Review set 5 Flashcards
Why is digestion critical?
large food molecules is essential
*Most food large/ complex – not readily usable (must be broken down for absorption and for reassembly into new products); Contains certain substances not suitable for human tissue (must be separated/ removed)
Explain the need for enzymes in digestion.
Enzymes = biological catalysts; allow breakdown of specific substrates in organism-specific temperatures/ pH/ etc.; substrates broken down independently of others
- Hydrolysis (hydro = water, lysis = breaking) reactions (catabolic reactions) dominate the digestive process
- Enzymes are globular proteins that lower the activation energy needed to start a chemical reaction and speed up the rate of chemical reactions (allow reactions to occur more quickly at body temperature/ increase rate of digestion)
- Digestive enzymes released into gut from exocrine glands (pancreas) - exocrine glands have ducts and secrete substances to an epithelial surface
- Enzymes break large, insoluble molecules into smaller, soluble molecules (monomers) that are easily absorbed into the bloodstream
Define enzymes
biological catalysts; allow breakdown of specific substrates in organism-specific temperatures/ pH/ etc.; substrates broken down independently of others
Draw the digestive system
Stomach should be ‘J’-shaped and be connected to the esophagus and small intestine Liver should look like a right-angled triangle and be superimposed to the left of the stomach (right side of the human) Bile duct (connected to gall bladder) and pancreatic duct should both feed into a U-shaped bend of the small intestine Small intestine should be thinner in width than the large intestine
Enzyme: Salivary amylase
State: Site of production,Site of Action, pH, Substrate(s), Product(s)/
Site of production: Salivary glands Site of action: Mouth/ Esophagus ph: Neutral (7) Substrate: Starch (amylose) Product: Maltose
Enzyme: Pepsin/ protease
State: Site of production,Site of Action, pH, Substrate(s), Product(s)/
Stomach Stomach Acidic (1-2) Proteins Peptides
Enzyme: Amylase
State: Site of production,Site of Action, pH, Substrate(s), Product(s)/
Pancreas Lumen of small intestine Neutral to slightly alkaline (7-8) Starch Maltose
Enzyme: Lipase
State: Site of production,Site of Action, pH, Substrate(s), Product(s)/
peter loves nicotine too much
Pancreas Lumen of small intestine Neutral to slightly alkaline (7-8) Triglycerides Monoglycerides/ fatty acids/ glycerol
Enzyme: Endopeptidase/ Protease
State: Site of production,Site of Action, pH, Substrate(s), Product(s)/
Pancreas Lumen of small intestine Neutral to slightly alkaline (7-8) Proteins/ peptides Amino acids
Enzyme: Nuclease
State: Site of production,Site of Action, pH, Substrate(s), Product(s)/
Pancreas Lumen of small intestine Neutral to slightly alkaline (7-8) Nucleic acids Nucleosides
Carbohydrates process of being digested
—>
Once carbohydrates are hydrolyzed to disaccharides, they are then hydrolyzed to monosaccharides by enzymes that are immobilized (such as maltase) on the epithelial lining of the small intestine
Lipids process of digesting
Lipids are first emulsified (broken down into physically smaller droplets) by bile (released into the small intestine from the gall bladder) and then hydrolyzed by lipases (secreted into the small intestine from the pancreas) into monoglycerides, fatty acids, and glycerol. They are then absorbed by the epithelial cells of the small intestine and transported (as chylomicrons) to the lacteal.
Alimentary canal is divided into
Stomach, Small Intestine, and Large Intestine
Stomach’s function
Protein (chemical) digestion (begins – acidic pH denatures and proteases break down); begins mechanical digestion (breaking food into smaller parts without breaking bonds); mixes food to promote digestion (churning); produces chyme
Small intestine
Completes digestion of food molecules; absorption of nutrients/ water; receives secretions from pancreas/ gall bladder to aid in digestion; mixing/ movement of digested food products (peristalsis); secretion of intestinal juices; contains villi (increase surface area for absorption)
Large Intestine
Absorption of water/ minerals/ ions; produces/ stores/ eliminates feces (solid waste/ cellulose/ lignin)
What are not broken down by humans and why?
