human physiology lecture exam 3

What is the difference between intra-alveolar pressure & intra-pleural pressure?

intra-alveolar = pressure within the alveoli

intra-pleural = pressure exerted outside the lungs within the thoracic cavity

What keeps the lungs stretched apart? 

1. intrapleural fluid cohesiveness

2. transmural pressure gradient = intra-alveolar pressure > intra-pleural pressure - expands lungs

3. gradient exists across thoracic wall - keeps thoracic cavity compressed

How does air flow into & out of the lungs?

changes in the intra-alveolar pressure due to respiratory muscle activity

What is Boyle’s Law? How does this relate to inspiration & expiration?

at any constant temperature, pressure exerted by a gas varies inversely with volume

• p1v1 = p2v2

• respiratory muscle dont directly affect lung volume, they affect volume of thoracic cavity

• diaphragm contracts —> increase volume of cavity —> lungs expand and intra alveolar pressure decreases

• air will come in as long as intra alveolar pressure < atmospheric pressure

What branch of the ANS controls bronchoconstriction? Bronchodilation?

branchoconstriction = parasympathetic = smooth muscle contraction

• histamine

Bronchodilation = sympathetic = smooth muscle relaxation

• epinephrine

What is alveolar surface tension? What is its function? Why do we need it?

definition = force exerted by H2O molecules on the alveolar surface

• determining factor of the passive recoil of lungs

• too high = lungs collapse and low compliance (hard to inflate)

1. tendency to oppose expansion of the alveoli

2. reduces size of the alveoli

3. allow elastic recoil

How do the pulmonary arterioles respond to decreased levels of oxygen? Is this different from systemic arterioles? 

pulmonary: vasoconstrict = decreases blood flow so more O2 transfer

systemic: vasodilate = increase blood flow to tissues

What is pulmonary surfactant? What cells secrete it? 

1. from type II cells

2. lowers cohesiveness of water = lower surface tension

   • increase compliancy = easier to inflate

   • reduces recoiling so lungs dont collapse

3. stabilize size of alveoli

What is the difference between obstructive & restrictive lung disease? 

obstructive = difficulty emptying lungs

• TLC normal

• FRC and RV elevated bc more air trapped in lungs

• less TLC available to be used in exchanging air with the atmosphere

restrictive = lungs less compliant - cant expand

• TLC, IC, VC reduced

What is dead-space volume? 

portion of inhaled air that is not available for gas exchange

Define partial pressure. 

pressure exerted by a gas within a mixture of gases

What factors influence gas diffusion?

1. SA

   • increase = increase diffusion

2. thickness of barrier

   • increase = decrease diffusion

3. diffusion coefficient of gas

   • increase = increase diffusion

How is oxygen transported in the blood? 

1. dissolved - very little

2. bound to hemoglobin

What is the law of mass action?

reversible reaction is determined by the concentration of the molecules involved

• Hb + O2 ←→ HbO2

• O2 increase (increase PO2) = HbO2 is favored

What does the oxygen-Hb dissociation curve tell us? 

relationship bw partial pressure of oxygen in the blood and the percentage of hemoglobin saturated with oxygen

• plateau = pulmonary capillaries

• steep = systemic capillaries

  • O2 dropped off to meet high tissue demands

How does Hb promote the movement of oxygen into the blood? 

1. O2 movement into blood is determined by PO2 gradient

2. O2 moves into blood —> Hb binds with it —> decrease PO2 in blood

3. alveolar and blood PO2 levels equilibrate = Hb is maximally saturated

What affects the ability of oxygen to bind to Hb?

1. increase in PCO2 = decreases affinity bw Hb and O2

   • important at systemic capillaries

2. increase in acidity = decreases affinity bw Hb and O2

   • indication of metabolic activity

What is the BOHR effect? 

CO2 binds to Hb —> Hb releases O2

What is the function 2,3 DPG? 

• increase in DPG decrease affinity bw Hb and O2

• DPG increase when HbO2 is below normal

  • allows O2 to be released, but also prevent O2 loading since RBC carry DPG

How is carbon dioxide transported in the blood? 

