Cells and Tissue

Question 1

What is a cell and why is it important in the human body?

Answer 1

A cell is the basic living and functional unit of life in the body.

Question 2

What are the three main structural components found in all cells?

Answer 2

Plasma Membrane

Cytoplasm

Nucleus

(all organelles)

Question 3

What are organelles and why are they important?

Answer 3

specialised structures within cells that perform specific functions

Question 4

Where do specialised cells originate from

Answer 4

stem cells

Question 5

(organelles) plasma membrain structure and function

Answer 5

• maintains structure
• separates internal and external environments
• regulates material transport
• participates in cellular communication
• form cellular identification system
• participate in enzymatic activities

Question 6

Nucleus function:

Answer 6

• control centre of the cell containing DNA
• directs all cellular activities and regulates structure

Question 7

(organelles) nucleus structure

Answer 7

*most cells have one but some cells have multiple nuclei
nuclei have a double membrane (nuclear envelope)
nuclear envelope has…
rough endoplasmic reticulum
nuclear pores

Question 8

what is found within the nucleus?

Answer 8

DNA
chromatin
nucleoulus

Question 9

what is chromatin

Answer 9

• condensed DNA wrapped around proteins which creates chromosomes

Question 10

What are the two types of chromatin:

Answer 10

two types of chromotin:
- Euchromatin = dispersed (uncoiled), active and producing proteins

• Heterochromatin = highly condensed (tightly coiled), inactive and not producing proteins

Question 11

What is the nucleolus:

Answer 11

spherical dark body found within the nucleus
site of RNA synthesis and initial ribosome assembly
visible when cells are synthesysing proteins (through chromotin)

Question 12

what is cytoplasm

Answer 12

the cytoplasm is holds all the cellular components between the nucleus and the plasma mebrane
Has two components…
1. cytoplasm
2. organelles

Question 13

What is the cytosol

Answer 13

intracellular fluid (that varies between cell) component of cytoplasm that surround the organelles

generally composed of 75-90% water and 10-25% of other extracellular substances

Question 14

what are the key organelles found within the cytoplasm

Answer 14

• endoplasmic reticulum
• ribosomes
• mitochondrion
• organelles
• Golgi complex/ apparatus
• lysosome
• vesicles
• microvilli, cilia, and flagella

Question 15

What is endoplasmic reticulum

Answer 15

There are two kinds…
Rough ER and Smooth ER
rough ER:
synthesyise and process proteins
- continuous with nuclear
- studded with ribosomes

Smooth ER:
lipid metabolism, detoxification and calcoum storage
- lacks ribosomes
- containes unique enzymes that synthesise fatty acids and steroids

Question 16

What are ribosomes

Answer 16

site of protein synthesis
- where they translate the genetic code from messenger RNA into specific sequences of amino acids, which then fold into form proteins
Located in two areas
- attached to RER (for either the plasma membrane or secretion into the cell)
- Free floating within the cytosol for use there

Question 17

What is the mitochondrion

Answer 17

Site of ATP (energy) production
- double membrane organelle containing its own DNA (outer and inner mitochondrial membrane)
- inner membrane contains folds providing large surface area

(cells that use more energy = more mitochondrion)

Question 18

What is the golgi complex/ apparatus

Answer 18

sorts and packages proteins exiting the RER
proteins leave the Golgi via vesicles

Question 19

What are lysosomes:

Answer 19

• membrane-bound vesicles that form from golgi complex
  contains enzymes that:
• break down molecules
• recycle worn-out cellular components
• digest other organelles

Question 20

What are vesicles

Answer 20

act as a vehicle
- carrier (transport)
- delivery (secretory)
*continuously being formed

Question 21

microvilli, cilia and flagella

Answer 21

all projections extending from the cell surface
microvilli:
- short extensions that increase surface area
Cilia
- hair like projections that move fluid along cell surface
Flagella
- longer than cilia and move the entire cell (like sperm cell tail)

Question 22

Why is the transport of materials across the plasma membrane good?

