Cells and Tissues

Question 1

What is a cell?

Answer 1

The basic structural functional unit of an organism, smallest structure capable of performing activities vital to life. Structure determines the functions

Question 2

What is the structure of a cell?

Answer 2

Plasma Membrane: Separating the internal environment from the external environment.

Cytoplasm: Consists all the cellular contents between the plasma membrane and the nucleus. Contains cytosol (fluid portion) and organelles. Everything inside the cell that is not the nucleus

Nucleus: Houses DNA the brain and control center of the cell

Question 3

Function:
Organelles: Plasma/cell membrane

Answer 3

Phospholipid bilayer embedded with different types of proteins that each have specific functions. Bilayer = two layers, phospholipid = phosphate head joint to lipid tails (two layers of those) embedded with proteins. It separates the outside of the cell to the inside.
- Ensures cell structural integrity, boundary for separating different environments, regulate entry and exit of substances into and out of the cell, selectively permeable, monitors ions that come in and out, participate in cellular communication, form cellular identification systems, participate in enzymic activities

Question 4

Function:
Organelles: Nucleus

Answer 4

The control center of the cell that contains genetic material (DNA), directs all cellular activities and regulates structure, majority cells have on nucleus however others like skeletal have multiple. Nuclei have a double membrane called the nuclear envelope, the outer membrane is continuous with rough endoplasmic reticulum

Question 5

Function:
Chromatin in the nucleus

Answer 5

Condensed DNA wrapped around proteins, DNA is made up of genes which encode proteins, when making proteins this needs to be lightly unwound. Euchromatin is dispersed and lightly stained which means the cell is active and producing proteins. Heterochromatin is highly condensed (tightly coiled) and intensely stained which means the cell is inactive and nor producing proteins

Question 6

Function:
Organelle: Nucleolus

Answer 6

A spherical dark body found within the nucleus, has no membrane, site of RNA synthesis and initial ribosome assembly
Visibly obvious in the cells that are synthesizing proteins, will not be obvious in cells that are not synthesizing proteins.
Crucial for protein production, made by segments of RNA in the nucleolus

Question 7

Function:
Organelles: Cytoplasm and Cytosol

Answer 7

Cytoplasm: All cellular components between the plasma membrane and the nucleus, has two components, cytosol and organelles

Cytosol: The intracellular fluid component of cytoplasm that surrounds the organelles. Each cell varies in composition and consistency but is generally 75090% water, the remaining 10-25% is comprised of dissolved suspended ions, glucose amino acids, proteins, lipids, ATP, waste products and some organic molecules

Question 8

Functions:
Organelles: Endoplasmic Reticulum

Answer 8

Two different types;
Rough Endoplasmic Reticulum: continuous with the nuclear envelope (out nuclear membrane), studded with ribosomes, which is what makes RER rough, used for protein synthesis

Smooth Endoplasmic Reticulum: Lacks ribosomes, contains unique enzymes that synthesize fatty acids and steroids

Question 9

Functions:
Organelles: Ribosomes

Answer 9

The site of protein synthesis, strands are transcribed and amino acid chains are formed. Ribosomes are assembled in the nucleolus and consists of two subunits, one large and one small

Location: Attached to the RER (produces proteins for either plasma membrane or for secretion for the cell, or free floating within the cytosol

Question 10

Function:
Organelle: Mitochondrion

Answer 10

Site of ATP (energy production) found in cells which use a lot of energy (skeletal). Double membraned organelle containing its own DNA, capable of self-replication, outer and inner mitochondrial membranes. Inner mitochondrial membrane contains folds known as cristae, these provide very large surface area

Question 11

Function:
Organelle: Golgi Complex/ Apparatus

Answer 11

Sorts and packages proteins exiting the RER made on ribosomes, the proteins from RER dock on the Golgi and send away in vesicles made of the Golgi body so parts of it break off to be used by the cell or sent out of the cell, made of small flattened membranous sacs called cisternae.

Two surfaces: Entry (facing the RER) Exit (facing the plasma membrane), protein leaves the Golgi complex via vesicles

Question 12

Functions:
Organelles: Lysosome

Answer 12

Membrane-bound vesicles that form the Golgi complex, need this membrane as they;
- contain enzymes that break down molecules, recycle worn out cellular components, digest other organelles

Question 13

Functions:
Organelles: Vesicles

Answer 13

Membrane bound organelle, many have blebbed off the Golgi with protein, secretory vesicles as it is secreting a product outside of the cell, act as a vehicle (carrier-transport) (delivery - secretory).

