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NUR1112 > Week 2 Bioscience > Flashcards

Week 2 Bioscience Flashcards

1
Q

Generalised cell

A
  • organelles: little organs found within a cell
  • each organelle has a specific function
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2
Q

Cytoplasm

A
  • the watery space between plasma membrane and the nucleus
  • contains the cellular organelles
  • composed of cytosol or Intracellular fluid (ICF)
  • contains dissolved proteins and nutrients
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3
Q

The nucleus

A
  • largest organelle
  • houses DNA
  • DNA contains the instructions which tells the cell what to do, in particular which protein to make
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4
Q

ribosomes

A
  • site of protein synthesis
  • free ribosomes: floating in cytosol produce proteins for use inside cell
  • membrane bound ribosomes: attached to endoplasmic reticulum proteins for export
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5
Q

Endoplasmic Reticulum

A

-interconnected tubes continuous with the nuclear envelop
-functions:
synthesis
storage
transport
detoxification

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6
Q

Rough Endoplasmic Reticulum (RER)

A

-studded with ribosomes
-proteins produced by ribosomes on RER are packaged and exported out of cell

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7
Q

Smooth Endoplasmic Reticulum (SER)

A

-no ribosomes attached
-synthesis of lipids, cholesterol and steroid based hormones
-involved in detoxification
-storage of calcium ions

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8
Q

Golgi apparatus (“the traffic director”)

A
  • consists of stacks of flattened sacs
  • functions:
    • modify, concentrate and packages proteins and lipids
  • forms vesicles and distributes them:
    1. within the cell
    2. move and become inserted within the plasma membrane
    3. move to the plasma membrane for the content to be exported out of the cell by exocytosis
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9
Q

Lysosomes (“the demolition crew”)

A

-membrane enclosed spheres
-contains lysosomal enzymes
-functions:
* dispose of invading bacteria and cell debris
* recycle molecules that have been broken down

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10
Q

Mitochondria (“the power house”)

A

-bean‐shaped organelle
-enzymes on surface of inner membrane
-function: cellular respiration
-releases energy in the form of ATP (adenosine triphosphate)

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11
Q

The cytoskeleton

A

-skeleton of the cell but not made of bone
-network of rods running through cytoplasm
-acts as cells bones, muscles and ligaments

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12
Q

Cilia and Flagellum

A
  • A flagellum is a single, long tail found on bacteria and sperm
  • it whips back and forth to move the sperm along
  • cilia are motile cellular extensions on the top of cells
  • they sweep in a wave like manner to move materials across the surface of them
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13
Q

Microvilli

A
  • minute fingerlike extensions of the plasma membrane that project from the cell surface
  • they increase the surface area of the cell
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14
Q

Plasma membrane

A
  • cell membrane = plasma membrane
  • holds the cell together, separating the ICF from ECF
  • acts like a zip‐lock bag, however the membrane selects what it lets into and out of the cell
  • helps maintain homeostasis (optimal working conditions)
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15
Q

Phospholipid structure

A
  • made of a phospholipid molecules
  • hydrophilic (“love water”) phosphate heads point toward water
  • hydrophobic (“hate water”) lipid tails point away from water
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16
Q

Plasma membrane structure

A
  • is a double layer (bilayer) phospholipid molecules
  • is a thin flexible membrane
  • fluid membrane the consistency of olive oil
  • selectively permeable: a membrane that allows some substance through and excludes others
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17
Q

Plasma membrane consists of:

A
  • phospholipids
  • integral proteins (channel and carrier)
  • peripheral proteins
  • cholesterol (membrane stability)
  • sugars (“name or ID tags”)
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18
Q

Concentration gradients

A
  • substances (atoms, molecules, particles, ions, solutes) are constantly moving
    -random movement (Brownian motion) due to kinetic energy
    -non‐directional movement that leads to collisions that ricochet the substance off in another direction
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19
Q

Concentration gradient and equilibrium

A
  • concentration: measure of the amount of a substance in an area
  • high concentration means there are higher numbers of the substance compared to another area
  • concentration gradient: the difference in concentration of a particular substance between 2 different areas
  • equilibrium: equal space between substances (state of stable conditions)
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20
Q