Cellulose and lignin are NOT broken down because humans lack enzymes to break down beta-glucose (the linkages found in cellulose and lignin) - important in diet though = “fiber” to clean out old cells/ bacteria and “work out” natural microflora
Structures of Villus
Microvilli, Rich capillary network, Single epithelial layer, Lacteals, Intestinal crypts (between villi), Membrane proteins/ mitochondria
Microvilli
increase surface area for absorption and contain immobilized enzymes (maltase etc.) for hydrolysis of disaccharides (maltose hydrolyzed to glucose)
Rich capillary network
minimize diffusion distance and maintain large concentration gradient for rapid absorption
Single epithelial layer
Minimal diffusion distance (cells connected by TIGHT JUNCTIONS - impermeable barrier/ ensure one-way flow of nutrients and ensuring separation of body and digestive fluids
Lacteals
Absorb lipids into lymphatic system
Intestinal crypts (between villi)
release juices that act as carrier fluids for nutrients
Membrane proteins/ mitochondria
Active transport
Structure of the Small intestine from outside to inside
Serosa Longitudinal muscles Circular muscles Submucosa Mucosa
Serosa
Protective outer covering
Longitudinal muscles
Peristalsis (move food along gut/ mix with enzymes)
Circular muscles
Segmentation (prevent backward movement of food/ mix with enzymes)
Submucosa
Separates innermost mucosa from muscles
Mucosa
Highly folded inner epithelial layer (villi and microvilli) to increase the surface area for absorption of monomers from the intestinal lumen
the Different methods of membrane transport are required to absorb different nutrients
Diffusion Osmosis Facilitated Diffusion Active Transport - requires ATP Endocytosis
Diffusion
Fatty acids and other small, non-polar substances easily pass through the hydrophobic cell membranes of epithelial cells through simple diffusion
Osmosis
Water diffuses across epithelial cell membranes in response to movement of ions and other hydrophilic monomers (occurs in small intestine and large intestine)
Facilitated Diffusion
Protein channels within epithelial cell membranes (of villi and microvilli) allow passage of hydrophilic food molecules (water-soluble/ polar molecules like fructose, vitamins, glucose, amino acids, and minerals)
Active Transport - requires ATP
Glucose and amino acids are pumped (membrane proteins) against their concentration gradients, or they are transported with Na+ ions (co-transport) as Na+ ions are actively pumped across the membrane (secondary active transport)
Endocytosis
Invagination of the cell membrane to form a vesicle around bulk fluids/ large molecules that must remain intact in the intestinal lumen and bring them into the cell (pinocytosis: “cell drinking”)
Ex: Absorption of antibodies (such as those in breastmilk – passed on to infants)
The endocrine system consists of these glands
pancreas, pineal, pituitary, ovaries, testes, adrenal, thyroid) that release hormones that are transported in the blood (widely distributed)
Homeostasis involves
maintaining the internal environment between limits, including blood glucose concentration, body temperature, appetite, and water balance, and involves negative feedback mechanisms:
What is Negative feedback mechanism?
Outcome of the mechanism is the OPPOSITE effect (ex: temp too high, negative feedback works to bring temp back down)
Pineal gland role, and other things you need to know
Produces MELATONIN (secreted in DARK), Retina (eye) detects light (amount/ duration), Dark/ longer nights = more melatonin produced, Bright light (daylight and screens) = more blue wavelengths = suppress/ inhibit melatonin production, Amount and timing of melatonin secretion become entrained in body over time (cycle causes jet lag in new time zones - melatonin supplements can alleviate (take at sleep time)
What occurs if blood glucose is too high vs blood glucose is too low
Blood glucose is too high vs too low
beta cells in the pancreas produce insulin vs alpha cells in the pancreas produce glucagon
Insulin is secreted into the bloodstream vs glucagon is secreted into the bloodstream
Insulin acts on all cells in the body, triggering them to take up glucose vs Glucagon stimulates hepatocytes to break down glycogen into glucose
Cellular respiration rates are increased causing an increase in breakdown of glucose vs Cellular respiration rates are decreased causing a decrease in breakdown of glucose
Glucose in liver cells, adipose cells, and muscle cells is converted to and stored as glycogen, decreasing blood glucose vs Glucose is released by hepatocytes into the bloodstream, increasing blood glucose levels
Glucose uptake and storage by cells decreases blood glucose levels vs Rising blood glucose levels stimulate less glucagon to be produced
Type I vs Type II
Type I vs Type II
Early onset vs adult onset
Beta cells damaged destroyed by body’s own immune system- autoimmune disease vs Insulin receptors on cells are fewer and or become less sensitive to insulin
Triggered by various- not usually genetic vs related to obesity, poor diet, genetic history, lack of exercise, age, ethnicity
Controlled by insulin injections to regulate blood glucose levels vs controlled by managing diet and lifestyle
Diabetes symptoms
high blood sugar, glucose in urine, increased thirst/ urination, hunger, fatigue, weight loss
Pancreas is both
produces and secretes two ANTAGONISTIC hormones into blood to maintain homeostasis of blood glucose (both an endocrine and exocrine gland!)