Contains: water, proteins, enzymes, hormones, waste

Question 14

Functions:
Organelles: Microvilli, Cilia, Flagella

Answer 14

All projections extending from the cell surface

Microvilli: Numerous, short extensions on surface of cells, increase surface area e.g. epithelial layer of the small intestine

Cilia: Hair like projections, move fluid along the cell surface

Flagella: Similar in structure to cilia but much longer, move entire cell

Question 15

How are substances transported across the plasma membrane?

Answer 15

Substances produces by the cell need to be moved out, substances can move across the cell in an active or passive process;

Active: use energy to work against the concentration gradient e.g. if there is a membrane with a high concentration in the inside, you are fighting the current which will require energy, however if there is a lot in the cell and need to move some out them it is easy as it does not require energy.

Passive: do not involve the use of energy, allows the substances to flow down their concentration gradient. 3 types; simple diffusion, facilitated diffusion and osmosis

Question 16

What is simple diffusion?

Answer 16

Only possible for substances that are permeable to the plasma membrane, small uncharged hydrophobic molecules. Where things can move down the plasma membrane with no help e.g. oxygen, carbon dioxide, nitrogen and steroids (also water with osmosis)

Question 17

What is facilitated diffusion?

Answer 17

Two types;
Channel mediated and carrier mediated: Both assist substances that are not permeable to the plasma membrane, small/medium charged hydrophilic can. Travel down the concentration gradient with no energy, channel mediated is faster than carrier mediated because carriers need to reset shape each time.

E.g. glucose, potassium, chloride, sodium, calcium

Question 18

What are factors that influence the diffusion rate?

Answer 18

Steepness of concentration gradient, temperature (higher temperature, faster diffusion), mass of diffusing substance, surface area of the diffusion membrane (larger surface area available, faster it will occur)

Question 19

What is osmosis?

Answer 19

A specialized type of passive transport for water which moves from an area of lower solute (a substance dissolved in a solution) to an area of higher solute concentration. Travels mainly through aquaporins but small amounts can diffuse straight through the plasma membrane, no energy requires, wants to make an equilibrium

Question 20

What is cell division?

Answer 20

40 trillion cells in the body got there by dividing and reproducing, it is essential for tissue development, growth, tissue renewal/replacement, repair

Mitosis: produced two identical daughter cells, normal cellular reproduction

Meiosis: Produces four genetically unique daughter cells (sex cells only) where one cell splits into 4 daughter cells, gametes that are different combinations of our parents DNA

Question 21

What is Cell death?

Answer 21

Cells need to die for us to remain health, constant balance between proliferation and programmed cell death.

Apoptosis: Programmed cell death, which is physiological, cell turnover, development, hormone atrophy e.g. skin, in the gastrointestinal tract every 3 days cells inside will replace

Necrosis: death of entire tissues e.g. physical insult, infection, oxygen deprivation, disease, non-natural

Question 22

What is epithelial tissue?

Answer 22

A protective barrier layer, an interface between two environments, lines vessels, similar to cell membranes but at a tissue level.
Controls passages of substances: secretion, absorption, transportation

Two types;
Surface/lining epithelium: Covers and lines all natural surfaces of the body

Glandular epithelium: Cells produce a secretion required by the body

Question 23

What are the structural features of epithelium tissue?

Answer 23

Highly cellular, consists of mainly epithelial cells. Avascular means it has no blood vessels, supplied by tissue, it has a polar appearance and underlying basement membrane it separates the epithelium from the connective tissue below it

Question 24

How do you classify epithelial tissue?

Answer 24

Layers:

One layer: simple
More than one layer: stratified
Pretending to be more than one layer: pseudostratified ( look like they are on different levels but the base layer is the same)

Shape (in the topmost layer):
Squamous (square) Cuboidal (cube), Columnar (columns), Transitional (goes from a square to a cube and back again)

Then look for any apical surface modifications (microvilli) (keratinization)

Question 25

Structure of epithelial tissue and its function:

Answer 25

Simple epithelium facilitates transfer of substances between different environments

Squamous shapes supports rapid passage of substances as it is small and thinner

Cuboidal and columnar shapes support absorptive and secretive functions

Stratified facilitates a protective barrier function

Cilia helps with movement of mucus, which is why smokers have a terrible cough as before they get emphysema they lose their cilia and have to manually get rid of mucus

Question 26

What is the function of Connective tissue?

Answer 26

Establishes a structural framework, transports fluids and dissolved materials (blood, lymph), forms a network and facilitates communication, provides protection insulation and cushioning. Supports surrounds and interconnects other types of tissue, provides a storage reservoir for energy, defends against foreign and invading pathogens, involved in repair of tissues

Question 27

Components of connective tissue?

