Nutrition Flashcards

Question

Vitamin E

Answer 1

Antioxidant - protects cell membranes Regulates activity of some enzymes. Neurological functions/wound healing Stored in liver, excreted in bile

Answer 2

Important in blood clotting Made by gut microflora Newborn babies given vitamin k injection. Vitamin K regulates the formation of several blood clotting factors (factors VII, IX, X and XII).

Answer 3

Form co-enzymes - involved with normal metabolic function – mostly involved in breakdown of macronutrients There are 8 B vitamins and choline which make up the B complex of vitamins. They are used to form co-enzymes which are involved with normal metabolic function – energy metabolism and synthetic pathways and they are water soluble. B9, or folic acid is involved in the production of red blood cells, metabolism of amino and nucleic acids and cell division and the correct development of the neural tube. It is particularly important in pregnant women and infants, with deficits increasing the risk of spina bifida, a condition where the spine does not form correctly during gestation.

Answer 4

Ruminants – produced by bacteria in rumen e.g., cows, sheep Cecal digesters – fermentation in caecum, coprophagy e.g., rabbits, mice Colonic digesters – may not absorb enough from colon, some ingestion of soil, e.g., elephant, horse

Answer 5

Important in wound healing, blood vessel/cartilage maintenance Antioxidant activity High levels in immune cells Produced by most animals except bats, guinea pigs, capybaras, many monkeys and apes (including humans) Vitamin C is a co factor in at least 8 enzymatic reactions, including those involved in the synthesis of collagen, an important structural protein, used in wound healing and maintenance of blood vessels and cartilage. It is required to synthesise carnitine, which transports fatty acids into mitochondria to generate energy and it is used in the synthesis of neurotransmitters. It is used in the synthesis and breakdown of tyrosine. It has antioxidant activity, so it is protective against oxidative damage and it is found in high levels in immune cells. Its precise function is unknown but it does deplete during infections and it is thought to be involved in the activity of phagocytes and lymphocytes.

Answer 6

CalciumChlorideMagnesiumPhosphorousPotassium Sodium

Answer 7

Those found in the body in large quantities - over 5 g

Answer 8

Arsenic Chromium Cobalt Copper Fluoride Iodine Iron Manganese Nickel Selenium Silicon Vanadium Zinc

Answer 9

Most abundant mineral in the body. Important for bones, teeth, muscle contraction Secretion of hormones, digestive enzymes and neurotransmitters 99% Ca stored in skeletal tissues

Answer 10

Second most abundant mineral. 85% Ph stored in bones and teeth - maintains structure with Ca. Important for DNA/RNA, energy transfer during metabolism (ATP), phospholipids Ca:Ph ratio 1:1 to 2:1

Answer 11

the physiological response to a lack of nutrients in the stomach/bloodstream

Answer 12

Pleasure associated with foods – rewarding, makes animal want to keep eating

Answer 13

Food reward modulated by palatability Consume sweet/salty foods past repletion, avoid sour/bitter foods even when food deprived. Flavours are indicative of nutritional value. Modified by post-ingestion cues – e.g. lithium chloride

Answer 14

Outbreak - Mormon crickets band together, start marching. Marching bands – 10km long, can travel 2km per day. Do not strip landscape – searching for particular foods? Flowers, seed heads, the leaves of legumes, carrion, animal faeces, urine-soaked soil and each other. Seeking salt and protein?

Answer 15

Filter feeding Deposit feeding Fluid feeding Bulk feeding

Answer 16

obtaining nutrients from particles suspended in water Typically pass water over a specialized filtering structure. E.g. Whale shark, flamingo, lots of aquatic invertebrates

Answer 17

Feed by obtaining nutrients from particles suspended in soil. E.g. earthworm, sea cucumbers, fiddler crabs, sand dollars (echinoderms).

Answer 18

Obtaining nutrients by consuming other organisms' fluids. Plant sap - Aphids, shield bugs, Nectar – butterflies, bees Blood - mosquitoes, assassin bugs, ticks, mites, fleas, leeches, vampire bats Blood feeding especially important for transmission of diseases in animals.

Answer 19

Obtaining nutrients by eating some or all of an organism. Most vertebrates, many invertebrates. Includes herbivores, omnivores, carnivores.

