Physiology Exam 5

What are the two types of control systems associated with Cannon’s Postulates?

Tonic and antagonistic control

What is tonic control?

Regulates physiological parameters in an up-down fashion (putting your foot on the gas, no break)

What is antagonistic control?

Controls heart rate, some speed it up while others slow it down (using the break)

What happens during positive feedback?

Response loop shuts off

What happens during negative feedback?

Feedback cycle, an outside factor needs to turn off the cycle

What are central receptors?

Are in or around the brain (eyes, ears, nose and tongue)

What are peripheral receptors?

Lie outside the brain

What are the steps in reflex control?

Stimulus, sensor/receptor, afferent pathway, integrating center, efferent pathway, target/effector and response

What is the first law of thermodynamics?

Energy cannot be created nor destroyed

What is the second law of thermodynamics?

Final entropy must be larger than initial entropy for an irreversible process

What is the third law of thermodynamics?

The entropy of a system approaches a constant value as the temperature approaches absolute zero

What are the six basic digestive processes of digestion?

Ingestion, digestion, secretion, motility, defecation and absorption

What is ingestion?

The process of taking food, drink or another substance into the body by swallowing or absorbing it

What is secretion?

The release of water, acids, enzymes, buffers and salts

What is motility?

the movement of food, from the mouth through the pharynx, esophagus, stomach, small and large intestine and out the body

What is digestion?

The complex process of turning the food you eat into nutrients

What is absorption?

The simple molecules that result from chemical digestion pass through cell membranes of the lining in the small intestine into the blood or lymph capillaries

What is defecation?

The act of expelling feces from the digestive tract via the anus

What are the three layers to the enteric nervous system?

Myentric plexus, submucosal plexus and mucosal epithelium

What does the myenteric plexus do?

Controls smooth muscle and regulates gastrointestinal tract motility

What does the submucosal plexus do?

Controls glands and endocrine cells

What does the mucosal epithelium do?

It has a sensory neuron that sends signals to autonomic and central nervous systems

What are the two patterns of motility?

Peristalsis and segmentation

What is peristalsis?

Promotes forward movement, circular and longitudinal muscles

What is segmentation?

No net forward movement, promotes mixing

What displays the two patterns of motility and what does it cause?

Autorhythmicity and it causes depolarizations that don't necessarily make it to threshold (slow wave potentials)

What moves when we swallow food?

The bolus

What is gastric mucosa?

Its arranged in pits and glands and it consists of folds called rugae

What is muscularis externa?

It contains an extra layer of smooth muscle and is oblique

What secretes mucus?

surface mucous cell and mucous neck cell

What secretes HCI?

Parietal cells

What secretes pepsinogen and gastric lipase?

Chief cells

What secretes gastrin?

G cells

Why does the increase of hydrogen ions in the stomach need energy?

It’s moving against the concentration gradient

What regulates HCI secretion?

Proton pump

What 3 things tell the parietal cells to secrete HCI?

Acetylcholine (parasympathetic activated, smells), gastrin and histamine

What does the exocrine pancreas do?

Secretes pancreatic juices containing many digestive enzymes

What does the endocrine pancreas do?

Secretes hormones insulin and glucagon to control the amount of sugar in blood

What does amylase do?

breaks down carbohydrates

What does trypsin do?

breaks down proteins

What does chymotrypsin do?

breaks down proteins

What does elastase do?

breaks down proteins

What does lipase do?

breaks down fats

What does ribonuclease do?

breaks down RNA

What does deoxyribonuclease do?

breaks down DNA

What does the liver secrete?

Bile

What does the gallbladder store?

Bile

What are the three different regions of the small intestine?

Duodenum, jejunum and lleum

What do bile salts do?

breaks down fat to make it more soluble

What is the order that the small intestine breaks down molecules?

Large to small molecules

What does maltase do?

breaks down

What does lipase do?

breaks down fat

What does secondary active transport with Na+?

Glucose and galactose

What does facilitated diffusion diffuse?

Fructose

What does secondary active transport with Na+ or facilitated diffusion diffuse?

Amino acids, dipeptides and tripeptides

What does simple diffusion diffuse?

