Bios 355 Exam 4 Flashcards
Water balance
Total fluids > 40 L
25 L is cytoplasm
15 L is ECF
ECF > plasma is 3 L, interstitial fluid is 10 L, transfluid is 2 L
Transfluid > saliva, GI fluid, ocular fluid, pleural fluid
Gain > 2.1 L (food and water)
> 0.3 L (metabolic water)
Oxidative phosphorylation in mitochondria
ETS
Final electron acceptor oxygen > forms H2O Gain > 2.4 L/day Loss > evaporation across skin: 0.35 L > respiratory evap. 0.35 L > feces: 0.2 L > urine: 1.5 L Water gain must equal water loss
Osmotic sensors
Located in the hypothalamus Increase OP sensor > increase AP freq. When sensor swells: physical change of cell alters the open probability of the channel \: decrease Na influx \: decrease AP freq.
Hypothalamic neurons
Axon lead to posterior pituitary
AP will cause the release of the hormone ADH (anti diuretic hormone) (vasopressure)
ADH released into blood when the osmotic sensors increase AP freq.
Role of ADH
- Target is cells of the collecting duct of the nephron
- Bond to ADH receptors on C.D.
> activate increase cAMP
> activate PKA
> stimulate insertion of vesicles into plasma membrane
Increase blood OP
Increase ADH > increase aquaporin, osmotic rate, and water reabsorption
Decrease urine vol.
increase urine OP
Decrease blood vol.
Decrease blood OP
Drink a large vol. of water
Decrease OP in blood/ECF Decrease osmotic sensor AP freq. Decrease rate of release of ADH Decrease aquaporin Decrease water reabsorption Increase urine vol. absence of ADH - collecting duct autonomically retrieves the aquaporin by endocytosis
Other mechanisms to cause the release of ADH
- Primary: osmotic sensors
- Vascular stretch receptors (baroreceptors)
> send AP to hypothalamus
Baroreceptors detect low vol. and pressure > stimulate hypothalamus > increase AP freq. > increase ADH release > water conservation and thirst
Increase blood vol. > increase blood pressure
Kidney-cardiovascular connection
ADH > produced by posterior pituitary
Role: 1. Increase water permeability of C.D. (Insertion of aquaporin channels)
2. Increase thirst
Result: decrease ECF OP
Thirst (behavioral drive)
Promoted by: high ADH
Angiotensin (activated by kidney)
Increase water intake from outside
Increase blood vol. > increase blood pressure
Feed forward systems
Sensors in GI tract that signal what is coming
Water sensors > respond (increase AP freq.)
>signal brain > decrease sensation of thirst
Control blood Na
Control blood volume
Control blood pressure
NaCl is the dominant ECF solute
Change NaCl - change OP and volume
How is NaCl, volume and pressure regulated
- Nephron of kidney has specialized cells called the juxtaglomerular apparatus (JGA)
- JGA cells can release an enzyme called renin
A) decrease afferent arteriole pressure
B) sympathetic nervous stimulation of JGA
C) macula densa can cause JGA to release renin when Na is low - Renin is a protease - convert an inactive plasma protein called angiotensinogen > made by liver > angiotensinogen I (cleave 10 amino acids)
- Angiotensin I > angiotensin II (active)
ACE: angiotensin converting enzyme - Angiotensin II
A) promotes peripheral vasoconstriction (increase resistance > increase pressure)
B) stimulates cardiovascular control center in medulla to increase sympathetic activity > increase HR, increase SV, increase C.O., increase BP
C) stimulates cells in the brain to promote behavioral changes and induce thirst > increase water intake, increase blood vol. > increase BP
D) causes adrenal gland to produce and secrete the steroid hormone aldosterone
Aldosterone
Steroid
Enter the cells of the distal tubule (contain receptor for aldosterone)
Aldosterone binds receptor
Complex is then imported into the nucleus
Behaves as a transcription factor
Cause the transcription factor of Na transporters (Na channels, Na/K exchangers, NaK-ATPase)
Distal tubule will then start reabsorbing more NaCl
> increase NaCl
> increase osmosis
> increase fluid reabsorption
> increase blood vol.
