Topic 2- Tissue types and movements of molecules across Plasma membrance

Question 1

What is a cell

Answer 1

Cell: basic structural and functional unit of living organisms, smallest unit of life which can replicate independently(200 different types of cells)

Question 2

What is Differentiation

Answer 2

process whereby cells assume their specialised structure and function

Question 3

cytoplasm

Answer 3

Water substance contains electrolytes, organic molecules and organelles

Question 4

Mitochondria

Answer 4

Powerhouse which produces ATP

Question 5

Rough Endoplasmic Reticulum

Answer 5

site of protein production(ribosomes)

Question 6

Smooth endoplasmic reticulum

Answer 6

Synthesis of lipids

Cell detoxification

Question 7

Golgi Apparatus

Answer 7

Modify, concentrate and package proteins and lipids from the ER

Question 8

Lysosomes

Answer 8

Breakdown foreign or damaged material

Membrane surrounds organelle to separate the ‘nasty’ enzymes from the cell

Question 9

Cytoskeleton

Answer 9

Transport of intracellular organelles

Cell motility, division and contractility

Question 10

Plasma Membrane

Answer 10

Semipermeable membrane which defines cell boundaries

Question 11

Nucleus

Answer 11

Central control of all function i.e. DNA, growth, metabolism and reproduction

Question 12

Plasma Membrane characteristics

Answer 12

Defines the cells boundary

Separates the intracellular and extracellular spaces (inside and outside of the cell)

Dynamic structure which alters to facilitate cellular requirements

Question 13

phospholipid

Answer 13

Polar hydrophilic head (water loving)

Derived from glycerol conjugated to nitrogenous compounds

Non polar hydrophobic tail (water fearing)

Two long chain fatty acids

One fatty acid is saturated (straight) which the other is unsaturated (kinked)

Question 14

Bilayer

Answer 14

Spontaneously forms a bilayer with hydrophilic heads faced outwards and hydrophobic tails forced inwards together

Structure is relatively weak and will separate if sufficient force is placed

Question 15

cholesterol

Answer 15

Fills the gaps between unsaturated fatty acid tails

Stabilise and regulate the fluidity of the phospholipid bilayer

Question 16

Proteins

Answer 16

Functional units within the plasma membranes

Integral proteins: incorporated within the membrane goes through both sides of the membrane

Transport channels or carriers

Enzymes

Receptors i.e. detects interactions with hormones

Peripheral proteins: embedded within the inner or outer surface

Cell recognition and cell to cell interactions i.e. glycoproteins

Cytoskeleton anchorage facilitates shape and placement of particular proteins

Question 17

membrane junctions determined by?

Answer 17

Glycoproteins (glue like)

Wavy contours of the membrane (tongue and groove)

Special cell junctions

Question 18

Desmosomes

Answer 18

Disk-shaped junctions that form cells into tissue

Found in areas that can be stretched prevents tearing due to arrangement of protein filaments i.e. found in organs subject to mechanical stress – heart

Due to cross-linkage of proteins which are densely accumulated at the cytoplasmic surface of each cell and in the extracellular space between cells

Question 19

Tight Junctions

Answer 19

The joining of the extracellular surfaces of two adjacent cells

Occurs in a band around the entire circumference of the cell

Blocks extracellular pathway between cells impermeable

Found in epithelial cells in the intestinal tract keeps enzymes and microbes from the blood

Question 20

Gap junction

Answer 20

Protein channels linking the cytosol of adjacent cells

Attached to each other via hollow cylinders connexons

-Composed of transmembrane proteins

Allow small molecules to pass through ions, simple sugars

Found in variety of cell types i.e. cardiac cells and smooth muscle

-Present in electrical excitable tissue where ion passage between cells enables synchronisation of their electrical activity and contraction

Question 21

interstitial fluid

Answer 21

a solution which bathes and surrounds cells

Question 22

interstitial fluid characteristics

Answer 22

main component of extracellular fluid containing hormones, fatty acids, amino acids, vitamins, neurotransmitters, hormones, sugars and wastes

Cells must be able to attain the correct balance of components for appropriate function

Question 23

passive transport

Answer 23

No energy required

Diffusion or osmosis

Down concentration gradients to achieve equilibrium

Question 24

Active transport

Answer 24

Requires energy (ATP)

Low high concentration against the gradient

Requires carrier proteins which combine specifically with the transport substance

-Phosphorylation of the protein facilitates movement

-E.g. hydrogen, sodium, potassium

Question 25

when is bulk transport used

Answer 25

Substances which cannot be moved across the plasma membrane moved by bulk transport

Question 26

Endocytosis

Answer 26

Bulk transport into the cell Cell membrane extends outwards and surrounds particles outside of the cell Forms a vesicle and can be released inside the cytoplasm

Question 27

Exocytosis

Answer 27

Bulk transport out of the cell Particles are transported in a vesicle to the cell membrane Vesicle and cell membrane fuse together releasing the contents

Question 28

what does diffusion depend on?