Short/long-chain fatty acids and monoglycerides

What do carbohydrates break down into?

Monosaccharides

Where are carbohydrates absorbed?

Small intestine

What are the enzymes for protein digestion?

Endo and exopeptidase

What is endopeptidase?

Digests internal peptide bonds

What is exopeptidase?

Digests terminal peptide bonds to release amino acids

What do triglycerides digest into?

Monoglycerides and free fatty acids

What is happening in the process of digestion and absorption of fats?

Bile salts coat fat droplets to make them more soluble which are then broken down by lipase and colipase into monoglycerides and fatty acids and are then absorbed with cholesterol and proteins to form chylomicrons

Where is most water reabsorbed?

Small intestine

What are the three phases of digestion?

Cephalic, gastric and intestinal

What does the cephalic phase do?

Prepares the mouth and stomach for food that's about to be eaten

What does the gastric phase do?

Promotes gastric juice secretion and gastric motility

What does the intestinal phase do?

Promotes digestion in the small intestine and slows the digestion in the stomach

What are the steps in the gastric phase of digestion?

Food enters stomach, pH of gastric juices increase and stretching of stomach walls begin, chemoreceptors and stretch receptors detect pH change, submucosal plexus, parietal cells secrete HCI and increase in acidity of the stomach chyme along with mixing of the stomach contents and emptying of the stomach

Where are long reflexes integrated?

CNS

Where are short reflexes integrated?

ENS

What are the steps of the GI reflexes?

Cephalic phase, secretory cells of the stomach/small intestine, GI peptides, Gi smooth muscle and exo/endocrine cells of stomach pancreas and intestine, and changes in GI motility release of bile and pancreatic secretions

What is absorptive state?

about 4 hours after a meal

What is postabsorptive state?

when the GI tract lacks nutrients and energy the body is supplies by the breakdown of the body's own nutrient storage

What are absorptive state reactions?

catabolism of glucose/amino acids/dietary lipids, protein synthesis, glyco/lipogenesis and transport of triglycerides

What are the steps in a fasted-state metabolism?

Liver glycogen becomes glucose, adipose tissue becomes free fatty acids and glycerol that enters blood, muscle glycogen can be used for energy and the brain can only use glucose and ketones for energy

What does insulin do?

helps sugar enter the body so it can be used for energy

What does glucagon do?

helps blood glucose levels increase

In a fed state what dominates?

Insulin

In a fasted state what dominates?

glucagon

What is a calorie?

the amount of heat energy it takes to raise 1 gram of water 1 degree Celsius

What is the energy content of carbohydrates, proteins and fats?

Carb is 4, prot is 4 and fats is 9 kcal/g

What do anabolic pathways do and what state is it?

Builds large molecules and is absorptive (fed) stated

What do catabolic pathways do and what state is it?

Breaks down large molecules and is postabsorptive (fasted) stated

What nutrient pools are available for immediate use?

Free fatty acids, plasma glucose and amino acid pool

How do you measure energy?

Direct calorimetry

What six factors affect metabolic rate?

Age and sex, amount of lean muscle mass, activity level, energy intake (diet), hormones and genetics

What is the glucostatic theory?

Proposes that blood glucose levels control the feeding and satiety centers

What is the lipostatic theory?

Proposes that the levels of body fat regulates the feeding and satiety centers

What does leptin do?

Inhibits neuropeptide Y so it makes you feel full

Where is leptin secreted from?

white adipose tissue

What does neuropeptide Y do?

Makes you eat even after you just ate and are full

What is energy output maintained by and why?

Thermal regulation because we are warm blooded

What can be burned to maintain body temperature?

Brown adipose tissue, but only if you are skinny

What are the mechanisms of heat transfer?

Radiation, convection, conduction and evaporation

What is radiation with an example?

From the sun, ex being outside under the suns rays

What is convection with an example?

The transfer of heat from one object to another by current such as gasses or fluids, ex fan blowing

What is conduction with an example?

The transfer of heat from one object to another through touch, ex heated seat

What is evaporation with an example?

The latent heat of a fluid used to transfer heat by absorbing the energy required to evaporate the fluid, ex sweating

Where is most heat/energy lost from?

Radiant energy (constantly emitting heat)