- behave like a tiny animals, living in or on a host and feeding from it

- made up of genetic code (DNA or RNA) which is coated by a protein - invades host cells to divide

- cause infection when they over grow, contain nucleus etc - protected by thick cell walls, makes them hard to kill

Module 1.02 Flashcards by Frances Fisher

what are the cell types in the small intenstine and what are their functions?

enterocytes = absorptive
Goblet cells = mucus
Paneth cells = lysozyme
Enteroendocrine cells = CCK
S cells = secrete secretin

How well did you know this?

Not at all

Perfectly

what are peyers patches and where are they found?

mucousa associated lymphoid tissue (MALT)

- most common in distal illeum

How well did you know this?

Not at all

Perfectly

what is the function of brunners glands and where are the found?

mainly duodenum
secrete HCO3-
Neutralise

How well did you know this?

Not at all

Perfectly

what are the adaptations of the small intestine?

plicae circulares -> most numerous in jejenum -> forces chyme to spiral
villi
microvilli

How well did you know this?

Not at all

Perfectly

what are the cells found in the large intestine?

enterocytes - absorption

goblet cells - mucus

How well did you know this?

Not at all

Perfectly

what is the gut flora?

microorganisms, mostly bacteria, present in a normal healthy individual

How well did you know this?

Not at all

Perfectly

what are the effcets of changes in the gut flora?

changes in general health
local trauma
hormonal changes

How well did you know this?

Not at all

Perfectly

what are the benefits of the flora?

production of inhibitory substances
colonisation causes resistance to virulent bascteria
digest nutrient in the bowel
resists other colonisation

How well did you know this?

Not at all

Perfectly

decsribe a parasite

behave like a tiny animals, living in or on a host and feeding from it

How well did you know this?

Not at all

Perfectly

describe a virus

made up of genetic code (DNA or RNA) which is coated by a protein
invades host cells to divide

How well did you know this?

Not at all

Perfectly

describe bacteria

made of a single cell

- live anywhere, only pathogenic bacteria cause disease

How well did you know this?

Not at all

Perfectly

describe fungi

cause infection when they over grow, contain nucleus etc

- protected by thick cell walls, makes them hard to kill

How well did you know this?

Not at all

Perfectly

How can bacteria be classified?

bacteria can be classified as gram positive and gram negative via gram staining

How well did you know this?

Not at all

Perfectly

describe the process of gram staining?

1) primary staining with CV which penetrates the cell wall making the cell purple
2) grams iodine (I) is added and forms CV-I complex
3) alcohol exposes peptidoglycogen layer
- > in gram positive purple stain stays
- > in gram negative CV-I washed away

How well did you know this?

Not at all

Perfectly

characteristics of IgG

enhance phagocytosis of bacteria and viruses
most abundant isotype in blood serum
fixes complement and passes to the fetal circulation

How well did you know this?

Not at all

Perfectly

characteristics of IgA

provides localized protection on mucous membranes
found in secretions such as saliva, tears and mucous
transported across the interior of the cell via transcytosis

How well did you know this?

Not at all

Perfectly

which T-cells produce CD 4 and CD 8

Helper T cells : express CD4

Cytotoxic T cells: express CD 8

How well did you know this?

Not at all

Perfectly

characteristics of IgE

-least abundant isotype in blood serum
provides immunity to parasites such as helminths
-mediates type 1 hypersensitivity reactions
binds to Fc receptors found on the surface of mast cells and basophils

How well did you know this?

Not at all

Perfectly

what are the 4 layers of the gastrointesinal tract from the lumen out?

mucousa
submucousa
muscle
serosa

what are 3 adaptations for absorption in the small intestine?

Plicae circulares - folds in lining, causes chyme to spiral and contact all parts of epithelium lining
Villi - projection of lamina propia (part of mucousa layer)
Microvilli - projections of absorptive cell membranes, forms brush border

what is protein broken down to in the stomach?

protein becomes peptide fragments with pepsin as the enzyme

what digestive enzymes are found in the small intestine to breakdown proteins?

trypsin, chymotrypsin and elastase (cleave specific peptide bonds)
carboxypeptidase (cleaves the carboxyl end of the peptide)

how are proteins digested in brush border, which digestive enzymes are involved?