Answer 20

The obvious one is some structure that can filter particles from the water. In baleen whales they either swim open mouthed and continuously filter, or they lunge at a concentration of krill gulp a large mouthful of water then squeeze the water out through their baleen. These are long hairlike structures that hang from the upper jaw and capture krill, which are small crustaceans. Barnacles are small crustaceans that as adults become affixed to a surface and filter feed. They cement themselves to a surface by their heads and the feathery structures that you see poking out of the shell are their feet. These filter tiny plankton from the water and pass them to the mouth, and from there into the stomach. Sea squirts are tunicates. Sea squirts feed by taking in water through the oral or incurrent siphon, which is equivalent to a mouth. The water enters the mouth and pharynx, flows through mucus-covered gill slits (also called pharyngeal stigmata) into a water chamber called the atrium, then exits through the atrial siphon. Tentacles at the opening to the pharynx and cilia inside the pharynx trap particles which are passed to the stomach.

Answer 21

The gut of the earthworm is a straight tube which extends from the worm's mouth to its anus. It is differentiated into a buccal cavity (generally running through the first one or two segments of the earthworm), pharynx (running generally about four segments in length), oesophagus, crop, gizzard (usually) and intestine. Food enters the mouth. The pharynx acts as a suction pump; its muscular walls draw in food. In the pharynx, the pharyngeal glands secrete mucus. Food moves into the oesophagus, where calcium (from the blood and ingested from previous meals) is pumped in to maintain proper blood calcium levels in the blood and food pH. From there the food passes into the crop and gizzard. In the gizzard, strong muscular contractions grind the food with the help of mineral particles ingested along with the food. Once through the gizzard, food continues through the intestine for digestion. Benthic sea cucumbers (not all spp), just like earthworms, use feeding tentacles to push sediment towards the mouth. This is then passed through the intestine where nutrients are absorbed and filtered sediments are excreted through the anus.

Answer 22

First of all a comparison of two insect fluid feeders. They are both flies, in the order diptera, both feed on blood but the modes of feeding and the adaptation of the mouthparts are quite different. First, mosquitoes, which have delicate syringe-like mouthparts. Here the labium is like a sword sheath housing the other mouth parts which together form a hollow needle. The mosquito inserts this needle into the skin and searches around for a capillary, then sucks up the blood. The horsefly in comparison, uses its mandibles and maxillae to cut into the skin, they then use their labium as a sponge to lap up the blood that wells out. This is a much coarser way to access the blood. This is why a mosquito can bite you without you having any idea it has happened, but a horsefly bite really hurts!

Answer 23

Birds tend to be bulk feeders with some exceptions, for example flamingos are considered to be filter feeders. Birds do not have teeth so they use their beaks and tongues to pick up and manipulate food. In some cases the beak can also break up food. For example, many predatory birds have sharp beaks that can tear flesh into small pieces. Finches that feed on seeds tend to have large, heavy beaks that can crush the seeds before they are swallowed. Other birds swallow food whole, for example, most fish-eating birds and pecking birds, like chickens. In many birds mastication is carried out after swallowing in the gizzard, which is a muscular stomach that can grind food, sometimes with the aid of grit or stones that birds swallow.

Answer 24

Most reptiles are carnivorous but despite having teeth tend not to use them to masticate food but rely on their digestive juices to break down food. Crocodiles and alligators swallow stones and these may aid in the breakdown of food in the stomach, which is muscular and acts as a gizzard. Some reptiles will use their teeth much as mammalian carnivores, to tear off chunks of food that are small enough to be digested. Some reptiles are herbivorous, such as iguanas, and much like herbivorous mammals use their tongue to manipulate and teeth to break off small pieces of plant matter which are then digested in the stomach with the aid of microbes. All snakes are carnivorous. They use their teeth, modified into fangs to deliver venom, which also contains digestive enzymes, helping to start the process of digestion before ingestion. They do not chew, instead they swallow their prey whole. Muscular contractions and strong digestive juices help to break down the food.

