modern bio ii nutrition
TRANSCRIPT
Autotrophic species – self feeders, photosynthetic organisms or producers.
Organisms are differentiated into two types:
1. Chlorophyll bearing – with green pigment.
2. Non chlorophyll bearing – absence of chlorophyll.
Autotrophs Plants Some Protists Some Bacteria Nearly all Archaea
• Heterotrophs– Animals– Fungi– Most Protists– Most Bacteria
• Heterotroph1. Saprophytes – mushrooms, bread molds and
decay bacteria.
2. Parasites – depend on other organisms for survival.
Why do we see green? Green color from white
light reflected NOT absorbed
Chloroplast: organelle responsible for photosynthesis
Chlorophyll: located within Chloroplast
Green pigment
Photosynthesis – physico-chemical process by which plants use the energy from sunlight to produce sugar which cellular respiration converts into ATP.
In plants and simple animals, waste products are removed by diffusion. Plants, for example, excrete O2, a product of photosynthesis.
2 Phases Light reaction Dark reaction
Light reaction: converts light energy into chemical energy; produces ATP molecules to be used to fuel light-independent reaction
Dark reaction: uses ATP produced to make simple sugars.
LIGHT Reaction Requires light Occurs in chloroplast (in thylakoids) Chlorophyll (thylakoid) traps energy from
light Light excites electron (e-)
Kicks e- out of chlorophyll to an electron transport chain
Electron transport chain: series of proteins in thylakoid membrane
Bucket brigade
LIGHT Reaction Energy lost along electron transport chain Lost energy used to recharge ATP from ADP
NADPH produced from e- transport chain Stores energy until transfer to stroma Plays important role in light-independent
reaction
Total byproducts: ATP, NADP, O2
LIGHT Reaction2 types:1. Photolysis/Hill reaction – compound is
broken down by light.2. Photophosphorylation – creating ATP
by using a Proton gradient created by the Energy gathered by sunlight.
Dark Reaction Does not require light Calvin Cycle
Occurs in stroma of chloroplast Requires CO2
Uses ATP and NADPH as fuel to run Makes glucose sugar from CO2 and Hydrogen
Soil is composed of minerals, organic matter, water, air, and organisms
Soil is full of microorganisms that break down and recycle organic debris
Most roots of plants are found within the topsoil Topsoil – a mixture of minerals, living
organisms and humus (partly decayed organic matter)
Only minerals that are dissolved in water are available for uptake by roots
Approximately one half of the soil volume is occupied by spaces known as pores, which may be filled with air or water
Water held in small pores is readily available to plants
Plants require 9 macronutrients and 7 micronutrients Macronutrients – used by plant in large
quantities Micronutrients – used by plant in trace
amounts Carbon, oxygen, hydrogen, nitrogen
(essential for amino acids), potassium, calcium, magnesium (the center of the chlorophyll molecule), phosphorus, and sulfur
Carnivorous plants have modified leaves adapted for luring and trapping prey
Prey is digested with enzymes secreted from specialized glands
Pitcher plants (common in northeast bogs) – have pitcher-shaped leaves with cavity filled with digestive fluid
Venus flytrap – (grows in bogs in North and South Carolina) – has 3 sensitive hairs on each side of leaf that, when touched, trigger the two halves of the leaf to snap together Once the prey is enfolded within a leaf,
secreted enzymes from leaf surfaces digest the prey
Sundews – secrete sticky mucilage, which traps small animals, and digestive enzymes
Epiphytes – an organism that grows upon, or attaches to a living plant
Most commonly refers to higher plants, but can also include bacteria, fungi, lichens, mosses, and ferns
“Air plants” – do not root in the soil Obtain moisture from the air or from
dampness (rain and cloud moisture) on the surface of their hosts
http://www.flickr.com/photos/pierre_pouliquin/74397619/
The human digestive system is a marvel of nutritional storage and acquisition!
Process of nutrition1.Ingestion – process of taking food into the body.2.Digestion – process of converting complex food into simple forms.Mechanical and Chemical Digestion3. Absorption – nutrients are taken into the cells.
4. Assimilation – utilizing nutrients for various functions.5. Egestion – process of excreting unusable or undigested material from cell or digestive tract.
Animals are classified on how they obtain food:Herbivores are animals that eat plants exclusivelyCarnivores are animals that eat other animalsOmnivores are animals that eat both plants and other animals
Animals are classified on how they obtain food:Scavengers are animals that eat dead animals.Insectivores are animals that feed on insects.
