Unit 5 Anatomy and Physiology P1 and P2 Cell Compnents and Tissue Structure

by rebeccahughes-allivecouk (student)

P1: Outline the functions of the main cell components.

We begin life as a clump of 8 stem cells, stem cells can become many different types of cell and can renew themselves. Each type of cell have a specific function; e.g. nerve cells, bone cells and muscle cells.

Each cell has three main parts:

Nucleus

The nucleus is the command centre for the cell and controls the way it works and coordinates all of the cells functions, it is the largest structure in the cell and although there is usually only one nucleus per cell, some cell types like muscle cells for example have more than one. The nucleus contains DNA, which is why some inherited conditions can affect the things nuclei control. The nucleus is surrounded by a selectively permeable plasma membrane that allows proteins and nucleic acids to pass through gradually.

Protective Membrane

The protective membrane surrounds and protects the entire cell.

Cytoplasm

Cytoplasm is a jelly-like substance that contains the internal structures that enable the cell to function. Chemical reactions, that make up the cells metabolism, happen in the cytoplasm, which contains a mix of chemicals and nutrients that feed the cell and keep it alive. Cytoplasm contains a variety of cell organelles.

Cell organelles are different structures inside a cell that each have their own function, they’re like mini versions of the body’s organs. The main organelles are; mitochondria, endoplasmic reticulum, the Golgi apparatus and lysomes.

Mitochondria

Mitochondria are the largest cell organelle and appear in large numbers in most body cells. They are sausage like or spherical in shape and their function is to make adenosine triphosphate (ATP) which is the major source of cellular energy. They have an unusual double membrane structure with a smooth outer layer and a folded inner layer. The large surface area of the inner layer allows for aerobic respiration to take place which how ATP is made.

Endoplasmic Reticulum

Endoplasmic eticulum is abbreviated to ER and is a system of channels spread throughout the cytoplasm. The outside surface is known as ‘Rough ER’ because it has ribosomes attached to it. The ribosomes make protein from amino acids and the rough ER collects and transports the proteins made by the ribosomes. Smooth ER doesn’t have ribosomes and is responsible for steroid production. It is where calcium is stored in skeletal muscle cells and it also contains enzymes that detoxify various molecules.

The Golgi Apparatus

These are a group of tightly packed fluid filled cavities that are thought to ...

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Endoplasmic Reticulum

The Golgi Apparatus

These are a group of tightly packed fluid filled cavities that are thought to play an important role in synthesising and modifying proteins, lipids and carbohydrates. Proteins made by the ribosomes attached to ER are packaged into vesicles that join with the Golgi apparatus for protein modification, once modified, they are secreted into the lysomes.

Lysomes

Lysomes are bags of digestive enzymes that are found in cell cytoplasm, in small vesicles produced by the Golgi apparatus. They contain lytic enzymes that destroy old or surplus cells, digest bacterium and carbon particles that are taken into the cell and destroy whole cells and tissues that are no longer needed. For example; lysomes would destroy all the milk-producing tissue after breastfeeding has finished and the muscle cells of the uterus after giving birth.

P2: Outline the structure of the main tissues of the body.

Tissue is a group of cells that are all of the same type, structure and function. There are four main types of tissue in the human body; epithelial tissue covers and lines various body structures e.g. the intestines, connective tissue is tough and fibrous and holds parts of the body together e.g. ligaments and tendons, muscular tissue is in all muscles including the heart and can contract producing movement and nervous tissue that is made up of neurons that conduct electrical impulses enabling communication to and from the brain.

Epithelial Tissue

Epithelial tissue acts as a barrier keeping different systems separate, there are two kinds.

Simple Squamous Epithelium is one layer of cells and can be found on the surface of lung alveoli. Ciliated epithelium tissue is a specialised form of simple squamous epithelium and can be found in the nose where its hair-like form cleans the air going into the nose.
Stratified Squamous Epithelium is layers of cells that are continuously replaced and can be found in the skin, mouth, tongue, oesophagus and vagina.

Connective Tissues

All connective tissues have a structural role in the body.

Bone

Bone is a specialised connective tissue, its extracellular matrix becomes calcified giving it the look and feel we know. It’s function is to provide internal support and places for tendons and muscles to attach to, bone protects our vital organs and is where calcium and phosphate are stored. Bone tissue is continuously formed throughout life.

Cartilage

Cartilage is a tough, smooth and flexible connective tissue, it’s purpose is to protect the surfaces of bones at the joints and maintain the structure of the trachea and bronchus. Cartilage can be found in our ears and nose.

Adipose

Adipose is body fat that makes up 15-20% of an average person’s weight and there are two types of adipose tissue;

White adipose tissue provides insulation, stores energy and forms protective pads between organs.
Brown adipose tissue generates heat and consumes energy, this tissue reduces with age in human beings.

Adipose tissue is found beneath the skin, around internal organs, in bone marrow and in breast tissue.

Blood

Blood is a fluid connective tissue that has plasma to separate the cells.

Areolar Tissue

Areolar is a loose connective tissue that is found in the dermis and subcutaneous layers of the skin where its function is to bind the outer layers of skin to the muscles beneath. It can also be found around mucous membranes, blood vessels, nerves and organs.

Muscle Tissue

Muscle tissue can contract and relax which makes it unusual, it contains protein fibres and has three main types;

Skeletal (striated) which is attached to the skeleton, produces movement and maintains posture. It can contract and relax rapidly and is under voluntary control.
Smooth (non-striated) is found in tubular organs, glands, bronchioles, the reproductive system and the gut. This muscle tissue controls the movement of substances along the tubes.
Cardiac muscles are found in the heart and generate their own contractions ,which is known as myogenic, that occur rapidly.

An inherited condition that effects the skeletal (striated) muscle tissues is Duchenne Muscular Dystrophy (DMD), it causes the muscle tissues to weaken, mainly the proximal muscles which are the hips and shoulders, making movement and mobility increasingly more difficult as the sufferer ages. The muscle cells contain a chemical protein called dystrophin which is necessary for muscles to function properly, when people inherit the faulty gene that is in charge of making dystrophin their muscles can’t function properly and the condition progresses as muscle tissue is damaged.

An inherited disease that effects cardiac muscles is Hypertrophic Cardiomyopathy (HCM). A mutation or change in the DNA means that the cells of the heart muscle become irregular and disordered causing the muscle wall of the heart to become thickened which could lead to arrhythmias, heart block or endocarditis.

Nervous Tissue

Nervous tissue contains elongated cells that sends electrical impulses to and from the brain. It’s function is to control and coordinate the body. When a person becomes paralysed because of an accident or injury it is because they have damaged nerve tissue and their nerve cells can’t communicate to the brain.