Diffusion

A

*the movement of a substance from an area of high concentration to an area of low concentration
*substances move in a net direction to achieve equilibrium

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21
Q

Factors that affect rate of movement

A
  1. concentration gradient: if a larger concentration gradient exists substances will move faster
  2. size of the substance: smaller substance move faster than larger substance
  3. temperature: warmer environments increase the rate of movement
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22
Q

The transport processes substances use to cross the plasma membrane

A
  • cell needs to transport substances such as nutrients, gases and waste across the plasma membrane to maintain homeostasis
  • substances are moved in and out of cells via the following mechanisms:
    Diffusion: simple and facilitated diffusion
    Osmosis
    Active transport
    Exocytosis and endocytosis
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23
Q

Transport process depends on the type of substance transporting

A
  • substances are classified as lipid soluble or water soluble
  • lipid soluble substance=water insoluble substance
    -not repelled by the lipid part of plasma membrane
  • water soluble substance=lipid insoluble substance
  • repelled by the lipid part of plasma membrane
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24
Q

Simple Diffusion

A
  • the unassisted transport of lipid soluble or very small particles across a plasma membrane
  • continues until equilibrium is reached then no net movement
  • Lipid soluble substances move by simple diffusion: eg O2 CO2
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25
Q

Facilitated Diffusion

A
  • the assisted transport of large or lipid insoluble substances from an area of high concentration to low concentration across a plasma membrane
  • requires an integral protein to facilitate the movement
  • integral proteins can be channel or carrier proteins
26
Q

Osmosis

A
  • diffusion is the movement of substances (solutes), osmosis is the movement of water (solvent) across the plasma membrane
  • osmosis: water molecules move down their concentration gradient, from an area of high water concentration to low water concentration
  • water can move directly through the phospholipid bilayer or through aquaporins
27
Q

Active Transport

A
  • diffusion and osmosis are examples of passive transport (they don’t require energy)
  • when molecules need to move against their concentration gradient (ie from low to high concentrations), the cell uses energy
  • called active transport
  • active transport moves molecules against their concentration gradients via special protein pumps in the membrane. In order to pump the molecules, the cell uses ATP
28
Q

Endocytosis and Exocytosis

A
  • transport processes that move large particles into or out of the cell. Both involve vesicles and the plasma membrane
  • exocytosis – out of the cell (eg products from golgi)
  • endocytosis – into the cell (Phagocytosis = cell eating)
29
Q

Tonicity

A
  • is the ability of a solution (fluid outside the cell) to affect the shape of a cell by altering the cells internal water volume (ICF)
  • the tonicity of the solution that surrounds the cell is determined by its concentration relative to ICF
30
Q

Isotonic

A

an isotonic solution has the same concentration as the ICF for both:
- substances/solutes
- water
isotonic solutions cause no change in cell volume or shape (no water shift)
isotonic solutions maintain homeostasis of cell

31
Q

Hypertonic

A
  • a hypertonic solution has a higher concentration of impermeable solutes than the ICF, therefore a lower amount of water than the cell
  • cells in a hypertonic solution will lose water → shrink (crenate)
32
Q

Hypotonic

A
  • a hypotonic solution has a lower concentration of impermeable solutes than the ICF, therefore a higher amount of water than the cell
  • cells in a hypotonic solution will gain water → swell. Cells can swell and burst or lyse (hemolysis in RBC)
33
Q

Ion concentrations and leakage channels

A
  • ECF: higher concentration of sodium ions (Na+ ) compared to ICF
    ➢Na+ moves into cell through Na+ leakage channel
  • ICF: higher concentration of potassium ions (K+ ) compared to ECF
    ➢K+ moves out of cell through K+ leakage channels
  • plasma membrane contains many more K+ leakage channels than Na+ so more K+ ions move out of the cell than Na+ moves in.
34
Q

Resting Membrane Potential

A
  • outside of plasma membrane is slightly positive, inside is slightly negative
  • resting potential ranges from –50 mV to –100 mV, depending on cell type
  • average voltage
    -70mV
  • means cytosol is 70mV more negative than ECF
35
Q

