mcdb 1b midterm 2

how do O2 and CO2 move

diffusion

how do animals speed up diffusion of gases

by increasing the surface area where gas exchange occurs (lungs, gills)

countercurrent exchange

water flows over gills in one direction, blood flows opposite to maximize exchange of gases

ventilating

moving air in and out

how do amphibians ventilate their lungs

by creating positive pressure to force air into lungs

trachea

large, stiff tube connecting larynx to bronchi

bronchioles

small tubes that branch off from bronchi and are wrapped in smooth muscle

bronchi

large, branching air passages that connect trachea and bronchioles

surfactants

mixtures of phospholipids and proteins that keep alveoli from collapsing by reducing surface tension btwn water molecules

inhalation

diaphragm contracts, air moves into long, and rib cage expands

exhalation

diaphragm relaxes, air moves out of lung, rib cage gets smaller

pleural cavity

the space where lungs are suspended

intra-alveolar pressure

pressure in the pleural cavity; lower than pressure in the lung

transpulmonary pressure

pressure differential that keeps the lung inflated

cause of collapsed lung

puncturing of pleural cavity and loss of pressure differential

anatomical dead space

spaces that do not participate in gas exchange

air in the alveoli has ____ O2 and ____ CO2 than air in the atmosphere

lower; higher

how is CO2 monitored in the respiratory system

by measuring blood pH

movement of gas in the alveoli

O2 moves into blood and CO2 moves into alveolar space

movement of gas in body tissues

O2 moves into interstitial fluid, then to cells, and CO2 moves into the blood

erythrocytes

red blood cells that bind O2 to hemoglobin to carry O2 in the blood

carbonic anhydrase

enzyme that catalyzes CO2 ←> H2CO3 reaction in both directions

role of carbonic anhydrase in tissues

convert CO2 to H2CO3

role of carbonic anhydrase in alveoli

convert H2CO3 to CO2 so CO2 can diffuse into alveoli

what must an animal’s diet provide

chemical energy, organic building blocks for macromolecules, and essential nutrients

chemical energy

ATP

essential nutrients

vitamins, minerals, and nutrients the body can’t synthesize and must obtain from food

uses of essential fatty acids

regulate membrane fluidity, synthesize Eicosanoids, generate ATP

eicosandoids

group of signaling molecules; synthesized by essential fatty acids

primary (dietary) vitamin A deficiency

insufficient consumption of foods containing preformed vitamin A or provitamin A carotenoids

secondary (malabsorption) vitamin A deficiency

medical conditions affecting fat absorption cause deficiency in vitamin A levels

causes of secondary vitamin A deficiency

celiac disease, crohn’s disease, cystic fibrosis, pancreatic insufficiency, post-bariatric surgery

vitamin A is important for

retinal production (vision), immune function, skin, and cell growth

what are fats broken down into

fatty acids and monoglycerides

what are proteins broken down into

amino acids

what are carbohydrates broken down into

monosaccharides (glucose)

goal of the digestive tract

break down food into absorbable units and move them to circulatory system for distribution in the body

digestion in the mouth

food is chewed into smaller bits and lubricated with saliva

what enzyme is in saliva

amylase

amylase

breaks down polysaccharides

epiglottis

blocks entry to trachea upon swallowing to keep food out of trachea

larynx

upper part of respiratory tract that guides bolus

bolus

wet ball of chewed food (YUCK!)

esophagus

smooth muscle tube that connects mouth to stomach

peristalsis

rhythmic contractions of muscles in the wall of the canal

sphincters

rings of smooth muscle that regulate movement of material btwn compartments

stomach

smooth muscle bag that stores food, slowly moves food into small intestine, and starts digestion of proteins

HCl in the stomach

kills bacteria, denatures macromolecules, activates pepsinogen

pepsin

starts digestion of proteins

pepsinogen

precursor to pepsin so that cell doesn’t digest itself

mucus

coats walls of stomach to protect it from being eroded and digested by HCl and pepsin

mucous cells

secrete mucus to line stomach

ulcer

results when walls of stomach are exposed directly to HCl and pepsin

gastric ulcers

lesions in the stomach lining

Helicobacter pylori

bacterium mainly responsible for presence of gastric ulcers

small intestine

where digestion is completed and absorption takes place

duodenum

first part of the small intestine where secretions from the gallbladder and pancreas enter the small intestine lumen

digestive mechanisms in the pancreas

bicarbonate fluid, proteolytic enzymes, amylases, nucleases, lipases

bicarbonate fluid

neutralizes stomach acid

proteolytic enzymes

digest proteins

nucleases

digest nucleic acids

lipases

digest fat

gall bladder

stores bile

bile

detergent-like fluid made in liver that aids in fat digestion

jejunum

longest section of small intestine where most absorption takes place

ileum

final segment of small intestine that absorbs vitamin B12, bile salts, and products of digestion not absorbed by jejunum

villi and microvilli

tiny structures on small intestine wall that increase surface area to increase absorption

tight junctions

complexes btwn cells that ensure contents in the lumen move thru cells instead of btwn them

hepatic portal vein

carries nutrient-rich blood from capillaries of villi to liver then to heart

liver

regulates nutrient distribution, interconverts organic molecules, detoxifies organic molecules

large intestine

make poop and reabsorb water

gastrin

turns on gastric secretions; produced in response to presence of food in stomach

CCK and secretin

stimulate pancreatic secretions into duodenum and stop stomach activity

enteric nervous system

controls the GI tract

liver glycogen

breaks down to release glucose back into circulation to feed other cells when needed

muscle glycogen

used within muscle cells during exercise

adipose triglyceride lipase

hydrolyzes triglycerides to release fatty acids into circulation

amino acids

used to make cellular components; potential source of nutrients in starvation

carbohydrate reserves

depleted in a single day without food intake

fat reserves

major energy reserve; depletes in 4 or 5 weeks without food

protein reserves

used for energy when body fat has been exhausted; lost at an accelerating rate with serious consquences

what hormones control glucose homeostasis

insulin and glucagon

insulin

lowers blood sugar by moving glucose from bloodstream into cells

glucagon

raises blood sugar by signaling liver to break down stored glycogen into glucose

diabetes mellitus

insulin/glucagon system breaks down

symptoms of diabetes

elevated blood glucose levels, dehydration, poor circulation, acidosis

type 1 diabetes

caused by destruction of insulin-producing beta cells in the pancreas

cause of type 1 diabetes

autoimmune reaction

treatment for type 1 diabetes

insulin injections

type 2 diabetes

beta cells still able to produce insulin, but cells do not respond and do not take up glucose

causes of type 2 diabetes

obesity, metabolic syndrome

metabolic syndrome

increased blood pressure, high blood sugar, excess body fat around waist, abnormal cholesterol/triglyceride levels

ghrelin

hormone that stimulates hunger btwn meals

insulin and PYY

hormones that decrease appetite; production increased by eating

satiety center

group of neurons in the hypothalamus that regulate feeling of hunger and satiety

leptin

hormone that decreases appetite; released when fat levels are adequate

primary signaling mechanisms

endocrine system and nervous system

endocrine system

signaling by hormones; chemical signals travel via circulatory system and cells with proper receptors respond

nervous system

signaling by neurons; nerves make direct contact with target cells

epinephrine

water soluble amino acid-derived hormone involved in stress response