Cells and Tissues

What is a cell?

A basic unit of a living organism

What is the difference between a unicellular and multicellular organism?

Unicellular - composed of a single cell
Multicellular - composed of multiple cells

What is the function of the cell membrane?

Provides structure and helps control movement of substances in and out of the cell

What is the function of the cytoplasm?

Fluid within the cell that helps maintain shape

What is the function of the nucleus ?

Contains genetic material

What is the function of ribosomes?

Manufacture proteins

What is the function of mitochondria?

Produce ATP for energy

What is the function of lysosomes?

- Break down old cell components and waste
- Destroy invading pathogens

What is the function of the endoplasmic reticulum?

Produces substances and sends them to the Golgi

What is the function of the Golgi?

Re-packages substances for delivery to their final destination

What is a tissue?

Similar cells working together to provide a specific function

What are the 4 major types of tissue?

- Connective
- Epithelial
- Muscular
- Nervous

What is the function of epithelial tissue?

Protection, secretion and absorption

What is the location of epithelial tissue?

- Cover body surface
- Cover and line internal organs
- Compose glands

What are the features of epithelial tissue?

- Lacks a blood supply
- Readily divides
- Tightly packed cells
- Always has a free (apical) surface exposed to the outside or internally to a hollow space
- Free surface can be modified for functions e.g. cilia
- Anchored to a basement membrane
- Nourished by cells in underlying tissue

What is simple squamous tissue and where is it found?

- A single layer of flattened cells
- Found in alveoli, blood vessels and body cavities

What is simple cuboidal tissue and where is it found?

- Main role is excretion and absorption
- Found in small glands and kidneys

What is simple columnar tissue and where is it found?

- Absorbs and secretes mucus and enzymes
- Ciliated is found in the bronchi and female reproductive tract
- Non ciliated is found in the digestive tract

What is pseudostratified columnar epithelium tissue and where is it found?

- Found in the upper respiratory tract
- Secretes and moves mucus

What is stratified squamous tissue and where is it found?

- Lines the mouth and oesophagus
- Provides protection

What is transitional tissue and where is it found?

- Lines the bladder and allows expansion and contraction

What is the function of connective tissue?

- Binds
- Supports
- Protects
- Fills spaces
- Stores fat
- Produces blood cells

What is the location of connective tissue?

All around the body

What are the features of connective tissue?

- Good blood supply
- Cells and further apart than in epithelial tissue with extracellular metric in-between composed of protein fibres
- Consistency varies from rigid to liquid depending on ground substance
- Most connective tissues can divide

Name the types of connective tissue

- Bone
- Blood
- Ligament
- Tendon
- Cartilage
- Adipose tissue

What are the 3 types of cartilage?

- Hyaline
- Elastic
- Fibrocartialge

What is hyaline cartilage?

- Most common cartilage in body
- Contains fine collagen matrix which appears glassy
- Found on ends of bones, supports respiratory structures and passages and joins ribs to sternum

What is elastic cartilage?

- Contains elastic fibres in dense network
- Provides framework for external ears and parts of the larynx

What is fibrocartilage?

- Tough tissue containing dense masses of white fibres
- Good shock absorber that is slightly flexible
- Found in intervertebral discs, knees and pelvic girdle

What are the 2 types of loose connective tissue?

- Areolar
- Adipose

What is areolar connective tissue?

- Forms thin delicate membranes
- Matrix consists of a gel-like ground structure with collagen and reticular fibres
- Binds skin to underlying tissues and is under most epithelial fibres

What is adipose connective tissue?

- Contains adipocytes which store fat in cytoplasm
- Found under skin, between muscles, around kidneys, around abdominal membranes and behind eyeballs
- Cushions joints and organs, stores energy and insulates body

What is dense connective tissue?

- Consists of densely packed collagen fibres and a network of elastic fibres
- Doesn't have many cells but most are fibroblasts
- Fibres are very strong so tissue can withstand pulling fibres
- Has a poor blood supply so heals slowly
- Found in tendons, ligaments and sclera

What is the function of muscle tissue?

Allows movement

What is the location of muscle tissue?

- Attached to bones
- In the walls of hollow internal organs

What are the features of muscle tissue?

- Able to contract in response to specific stimuli
- 40% of body weight is skeletal muscles
- 10% of body weight is cardiac and smooth muscle

What is skeletal muscle?

- Makes up muscles that attach to bone
- Under voluntary control
- Cells are long and cylindrical, striated and have many nuclei
- Only contract when stimulated by nerve cells
- Skeletal muscle moves head, trunk and limbs

What is smooth muscle tissue?

- Found in the walls of hollow internal organs
- Lacks striations
- Cells are spindle shaped with a central nucleus
- Involuntary

What is cardiac muscle tissue?

- Found only in the heart
- Consists of branching cells, each with a single nucleus
- Cells are connected together with intercalated discs, special gap junctions that send impulses from cell to cell
- Involuntary
- Striated

What is the function of nervous tissue?

- Conducts impulses for coordination
- Regulation, integration and sensory reception

What is the location of nervous tissue?

- Brain
- Spinal cord
- Nerves

What are the special features of nervous tissue?

- Cells communicate with each other and other body parts
- Neurons have unique cellular processes called dendrites and axons
- Neuroglia are cells that support, nourish and communicate with neurons, but do not conduct impulses