Aminopeptidases cleaves the terminal amino acid

- Dipeptidase cleaves amino acids

how is starch broken down in the upper GI tract (enzyme and products) ?

enzyme: salivary/ pancreatic enzymes
products: maltose, maltotriose, a-dextrins

what enzymes involved in the digestion of starch are present in the brush border of the small intestine?

- maltase - a-dextrinase - sucrase - lactase

what enzymes are involved in the breakdown of triglycerides and what are the products? (in both stomach and small intestine)

Stomach: - enzyme: lingual/ gastric lipase - products: monoglyceride and 2 fatty acids Small intestine: - enzymes: pancreatic lipase - products: monoglyceride and 2 fatty acids

what enzymes are involved in breakdown of nucleic acids in the small intestine and what are the products?

enzyme: deoxyribonuclease, ribonuclease product: nucleotide

what enzymes are involved in the breakdown of nucleotides in the brushborder of the small intestines and what are the products?

enzyme: nucleosidases/phosphatases products: Pentose, Phosphate, Base

what are the 3 functions of the large intestine?

1) absorption of water and ions 2) storage of faeces 3) maintenance of gut flora - mainly gram negative and anaerobic - most common organism= bacteriodes fragillis

describe the innervation of the musculature of the GI tract

The muscle layers are innervated by intrinsic nerves of the myenteric plexus that receive branches from the submucosal plexus and parasympathetic vagal nerves from the medulla.

describe the electrical and conctractile activity of gastric smooth muscle

- rythmic contractile activity driven by pacemaker cells in the greater curvature of the stomach - this is driven by fluctuations in the membrane potential of muscle known as slow waves (does not depend on input) - if threshold is reached muscle will contract and electrical activity spreads in a circular motion causing a band of contraction

what type of gastric smooth muscle does charge pass through more quickly?

- electrical coupling between smooth muscle cells is faster in the circular than in the longitudinal direction

where are pancreatic enzymes synthesised?

- in the rER of acinar cells

where are the myenteric plexus and the meissener plexus found in layers of GI tract and hoe does this effect its function?

myenteric plexus: inbetween longitudinal and circular layer of muscle and is responsible for gut motility messiner plexus: found in submusocusal layer and is reponsible for absorption and secretion

what are the pacemaker cells of the GI tract?

- ICCs (interstitial cells of Cajal)

how does fluid move between compartments?

- Hydrostatic Pressure - Oncotic pressure - Net fluid movement

how odes hydrostatic pressure and oncotic pressure differ?

- they are two competing forces - hydrotatic pressure pushes water out - oncotic pressure pulls water in

how does oncotic pressure act on capillaries?

- Water moves by osmosis from an area of low oncotic pressure to high oncotic pressure - Interstitial fluid contains less protein than blood – lower oncotic pressure - Water PULLED back into capillaries

How does hydrostatic pressure work on capillaries?

- Water moves from an area of high hydrostatic pressure to low hydrostatic pressure - High blood hydrostatic pressure in capillaries - Low interstitial hydrostatic pressure - Water PUSHED from capillaries to tissues

how can net pressure be calculated?

(HP in caplillary - HP in surround tissue) - ( OP from plasma protein - OP from protein in ISF)

what are 3 assumptions for net pressure to be correct?

1) proteins dont cross the capillary wall 2) Hydrostatic pressure is constant 3) water flows freely across the capillary wall

What is the difference between gram positive and gram negative bacteria?

- gram positive cell walls have a thick peptidoglycan layer and a cell membrane - gram negative have 3 layers: inner and outter membranes and a thinner petidoglycan layer

how can bacteria be identified? (7)

- gram reaction - cell shape - endospore - fastidiousness - key enzymes - serological reactions - DNA sequences

what 3 bacteria are found in the normal flora of the small intestine?

- enterobacteriaceae - enterococci (e.coli) - candida

what 4 bacteria are found in the normal flora of the lower bowel (larger intestine) ?

- bacteriodes - bifidobacteria - clostridium - peptostepdococci

what are the main differences between prokaryotic and eukaryotic cells?

- prokaryotes are smaller - prokaryotes have no nucleus - prokaryotes are unicellular and eukaryotes are multicellular - prokaryotes dont have : ER, golgi apparatus, vacuole - in prokaryotes chlorophyll is scattered in the cytoplasm