2: Cells, tissues and skin

Question 1

List some features common to all cells

Answer 1

• plasma membrane
• cytoplasm
• nucleus

in order to become more specialized for their unique role, cells, gain individual structures that lead to specific functions. - specific genes get turned on and off.

Question 2

Describe cytoplasm

Answer 2

Structure= waterly fluid

Function= suspend organelles and maintain cell structure.

composed of= cytosol or ICF
contains; organelles and dissolved nutrients and proteins.

Question 3

Describe the nucleus

Answer 3

Largest organelle
Function= houses DNA (contains the instructions for cell and protein synthesis)
“The control center”

Question 4

Describe ribosomes

Answer 4

Function= site of protein synthesis
- adds amino acids together to form a long protein strand.

Free ribosomes= float around in cytosol/ICF and produce proteins for use inside the cell.

Membrane-bound ribosomes= attached to the endoplasmic reticulum produce proteins for export

Question 5

Describe the endoplasmic reticulum

Answer 5

Structure= interconnected tubes continuous with the nuclear 
Function= synthesis, storage, transport, detoxification

Question 6

Describe the rough endoplasmic reticulum (RER)

Answer 6

looks rough due to the presence of ribosomes. ER turns the amino acid chains produced from the ribosomes into the functional protein which it sends to the golgi apparatus.

Question 7

Describe the smooth endoplasmic reticulum (SER)

Answer 7

no ribosomes attached. Synthesis of lipids and steroids hormones, storage of calcium ions

Question 8

Synthesis and export of protein by RER

Answer 8

Cistern= body of water (sytoplasm)
1= protein is synthesised on the ribosome then migrates through the RER cistern.
2. the protein folds into its functional shape. short chains of sugar may be attached to the protein.
3. protein is packaged in tiny membrane sac called transport vesicles
4. The transport vesicle buds from the rough ER and travels to the Golgi apparatus for further processing.

Question 9

Describe the golgi apparatus

Answer 9

Structure= flatternwd sacs 
Function= modify, concentrate and package proteins and lipids 

forms vesicles and distributes them;

• within the cell
• move and become inserted within the plasma membrane
• move to the plasma membrane for the contact to be exported out of the cell by exocytosis

Question 10

Describe mitochondria

Answer 10

“power house”
Structure= bean-shaped with enzymes on the surface of the inner membrane.
Function= cellular respiration- releases energy in the form of ATP
Enzyme outside of folds carry out a chemical reaction that break down nutrients from food and converting them into ATP.

Question 11

Describe Lysosomes

Answer 11

“the demolition crew”
Structure= membrane-enclosed spheres that contain lysosomal enzymes.
Function= digest biological material including proteins and cell debris, dispose of invading bacteria, virus and toxins and recycle molecules

Question 12

Describe the cytoskeleton and its three parts

Answer 12

A network of rods running through cytosol which act as a skeleton of the cell

Three types
1. microfilaments: thinnest, Structure= made up of a protein called actin.
Function= contract to make cell move.
2. intermediate filaments= resist pulling on call
3. Microtubles=
Structure= long, hollow, rigid.
Function= Determine the overall shape of cells involved in cell division and intracellular transport.

Question 13

List the 3 types of cellular extensions and describe them.

Answer 13

Cilla- moving, on top of cells. sweep like waves to move materials across the surface.

Flagellum- single, long tail on bacterium and sperm. WHips for movement

Microvilli- finger-like extensions of the plasma membrane that project from cell surface increasing area.

Question 14

Describe the characteristics of the plasma membrane

Answer 14

• thin and flexible boundary separating ICF and ECF
• consistency of olive oil.
• selectively permeable
• Allows for different chemical compositions between ICF and ECF to maintain homeostasis.

Question 15

Explain the characteristics of the phospholipid bilayer

Answer 15

Hydrophilic phosphate head (polar)
Hydrophobic lipid tail (nonpolar)

all hydrophobic tails face the air and hydrophilic heads face the water.