Answer 25

The anteater's tongue is covered with thousands of tiny hooks called filiform papillae which are used to hold the insects together with large amounts of saliva. We have these papillae too, they are the rougher bumps on our tongues at the front and down the centre that don’t contain taste buds. Their function in humans isn’t so obvious but they might aid in creating the bolus of food and manipulating it around the mouth. After manipulating the insects into a ball, swallowing and the movement of the tongue are aided by side-to-side movements of the jaws. The anteater's stomach, similar to a bird's gizzard, has hardened folds and uses strong contractions to grind the insects; a digestive process assisted by small amounts of ingested sand and dirt. The tongue is attached to the sternum and moves very quickly, flicking 150 times per minute. The duck billed platypus is a carnivore that has no teeth and has an extended upper and lower jaw. The bill is in fact a sensory organ that has mechano- and electroreceptors. When diving in silty water the platypus closes its eyes, nostrils and ears and so hunts entirely via sensing movement and tiny changes in the electrical field around its bill caused by worms and crustaceans in the water or riverbed. It carries prey in its cheek pouches and takes them to the surface where they are eaten. In place of teeth there are hard ridges on the jaw that are used to masticate the prey before swallowing.

Answer 26

Lips, teeth and tongue grasp and manipulate food. Pigs use snout to root in ground and pointed lower lip to convey feed into mouth. Teeth tear/masticate food Tongue tastes food Saliva – moistens and softens food, initiates digestion.

Answer 27

cutting teeth, implanted in front of incisive bones of maxilla and anterior part of mandible.

Answer 28

used to hold food for tearing, situated behind the incisors.

Answer 29

mainly for chewing. Broad irregular grinding surfaces

Answer 30

shearing meat, last upper premolar in maxilla, very large, 3 roots – found in carnivores only

Answer 31

Teeth grow throughout life Continuous wear E.g., Rabbits, horses, rodents.

Answer 32

Some spp – saliva contains alpha - amylase Amylase breaks down starch into maltose Maltose – disaccharide of glucose. Amylase - inhibited by stomach pH.

Answer 33

Protects lining Produced in all parts

Answer 34

Hormone - stimulates gastric gland to secrete pepsinogen and HCl

Answer 35

Acted upon by HCl to produce pepsin

Answer 36

Low pH needed for pepsin. Softens food, kills microbes (and bacteria from rumen).

Answer 37

Coagulates milk to < rate of passage (activated by HCl) Found in young mammals

Answer 38

Majority of digestion and absorption Surface area increased by villi Enzymes break down nutrient molecules into building blocks: Protein >> Amino Acids Carbs >> Simple Sugars Fats >> Fatty Acids Nucleic Acid >> Nucleotide

Answer 39

Hormones triggers secretion of bile from liver and bicarbonate and enzymes from pancreas

Answer 40

Common bile duct from liver carries bile salts – emulsifies fat, activates lipases (Inverts form fatty acid-amino acid and glycolipid complexes).

Answer 41

Trypsin, chymotrypsin, procarboxypeptidases, pancreatic amylase, pancreatic lipase, bicarbonates

Answer 42

Trypsin, chymotrypsin, carboxypeptidases, amylase, lipase, bicarbonates, disaccharidases, peptidases, nucleotidases, lysozymes, chitinases*, gluconases* Vertebrates also have bicarbonate and disaccharides

Answer 43

Herbivores 4 parts to stomach Cattle, goats, sheep

Answer 44

Herbivores 1 part to stomach Camels, llamas, whales

Answer 45

Herbivores 1 part to stomach Rabbits, guinea pigs, chinchillas

Answer 46

Omnivores/ carnivores 1 part to stomach Ferrets, cats, dogs, pigs, primates, humans

Answer 47

Ruminants Non-ruminants Caecal Colonic

Answer 48

each villus has a vein and artery for collection and transport of digested nutrients, and a lacteal, which is a lymph capillary for the collection of fats. Each villus is coated with an epithelial layer of cells covered in microvilli, which are called enterocytes. The layer of microvilli that cover the villus are referred to as the “brush border” .