> increase blood pressure
Other factors that can induce aldosterone release
1. Increase in ECF K conc. > stimulate the adrenal cortex to release aldosterone > make more Na/K exchangers > reabsorb Na but secrete K 2. Renin-angiotensin coupling
Regulatory response to high blood pressure
Pressure is measured at baroreceptors
Pressure is measured in atrial stretch receptors
Increase pressure in atria > produce and release atrial natriuretic factor (ANF)
What does ANF do?
A) cause vasodilation B) decrease NaCl transport and fluid reabsorption > Distal tubule Decrease NaCl Decrease fluid reabsorption Increase urine vol. Decrease blood vol. > GI tract Decrease NaCl Decrease fluid absorption Decrease fluid entering body C) ANF stimulates mesangial cells of glomerulus > decrease slit resistance > increase GFR > increase urine production (decrease blood vol.) D) ANF decrease sympathetic activity at the cardiovascular control center in medulla (decrease C.O., and BP)
ANF
Decrease NaCl transport Decrease fluid reabsorption Decrease blood vol. Decrease blood pressure Vasodilator > decrease resistance flow > decrease pressure Decrease sympathetic activity Decrease slit resistance at the glomerulus > increase GFR > increase urine production > decrease blood pressure
Adrenomedulin
Peptide
Produced by adrenal gland, kidney, cardiac tissue
Increase K conductance > hyper polarize
A) decrease sympathetic AP freq. (short term response)
B) decrease aldosterone secretion
(Long term response)
Control acid-base balance
pH has a dramatic influence on protein structure > therefore, must maintain pH within narrow limits 1. Fixed acids > amino acids > fatty acids > nucleic acids > citric acids 2. CO2 production CO2 + H2O <> H2CO3 <> H + HCO3 Increase CO2 > increase H (decrease pH)
Mechanisms to combat changes in pH
1. pH buffers > very fast > low overall capacity 2. Ventilatory compensation > fast (respiratory compensations) 3. Renal excretion > very high capacity > slower 1 and 2 provide time to allow renal system to physically excrete protons (H)
Buffers
Proteins
Phosphate
HCO3
Bind or release protons (H) depending on pH
Respiratory compensation
Changes in ventilation rate drives by changes in pH
Respiratory compensation for metabolic acidosis
> lactic acid > keto acids Increase ventilation Decrease PCO2 Decrease H (proton conc.)
Respiratory compensation for metabolic alkalosis
Vomiting Increase pH Ventilation decrease > increase PCO2 > increase H (proton conc., decrease pH)
Renal compensation
Proximal tubule Decrease pH in urine Amino acid deamination > release ammonia (NH3) > very toxic Liver NH3 converted into urea NH3 + H > NH4 (when pH decreases) NH3 > permeable (can exit urine) NH4 > charged > impermeable > trapped in urine
Distal tubule
Type A intercalated cells
Secrete protons (H) into urine Decrease pH in urine Increase pH in blood H into urine HCO3 into blood Cl into cell HCl into urine
Type B intercalated cell
Secrete HCO3 into urine and H into blood Increase pH in urine Decrease pH in blood HCO3 into urine Cl from urine into cell H into blood
Intercalated cells of distal tubule
Responsible for fine tuning blood pH
Bring either secreted excess H into the urine (type A)
Or secrete excess HCO3 into the urine (type B)
Regulation of calcium
C-cells of the thyroid
Chief cells of the parathyroid
Above monitor Ca conc.