Answer 28

Diffusion depends on: molecule, size, charge, solubility and kinetic energy of the particles involved

Question 29

Simple Diffusion

Answer 29

Non-polar or lipid molecules diffuse directly through the plasma membrane

Question 30

Channel mediated facilitated diffusion

Answer 30

Transmembrane channels (proteins) facilitate diffusion via water filled channels Selective depending on channel size and charge Leak channels always open allowing movement according to concentration gradients Chemically gated channels chemically/ligand gated channels open when the appropriate chemical binds Voltage gated channels open and close in response to changes in membrane potential Mechanical gated channels open in response to deformation of membrane i.e. via sensory receptors

Question 31

Carrier mediated facilitated diffusion

Answer 31

Transmembrane proteins (carriers) transport certain polar molecules which are too large Alteration in the shape of the channel facilitate movement

Question 32

Factors affecting the rate of diffusion

Answer 32

Size of the chemical substance (smaller = faster) Temperature (hotter = faster) Difference in concentration (larger difference = faster)

Question 33

Osmosis

Answer 33

Passive transport of water from low solute concentration to high solute concentration

Question 34

Osmolarity

Answer 34

the number of solute particles present in a 1L of solution (~300 mOsmol/L in our cells) i.e. 1 M NaCl = 2 Osmol/L solution depends on the dissociation of the solute

Question 35

Tonicity

Answer 35

the ability of a solution to change the shape or tone of cells by altering the cells internal water volume

Question 36

isotonic

Answer 36

solutions which have the same number of molecules, or the same osmolarity as our cells Cells retain normal shape due to no fluid movement

Question 37

Hypertonic

Answer 37

solutions which have a higher number of molecules than those seen in the cell Cells shrink/crenate

Question 38

Hypotonic

Answer 38

he solution is more dilute than those in the cells Cells swell/lyse

Question 39

ATP

Answer 39

Adenosine Triphosphate Glucose, fatty acids and amino acids are sources of energy for ATP synthesis Production: Metabolic pathways -Product of one enzyme reaction becomes the substrate for the next -Inefficient -> Heat is bi-product ATP-ADP cycle (occurs within mitochondria) -When bonds are broken, energy is released -----------ATP -> ADP + Pi + energy -----------Faciliated through ATPase

Question 40

Glycolysis (anaerobic)

Answer 40

The breakdown of 6-carbon glucose into two 3-carbon pyruvic acid units The hydrogens removed join with the hydrogen carrier NAD+ to form NADH Although some energy is needed to start glycolysis, there is an overall net gain of 2 ATP Occurs in the cytoplasm

Question 41

Krebs Cycle

Answer 41

Pyruvate moves into the mitochondria Pyruvic acid Acetyl CoA produces NADH as a by-product 2 Acetyl CoA produced per glucose i.e. 1 Acetyl CoA per pyruvate molecule FADH2 is also produced NAD and FAD are carrier molecules that transport hydrogen atoms and electrons 1 ATP produced per Acetyl CoA

Question 42

Electron Transport Chain

Answer 42

High energy electrons help pump H+ across the inner mitochondrial membrane creating a concentration gradient ATP synthase – site of ATP production H+ flow through, capturing energy Hydrogen combines with oxygen to form water

Question 43

Aerobic respiration

Answer 43

Aerobic: with O2 The presence enables pyruvic acid acetyl CoA

Question 44

Anaerobic

Answer 44

Anaerobic: without O2 Undergoes purely glycolysis Production of NADH ‘clogs’ up glycolysis Pyruvic acid Lactic acid which enables NADH to provide its electrons to it Lactic acid build-up causes pain

Question 45

Paracrine/Autocrine

Answer 45

Local communication: Paracrine: Adjacent or close cells Autocrine: Same cell -Involved in positive feedback loops to perpetuate a response

Question 46

Hormones

Answer 46

Part of the endocrine system: Slow but long lasting Long range chemical messengers The blood carries the messenger to other sites in the body, where they exert their effects on their target cells some distances from their site of release. Only the target cells of a particular hormone have receptors