Question 16

Describe the plasma membrane structure

Answer 16

• double layer (bilayer) of phospholipids.
• Hydrophilic head face ECF and ICF (watery)
• Hydrophobic tails face towards each other creating a lipid core

this self-orienting property ensure molecules stick together

Question 17

Explain the relationship between lipid and water solubility and repletion from the membrane core

Answer 17

lipid-soluble substance= water insoluble
- not repelled by the lipid core of plasma membrane
Water-soluble substance= lipid insoluble
- repelled by the lipid core of plasma membrane

Question 18

List the 4 components of the plasma membrane

Answer 18

1- phospholipids
2- proteins (integral and peripheral)
3- cholesterol (membrane stability)
4- carbohydrates (“name or ID tages”)

Question 19

Explain the two proteins of the membrane

Answer 19

Peripheral proteins
- not embedded- loosely attached to integral proteins or float free.
function= plasma membrane support, enzymes or motor function

Integral proteins

• embedded within the plasma membrane and span entire membrane
• classified as channel or carriers for substance transport (substance specific)
• substance-specific
• act as enzyme receptors

Question 20

List the two-channel proteins (integral)

Answer 20

Leakage channels

Gated channels

Question 21

Describe leakage gated channels

Answer 21

always open at both ends

e.g. substances that use them: water (aquaporin channel) and ions such as Na+ and K+

Question 22

Describe gated channels

Answer 22

open at one end and can open and close at the other end. 
there are three types 
- mechanically gated 
- chemically gated 
- Voltage-gated

Question 23

Describe carrier proteins

Answer 23

• transform shape to allow substances to pass.
• transport lipid insoluble or to large substances
  e. g. glucose, amino acids

Question 24

Define the term concentration and the concentration gradient gradient

Answer 24

concentration= measure of the amount of substance in an area
- high concentration= high number of a substance compared to other area and vice verse

The difference in the concentration of a particular substance between 2 different areas.

Question 25

Define equilibrium

Answer 25

equal space between substances (state of stable conditions) no net movement

Question 26

Define diffusion

Answer 26

the movement of a substance from an area of high concentration to an area of low concentration. (down/along the concentration gradient)

Question 27

List factors affecting rate of substance movement

Answer 27

- concentration gradient (the increased difference=increased speed) - Size of substance (small= move faster) - temperature (warmer faster)

Question 28

List the 2 types of transport

Answer 28

1- passive transport | 2- active transport

Question 29

Describe passive transport

Answer 29

- requires no eneergy - substances move down the concentration gradient - includes; simple diffusion, facilitated diffusion and osmosis

Question 30

Describe active transport

Answer 30

- requires energy (ATP) - substances move up the concentration gradient - includes; primary active transport with Na+/K+ ATPase pump

Question 31

Explain simple diffusion

Answer 31

- unassisted transport of lipid-soluble or very small substances across the plasma membrane down its concentration gradient. - continues until equilibrium is reached - Lipid soluble substances move by simple diffusion e. g. O2, CO2, fats, steroid hormones and alcohol

Question 32

Explain facilitated diffusion

Answer 32

- assisted transport of large lipid insoluble substances from high to low across the membrane. - Uses integral proteins - for large or lipid insoluble substances e. g. glucose, Na+ and K+

Question 33

Explain osmosis

Answer 33

= the net movement of water (solvent) through a selectively permeable membrane from an area of more water (less solute) and an area of more water (less solutes) when the solute can not pass through the membrane (impermeable) - water can move directly through bilayer (due to size, despite being lipid insoluble) or through channel proteins called aquaporins remember osmosis looks at the movement of water from an area of high to low (when solute cant pass membrane). So this means it moves from low solute to high solute to dilute it.

Question 34

Explain what diffusion and osmosis would look like through permeable and impermeable membranes

Answer 34

through a permeable membrane, water and solute would reach equilibrium. Through an impermeable membrane, water would reach equilibrium but solute wouldn't not.

Question 35

Explain active transport

Answer 35

When substances move against their concentration gradient (i.e. from low to high), the cells uses energy ATP - uses carrier proteins called Ma+/K+ ATPase pump - allows for maintenance of concentration differences on each side (import for RMP)

Question 36

Define exocytosis

Answer 36

transport process that moves substances to large for internal proteins out of the cell - e.g. products from Golgi apparatus

Question 37

Define endocytosis

Answer 37

transport process that moves substances to large for internal proteins into of the cell - by phagocytosis

Question 38

Define tonicity

Answer 38

the ability for a solution (fluid outside the cell) to affect the shape of a cell by altering the cells internal water volume (ICF) - determined by the solutions surrounds and concentrations

Question 39

Define isotonic tonicity

Answer 39

when an isotonic solution has the same water and solute concentration as the ICF. - no change in shape - maintain homeostasis of cell

Question 40

Isotonic solution is what % saline

Answer 40

9%

Question 41

Define Hypotonic tonicity

Answer 41

the solution has a lower concentration of impermeable solutes than ICF therefore a higher amount of water than the cell Hypo= a high amount of solutes in the cell so the water rushes in to dilute it. lyse= grow to an O

Question 42

Define Hypertonic tonicity

Answer 42

the solution has high concentration of solute so ICF flows out of cell causing it to create.