Calcium decreases in the blood
parathyroid releases PTH
Result: 1. PTH stimulates osteoclasts
Osteoclasts involved in bone remodeling, demineralization, release Ca into blood
2. Inhibit osteoblasts
> bone producing cells
> decrease rate of Ca deposition in the bone
3. Stimulates urinary Ca reabsorption (transport) > increase Ca reabsorption in the nephron
4. Stimulates production of calcitriol by the kidneys
Calcitriol
Steroid
Promotes transcription of Ca transporters
A) nephron
B) GI tract (increase uptake of Ca and overall body Ca)
Calcium increases in blood
Stimulate thyroid to release calcitonin
Result: 1. Inhibit osteoclasts
2. Inhibit or reduce Ca transport in the nephron distal tubule
Increase urinary Ca excretion
Digestion
Mouth Pharynx Epiglottis Esophagus > esophageal sphincter Stomach > pyloric sphincter Small intestine > duodenum, jejunum, ileum Large intestine > colon, rectum Anal sphincter (15 ft long) Accessory organs > secrete into GI tract A) salivary glands B) pancreas C) liver
Layers of GI tract
Mucosa
Sub mucosa
Musculature
Serosa
Mucosa
Inner lining Lots of invaginations Increase surface are Increase transport rate Cells have micro villi
Submucosa
Connective tissue
Blood vessels
Lymph vessels
Enteric nerves (unique to GI tract)
Musculature
Layers of SM Circular SM (changes radius) Longitudinal SM (changes length) Myenteric plexus controls and coordinates the motor activity of the muscularis externa
Serosa
Connective tissue
Holds the macrostructure in place
Continuation of the peritoneal that lines the abdominal cavity
Motility (movement)
How do you control the GI SM A) enteric nerves B) GI hormones C) local paracrine factors D) stretch activated (mechanically gated ion channels)
Peristaltic contractions
Progress wave of SM contractions
Move food forward
Segmental contractions
Mixing
Kneading
Back and forth contractions
Controlled by enteric nerves
Route through GI tract
- Physically > mastication (chewing), essentially breaking in down into smaller pieces (⬆️ surface area)
- Saliva > moisten, lubricates,water, antibodies, mucus, salts, amylase
- Swallowing reflex > trigger reflex by pushing the food bolus against the soft palate
- Pressure on the esophagus side of the esophageal sphincter cause the sphincter to relax, if sphincter does not close properly can lead to heart burn
- Enters stomach, segmental and peristaltic contractions > push chyme against pyloric sphincter
- Empty stomach slowly
- SI SM becomes activated, segmental followed by peristaltic contractions
- Continued until rectum > stored, wait for defication
Amylase
Breaks glycosidic bonds that form polymers
Breaks down carbs
Keep mouth clean
Chemical digestion
Starts in stomach > gastric glands that produce hormones, histamines, acid, digestive enzymes Protection > mucus bicarbonate Parietal cells > produce HCL Chief cells > make pesinogen Enterochromatin cells > histamines Endocrine cells > hormone (gastrin) D-cells G-cells Mucus cells > binds water
Digestion
Pancreas > stimulated by CCK to release enzymes
Reach intestine > trypsinogen to trypsin by enteropeptides
Trypsin activates all other enzymes
Trypsin and chymotrypsin are both endopeptidase
Carboxypeptidase > pancreas
Aminopeptidase > intestine
Gastric glands
Mucus cells > produce the protective barrier that lines the stomach, constantly replenished
Parietal cells > produce HCl
Chief cells > make and release digestive enzymes, pepsinogen, and gastric lipase
Release contents by exocytosis
K and Cl move out along with water by osmosis
KCl helps power HCl, trade K for H
Activating gastric gland
Parasympathetic innervation (Ach) > stimulates muscorinic cholinergic receptors
Reflex stimulation > sight, smell, taste, anticipation
Feed forward response
G-cells of the gastric gland > release gastrin
Further stomach activation
SM churning action
Activate the enzymes by low pH
Pepsinogen to pepsin
Endopeptidase breaks a peptide bond in the middle of the chain
Pepsin
Cleave glycine-lysine linkages
Very common in collagen
Designed to break connective tissue
CCK
Produced by endocrine cells in small intestine
Stimulates the pancreas
Promotes the secretion of digestive enzymes (made in acinar cells)
Enzymes
Trypsinogen Chymotrypsinogen Pro-carboxypeptidase Phospholipase Lipases target triglycerides/fat Amylase targets carbs Nuclease breaks polymer bonds, DNA/RNA Enzymes are inactive in the pancreas
Inactive enzymes
Zymogens
High activity in beginning
Activate decreases as you progress (self degradation)
Small intestine
Receiving chyme from stomach