1. physically dissolved

2. bound to Hb

3. as bicarbonate

4. chloride shift

What is the HALDANE effect? 

release O2 —> snatch CO2

What is hypoxia? What are the different types of hypoxia? 

hypoxia = insufficient O2

1. hypoxic = low arterial PO2, inadequate Hb saturation

   • high altitude or suffocating environment

2. anemic = reduced O2 carrying capacity of blood

   • decrease in RBC or Hb or CO poisoning

3. circulatory = too little oxygenated blood delivered to tissue

   • heart failure or vessel blockage

4. histotoxic = O2 delivery is normal but cells cant use it

   • cyanide poisoning block ETC

What is hyperoxia? 

high arterial PO2

• O2 toxicity = high PO2 can damage cells

What is hypercapnia? What is hypocapnia?

hypercapnia = excess CO2

• caused by hypoventilation

hypocapnia = below normal CO2

• caused by hyperventilation

What is respiratory acidosis? Respiratory alkalosis?

acidosis = hypercapnia; excess CO2 generated H+

alkalosis = hypocapnia - less CO2 generated H+

 What is the difference between a tropic hormone & a non-tropic hormone? 

tropic = regulate production of another hormone

non-tropic = exerts its effect on non-endocrine target tissues

What hormone is secreted by the pineal gland? What are the functions of this hormone?

secretes melatonin - sleep

What hormones are secreted by the anterior pituitary gland? What are their functions?

** hypothalamus controls secretion

Growth hormone - overall body growth

TSH - Stimulates thyroid hormone secretion; growth of thyroid gland

ACTH - Stimulates cortisol secretion by adrenal cortex; growth of adrenal cortex

FSH - Stimulates gamete production

LH - Stimulate ovulation; secretion of estrogen & progesterone in females; testosterone in males

Prolactin- Enhances breast development & milk production

What hormones are secreted by the posterior pituitary? Where were these hormones produced (be specific)?

• secreted by it BUT produced in supraoptic and paraventricular nucleus

1. Oxytocin- Increases uterine contractility; Stimulates milk ejection

2. Vasopressin- Increases H2O permeability in kidneys’ collecting tubules; Induces arteriolar vasoconstriction

What is calcitonin & what cells secrete it? 

• proper calcium metabolism

• secreted by C cells

What are T3 & T4? 

inhibit TSH release

What are the 3 layers of the adrenal glands cortex? What hormones are produced by them?

1. zone glomerulosa - aldosterone

2. zona fasciculata - cortisol and sex hormone production

3. zona reticularis - cortisol and sex hormone production

What hormone classes are secreted by the adrenal glands? 

1. mineralcorticoids - mineral balance

   • aldosterone

2. glucocorticoids - energy metabolism

   • cortisol

3. sex hormones

What are the functions of aldosterone? How is its release stimulated? 

• transported by albumin

1. Na+ retention in distal & collecting tubules

2. Enhances K+ secretion

3. Activated by renin-angiotensin system due to blood pressuredrop/Na+ decrease

4. Direct stimulation of adrenal cortex by elevated K+

What is the function of cortisol? 

• transported by transcortin

1. Stimulates hepatic gluconeogenesis = conversion of non-carbohydrate sources into carbohydrates

2. Inhibits glucose uptake by tissues, except the brain

3. Stimulates protein degradation

4. Facilitates lipolysis- lipid breakdown

5. glucose, fat, and protein metabolism

Cortisol is regulated by what hormone? 

ACTH

What is the function of DHEA? What hormone regulates it?

maintenance of female sex drive

• ACTH

What cells secrete insulin? What is its function? 

• secreted by beta cells

• promote storage, lowers blood glucose

What causes insulin to be released?

1. increase in blood glucose

2. increase in blood amino acid levels

3. GIP is released in response to food

4. parasympathetic stimulation

What is the difference between type I and type II diabetes? 

I = lack of insulin secretion

II = reduced sensitivity of insulin target cells

What cells secrete glucagons? What is its function?

• secreted by pancreatic islet alpha cells

• increase blood glucose

What are the vascular, combined vascular/tubular, & tubular components of the nephron?

VASCULAR

1. afferent arteriole

2. glomerulus

3. efferent arteriole

4. peritubular capillaries

COMBINED

1. juxtaglomerular apparatus

TUBULAR

1. bowman’s capsule

2. proximal convoluted tubule

3. loop of henle

4. distal convoluted tubule

5. collecting duct

What are the 3 structures that filter blood plasma into filtrate/urine? 

1. endothelial fenestrations - restrict RBC

2. basement membrane - large proteins

3. podocyte slit membranes - medium sized protein

What are the factors that move water into and out of the glomerulus? 

1. glomerular capillary blood pressure

2. plasma-colloid osmotic pressure

3. bowman’s capsule hydrostatic pressure

GFR = ? 

GFR = Kf x net filration pressure

What is Kf? What variables are built into Kf?

