The Human Body: A Nutrition Perspective Chapter 3 BIOL1400 Dr. Mohamad H. Termos

Chapter 3 objectives Following this lecture, you should be able to describe: The Cell Basic functions Cell organelles Cell membrane Body systems as they relate to human nutrition

Human physiology - Production and break down of substances constantly occurs in every cell - Cells require constant supply of nutrients - Cells also require oxygen - A healthy diet is required to supply the body with these substances

The Cell The basic unit of a living organism. Only seen using microscopes Differ in shape, size, and function.

The Cell Functions Organisms contain organs that do individual jobs for the survival of the organism; cells have “mini organs”, called organelles to do their basic jobs! An Idealized Animal Cell

Major parts of a Cell

Major parts of a Cell

Organelles: The nucleus Cellular Anatomy The largest cell structure Usually a sphere in the center of the cell Considered as the cell control center. Houses the heredity molecules (DNA) We’ll start by seeing what role these parts play in making and moving proteins.

The Nucleus Anatomy of the nucleus: Nuclear envelope (Outer and inner nuclear membranes) Nuclear pores (permit molecule movements) Nucleolus

The Endoplasmic Reticulum (ER) The Cytoskeleton in Action Made up of many fattened membrane sacs Part of it is dotted with ribosomes for protein synthesis, the rough ER (RER). The part that has no ribosomes, is called smooth ER. The smooth ER is a site of lipid synthesis Smoker’s cough is due to destruction of cilia linking the airways.

The Golgi Apparatus Analogous to postal service for the cell After rough ER protein is sent to Golgi Protein will be modified, packaged, and sent to various destinations (outer membrane of the cell or secreted outside of the cell entirely)

Mitochondria The powerhouses of the cell Major energy source Surrounded by outer and inner membrane Cells may have varying number of mitochondria, according to their energy requirements.

Lysosomes and Peroxisomes The cell “stomach” Houses acidic environment and digestive enzymes Site of molecules break down. Peroxisomes: Degrade lipids and alcohol Degradation of these produce hydrogen peroxide (toxic byproduct). Luckily, peroxisomes degrade this toxic molecule too.

The Cell Membrane Plasma membrane of the cell is the outer wall of the cell. Separates the inside fluids and organelles (that are found in the cytoplasm) from the outside environment (the interstitial fluid)

The Cell Membrane The cell membrane is made up of phospholipids. These phospholipids are arranged in a bilayer and they act as an excellent barrier for the cell. The cell membrane is also “equipped” with protein channels that regulate the passage of molecules in and out of the cell.

Types of Tissue 1- Epithelial tissues: cover surfaces inside and outside the body. Function in substance secretion, nutrient absorption, and waste excretion. 2- Connective tissues: support and protect the body. store fat and produce blood cells 3- Muscle tissues: designed for movement 4- Nervous tissues: designed for communication. Found in the brain and spinal cord