Maintenance of Resting Membrane Potential

A
  • to stop the ions from diffusing across the plasma membrane until equilibrium is reached the plasma membrane has the Na+ /K+ ATPase pump:
    ➢pumps out 3 Na+ ions
    ➢pumps in 2 K+ ions
  • active transport: requires ATP
  • this maintains concentration gradient for ions to continue to diffuse through the leakage channels
36
Q

Cell differentiation

A
  • all cells in our body arise from the same fertilised cell
  • all cells have the same DNA and genes
    • So, how can they look and function differently (eg RBC, neuron, liver cell etc)?
  • cell differentiation is the development of specific and distinctive features
    • cells specialise early in gestation
    • cells change from a generalised “all-purpose” state (stem cell) into one suitable for a specific function
37
Q

Formation of tissues

A

Cell differentiation from stem cells forms collection of similar types of specialised cells to form 4 primary tissue types:
- epithelium
- connective tissue
- nervous tissue
- muscle

38
Q

Nervous tissue

A
  • nervous tissue is the main component of the brain, spinal cord and nerves
  • composed of neurons and supporting cells
  • communication
  • nervous tissue transmits electrical signals to regulate and control body functions
39
Q

Muscle tissue

A
  • composed of muscle cells that contain 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, gut, bladder, uterus
40
Q

Epithelial Tissue

A
  • epithelium is a sheet of cells that can *
    • cover the body
    • line internal organs
    • form glands
  • anything that is exposed to the external environment is covered by epithelium so forms boundaries between different environments
41
Q

Connective tissue (CT)

A
  • is the connecting tissue of the body
  • most abundant and widely distributed
    1.CT proper
    2.Cartilage
    3.Bone
    4.Blood
42
Q

Connective Tissue Proper

A
  • broken into 6 subclasses of loose and dense connective tissue (do not need to know the 6 classes)
  • 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 contains adipocytes
  • functions: support, binding, storage and insulation
43
Q

Cartilage

A
  • 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
  • lacks nerve fibers and is avascular
  • functions: support and absorb compression
44
Q

bone

A
  • 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
  • contains blood vessels and nerve fibers
  • functions: support, protection and storage
45
Q

Blood

A
  • 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
46
Q

Skin

A
  • is the largest and heaviest organ
  • surface area ~2 m2 weighs 4-5 kg
  • also called integument which means “covering”
  • is part of the integumentary system which also includes other accessory structures – nails and hair
47
Q

epidermis

A
  • like all epithelium, the epidermis is avascular (it lacks blood vessels)
  • oxygen and nutrients diffuse from blood vessels of the dermis
  • cells of the epidermis are tightly joined together to create continuous sheets of cells that prevent substances moving through spaces between the cells, providing a formidable barrier to microorganisms
  • epidermis is in a dynamic steady state
    • cells are constantly dying and being shed from the surface
    • dead cells are replaced with new cells which originate from stem cells in the deepest epidermal layer
  • constant renewal of cells means that your epidermis is replaced every 25-45 days
  • as cells move from the deepest layer of the epidermis to a more superficial layer, they flatten, and eventually die.
48
Q

Dermis

A
  • consists of connective tissue
    • cells include macrophages and fibroblasts
    • fibroblasts produce collagen & elastic
      fibers: provide strength & flexibility
  • contains
    • blood vessels
    • nerves & sensory receptors
    • glands (from epidermis tissue folding in to
      produce the gland)
    • sweat: produce sweat
    • sebaceous: produce sebum
  • hair follicles
49
Q

Hypodermis

A
  • consists mostly of adipose tissue
  • functions:
    • anchors skin to underlying tissue
    • stores fat
    • shock absorber
    • insulator
50
Q

Functions of the Skin

A

The skin functions in the following ways:
1. Protection
* Physical
* Chemical
* Biological
2. Sensation
3. Metabolic function
4. Excretion
5. Blood reservoir
6. Temperature regulation

51
Q

Functions - Protection

A

Skin protects underlying tissues from damage

Physical/mechanical barriers
* tightly joined epidermal cells, keratin and oily secretions block most water and water- soluble substances leaving or entering the body
* some penetration of skin by lipid-soluble substances: e.g. some drugs

