mitochondria Cytoskeleton Centrioles

CELLS Cell Division – Mitosis & Cytokinesis Mitosis is division on the cell’s nucleus There are 4 stages of mitosis Prophase Metaphase Anaphase Telophase Cytokinesis – division of the cytoplasm. Begins during late anaphase and completes during telophase

TISSUES

TISSUES Groups of cells that are similar in structure and function are called tissues. The 4 primary tissue types are: Epithelium - covering Connective tissue - support Nervous tissue - control Muscle tissue - movement

TISSUES EPITHELIUM The lining, covering and glandular tissue of the body. Epithelial functions include: Protection – protects against bacterial/chemical damage Absorption – lines some of the digestive system (stomach, small intestine) which absorb food. Filtration - kidneys Secretion – speciality of the glands, which produce sweat, oil, digestive enzymes and mucous Epithelial cells fit closely together and forms sheets Epithelial cells have no blood supply, they rely on connective tissue for food and O2 Epithelial cells regenerate themselves easily

TISSUES CONNECTIVE TISSUE Connective tissue connects body parts It is found everywhere in the body and is the most abundant and widely distributed type of tissue. Most connective tissue has a good blood supply, however, tendons and ligaments have a very poor blood supply, and cartilage has no blood supply. The extracellular matrix is what gives the connective tissue its strength. Depending on the type of connective tissue, the matrix may be liquid, semi-solid, gel like or very hard. The main functions of connective tissue are: Protecting, supporting and binding together.

TISSUES TYPES OF CONNECTIVE TISSUE From most rigid to softest: Bone – Very hard matrix, protects and supports organs Cartilage – less hard and more flexible than bone. There are 3 types: Hyaline cartilage – rubbery, forms the larynx, attaches the ribs to the breastbone, and covers the ends of bones where they form joints Elastic cartilage – elastic and flexible. The ear Fibrocartilage – forms cushionlike discs between the vertebrae of the spinal column

TISSUES Dense connective tissue– forms strong rope like structures such as tendons, ligaments, and skin Loose connective tissue – soft tissue. 3 types Areolar tissue – soft tissue that cushions, protects, and holds organs in place Adipose tissue – is fat. Forms subcutaneous tissue beneath the skin. Insulates and protects the body. Reticular connective tissue - internal framework for lymph nodes, spleen, and bone marrow Blood – considered a connective tissue because it has blood cells and plasma.

TISSUES NERVOUS TISSUE Nervous tissue is made up of neurons Neurons receive and conduct electrochemical impulses from one part of the body to another. Neurons along with supporting cells, Insulate Support Protect and Make up the nervous system

TISSUES MUSCLE TISSUE Muscles tissues are specialized to contract or shorten to produce movement There are 3 types of muscle tissue Skeletal muscle – packaged into sheets which are attached to the skeleton and are controlled voluntarily. When skeletal muscles contract, they pull on bones or skin which causes movement. Cardiac muscle – only found in the heart. When it contracts, the heart acts like a pump. Cardiac muscle is involuntary. Smooth muscle – found in the stomach, bladder, uterus and blood vessels. When it contracts the organ either constricts or dilates.