Question 43

Define resting membrane potential

Answer 43

potential energy (called voltage and measured in volts) that exists across the plasma membrane resulting from separating oppositely charged ions by the plasma membrane resulting from separating oppositely charged ions by the plasma membrane

Question 44

Which side of the membrane has K+ and which has Na+

Answer 44

``` K+= ICF (K+ ill go to doolies) Na+= ECF (Na+ this is bad im leaving) ``` membrane has more K+ leakage channels so more K+ moves out then Na+ in this creates an unstable membrane potential

Question 45

How is a resting membrane potential generated?

Answer 45

- mainly by the movement of K+ ions from ICF to ECF through K+ leakage channels in plasma membrane leaving the outside of plasma membrane positive relative to the negative side.

Question 46

How is resting membrane potential maintained

Answer 46

via ATPase pumps that sends 3x Na+ ions out 2x K+ ions in active transport: requires ATP this maintains the concentration gradient for ions to continue to diffuse through the leakage channels

Question 47

Average resting membrane potential

Answer 47

-70mV

Question 48

Identify 4 primary tissue types that all originated from stem celled

Answer 48

1- epithelial tissue 2- nervous tissue 3- Connective tissue 4- Muscle tissue

Question 49

Describe properties of nervous tissues

Answer 49

- internal communication that transmits electrical signals to regulate and control body function location: brain, spinal cord, and nerves - composed of neurons and supporting cells function: communication

Question 50

Describe properties of muscle tissues

Answer 50

- contracts to cause movement muscles can: - attach to bones (skeletal) - Be in the heart (cardiac) - on walls of hollow organs (smooth) composed of muscle cells that contractile microfilaments - specialised for contraction to allow movement - three types of muscle skeletal muscle- voluntary skeletal movement cardiac muscle- involuntary and found in heart. - smooth muscle involuntary in blood vessels, guts, bladder, uterus

Question 51

Describe properties of epithelial tissue

Answer 51

forms boundaries between different environments, protect, secretes, absorbs, filters. e.g. skin surface (epidermis) the lining of GI tract organs and other hollow organs - sheet of cells that can cover the body, line internal organs form glands. - anything that us exposed to the external environment is covered by epithelium so forms boundaries between different environments.

Question 52

Describe properties of connective tissue

Answer 52

supports protects, binds other tissues | e.g. bones, tendons, fat, and other soft padding tissue

Question 53

describe the structure of epithelial tissue

Answer 53

- composed of epithelial cells that are close together to form a sheet. - these cells have one free surface and one attached to the basement membrane - lack blood vessels (avascular) - O2 and nutrients are delivered via diffusion from surrounding tissues - contains neve cells for innovation - susceptible to damage but can regenerate quickly

Question 54

List 2 structural adaptations to epithelial tissue

Answer 54

Cilia: hair like cellular extensions that propel substances Microvilli: finger-like extensions to increase surface area

Question 55

what are the two classifications by layer ao epithelial cells

Answer 55

1- simple - single layered absorption, secretion, filtration location= lungs, kidneys, digestive tract 2- stratified - multiple layers of cells stacked on top of each other protection location= high abrasion areas (skin mouth )

Question 56

Classification of epithelial cells by cell shape

Answer 56

squamous: flattened and slace like Cuboidal: box like Columnar: tall and column shape

Question 57

Describe connective tissue

Answer 57

- connecting tissue of the body | most abundant and widely used of all tissue types

Question 58

List the connective tissue types

Answer 58

1- CT proper: loose and dense 2- cartilage 3- Bone 4- Blood

Question 59

What are the three characteristics of all CT

Answer 59

1. specialised cells 2. ground substance 3. protein fibres CT varies greatly in appearance with many different types of cells

Question 60

Key property of CT

Answer 60

has large expanses of extra cellular matric and few cells.

Question 61

Describe CT's extracellular matrix

Answer 61

- nonliving composed of ground substance and protein fibers - holds large volumes of ISF - can bear weight and withstand great tension

Question 62

Describe 3 types CT protein fibres

Answer 62

collagen fibres= tough w/ high tensile strength Elastic fibers= long thin fibers for stretch and recoil reticular fibers= short fibers continuous with collagen fibers

Question 63

Explain the CT specialised cells immature and mature names

Answer 63

