Week 2 Bioscience Flashcards

Question

Facilitated Diffusion

Answer 1

* 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

Answer 2

* 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

Answer 3

* 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

Answer 4

* 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)

Answer 5

* 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

Answer 6

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

Answer 7

* 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)

Answer 8

* 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)

Answer 9

* 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.

Answer 10

* 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

Answer 11

* 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

Answer 12

* 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

Answer 13

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

Answer 14

* 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

Answer 15

* 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

Answer 16

* 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

Answer 17

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

Answer 18

* 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

Answer 19

* 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

Answer 20

* 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

Answer 21

* 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

Answer 22

* 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

Answer 23

* 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.

Answer 24

* 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

Answer 25

* consists mostly of adipose tissue * functions: * anchors skin to underlying tissue * stores fat * shock absorber * insulator

Answer 26

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

Answer 27

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

Answer 28

* 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)

Answer 29

Excretion - nitrogenous wastes and salt are excreted in sweat

Answer 30

* 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

Answer 31

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

Answer 32

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

Answer 33

* 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

Answer 34

* 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

Answer 35

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

Answer 36

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

Answer 37

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

Answer 38

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

Week 2 Bioscience Flashcards

(62 cards)