Chemical barrier
* low pH secretions (acid mantle) prevents bacteria from multiplying
* defensins (natural antibiotic) secreted by skin cells to kill bacteria
* melanin protects DNA in underlying cells from UV damage

Biological barriers
* macrophages engulf and dispose of microorganisms that manage to penetrate the epidermis

52
Q

Functions – Sensation

A
  • dense network of nerves
    • control blood flow (vessel diameter)
    • control glandular secretion (e.g. sweat)
    • collects sensory information:
      • pain collected by pain receptors (nociceptors)
      • temperature (thermoreceptors)
      • touch, pressure & vibration (mechanoreceptors)
53
Q

Metabolic function - synthesis of vitamin D precursor

A

Excretion - nitrogenous wastes and salt are excreted in sweat

54
Q

Blood reservoir

A
  • can hold up to 5% of body’s blood volume
  • a dense blood vessel network exists in the dermis
  • the amount of blood flow through these blood vessels can be regulated by the diameter of the vessel
  • e.g. for temperature control
55
Q

Functions - Temperature regulation

A

At elevated temp: dilation of dermal vessels and increased sweat gland activity cool the body.
At low temp: constriction of dermal vessels to minimise heat loss to external environment

Heat input and output are balanced
- monitored by skin thermoreceptors
- information sent to “thermoregulatory centre” in brain which compares current temperature to set point of 37 degrees celcius
- control centre coordinates response via the circulatory system (vasodilation/constriction) and sweat glands (increased sweat) to maintain homeostasis

56
Q

Tissue repair

A

occurs differently in different tissues
➢ depends on the ability of the tissue to divide
➢ nutrition
➢ severity of wound
* minor wounds involve just the epidermis
* major wounds involve both epidermis & dermis
*repair of skin generally involves 2 processes: regeneration and fibrosis

57
Q

Tissue repair: regeneration

A
  • replaces destroyed tissue with the same kind of tissue
  • can be restored to normal if:
    • damage is minor
    • epidermal stem cells present to regenerate lost tissue
58
Q

Tissue repair: fibrosis

A
  • 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
59
Q

3 stages of tissue repair

A

Stage 1. inflammation: includes the formation of a blood clot
Stage 2. organisation or proliferation: includes the formation of granulation tissue
Stage 3. maturation or remodeling: includes regeneration and fibrosis

60
Q

Stage 1. Inflammation

A

Function: prepares the wound for repair, eliminates invading microorganisms and removes debris and dead tissue.

  • damaged cells release inflammatory chemicals that causes inflammation
  • signs of inflammation: redness, pain, heat and swelling
  • blood vessels become more permeable: fluid released into area including:
    ➢ macrophages: engulf debris/invading microorganisms
    ➢ clotting proteins: produce a blood clot to stop blood loss,
    minimise fluid and electrolyte loss, hold wound together and
    prevent any further invasion from microorganisms
  • clot on surface dries and forms a scab
61
Q

Stage 2. Organisation or proliferative stage

A

Function: extracellular matrix synthesis including collagen and restore a blood supply

*blood clot is replaced by granulation tissue
*granulation tissue composed of:
➢capillaries that grow across the wound to restore blood supply, bring
oxygen and nutrients required for healing
➢fibroblasts → produce collagen fibers that bridge the gap
➢macrophages → engulf cell debris, invading microorganisms and blood
clot
* epithelial stem cells multiply and migrate over the granulation tissue

62
Q

Stage 3. Maturation or remodeling

A

Function: complete permanent skin repair

  • collagen laid down in stage 2 is remodeled and contracts to pull wound edges together
  • existing blood vessels are compressed, so the scar is avascular and white in appearance
  • if epithelial stem cells present near the wound site divide and grow under scab and regenerate epithelium → scab falls off and skin reflects preinjury tissue although will still have underlying area of scar tissue
  • if a major wound scar tissue is visible → repair predominantly by fibrosis
  • scar tissue → tough but no elasticity or flexibility, no hair, sweat or oil glands
  • amount of scar depends on the severity of the wound

NUR1112 (24 decks)

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