Hypothermia vs Hyperthermia
Body temp is too low vs body temp is too high
Thermoreceptors in skin send signals to hypothalamus
Hypothalamus release chemical signals that trigger: - Vasoconstriction ( arterioles get smaller, blood is diverted to deep tissues/organs less heat loss) -Shivering of skeletal muscle (generates heat) - Goosebumps- raises hair follicles on skin vs Hypothalamus releases chemical signals that trigger -Vasodilation( arterioles get bigger, fill with blood, transfer heat to skin and out of body) - Increased sweat gland activity
Thyroid Gland
-Produces and secretes THYROXIN (in response to signals from hypothalamus) -Thyroxin regulates body’s basal
metabolic rate (amount of energy used at rest)
-When released, thyroxin acts on ALL cells, causing increase in energy use/more oxidation of glucose and fatty acids, increase in metabolic rate, increase in oxygen consumption/ ATP hydrolysis (which produces more heat too and increases body temperature)
What is Kidneys function?
Kidney function = filters blood: remove toxins, osmoregulation (water/ solute balance), reabsorption of nutrients (glucose/ amino acids) and excretion = removal of nitrogenous waste products of metabolism (urea etc.)
Type of nitrogenous waste produced is
correlated with evolutionary history
What are the types of nitrogenous waste?
Ammonia, Urea, Uric Acid
Ammonia
VERY TOXIC, so requires LOTS of water to dilute, but not much energy to produce = fish/ aquatic organisms
Urea
Somewhat toxic, but can be stored short-term; requires some water to dilute and some energy to produce = mammals, amphibians, and sharks
Uric Acid
Requires LOTS of energy to produce, but insoluble in aqueous solutions and does not need to be diluted so can be stored long-term and in developing eggs (reptiles, birds, and insects)
Insects have
MALPIGHIAN TUBULES to carry out removal of nitrogenous wastes and osmoregulation:
MALPIGHIAN TUBULES
Tubules branch off intestine Filter water, salts, and ammonia out of hemolymph that surrounds them (hemolymph = fluid like blood) into digestive tract Water, salts, and solutes reabsorbed into hemolymph and ammonia forms a solid paste and combines with undigested food and is eliminated with feces
Nephron
functional unit of kidney - be able to diagram and label and describe processes happening in each part and relate structure of each part to its function.
Steps of the nephron
- Blood (from the renal artery) enters the capsule through the afferent arteriole (which is larger than the efferent (draining) arteriole -creating extremely high pressure inside the capsule)
- High pressure forces water and blood contents (except large proteins, platelets and blood cells) through fenestrations (small slits/ pores) in the glomerulus (which is highly branched = increased SA).
- Filtered contents of the blood (glomerular filtrate - water, glucose, salts, amino acids, urea) then pass through fine mesh structure of basement membrane (which blocks large proteins, blood cells, and platelets from passing through),
- Filtered contents of the blood then pass through fenestrations in the podocytes (cells) lining Bowman’s capsule (only one cell layer thick = decreases filtration distance) into the capsule space, forming, a fluid called filtrate, which then passes into the proximal convoluted tubule.
- Blood cells, proteins, platelets etc, that do NOT become part of the filtrate exit the capsule through the efferent arteriole, which then branches into the peritubular capillary bed (vasa recta) surrounding the proximal and distal convoluted tubules and the loop of Henle
Step 1 for Ultrafiltration in the Nephron
Blood (from the renal artery) enters the capsule through the afferent arteriole (which is larger than the efferent (draining) arteriole -creating extremely high pressure inside the capsule)
Step 2 for Ultrafiltration in the Nephron
High pressure forces water and blood contents (except large proteins, platelets and blood cells) through fenestrations (small slits/ pores) in the glomerulus (which is highly branched = increased SA).
Step 3 for Ultrafiltration in the Nephron
Filtered contents of the blood (glomerular filtrate - water, glucose, salts, amino acids, urea) then pass through fine mesh structure of basement membrane (which blocks large proteins, blood cells, and platelets from passing through),
Step 4 for Ultrafiltration in the Nephron
Filtered contents of the blood then pass through fenestrations in the podocytes (cells) lining Bowman’s capsule (only one cell layer thick = decreases filtration distance) into the capsule space, forming, a fluid called filtrate, which then passes into the proximal convoluted tubule.