Answer 27

Cells: multiple types
Extracellular Matrix (ECM): Fibers (collagen, reticular, elastic), Amorphous ground substances (AGS)
Amounts is dependent on connective tissue type

Question 28

Connective Tissue: Cells

Answer 28

Fibroblast:
Most common, produce all of the fibers of CT and AGS, Form scar tissue (collagen)

Adipocyte (fat cells):
Storage of fat (energy), insulation/protection/shock absorption

Leukocytes (WBC’s)
Lymphocyte: Immune reactions - a type of white blood cell
Neutrophil: Acute inflammation

Macrophage:
Defense via phagocytosis - to eat things and clean up waste
Cell type similar to lysosome

Question 29

Connective tissue: Fibers

Answer 29

Collagen: Most abundant, structural protein, has no stretch, gives strength and cushioning, amount vary across CT type

Reticular: Structural protein, provides flexible net like framework, supports cellular structures

Elastic: Provide flexibility and elasticity, allows for coil and recoil, diminishes with age

Question 30

Connective tissue: AGS (Amorphous Ground Substance)

Answer 30

Amorphous, lacks defining shape. Clear, colorless, secreted by fibroblasts, supports surrounding cells and fibers, regulates intercellular communication

Question 31

What is loose connective tissue made of? Where is it located?

Answer 31

Mostly AGS, little fibers and cells
Function: Nourishment, cushioning, binding of organs, immune defense, passageway for nerves and blood vessels

Location: underlining of all epithelia, outer coverings of blood vessels, nerves, fascia between muscles and pleural and pericardial sacs

Question 32

What is Dense connective tissue?

Answer 32

Composed of mostly fibers, little cells and AGS; Two types;

Dense regular: Fibers are bundles in a parallel fashion, enhances tensile strength and resistance to stretching in the direction of fiber orientations, attachment of bone to bone, attachment of muscle to bone, transmission of force, in ligaments and tendons

Dense irregular: Fibers are not arranged in parallel bundles and instead the direction of fibers is random, greater strength in one particular direction, protection of organs from injury, encapsulation of organs, in the dermis of skin, capsules liver spleen and other organs

Question 33

Types/ classification of connective tissue?

Answer 33

Blood - transports gases, nutrients, hormones, and cells throughout the body, defense cells protect against pathogens/microorganisms

Lymph - drainage of excess interstitial fluid from tissue spaces into blood, transports lipids and vitamins, defense cells (lymphocytes) carry out immune responses

Bone - forms a rigid supportive framework for the body, stores minerals such as calcium, protects underlying structures from injury

Cartilage - prevents the large airways from collapsing, supports the nose and ears, present on the surface of bones (at joints) to minimize friction and act as a shock absorber.

Question 34

Which component of connective tissue is found between the cells and fibers and provides support, transports substances, and regulates intercellular communication?

Answer 34

Amorphous Ground Substance

Question 35

Which type of epithelial tissue is found in lining the heart, blood vessels and lymphatic vessels?

Answer 35

Simple Squamous Epithelium

Question 36

Where is pseudostratified columnar epithelium with cilia found?

Answer 36

Respiratory tract

Question 37

What organelles are responsible for assembling amino acids into polypeptides and proteins

Answer 37

Rough Endoplasmic Reticulum, Ribosomes

Question 38

Cells that contain large numbers of mitochondria mean that?

Answer 38

They have a high energy demand

Question 39

What is Connective tissue proper?

Answer 39

• Under every epithelial tissue
  
  • Includes those connective tissues with many types of cells and extracellular fibers in a syrupy ground substance
  • Loose - fibers create loose open framework. Areolar tissue, adipose tissue, reticular tissue, more cells than fibers
    Dense - Fibers densely packed. Dense regular, dense irregular, elastic. All to do with how the fibers are aligned.

Question 40

What is fluid connective tissue?

Answer 40

• Have distinctive populations of cells suspended in a watery matrix that contains dissolved proteins
  
  • Blood - flows within cardiovascular system
    Lymph - flows within lymphatic system

Question 41

What is supportive connective tissue?

Answer 41

• Differ from connective tissue proper in having a less diverse cell population and a matrix containing much more densely packed fibers. Supporting connective tissues protect soft tissues and support the weight of part or all of the human body
  
  • Cartilage - Solid, rubbery matric, hyaline cartilage, elastic cartilage, fibrous cartilage
  • Bone - solid, crystalline matrix

Question 42

What is the exocrine gland?

Answer 42

Secretes their substances through ducts onto your body’s surfaces e.g. sweat, salivary, mammary glands