Anatomy final

Fluid compartment - Intracellular compartment

•cytosol inside each cell (~66% of total body water)

fluid compartment - Extracellular fluid compartment

•internal body environment (~33% of total body water)

fluid compartment - Blood Plasma

Fluid inside blood vessels

Electrolytes

chemical compounds that are joined via ionic bonds and dissociate into ions in the water

Nonelectrolytes

covalently bound and do not dissociate.

Electrolyte examples

•Inorganic salts

•Inorganic and organic acids and bases

•Proteins

Nonelectrolyte examples

­Glucose

­Lipids

­Urea

Sodium (Na+)

high levels in blood and interstitial fluid (Na+ pumps), good for •Osmotic gradients in nephrons (Na+/K+ pumps)

•Neuron excitability

Blood pressure (water balance)

Potassium (K+)

high levels in intracellular fluid (K+ pumps) its similar to sodium because of the pumps

Chloride (Cl-)

high levels in blood and interstitial fluid and is used in •Chloride shift (blood)

•NaCl salt (interstitial fluid)

Bicarbonate (HCO₃^-)

high levels in blood and interstitial fluid and is used in •Regulation of pH in blood and interstitial fluid

Proteins

high in blood and intracellular fluid and used in •Antibodies, enzymes, hemoglobin, etc

•Found inside cells and in blood, but not interstitial fluid between cells.

main regulators of sodium(Na+) balance

Aldosterone and ANP

potassium (K+) levels are tightly regulated by

aldosterone

potassium (K+) balance - if blood K+ increases,

K+ enters cells

K+ exits cells

potassium (K+) balance - if blood K+ decreases,

K+ exits cells

potassium (k+) balance - if blood H+ increases,

H+ enters cells and K+ exits cells

potassium (k+) balance - if blood H+ decreases,

H+ exits cells and K+ enters cells

potassium (k+) balance - insulin ______ movement of both glucose and K+ into cells

increases

calcium balance - When PTH levels rise, it stimulates ______ to release calcium into the blood.

osteoclasts

pH and H⁺ ion balance - Hydrogen ions

influence nearly all biochemical reactions, Regulated by 3 buffer systems: chemical buffers, respiration, and renal mechanisms

Buffering systems - Kidneys

physiologic system (renal mechanism) secreting H+ or bicarbonate

Buffering system - lungs

physiologic system (respiratory mechanism) eliminating CO2 to regulate carbonic acid.

buffering system - Phosphate buffering system

chemical buffering system, buffer within cells, works similarly to bicarbonate system

buffering system - protein buffers

chemical buffering system, (proteins act as buffers within cells and blood by releasing or binding H+ ions

isotonic solution

Interstitial fluid is the same concentration as cytosol (no net movement of water)

hypotonic solution

Interstitial fluid has a higher water concentration than cytosol (water enters the cell)

hypertonic solution

Interstitial fluid has lower water concentration than cytosol (water leaves cell)

Fluid moves into cells from blood when

hydrated

Fluid moves from cells into the blood when

dehydrated

Movement from blood plasma to interstitial fluid occurs across the

capillary walls (driven by both hydrostatic and osmotic pressure)

Movement from interstitial fluid to intracellular fluid - nutrients, respiratory gases

•usually flow unidirectionally INTO cells.

Movement from interstitial fluid to intracellular fluid - waste products

usually flow unidirectionally OUT OF cells.

•How many membranes must a substance cross to get from ICF to blood?

•Cell membrane and plasma membrane

Edema

•atypical accumulation of fluid in the interstitial space.

Edema is caused by

• Increase in hydrostatic pressure in the capillaries

• Increased interstitial fluid osmotic pressure

• Hypoproteinemia

Fluid Intake (2500 mL/day)

ingested water (drink and food)

drink 1600ml

food 700ml

metabolic water 200mL

Fluid Output (2500 mL/day)

Insensible water loss

Sensible water loss

Obligatory water loss

Facultative water loss

Obligatory Water loss

what we must lose for normal body processes. (urine, feces, insensible water losses)

Facultative water loss

what can be adjusted to prevent dehydration (urine)

Sensible water loss

is loss of water in waste (feces and urine)

Insensible water loss

loss of water across skin and mucous membranes (sweat, expired air, and cutaneous transpiration)

Water intake is regulated by:

Osmoreceptors

ECF osmolality changes via stretch receptors in the plasma membranes of cells. Small changes can trigger this.

Dry mouth

An increase in osmotic pressure causes less saliva production due to less water moving from the blood to the salivary glands.

Decrease in blood volume/pressure

Baroreceptors and angiotensin II mechanisms sense a decrease in blood pressure and activate the thirst mechanism.

