WEEK 1 MOD 2 - cells and tissues

What is the basic unit of life?

The cell

What does classical cell theory state?

• All organisms are made of cells 

Cells = basic units of organisation in all organisms 

Single-celled bacteria to complex multicellular organisms like humans 

• Cells are the basic units of life 

Cells are the smallest entity  

Carry out all processes necessary for life 

Metabolism, growth, reproduction 

• All cells come from other cells 

New cells are produced by division of existing cells 

What is the modern cell theory's view on cell composition?

• Cell composition: All cells have the same chemical composition and metabolic processes, especially within species.

• Cell activity: Depends on the activities of sub-cellular structures called organelles 

• Cell heredity: All cells contain DNA that is passed from cell to cell during division 

What is the function of the nucleus in a cell?

It contains genetic material (DNA) and acts as the control center.

• DNA holds genes which give instructions for making proteins and important for cell structure and function 

• All cells except reproductive cells contain our genes and each cells uses genes that are necessary for own functions 

What are organelles?

• Specialized parts of the cell that perform specific functions, similar to organs.

• Enclosed by membranes like cell membrane = create spaces and allow organelles to carry out tasks in controlled conditions 

What is the role of ribosomes?

Sites where proteins are made using instructions from DNA.

• Float freely in cytoplasm or attach to rough ER 

What is the function of mitochondria?

They produce ATP through cellular respiration, acting as the powerhouse of the cell.

What do lysosomes do?

small sacs that Break down waste, damaged organelles, and microbes to maintain cell health.

What is the role of the cytoskeleton?

It supports the cell's shape and organizes its contents, assisting in movement.

• Components of cytoskeleton = actin, microtubules, intermediate filaments 

What is the phospholipid bilayer?

A structural component of the cell membrane made of phospholipid molecules.

What is the function of channel proteins in the cell membrane?

They allow specific substances to move through the membrane.

What is the glycoalyx?

Sugar groups on the cell surface that serve as a physical barrier and cell fingerprint.

• attach to either protein or lipid = glycolipid and glycoprotein

How do receptor proteins function?

They interact with chemical messengers to increase or decrease specific cellular activity.

What is the function of cholesterol in the cell membrane?

It stabilizes the membrane, preventing it from becoming too rigid or too fluid. found in the hydrophobic core

What is the role of the smooth endoplasmic reticulum?

It makes lipids and lipid-based hormones from cholesterol.

What distinguishes rough endoplasmic reticulum from smooth endoplasmic reticulum?

Rough ER is covered in ribosomes and is involved in folding and modifying proteins.

What is the function of the Golgi body?

It modifies, sorts, and packages proteins and other products from the ER.

What is the primary function of erythrocytes?

Transporting oxygen throughout the body.

What special feature do sperm cells have?

They have flagella for propulsion.

How do macrophages protect the body?

They have membrane extensions to trap microbes and abundant lysosomes to degrade them.

What is the function of fat cells?

They store nutrients and fluids in large vacuoles.

What is the role of skeletal and smooth muscle cells?

They are elongated structures that contract to facilitate movement.

What is the significance of DNA in the nucleus?

It holds genes that provide instructions for making proteins necessary for cell function.

What happens to the nucleus during cell division?

It breaks down, and DNA is released into the cytoplasm.

What is the function of peroxisomes?

They break down fatty acids and neutralize toxic substances like hydrogen peroxide.

What is the importance of cell specialization?

Different cell types have various structures that relate to their specific functions.

What are cell extensions?

Regions of the cell membrane that project outwards from the cell surface.

Face the space inside vessel/organ cavity like lumen because they act on contents within the space 

What is the purpose of microvilli?

To increase surface area of the cell membrane to support the transport of molecules.

Where are microvilli abundant?

In the digestive tract to absorb nutrients and in kidneys to reabsorb nutrients.

What are cilia?

Longer than microvilli, they can move and have various functions depending on cell location.

What is the role of cilia in the airways?

To move substances along the wall of the cell surface.

What is a flagellum?

A single elongated cilium that projects from the cell and moves the entire cell forward, found in sperm cells.

What does it mean for a cell membrane to be semi-permeable?

It allows certain substances to move through while restricting others.

How do lipid-soluble substances move through the cell membrane?

They move directly through the phospholipid bilayer down their concentration gradient via simple diffusion.

What is facilitated diffusion?

The process where water-soluble substances pass through transmembrane proteins without needing energy.

What is active transport?

The movement of substances from low to high concentration requiring energy from ATP molecules.

What is exocytosis?

The process where cellular proteins are packaged into vesicles to be released from the cell.

What is endocytosis?

The process where substances are engulfed by the cell membrane and pinched off into a vesicle.

What is osmosis?

The movement of water down its concentration gradient from high to low water concentration.

What is osmolarity?

A unit to measure the concentration of solutions in the body.

What is an isotonic solution?

When extracellular fluid has the same osmolarity as intracellular fluid.

What is a hypotonic solution?

When extracellular fluid has less solutes than intracellular fluid, causing water to move into the cell.

What is a hypertonic solution?

When extracellular fluid has more solute than the cell, attracting water out of the cell.

What are the four basic tissue types?

Nervous, muscle, epithelial, and connective tissue.

What is the main component of nervous tissue?

It controls and regulates body functions via transmission of electrical impulses.

What are the subtypes of muscle tissue?

Skeletal, cardiac, and smooth muscle.

What is the function of epithelial tissue?

To form boundaries between different environments, protect, secrete, absorb, and filter.

Where is connective tissue found?

In bones, tendons, fats, and blood.

What is the function of simple squamous epithelium?

Effective for movement of substances across tissue, found in blood vessels and air sacs in lungs.

What is the role of stratified squamous epithelium?

Acts as a protective barrier against physical abrasion, found in the mouth and skin.

What is the composition of the dermis?

It has two parts: papillary dermis (loose areolar connective tissue with rich blood supply) and reticular dermis (dense irregular connective tissue for strength and elasticity).

What is the function of sweat glands?

To regulate temperature, excrete waste, and provide protection from microbes.

What is the role of sebaceous glands?

To secrete sebum that protects from dryness and microbes (low pH).

What is the hypodermis composed of?

Adipose tissue. innermost layer of skin

What is the purpose of sensory receptors in the skin?

To detect physical stimuli like touch, pressure, and vibration.

What is the function of smooth muscle in the skin?

Attached to hair follicles, allowing hair shafts to stand upright and trap warm air.

whats the epidermis

outermost layer of skin and composed of stratified squamous epithelium for protection

what is hair tissue

complex structure made from epithelial and connective tissue, function determined by gross structure rather than individual tissue types

difference between hair follicle and hair shaft

• Hair follicle: beneath surface of skin, made of living tissue and keratin producing cells, stem cells, dense connective tissue that anchors hair to dermis 

• Hair shaft: external to skin, shaft made predominantly of keratin and dead keratin producing cells