• filtration coefficient

1. surface area

2. permeability

How is capillary blood pressure regulated to maintain a constant GFR? 

• regulating blood flow into the glomerular capillaries via changes in the arteriole resistance

• auto-regulation prevent spontaneous change in GFR

1. GFR changes are directly proportional to arterial pressure

2. kidneys maintain constant GFR via myogenic mechanism or tubuloglomerular feedback mechanism

What is the myogenic mechanism ?

When blood pressure increases (GFR increased), afferent arteriole (smooth) are stretched and respond by contracting to resist the pressure, resulting in little change in flow and restore GFR back to normal

tubuloglomerular feedback mechanism

1. macula densa cells detect changes in the flow rate of fluid passing by them

2. they signal granular cells in the wall of the afferent arteriole to release vasoactive chemicals

3. These chemicals will either vasodilate or vasoconstrict the arteriole to re-establish normal arteriolar pressure and hence GFR

How can the GFR autoregulatory mechanism be harmful to us?

if plasma volume drops —> blood pressure decreased = GFR decreased

• mechanism would increase GFR by vasodilating afferent arteriole leading to normal urine excretion

 extrinsic control mechanism for blood pressure and how does it relate to renal functioning

1. plasma loss = decrease in BP

2. baroreceptor reflex kick in = increased sympathetic activity

3. vasoconstriction of arterioles

4. decreases glomerular capillary blood pressure

5. decreases GFR = decrease urine volume = conservation of fluid and salt

6. increases arterial blood pressure

How can Kf be modulated? 

modify SA (mesangial cell) and permeability (podocytes)

What cells serve as pre-capillary sphincters in the glomerulus? 

mesangial cell

• contract = close off section of capillaries

 How can the permeability of the glomerulus be modulated?

podocytes contract = less number of slit filters

What reabsorbed molecules rely on sodium reabsorption? 

• glucose, amino acid, H2O, Cl-, urea

What secreted molecules rely on sodium reabsorption?

k+ and H+

Where is the sodium-potassium ATPase pump located/ 

basolateral membrane

How is sodium reabsorption regulated (discuss aldosterone & atrial naturetic peptide)?

IN DISTAL

• renin-angiotensin-aldosterone promote uptake

• atrial natriuretic peptide promote loss

How are glucose & amino acids reabsorbed? 

by Na+ dependent secondary active transport

• lumen - has co transport carriers

• basolateral - has facilitated carriers

What is Tm? 

maximum rate at which a substance can be reabsorbed or secreted by the kidney tubules

• glucose cant be altered

What determines Tm?

1. max number of available carriers

2. once all carriers are bounded, the rate will plateau

What does parathyroid hormone regulate?

alter Tm and hence renal threshold to alter PO4 reabsorption

How are potassium & hydrogen ion secretion related to one another? 

basolateral membrane pump can exchange either K+ or H+ for Na+

• secretion of one will affect the other

 What does the vertical osmotic gradient refer to? 

• from cortex medulla junction to the deep part of medulla ( in kidney)

• has zones of different osmolarity stacked

 What parts of the tubule and impermeable vs. permeable to water?

permeable: descending limb of the loop of henle

impermeable: ascending limb of the loop of henle

How does ADH make the collecting tubules permeable to water?

• ADH will change the permeability of the collecting ducts so that water can be reabsorbed

• ADH reaches the basolateral membrane —> binds to receptors —> activates cAMP second messenger

• increase cAMP stimulates incorporation of water channels into the apical membrane —> increase permeability

What can result in renal failure? 

1. metabolic acidosis - inability of the kidneys to secrete H+ = depression of the CNS

2. Potassium retention - Leading to altered cardiac & neural excitability

3. Anemia- Caused by inadequate erythropoetin production

4. Uremic toxicity- Caused by retention of waste products = leading to nausea, vomiting, nervous system abnormalities

5. Loss of plasma proteins- Leading to edema

What cells initiate slow wave potentials? 

interstitial cells of Cajal

What 2 nerve plexuses modulate digestive tract activity?

1. myenteric (auerbach)

2. submucosal (meissner)

What enzymes are utilized in the mouth? 

1. salivary amylase = carbohydrates

2. lingual lipase = lipids

3. lysozyme = antibacterial

What stomach factors determine how fast the stomach empties (gastric emptying) its contents?