Decreases pH > cause release of secretin > cause the pancreas to produce an alkaline fluid to neutralize the acid
Increase proteins
Increase carbs > release CCK > cause pancreas to release digestive enzymes
CCK
- Release digestive enzymes
- Inhibits gastrin secretion (slow the rate of chyme entry into SI)
- Stimulates gall bladder (contracts and push bile into SI)
- Stimulates intestinal SM peristalsis (contractions)
- Acts on the CNS > decrease hunger
Mucous surface cell
Substance secreted:
Function of secretion:
Mucus
Physical barrier between lumen and epithelium
Mucous neck cell
Substance secreted
Function of secretion
Bicarbonate
Buffers gastric acid to prevent damage to epithelium
Parietal cells
Substance secreted
Function of secretion
Gastric acid (HCl) and intrinsic factor
HCl: activates pepsin; kills bacteria
IF: complexes with vitamin B12 to permit absorption
Enterochromaffin-like cell
Substance secreted
Function of secretion
Histamine
Stimulates gastric acid secretion
Chief cells
Substance secreted
Function of substance
Activation of enzymes
Pepsin(ogen) and gastric lipase
Pepsin: digest proteins
GL: digest fats
Ach and acid secretion
D cells
Substance secreted
Function of substance
Somatostatin
Inhibits gastric acid secretion
G cells
Substance secreted
Function of substance
Gastrin
Stimulates gastric acid secretion
Gastric lipase
Breaks down triglycerides (fats)
Secreted by chief cells
Pepsin
Secreted by gastric gland Protein digestion Effective on collagen so digests meat Protease Cleaves glycine-lysine linkages
Trypsin
Converts other pancreatic zymogens to their active forms
Protease
Pancreas
Chymotrypsin
Protease
Pancreas
Carboxypeptidase
Exopeptidase
Act on carboxy-terminal end
Pancreas
Aminopeptidase
Exopeptidase
Acts on amino-terminal end of protein
Intestine
Endopeptidase
Digest protein
Attacks peptide bonds in their interior of the amino acid chain and break long peptide chain
Pancreas
Enteropeptidease
Concerts trypsinogen to trypsin
Pancreas
Amylase
Digest starch to maltose
Made by pancreas
Breaks long glucose polymers into smaller glucose chains and disaccharide maltose
Exopeptidase
Digest protein
Release single amino acids from peptides by chopping them off the ends, one at a time
Secreted by pancreas
Lipase
Breaks down triglycerides
Removes two fatty acids
Gastrin
Site of production
Target effects
Stimulus for release
G cells
Stomach
Stimulates gastric acid secretion and mucosal growth
Peptides and amino acids; neural reflexes
Cholecystokinin (CCK)
Site of production
Target effect
Stimulus for release
Small intestine
Stimulates gallbladder contraction and pancreatic enzyme secretion and inhibits gastric emptying and acid secretion
Fatty acids and some amino acids
Secretin
Site of production
Target effect
Stimulus for release
Small intestine
Stimulates HCO3 secretion, inhibits gastric emptying and acid secretion
Acid in small intestine
Motilin
Site of production
Target effect
Stimulus for release
Small intestine
Stimulates migrating motor complex
Fasting
Gastric inhibitory peptide (GIP)
Site of production
Target effect
Stimulus for release
Small intestine
Stimulates insulin release (feed forward) inhibits gastric emptying and acid secretion
Glucose, fatty acids, and amino acids in small intestine
Glucagon-like-peptide-1 (GLP-1)
Site of production
Target effect
Stimulus for release
Small intestine
Stimulates insulin release, inhibits glucagon release and gastric function
Mixed meal that includes carbs or fats in lumen
Basophils and mast cells
Abundance
Function
Classification
Rare
Release chemicals that mediates inflammation and allergic responses
Granulocytitic
Eosinophils
Abundance
Function
Classification
1-3%
Destroy invaders, particularly antibody coated parasites
Cytotoxic and granulocytitic
Neutrophils
Abundance
Function
Classification
50-70%
Ingest and destroy invaders
Phagocytitic
Monocytes and macrophages
Abundance
Function
Classification
1-6%
Ingest and destroy invaders, antigen presenting
Antigen presenting
Phagocytitic
Lymphocytes and plasma cells
Abundance
Function
Classification
20-35%
Specific responses to invaders, including antibody production
Antigen presenting and cytotoxic
Dendritic cells
Abundance
Function
Classification
N/A
Recognize pathogens and activate other immune cells by antigen presenting
Antigen presenting
IgG antibody
Found in plasma of adults
IgA antibody
Found in external secretions (saliva, tears, interstitial and bronchial mucus, breast milk)
IgE antibody
Attach to basophils and mast cells
IgM antibody
Blood group antigens
IgD antibody
Appear on the surface of B lymphocytes along with IgM antibodies