Answer 49

a tubular epithelial organ composed of a monolayer of cells surrounded by muscles. The gut is divided into the foregut, the midgut, and the hindgut, based on the developmental origin. The crop stores the food ingested by the flies, and the first half of the cardia belongs to the foregut. The Malpighian tubules, a functional equivalent of the mammalian kidney, connect at the midgut-hindgut junction. The midgut is the main site of digestion, and most studies of Drosophila gut immunity have focused on this compartment. (B) A cross section of the adult Drosophila midgut. The adult midgut contains several types of cells: absorptive enterocytes (ECs), secretory enteroendocrine cells (EEs), and pluripotent intestinal stem cells (ISCs). Muscle cells are present under the basement membrane of epithelial cells. Between the lumen and epithelia, a semipermeable non-cellular structure, the peritrophic matrix, protects the enterocytes from abrasive particles and pathogens. In addition, a mucus layer lies between the peritrophic matrix and ECs along the midgut

Answer 50

allows a longer transit time, increasing time and surface area for absorption of nutrients from harder to digest plant material.

Answer 51

Micelles -> fatty acids and monoglycerides Diffuse across cell membrane of enterocyte Recombined into fat (TAG) in the ER Packaged into lipoproteins (+cholesterols and vitamins) – Chylomicrons- released by exocytosis Too large for capillaries – enter lymph via lacteals –transported to blood. Chylomicrons then flow into the circulation via lymphatic vessels, which drain into the general circulation at the large veins in the chest. When large numbers of chylomicrons are being absorbed, the lymph draining from the small intestine appears milky and the lymphatics are easy to see. That lymph passes through mesenteric lymph nodes (LN) and then into larger lymphatics.

Answer 52

Hydrophilic - can’t diffuse across lipid cell membrane. Monosaccharides carried across membrane into enterocyte via specific transporters. Transported across basal membrane into blood via diffusion gradient. moves across the basal cell membrane through a glucose uniporter (GluT2) via the diffusion gradient and from there into blood where it is carried around the body, either to be used in cells and the brain as required or stored in the liver as glycogen. Fructose is transported in exactly the same way but using a different transporter.

Answer 53

The lumenal plasma membrane of the absorptive cell bears at least four sodium-dependent amino acid transporters - one each for acidic, basic, neutral and amino acids. These transporters bind amino acids only after binding sodium. The fully loaded transporter then undergoes a conformational change that dumps sodium and the amino acid into the cytoplasm, followed by its reorientation back to the original form. Thus, absorption of amino acids is also absolutely dependent on the electrochemical gradient of sodium across the epithelium. Further, absorption of amino acids, like that of monosaccharides, contributes to generating the osmotic gradient that drives water absorption. The basolateral membrane of the enterocyte contains additional transporters which export amino acids from the cell into blood. These are not dependent on sodium gradients. There is virtually no absorption of peptides longer than four amino acids. However, there is abundant absorption of di- and tripeptides in the small intestine. These small peptides are absorbed into the small intestinal epithelial cell by cotransport with H+ ions via a transporter called PepT1. Once inside the enterocyte, the vast bulk of absorbed di- and tripeptides are digested into amino acids by cytoplasmic peptidases and exported from the cell into blood. Only a very small number of these small peptides enter blood intact. In the first place, very few proteins get through the gauntlet of soluble and membrane-bound proteases intact. Second, "normal" enterocytes do not have transporters to carry proteins across the plasma membrane and they certainly cannot permeate tight junctions.

Answer 54

The simplest means to assess the nutritional composition of foods is to detect different nutrients by tasting them. Not surprisingly, therefore, all organisms, from bacteria to mammals, possess specialized receptors for the detection of key nutrients such as amino acids, sugars, and salts. Animals bear these receptors in several places: on external appendages, such as the tarsi (feet) and mouthpart palps of insects and the long finger-like barbels of some fish; within the oral cavity (mouth), such as on the tongue of vertebrates; and lining parts of the alimentary canal (the gut). Together, these receptors provide the central nervous system with information about the nutritional composition of food before, during, and after ingestion (Dethier 1976; Finger 1997; Yarmolinsky et al. 2009). Typically these taste receptors provide an increasingly strong signal as the concentration of the stimulating nutrient in the food increases, up to a point where excessively high concentrations may cause reduced responses.

Answer 55

Balance of phagostimulatory and phagodeterrent inputs detected by CNS. Positive – receptors responding to nutrients Negative – receptors stimulated by potentially toxic compounds eg bitter Net – phagostimulatory power of food.

Answer 56

Optimum – 2% salt Caterpillar should choose B (2%) Works if B has highest phago-stimulatory power – i.e., tastes best. Optimum – 2% salt Caterpillar should choose 50% A and 50% C Works if A and C have equal phago-stimulatory power – i.e. taste equally acceptable. Optimum – 2% salt Caterpillar should choose 75% A and 25%D Works if A has 3X phago-stimulatory power of D.