``` blast= immature Cyte= mature CT proper= Fibroblasts, fobrocytes Cartilage= chondroblasts, chondrocytes Bone= osteoblasts, osteocytes Blood= haematopoietic stem cells (blast cells), erythrocytes (RBC) and leukocytes (WBC) ```

Question 64

Name some other cells found in CT

Answer 64

- RBC - WBC - adipocytes (fat cells: store aft) - macrophages - mast cells

Question 65

Summaries the properties of Connective tissue proper

Answer 65

- broken into 6 sub classes of loose and dense connective tissue - contains fibroblasts and fibrocytes - loose CT characterised by loose arrangement of fibers and large amounts of ground substance - dense CT characterised by closely packed bundles of fibers, little ground substance and poorly vascularised - one class of CT proper is adipose tissue which contains adisotites function= support, binding, storage and insulation

Question 66

Summaries the properties of cartilage

Answer 66

3 types: hyaline, elastic and fibrocartilage - cartilage that has qualities between dense CT and bone - ECM up to 80% water - consists of collagen and some elastic fibers so can withstand tension and compression - contain chondroblasts and chondrocytes - lack nerve fibres and is avascular function= support and absorption compression

Question 67

Summaries the properties of bone

Answer 67

- consists of abundant collagen fibers - matrix is hard due to calcium phosphate crystals - contains osteoblasts to produce organic portion of matrix - osteocytes resorb bone as needed - contain blood vessels and nerve fibers Function= support, protection and storage

Question 68

Summaries the properties of blood

Answer 68

- fluid within blood vessels - consists of blood cells surrounded by matrix called plasma - contains erythrocytes (RBC), leukocytes (WBC) and platelets Function: transport substances throughout the body

Question 69

What part of skin are each tissue type in?

Answer 69

stratified squamous, epithelial tissue= hypodermis and dermis Connective tissue= dermis and mypodermis smooth muscle tissue= arterioles nervous tissue= skin with nerves

Question 70

List the three layers of the skin

Answer 70

epidermis- outer epithelial layer Dermis- a deep supporting layer of connective tissue Hypodermis- a subcutaneous layer of connective tissue and adipose

Question 71

Explain some features of the epidermis

Answer 71

- avascular - oxygen and nutrients diffuse into cells - tightly joined cells create sheet to prevent substances from moving through spaces between the cells= great barrier cells are constantly dying and being shed then dead cells are replaced. cells renewed 25-45 days

Question 72

List the levels of the epidermis from most superior to least

Answer 72

``` Stratum Corneum Stratum Lucidum Stratum Granulosum Stratum Spinosum Stratum Basale ```

Question 73

Describe features of the stratum corneum

Answer 73

- 20-30 layers thick dead keratinised flattened keratinocytes - continuously shed - protective barrier (abrasion, dehydration, penetration) the cells flatten and die as they get up to the surface

Question 74

Describe features of the stratum basale

Answer 74

- single layer of dividing epidermal stem cells - produce a new keratinocyte above the stem cell - push older cells towards surface - also contains melanocyte (produces pigment)

Question 75

What 5 cell types compose the epidermis

Answer 75

- stem cells: divide - keratinocyte: predominate cell of skin, produce keratin - Melanocyte: produce melanin - Merkel cells (tactile): touch receptors - Langerhans cells/dendritic cells (macrophages): active immune system

Question 76

Explain parts of the dermis

Answer 76

- consists of connective tissue - includes macrophages and fibroblasts - fibroblasts produce collagen and elastic fibers: provide strength and flexibility contains - blood vessels - nerves + sensry receptors - glands (sweat and sedaceous- produce sebum) - hair follicles

Question 77

Purpose of the hypodermis

Answer 77

``` - consists modly of adipose tissue function= - anchors skin to underlying tissue - stores fat - shock absorber - insulator ```