Answer 22

• essential to cell life
• support metabolic reaction
• exports waste

Question 23

What are the two types of transport of substances across the membrane

Answer 23

Active transport = involving energy (ATP) use, against their concentration gradient

Passive transport = no energy use, flows down their concentration gradient

Question 24

what are the 3 main types of passive transport:

Answer 24

simple diffusion
facilitated diffusion
osmosis

certain substances can flow through the membrane depending, via the passive processes, depending on size and polarity (selective permeability)

Question 25

What is simple diffusion

Answer 25

only possible for small, uncharged, hydophobic substances - travel down concentration gradient, from area of high to low concentration of substance - no energy - substances that can travel include oxygen, nitrogen, steroids

Question 26

What is facilitated diffusion

Answer 26

possible for small/medium, charged, hydrophillic travel with/down teh concentration gradient two types: channel-mediated - faster carrier-mediated - slower, need to reset shape substances that can travel = glucose, potassium, chloride, sodium and calcium

Question 27

Factors that influence diffusion rate:

Answer 27

- steepness of concentration gradient (greater the concentration difference = faster diffusion) - temperature (higher temp = faster diffusion) - mass of diffusing substance (larger mass = slower diffusion) - surface area of diffusion membrane (larger surface area = faster diffusion)

Question 28

what is osmosis

Answer 28

Specialised type of passive transport for water - water moves from an area of lower solute concentration to a higher area of solute concentration (attempting to equal concentration on both sides) no energy required water travels mainly through aquaporins

Question 29

What is a tissue and what are the four main types?

Answer 29

A tissue is a group of similar cells that work together to perform a specific function. The four main types are: Epithelial tissue – covers surfaces and lines cavities. Connective tissue – provides support and structure. Muscle tissue – responsible for movement. Nervous tissue – generates and transmits nerve impulses.

Question 30

Epithelial functions

Answer 30

- protective barrier - interface between two environments - controls passage of substances Two different functional epithelial types Surface lining epithelium: covers and lines all natural surface of the body Glandular epithelium: tissue responsible for secreting substances found in glands of the body

Question 31

What are the structural features of epithelium

Answer 31

- highly cellular - avascular - polar appearance = apical (outermost) basal (innermost) - underlying basement membrane (basal lamina), separates the epithelium from the connective tissue

Question 32

How do you classify epithelial tissue?

Answer 32

Through appearance: Layers: one layer = simple more than one = stratefied pretending to be more than one = pseudostratefied Shape: squamous = wide cuboidal = square columnar = tall apical surface modifications cilia microvilli keratinisation

Question 33

How does epithelium structure relate to function

Answer 33

simple epithelium facilitates transfer of substances between different environments stratefied epithelium facilitates a protective barrier function (underlying tissue = protection from wear and tear)

Question 34

What are connective tissue functions:

Answer 34

- establishes structural framework of the body - transports fluids and dissolved materials around - forms a network and facilitates communication - provides protection, insulation and cushioning - supports, surround and interconnects with other tissue - provides storage reservior for energy - defends the body against pathogens - involved in repare of tissue

Question 35

What are the components of connective tissue

Answer 35

cells extracellular matrix (ECM)... fibres: - collagen - reticular - elastic - amorphous ground substances (AGS)

Question 36

What are the classification of connective tissue?

Answer 36

connective tissue proper fluid connective tissue supporting connective tissue

Question 37

What are the types of connective tissue proper

Answer 37

- loose connective tissue - dense connective tissue

Question 38

Loose connective tissue:

Answer 38

function: - nourishment and cushioning of epithelia - immune defence - binding of organs - passageway for nerves and blood vessels location: - underlying of all epithelia - outer coverings of blood vessels and nerves - fascia between muscles pleural and pericardial sacs

Question 39

Dense connective tissue

Answer 39

Two types: Dense regular: - fibres bundled in a parallel fashion - enhances srength and resistance to stretching Function: - attachment of bone to bone - attachment of muscle to bone - transmission of forse location - ligaments and tendons Dense irregular: - random fibre arrangement Function: - protects organ from injury - encapsulation of organs location: - dermis of skin - capsules around liver spleen and other organs - around bone

Question 40

Types of fluid connective tissue

Answer 40

blood = transports gases, nutrients and hormones lymph = drainage of excess fluid from tissue spaces int blood

Question 41

Types of supporting connective tissue

Answer 41

cartilage = prevents large airways from collapsing supports nose and ears present on the surface of bone bone = forms rigid supportive framework for the body stores minerals