Step 5 for Ultrafiltration in the Nephron
Blood cells, proteins, platelets etc, that do NOT become part of the filtrate exit the capsule through the efferent arteriole, which then branches into the peritubular capillary bed (vasa recta) surrounding the proximal and distal convoluted tubules and the loop of Henle
How are Salt ions and vitamins reabsorbed
Actively transported from filtrate into epithelial cells (have microvilli to increase SA, On cell layer thick to decrease diffusion distance, then Passively transported from epithelial cells into blood stream
How is Glucose and Amino Acids reabsorbed?
Cotransported with sodium ions inot epithelial cells until equilibrium reached then Actively transported into epithelial cells after 50% reabsorbed until 100% reabsorbed from filtrate (NEVER GLUCOSE IN URINE)
How is water reabsorbed?
Reabsorbed passively by osmosis
What does Glucose in Urine indicate?
glucose in urine indicates an EXCESS of glucose in blood – active transport in PCT has maximum rate and in diabetics (high blood sugar due to lack of insulin or decreased insulin sensitivity) maximum concentration of glucose that can be transported by protein pumps is exceeded, so some remains in urine
How is structure of PCT adapted to its function?
Lumen of PCT surrounded by wall ONE CELL THICK; microvilli increase surface area for absorption; peritubular capillaries surround PCT for reabsorption
What helps maintain water/ solute concentration balance of the blood?
The loop of Henle, medulla, collecting duct and ADH
What is the length of loop of henle correlated two?
is positively correlated with need for water conservation (longer in desert animals -kangaroo rats, shorter in amphibians- frogs and toads)
Osmoregulators
organisms whose internal tissues maintain DIFFERENT solute concentrations than environment (requires more energy to strictly control internal conditions but can live in more habitats) - birds, mammals, freshwater fish
Osmoconformers
organisms whose internal tissues maintain the SAME solute concentrations as environment (iso-osmotic); requires less energy and there is less water movement in/ out of cells, but VERY restricted habitats - sharks, crabs, mussels, jellyfish
The Descending limb of Loop of Henle is permeable to what
to water (water passes out of filtrate by osmosis into high salt concentration – hypertonic environment – in medulla of kidney); decreases filtrate volume
The Ascending limb of Loop of Henle is permeable to what?
to salt ions (salt ions actively pumped out of filtrate into medulla); creates more dilute filtrate
Osmoreceptors in hypothalamus monitor
water content of blood
If water content too low what occurs?
pituitary releases ADH (anti-diuretic hormone = released when you Are DeHydrated) into blood
why is water/ solute balance so important?
are essential for health of an organism. Too little water = dehydration (sleepiness, constipation, dry mouth and skin, dizziness and headache, lower blood pressure which causes increased heart rate, inability to produce sweat (cannot lower body temp), seizures, brain damage, and even death); Too much water = overhydration (confusion, delirium, blurred vision, muscle cramps, nausea/ vomiting, cells swell (and can burst and cause tissue damage), seizures, coma, and even death)
Urinalysis: detection blood cells
Do not get filtered (too large so should not be in urine) - indicate infection, kidney malfunction, bleeding in renal tubes
Urinalysis: detection Glucose
ALL reabsorbed (in PCT) so should not be in urine - indicates diabetes
Urinalysis detection Proteins:
Do not get filtered (too large so should not be in urine) - indicated disease, hormonal conditions, or even pregnancy (hCG)
Urinalysis detection drugs
Drugs: Not naturally found in body so filtered out if taking them
Kidney Failure solutions
Hemodialysis (short-term solution) - filters blood through dialyzer externally Kidney transplant (requires genetic match and immunosuppression)
Urea, Renal Artery Composition, Renal vein composition, and reason
Urea, Higher, Lower, Urea removed through ultrafiltration and excretion
oxygen, Renal Artery Composition, Renal vein composition, and reason
higher, lower, Oxygen used to make ATP for active transport of essential substances (glucose, amino acids) back into blood
Carbon Dioxide, Renal Artery Composition, Renal vein composition, and reason
Lower, higher, waste product of cell respiration in kidney as make ATP for active reabsorption
Glucose, Renal Artery Composition, Renal vein composition, and reason
Higher, a LITTLE lower, used to dilute urea (more reabsorbed in PCT)
Sodium and Chloride Ions, Renal Artery Composition, Renal vein composition, and reason
Higher, Lower, pumped into medulla (or excess excreted) and diluted if ADH secreted
Water, Renal Artery Composition, Renal vein composition, and reason
Higher, lower, Used to dilute urea (more reabsorbed if ADH secreted)
Drugs/toxins, Renal Artery Composition, Renal vein composition, and reason
Higher, lower, excreted in urine