Question 78

What are the 6 function of the skin

Answer 78

``` 1- Protection - physical - chemical - Biological 2- Sensation 3- Metabolic function 4- Excreation 5- Blood reservoir 6- Temperature reulation ```

Question 79

Function of skin- Protection (physical/mechanical)

Answer 79

- tightly joined epidermal cells, keratin and oily secretions blocking most water and water-soluble substances

Question 80

Function of skin- chemical barriers

Answer 80

- low pH secretion preventing bacteria from multiplying - defensins (natural antibiotic) secreted by skin cells to kill bacteria - melanin protects DNA in underlying cells fro, UV da,age

Question 81

Function of skin- biological barriers

Answer 81

- macrophages engulf and dispose of microorganisms tat manage to penetrate the epidermis

Question 82

Function of skin- sensation

Answer 82

Dense network of nerves - controls blood flow (vessel diameter) - controls glandular secretion (e.g. sweat) Collects sensory info: - pain (nocioceptors) - Temp (Thermorecpetors) - touch, pressure and vibration (mechanoreceptors)

Question 83

Other function

Answer 83

metabolic function- synthesizes Vitamin D Excretion- nitrogenous wastes and salts are excreted in sweat Blood reservoir- can hold 5% of bodies blood - dense blood vessel network - amount of blood flow through these blood vessels can be regulated by the diameter of the vessel e. g. for temp control

Question 84

Function of skin- Temp reulation

Answer 84

- vaso dilation and contriction - sweat glands monitored by thermoreceptors and thermoregulatory centre

Question 85

describe the effect of ageing on skin

Answer 85

skin thins- more cells lost then formed wringles form= decreased fibroblasts which lead to lack of collagen and elastin skin dies and itches= decreased sweating and gland activity other chnages- loss of hair, grey hair, colder skin, thicker nails

Question 86

Describe the three membranes of the body

Answer 86

Cutaneous membrane - skin, exposed to air and is dry Mucous membrane - lines body cavities that are outside of the body. - In digestive, respiratory and urogenital tracts - we membrane due to secretions Serous membrane: - line closed ventral body cavities. - secretes a clear serous fluid to lubricate surface. - wet membranes that are not exposed to external environment

Question 87

Two main processes of tissue repair

Answer 87

1. regeneration '- replaces destroyed tissue with the same kind of tissue - can be restored to normal if the damage is minor or epidermal stem cells present to regenerate lost tissue. 2. fibrosis - replaces destroyed tissue with scar tissue - damage that includes the dermis leads to repair by fibroblasts - scar tissue does not have any of the same qualities as the tissue before the injury

Question 88

What are the 3 stage of tissue repair

Answer 88

stage 1: inflammation Stage 2: organisation or proliferation stage 3: maturation or remodeling

Question 89

Explain stage 1: Inflammation

Answer 89

Function: prepares the wond for repair, eliminated invading microorganisms and removes debris and dead tissue. - damaged cells release inflammatory chemicals that cause inflammation - signs of inflammation: swelling, redness, pain and heat - blood vessels become more permeable: fluid released into are included; macrophages: enjulf debris/invading microorganism Clotting protein: produce blood clots to stop blood loss, minimise and electrolyte loss, holds wound together and prevent new invading microorganism. - clot on surface dries and forms a scab

Question 90

Stage 2: Organisation or proliferative stage

Answer 90

Function: extracellular matrix synthesis including collagen and restore a blood supply. - blood clots replaced by granulation tissue- comprised of capillaries that grow across the wound to restore blood supply, bring oxygen and nutrients required for healing - fibroblasts-> produce collagen fibres that bridge the gap - macrophages-> engulf cell debris, invading microorganisms and blood clot epithelial stem cells multiply and migrate over the granulation tissue.

Question 91

Stage 3: maturation or remodeling

Answer 91

Function: complete permanent skin repair - collagen laid down in stage 2 is remodeled and contracts to pull wound edges together. - scar is avascular - if stemn cells are present naer cell they can regenerate epitheliaum - repair predominantly by fibrosis - scar tissue= thouh but not elastic or flexible, no hair, sweat or oil glands

Question 92

Skin damage during burns

Answer 92

- may lead to protein denature , cell death, tissue damage - loss of skin function immediate threat to life resulting from fluid loss due to loss of physical protection of skin. - leads to dehydration, electrolyte imblance then renal shutdown and circulatory shock infection via microorganisms.

Question 93

Burns classification

Answer 93

superficial- 1st degree= epidermisi Partial thickness- 2nd degree; epidermis and part of dermis Full thickness- 3rd degree: entire thickness of skin

Question 94

Treatment of full thickness burns

Answer 94

usually require gerafts | as many components of skin are lost so it cant heal and have adequate function without stem cells especially.