Types of digestion1.Intracellular 2.Extracellular
- Series of tubelike organs that convert food into energy and convert waste into excretable materials.
Ingested food may be stored or first subjected to physical fragmentation
Chemical digestion occurs next, which breaks the food down into subunit molecules
Food particles then pass through the gut’s epithelial lining into the blood (absorption)
Wastes are excreted from the anus
Digestive Tract – tubular passage of mucous membrane and muscle extending about 8.3 meters from mouth to anus.
Mouth, pharynx, esophagus, stomach, small and large intestines and anus.
MouthAccessory Organs1. Teeth – hard bonelike
structures in the jaws.1.1 Temporary teeth –
primary teeth (20)1.2 Permanent teeth –
(32) after the age of 6.
MouthIncisors – front four teeth. Canines – longest and
most stable teeth.Premolars – transitional
teeth between canine and molar.
Molar – large and flat surface.
Tongue – fleshy, movable, muscular organ attached to the floor of the mouth.
Papillae – raised protrusions where majority of the taste buds are located.
4 types of papillae:1.Fungiform – slightly mushroom shaped located at the apex.2.Filiform – thin, long V-shaped cones without taste buds.3.Foliate – ridges and grooves at posterior part of tongue.4.Circumvallate – 3-14 in number present at the back of the oral part of the tongue.
Pharynx – passageway for air and food.3 parts:1.Nasopharynx – nasal cavities 2.Oropharynx – palatine tonsils3.Laryngopharynx – esophagus
EsophagusStraight muscular tube connecting the oral cavity to the stomach.4 basic layers:1.Mucosa – mucous2.Submucosa – mucous secreting gland (papillae)3.Muscularis – upper part4.Adventitia – outermost layer.
StomachMuscular J – shaped organ that lies between esophagus and small intestine.Sphincter – located between esophagus and stomach.Pyloric valve – between stomach and small intestine.
Secretes:Gastric juices and
gastrin (hormone)3 general areas:1. Fundus – upper
portion2. Body – middle3. Antrum – pyloric
sphincter.
Small IntestineLongest portion (22-25ft)Digestion and nutrient absorption is completed.
3 parts:1. Duodenum –
receives partly digested food, bile and other enzymes.
2. Jejunum – mid section
3. Ileum – final portion
Large IntestineExpanded tube which serves as temporary storage of waste product.
Accessory digestive organs Liver – largest organ in body; produces bile
which emulsifies fat Gallbladder – stores and concentrates the
bile Pancreas – produces pancreatic juice which
contains digestive enzymes Bile and pancreatic juice are secreted into
the small intestine
Liver – chemically modifies substances absorbed from the digestive tract before they reach the rest of the body Removes toxins and carcinogens,
converting them to less toxic forms Regulates levels of steroid hormones
(makes them more water soluble) Produces most proteins found in blood
plasma
Digestive Glands – produce secretion needed for conversion of complex food to simple substance.
A. Salivary Glands – produces SalivaSaliva – contains 99% of waterMucin – present in saliva which helps in
lubrication.Salivary Amylase (ptyalin) digests starch
into simple substance.
3 major glands that secrete saliva:1. Parotid – between the ear and back of
lower jaw.2. Submaxillary – lower side of the jaw.3. Sublingual – floor of the mouth near the
chin.
Liver – largest gland on the upper ride of abdomen.
Secretes: Bile juice and bile salts – helps in neutralization
Bilirubin and Biliverdin – greenish yellow pigment in bile juice.
Bile juice – removes wastes from blood stream.
Bile salts – emulsification of fats
Functions of Liver:Digestion of fatsConverts glucose to glycogen in controlling blood sugarDeamination of amino acidsStorehouse of fats, glucose, vit. A,D,E,K, iron and copperStores water
Functions of Liver:Produces RBCs in embryoDestroys old RBC in adultsProduces heparin (clotting factor)Metabolizes toxic chemicalsProduces 80% cholesterol of human body.
Pancreas- Long, yellowish, irregularly shaped gland
beneath the stomach and connected to small intestines.
- Secretes digestive enzymes and hormones.- Neutralizes chyme and break down
proteins, fats and starch.- Secretes insulin and glucagon in blood
stream.