Question 47

Neurotransmitter

Answer 47

Nervous System: Short range chemical messengers Secreted at synapse Exerts effects dendrites of post-synaptic neuron or neuromuscular junction (muscle cell) Fast-response Short lasting because cleared by reuptake, enzyme degeneration Prevents any unwanted signals Excitatory or inhibitory

Question 48

Control of hormones release

Answer 48

Hormone release results from gland stimulation, however patterns may vary -Spurts -Evenly -Sporadically as needed Controlled by: -Humoral stimuli (chemical changes in blood nutrients, iron levels) -Neural Stimuli (nerve fibres stimulates glands) -Hormonal stimuli (can attach to a gland, which triggers to release another hormone)  

Question 49

compare hormones and neurotransmitters based on duration, speed of response, transport and clearance

Answer 49

duration hormone= prolonged Neurotransmitter=immediate Speed of response Hormone= slow Neurotransmitter=fast Transport Hormone= blood stream Neurotransmitter= across synapse Clearance Hormones= Enzyme degradation Neurotransmitter= Reuptake/diffusion

Question 50

Epithelial tissue

Answer 50

A sheet of cells that covers a body surface or lines a body cavity – form body boundaries Function: protection, absorption, filtration, excretion, secretion – defends on structure Forms in the body;

Question 51

Covering and lining epithelium

Answer 51

Covering and lining epithelium: forms the outer layer of the skin, dips into and lines the open cavities of the urogenital, digestive and respirator systems and covers the walls and organs of closed ventral body cavity

Question 52

Granular epithelium

Answer 52

Glandular epithelium: surrounds the glands of the body

Question 53

Main characteristics of epithelium tissue

Answer 53

polarity, specialised contacts, supported by connective tissue, Avascular and innervated, regeneration, simple or stratified

Question 54

Polarity

Answer 54

Polarity: all epithelia have an apical (top) surface and a lower attached basal (bottom) surface that differ in structure and function Apical sections often have microvilli (small extensions which increase SA) or motile cilia (slender protuberances that beat in waves)

Question 55

Specialised contacts

Answer 55

Specialised contacts: epithelial cells fit close together and form continuous sheets tight junctions and desmosomes

Question 56

Support by connective tissue

Answer 56

Supported by connective tissue: reinforces the epithelium and helps resist tearing and stretching

Question 57

Avascular and innervated

Answer 57

Avascular and innervated: no blood tissues but supplied by nerve fibres Nourished by diffusion of nutrients from blood vessels in underlying connective tissue

Question 58

Regeneration

Answer 58

Regeneration: regenerative capacity given adequate nutrition Classification of Epithelia: (number of cell layers) (cell shape)

Question 59

simple or stratified

Answer 59

Simple or stratified (2 or more layers): simple for absorption and filtration and stratified for durability and protection

Question 60

Connective tissue

Answer 60

Tissue that connects, supports, binds or separates other tissues or organs Highly vascular with exception of cartilage

Question 61

What are the three main components of connective tissue?

Answer 61

Ground substances(clear, colourless, viscous fluid that fills the space between the cell and fibres Fibres Cells --Ground substances+fibres= extracellular matrix --composition of each component differs in different tissues resulting in versatility

Question 62

What are the three types of fibres

Answer 62

collagen. elastic and reticular

Question 63

Collagen

Answer 63

Collagen: fibrous protein – extremely tough and provides high tensile strength Cross link and bundle together into thick fibres

Question 64

Elastic

Answer 64

Elastic: long thin fibres (elastin) which form branching networks which allow stretching and recoil

Question 65

Reticular

Answer 65

Reticular: short, fine collagenous fibres which branch extensively to form a delicate network Important around other tissue types – form fuzzy nets which allow more ‘give’ than collagen

Question 66

Specific cell types

Answer 66

-blast, -cyte fat cells -blast immature, non-differentiated cells Actively proliferating and secrete the ground substance and the fibres characteristic of their particular matrix -cyte mature Maintain the health of the matrix Can revert to their active/immature state to repair and regenerate the matrix Fat cells: store nutrients

Question 67

Muscle Tissue

Answer 67

Make ~50% of body mass Cardiac muscle: contracts the heart to pump blood Skeletal muscle: moves bones and other structures Smooth muscle: changes shape to facilitate bodily functions Characteristics

Question 68

Nervous Tissue

Answer 68

Nervous tissue is found in the central and peripheral nervous systems The brain, spinal cord and nerves Regulates and controls body function Well vascularised (supplied by blood vessels)

Question 69

Simple squamous