1. volume of chyme = distends smooth muscle increases emptying

2. vagus nerve and gastrin = increase emptying

3. fluidity of chyme = increased fluidity = increased emptying

What duodenum factors halt gastric emptying? 

fat, acid, hypertonicity, and distension all halt emptying = decrease antral peristaltic activity via nerve and hormones

What hormones are involved in inhibiting gastric emptying? 

secretin, CCK, GIP (gastric inhibitory peptide)

What 3 cell types are found in the gastric pits of the fundus & body? What do they secrete?

1. mucous neck cells - mucus

2. chief cells - pepsinogen

3. parietal cells - HCl and intrinsic factor

What cell in the stomach secretes gastrin? 

G cells

What is the function of enterokinase? 

turns trypsinogen to trypsin

Name all of the enzymes secreted by the pancreas 

amylase = carbohydrate

lipase = lipid

ribonuclease and deoxyribonuclease = nucleic acid

trypsinogen, chymotrypsinogen, procarboxypeptidase = protein

What is the function of the gall bladder?

stores and concentrates bile

What is the function of bile? 

emulsify fat into small droplets - increase SA for lipid digestion

What hormones are involved in regulating pancreatic secretions?

1. hormonally regulated with small parasympathetic influence

2. secretin - in response to acid in duodenum

3. CCK - in response to fat and protein in duodenum

What are brush border enzymes? 

• break molecules into monomer for absorption

enterokinase

disaccharidases (carbohydrate) - maltase, sucrase, lactase, alpha-dextrinase

protein - peptidase

nucleotides - nucleodases and phosphatases

What is the function of having villi & microvilli in the small intestines? 

increased SA and absorption

What are the 3 sections of the small intestines?

duodenum, jejunum, ileum

Know everything concerning the uterine & ovarian cycles! 

MENSTRUAL PHASE

1. menstrual flow

2. secondary follicles in ovaries enlarge

3. stratum functionalis sloughed off bc of decrease in estrogen and progesterone

PREOVULATORY

1. FSH stimulates growth of follicles, each will secrete estrogen and inhibin

2. one follicle will outgrow and inhibit others by secreting more estrogen and inhibit —> decrease FSH secretion

3. one follicle —> graafian follice

   • produce estrogen will stimulate growth of stratum functionalis

4. climbing estrogen levels = inhibits FSH secretion at pituitary gland and hypothalamus

5. LH secretion is steadily rising

OVULATION

1. high levels of estrogen causes hypothalamus and pituitary to increase FSH and LH secretion

2. LH surge induce ovulation

3. ovum is ovulated and follicle becomes corpus hemorrhagicum —> corpus luteum

   • luteum secretes progesterone, estrogen, relaxin, inhibin

Know all of the male accessory sex glands, their secretions, & functions.

1. seminal vesicle - prostaglandin for sperm viability and induce female contractions

   • semenogelin to coagulate - keep sperm in reproductive tract

   • fructose for energy

2. prostate gland - clotting enzyme for semenogelin to coagulate

• fibrinolysin decoagulates

• citric acid for energy

1. cowper gland - consist of alkaline mucus to lubricate lumen of the urethra

What muscle regulates the temperature of the testes? 

cremaster muscle

What are the functions of Sertoli cells & Leydig cells? 

SERTOLI

• support, protect, nourish developing spermatogenic cells

• mediate the effects of testerone and FSH on sperm

LEYDIG

• secrete testerone

What is the acrosome? 

secretory vesicle filled with fertilization enzymes to penetrate zona pellucida and corona radiata

What is the function of the epididymis? 

site of sperm maturation, sperm storage, and dead sperm reabsorption

What are the 3 sections of the male urethra? 

1. prostatic urethra

2. membranous urethra

3. spongy (penile) urethra

What are the spongy masses in the penis

corpus spongiosum

 What ligaments support the penis? 

fundiform and suspensory

What ligaments support the ovaries?

broad - ligament of uterus which attaches to the ovaries

ovarian - anchor to uterus

suspensory - anchor to pelvic wall

What is the function of the corpus luteum? 

produces progesterone, estrogen, relaxin, inhibin

What are the corona radiata & zona pellucida?

corona radiata - outer layer around the zona pellucida

zona pellucida - clear glycoprotein layer bw primary oocyte and granulosa cell

What are the 3 sections of the fallopian tubes? 

1. infundibulum

2. ampulla

3. isthmus

What are the 3 layers of the uterus’ wall?

perimetrium - outer

myometrium

endometrium

What are the two layers of the endometrium?

stratum functionalis

stratum basalis

 What is the function of the myoepithelial cells of the mammary glands?

surround alveoli and provide contractile force to move milk within breast