Gastric glands – branched, tubular glands in the mucosa of the fundus and body of stomach.Secretes:HClZymogen (produces pepsin)Mucous cells(mucus)
Intestinal glands – simple tubular glands located in the mucous membrane of the intestine.Secretes: SucraseMaltaseEndo and exopeptidasesSecretory cells
In general, carnivores have shorter intestines for their size than herbivores
Herbivores ingest a large amount of plant cellulose, which resists digestion; these animals have a long, convoluted small intestine
In the mouth, food is physically broken down by teeth (mastication) Similar in function to the gizzard of birds
and worms Salivary glands excrete saliva
Antibacterial agents, mucin production Breaks down starch into glucose Controlled by the nervous system;
tasting, smelling, or even thinking about food stimulates salivation
Vertebrate teeth are adapted to their food source
Carnivorous teeth are pointed that lack flat grinding surfaces
Herbivores have large, flat teeth suited for grinding cellulose cell walls of plant tissues
Humans (omnivores) have carnivore-like teeth in the front and herbivore-like teeth in the back
Swallowing is initiated by voluntary action, but is continued under involuntary control
When food is ready to be swallowed, the tongue moves it to the back of the mouth
In mammals, the soft palate elevates, pushing against the back of the wall of the pharynx
Elevation of the soft palate seals off the nasal cavity
Pressure against the pharynx triggers the swallowing reflex
Bolus (food)
The uvula is the projection from the posterior edge of the middle of the soft palate
Not to be confused with the epiglottis
Plays a key role in the articulation of sound
Initiates the gag reflex Can contribute to
snoring
The esophagus actively moves a processed lump of food (bolus) through muscular action
Swallowing stimulates successive, uni-directional waves of contraction that move food along the esophagus into the stomach peristalsis
The stomach is a sac-like portion of tract Has convoluted surface, allowing
expansion Stores food (functions as crop of other
animals) Contains an extra layer of smooth
muscles for churning food and mixing it with gastric juice – an acidic secretion of the tubular gastric glands of the mucosa
Parietal cells of stomach secrete hydochloric acid (HCl)
Chief cells secrete pepsinogen (inactive), which becomes pepsin (active) at low pH (~2)
2 liters of HCl and other secretions is produced by human stomach every day!
The low pH of the stomach helps denature proteins
Acidity of stomach also kills most bacteria ingested with food
Overproduction of gastric acid can lead to ulcers, a hole through the wall of the stomach
The mixture of partially-digested food and gastric juice is called chyme; chyme leaves the stomach and enters the small intestine
Site of terminal digestion of carbohydrates, lipids, and proteins
Site of absorption of products of digestion (amino acids, glucose, fatty acids, etc)
Efficient digestion takes time, and so only small amounts of chyme may be introduced into the small intestine at any one time
Longest part of the digestive tract Up to 6 meters in humans
Consists of duodenum, jejunum, and ileum Duodenum – first 25 cm; site of most digestion,
receives enzymes from the pancreas and bile from the liver and gallbladder
Jejunum and ileum – site of absorption
• Very large surface area (3200 ft2) – folds, villi and microvilli– Similar to function of mycorrhizae
From liver
Gallbladder
Pancreaticduct
PancreasCommonbile duct
Duodenum
cell
cell
Pancreatic islet(of Langerhans)
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The large intestine concentrates and stores wastes
Much shorter than the small intestine, but larger diameter
Small intestine empties directly into the large intestine at a junction where 2 vestigal structures remain The cecum and appendix
No digestion occurs Absorption of water, remaining
electrolytes and vitamin K (products of bacterial metabolism)
Many bacteria live and reproduce within the large intestine; excess bacteria are incorporated into the feces
Feces are moved along by peristalsis and exit the body through the anus
Animals lack the enzymes necessary to digest cellulose, the structural component of the primary cell wall of green plants
However, the digestive tracts of some animals contain bacteria and protists that convert the otherwise undigestable cellulose into substances that the host can absorb
The activities of the gastrointestinal tract are coordinated by the nervous system and the endocrine system
The nervous system stimulates salivary and gastric secretions in response to sight, smell, and consumption of food
When food arrives in the stomach, proteins in the food stimulate the secretion of gastrin, which triggers the release of HCl and pepsinogen from the gastric glands
After a carbohydrate-rich meal, the liver and skeletal muscles remove excess glucose from the blood and store it as glycogen
During fasting or exercise (low levels of glucose), an increased secretion of glucagon by the pancreas promotes the breakdown of glycogen and release glucose (glycogenolysis)
Type 1 diabetes – insulin-dependent diabetes, common in children Too much glucose, little or no insulin
(mutation, no insulin made or non-functional), glucose excreted in urine
Type 2 diabetes – insulin-independent diabetes, adult onset Normal or elevated levels of insulin, but
cells no longer respond to the insulin Insulin is the only hormone that
decreases glucose in the body