Water loss is mainly regulated hormonally, most notably by

antidiuretic hormone (ADH).

first step in water regulation output

Low blood volume and pressure are detected from baroreceptors in the heart and vessels, and angiotensin is produced

second step in water regulation output

The hypothalamus responds to stimuli

third step in water regulation output

The hypothalamus increases nerve signals to the posterior pituitary to release ADH into the blood

fourth step in water regulation output

The thirst center is activated

increased number of aquaporins

vasoconstriction: increases peripheral resistance and blood pressure

mouth esophagus and anis are composed of this type of cell

stratisfied squamous epithelial

Gi Tract/ Alimentary Canal

tube that conveys food and breakdown products from mouth to anis

Accessroy digestive organs

helper organs that produce secretions

parts of the gi tract

mouth, pharynx, esophagus, stomach, small intestine, large intestine, anus

accessory organs

Teeth (mouth)

Tongue (mouth)

Salivary glands (mouth)

Liver (and gall bladder)

Pancreas (and ducts)

salivary glands

produce saliva, which begins breakdown of food (parotid, sublingual, submandibular).

saliva

Water

Electrolytes (Na+, K+, Cl-, HCO3-)

Digestive enzymes (salivary amylase, lingual lipase)

Proteins (mucin, IgA antibodies)

Metabolic wastes (urea, uric acid)

deglutition

swallowing, movement of food out of mouth and inferiorly through esophagus into stomach

Mechanism of swallowing

Buccal (voluntary) phase Pharyngeal phase (involuntary)

Esophageal phase (involuntary

Esophageal phase

bolus is now in esophagus (Stage 3)

pharyngeal phase

Tongue pushes food back into oropharynx. Uvula and soft palate close off nasopharynx. Esophagus opens. Epiglottis closes off larynx. (stage 2)

buccal (voluntary) phase

esophagus is closed, tongue presses against hard palate. (stage 1)

what happens in esophageal phase

muscles of the pharynx contract to move bolus inferiorly into esophagus

superior esophageal sphincter closes to prevent emesis

inferior esophageal sphincter opens and bolus enters stomach

emesis

vomiting - a reflex hat empties the stomach through esophagus and pharynx

induced by 2 areas in the medulla (chemoreceptor trigger zone and vomiting center)

anti emetic drugs

bind to receptors in vomiting center to block signals from CTZ and GI Tract

layers of stomach wall

mucosa

submucosa

muscularis

serosa

gastric pits

microscopic infoldings in the mucosa of the stomach wall that lead to gastric glamds

gastric glands

help excel gastric secretions (hormones, gastric acid)

what does this stomach cell secrete: surface mucous cell

alkaline mucous

what does this stomach cell secrete: parietal cell

intrinsic factor, HCL

what does this stomach cell secrete: chief cell

pepsinogen, gastric lipase

what does this stomach cell secrete: g cells

enteroendocrine cells, secrete gastrin and ghrelin into blood

gastrin

hormone released by G cells in the mucosal layer of the stomach in response to:

Peptides

Stretch receptors in stomach (enterogastric reflex)

Lower stomach pH

what does gastrin induce

Histamine production, muscle contraction, mass movements

ghrelin

produced when stomach is empty, Regulates insulin secretion by pancreas and tells the body It’s time to eat!

Cells of the mucosa:

Simple columnar epithelial cells (with microvilli)

Cells of the mucosa: goblet cells

produce mucous (lubrication, protection)

cells of mucosa: Enteroendocrine cells

secrete hormones (CCK and Secretin)

Cells of the mucosa: paneth cells

secrete lysozyme (innate immune system)

lipid digestion and absorprion

emulsified into bile salts, triglycerides turn into monoglycerides, assemble into micelles, micelles diffuse into intestinal cells, are packaged into chylomicrons and are transported away

regions of small intestine

duodenum, jejunum, ileum

duodenum

(primary region for nutrient breakdown, connects to liver/gall bladder and pancreas)

jejunum

(primary region for nutrient absorption)

ileum

(absorption continues here, connects to colon via ileocecal valve)

ileum - ileocecal valve

between the ileum and the cecum of the large intestine.

Controls movement of digested substances from small intestine to large intestine.

ileocecal reflex

propels digestive juices from ileum of small intestine into the cecum of the large intestine.

intestinal juice

secreted by small intestine in response to acidic chyme from stomach

what does intestinal juice contain

Amylases from the pancreas (carbohydrate breakdown)

Brush border enzymes from the small intestine (disaccharide breakdown)

Peptidases from pancreas (protein breakdown)

Lipases and bile from liver (lipid breakdown)

carbohydrate breakdown in small intestine Step 1

pancreatic amylase is produced by the pancreas and secreted into small intestine

carbohydrate breakdown in small intestine Step 2

pancreatic amylase continues the digestion of starch that began in the oral cavity by salivary amylase

carbohydrate breakdown in small intestine Step 3

Brush Border enzymes complete the breakdown of starch to individual glucose molecules, and are responsible for the digestuon of disaccharides

brush border enzymes

lactase and sucrose

what do lactase enzymes break down

break down lactose into glucose and glactose

what do sucrase enzymes break down

break down sucrose into glucose and fructose

large intestine function

excrete waste,

Fluid absorption (last chance to retain water)

Bacterial action (gut microbiota; appendix)

Feces (stool) formation

Defecation - feces is forced into the rectum, which initiates the defecation reflex

large intestine histology

does not have intestinal villi, but rather intestinal glands (intestinal crypts)

ascending colon

responsible for bacterial action and fluid absorption. (retroperitoneal)

transverse colon

continues fluid absorption from the ascending colon.

It is intraperitoneal and begins at the right colic flexure and ends at the left colic flexure.

descending colon

begins the process of stool formation/storage