Answer 57

Eat predominantly from optimal food Distribute feeding amongst 2 or more complementary foods to mix optimal diet. If restricted to suboptimal/non complementary diets – eat most of food (or mix of foods) closest to optimal.

Answer 58

When protein deprived and sugar replete, levels of AAs in blood fall and sugar rises. Causes GNs to become more sensitive to AAs and less sensitive to sugar. Insect becomes highly responsive to AAs and ignores sugary foods – nutrient specific feedbacks have changed PS power of foods.

Answer 59

All cells can assess nutritional/energy status. Coordination at level of animal carried out by brain in conjunction with liver, gut and pancreas (verts) and fat body (inverts) Conc of AAs, glucose, fatty acids, mineral ions in blood provides instant measure of nutritional state. Reflect net result of nutrients arriving from gut and those removed to meet energy/growth needs of tissues.

Answer 60

Info from blood could be inaccurate during nutrient deprivation. Body fat, liver glycogen and protein from muscles released into blood during deprivation. Could lead to overestimate of nutritional state Need second measure – size or rate of reduction of reserves. Chemical signals released from tissues – e.g. leptin or adiponectin released by fatty tissue, and insulin and glucagon, released from pancreas to signal C status. FGF21 (fibroblast growth factor)released by muscle for P status (low P:C)

Answer 61

At cellular level – 2 main protein kinase pathways that sense nutrients – AMPk and TOR AMPk responds to decline in glucose, AAs, fatty acids, and increasing AMP:ATP ratio (low energy). Triggers catabolic processes, release of stored nutrients, inhibition of growth and reproduction. TOR Stimulated by high ATP and nutrients, particularly BCAAs (e.g. Leucine), and the glucose:AA Triggers anabolic processes stimulating growth and reproduction.

Answer 62

Stimulated by high ATP and nutrients, particularly BCAAs (e.g. Leucine), and the glucose:AA Triggers anabolic processes stimulating growth and reproduction.

Answer 63

responds to decline in glucose, AAs, fatty acids, and increasing AMP:ATP ratio (low energy). Triggers catabolic processes, release of stored nutrients, inhibition of growth and reproduction.

Answer 64

Taste receptors on the tongue are stimulated by food in the mouth and activate neurons that send their inputs to the hindbrain. Also projecting to the hindbrain are stretch receptor inputs from the upper gastrointestinal tract (GI), nutrient receptor inputs from the GI and liver (carried via the vagus nerve), and neural signals coming from the forebrain. Another source of signals associated with food in the gut is a suite of hormones that are released from the GI and act variously on gut motility, digestive enzyme secretion, the vagus nerve, and directly on the brain.

Answer 65

Low blood conc of AAs, glucose, fatty acids, high AMP:ATP Secretion of ghrelin by gut Activation of NPY/AgRP neurons in hypothalamus -mediated by AMPk Release of NPY/AgRP proteins Stimulate feeding

Answer 66

High blood conc of AAs, glucose, fatty acids, low AMP:ATP Stretch receptors in gut send “full” messages to brain Low levels of ghrelin, secretion of CCK, PYY, GLP-1 by gut, leptin (fat), insulin (pancreas) Inhibition of NPY/AgRP neurons in hypothalamus Stimulation of POMC/CART neurons in hypothalamus -mediated by TOR Release of a-melanocyte stimulating hormone, inhibits feeding.- binds to melanocortin-4 receptors

Answer 67

Learned aversions and positive learning associations Learning – associate food properties with nutrition e.g. colour, shape, smell, taste – positive and negative. Rats given saccharin during gamma irradiation learned to avoid it. Typically - short delay between stimulus and outcome is most effective e.g. Pavlov’s dog Food aversion – delay can be several hours – evolutionarily conserved response to dangerous toxins.

Answer 68

Compensate for a previously imbalanced diet by choosing alternate prey

Answer 69

Compensate for a previously imbalanced diet by restricting consumption of ‘wrong’ prey I.e. the one that contained an overabundance of the nutrient that they didn’t need. They could afford to do this because they have the option of moving location and perhaps catching prey that have a different body composition, depending on what is abundant in that area.

Answer 70

Compensate for a previously imbalanced diet by differentially extracting nutrients from single prey

Answer 71

Changing efficiency of digestion and absorption from gut. -Adjust digestive enzyme secretion -Vary rate of passage -Change shape and size of gut. Differential utilisation of absorbed nutrients.

Answer 72

Prevailing view: Gut – function is to maximise digestion and absorption of contents Enzymes stimulated by presence of nutrients Abundance of transporters correlated to nutrients in diet Gut efficiently extract available nutrients – what to do with them occurs post-absorption IS THIS TRUE? Nutrients at correct ratio for animal’s requirements (balanced P:C for locusts) - intake target can be met by eating more or less. Compensatory feeding can’t correct dietary imbalance – every extra mouthful gives more unbalanced food! If complementary food not available, postingestive processing can help to correct imbalance and bring animal closer to its intake target.

Answer 73

Faster transit can reduce rate of nutrients absorbed from gut. Also change balance of nutrients absorbed? If AB in blood. If intake target is A>B then flushing gut after t would match intake target. Achieved by eating again, new food pushes out old food, or by gut nutrient sensors changing gut motility.

Answer 74

This has been shown in rats during lactation, which is a time of high nutritional demand. The short intestine did not change during pregnancy, but during lactation it increased in length and mass, regressing after weaning. Perhaps the most extreme example comes from pythons (Secor and Diamond 2000). These sit-and-wait predators feed only infrequently, on prey that can be larger than themselves. After each meal the small intestine of the python doubles in mass, and nutrient transport rates increase up to 20-fold. Once digestion is complete, the gut atrophies and returns to its smaller, less expensive-to-maintain state. Remodelling found in other animals, e.g., grasshoppers, mammals E.g., gut grows larger with high fibre diet Regulatory response, allow larger meal sizes to compensate for low energy density of meal.

Answer 75

After entering circulation, nutrient imbalance can be partially rectified by differential utilisation of absorbed nutrients. Under-consumed nutrients – conserve, don’t waste Over-consumed nutrients – elimination of excess Eg nitrogen excretion

Answer 76

High protein intake, breakdown of excess AAs, nitrogen excretion increases. When on high P:C diet, locusts overeat protein to gain limiting carbs. Elevated AAs in blood inhibit feeding Selective excretion of Lysine – most potent of AA mix. Allows “unjamming” of feeding control mechanism.

Answer 77

Rodents on high fat diet - leptin resistant, allows overeating of fat to gain limiting protein. Excess carbs/fats generally converted to body fat and stored. Excesses can be excreted in urine as glucose, signal of diabetes. Can also be burned off – facultative diet-induced thermiogenesis (fDIT)

Answer 78

fDIT – occurs in bacteria, plants, inverts, mammals. Mammals – brown adipose tissue, site of fDIT Futile substrate cycles, mitochondrial uncoupling proteins, allow “burning off” of excess nutrients without creating ATP – produces heat. Allows ingestion of excess fat/carb to gain limiting protein – enriches nutrient poor diets. common in animals eating low-protein diets relative to requirements Highly developed in nectar and fruit eaters e.g. fruit bats, marmosets Need to be able to dissipate heat produced, not effective in animals with small surface area:volume.

Answer 79

Environment Mismatch between current and evolved environment Food availability, nutritional density e.g., Kosrae, Micronesia Genetics Some genotypes more prone to obesity

Answer 80

strongly defend protein intake, allowing C&F intake to fluctuate as necessary to accommodate it

Answer 81

High blood conc of AAs, glucose, fatty acids, low AMP:ATP Stretch receptors in gut send “full” messages to brain Low levels of ghrelin, secretion of CCK, PYY, GLP-1 by gut, leptin (fat), insulin (pancreas) Inhibition of NPY/AgRP neurons in hypothalamus Stimulation of POMC/CART neurons in hypothalamus -mediated by TOR Release of a-melanocyte stimulating hormone, inhibits feeding.- detected by MCr4 receptor

Answer 82

MC4R AGRP POMC

Answer 83

Frameshift mutation Disrupts satiation signalling outcome of this mutation in the dogs was that the red section produced inactive proteins, particularly beta melanocyte stimulating hormone and beta endorphin.