Phys Test

Alveoli

site of gas exchange with the blood

Type 1 alverolar cells

flat epithelial cells = continuous layer

type 2 alveolar cells

produce surfactant

Lungs

Passive, elastic structures, volume fluctuates

As volume increases

pressure decreases

as volume decreases

pressure increases

Main function of the respiratory system

supply the body tissues with oxygen and dispose of CO2

Respiration includes

pulmonary ventilation and gas exchange

what is pulmonary ventilation

exchange of air btw atmosphere and alveoli

External respiration

movement of O2 from lungs into blood, CO2 from blood to lungs

Internal respiration

Movement of O2 from blood into tissue cells, CO2 from cells to blood.

during inspiration

atmosphere pressure > Alveoli pressure

during expiration

atmosphere pressure < alveoli pressure

What does the diaphragm do during inspiration

Flattens/ contracts

what does the diaphragm do during expiration

Releaxes/ dome shape

How does inspiration work

Motor neurons firing AP into intercostal muscles and diaphragm

Enlarging thoracic cavity allows what

lungs to enlarge and cause increase in size of alveoli

inspiration is a

active movement, uses energy (ATP)

how does expiration work

motor neurons decrease AP, muscles relax

expiration is a

passive movement of lungs

How do O₂ and CO₂ move between alveoli, blood, and tissues?

Gases move from HIGH partial pressure → LOW partial pressure

O₂ movement:

Alveoli (HIGH) → Blood → Tissues (LOW)

CO₂ movement:

Tissues (HIGH) → Blood → Alveoli (LOW)

Oxyhemoglobin

binding oxygen with hemoglobin

deoxyhemoglobin

produced when oxyhemoglobin releases oxygen

what are the 2 forms of O2 in the blood

Dissolved in plasma and combined with hemoglobin molecules

What is oxygen loading?

Loading = oxygen binding to hemoglobin in the lungs
Occurs when PO₂ is high
O₂ moves from alveoli → pulmonary capillaries
Forms oxyhemoglobin

What is oxygen unloading?

Unloading = oxygen released from hemoglobin in tissues
Occurs when PO₂ is low
O₂ moves from blood → tissues
Forms deoxyhemoglobin

Where does loading occur vs unloading?

Loading → lungs
Unloading → systemic tissues

What causes oxygen loading?

High PO₂ in lungs
High affinity of hemoglobin for oxygen
O₂ diffuses alveoli → blood

What causes oxygen unloading?

Low PO₂ in tissues
Tissues using oxygen
O₂ diffuses blood → tissues

What decreases hemoglobin affinity and promotes unloading?

Low pH
High temperature
These decrease affinity and cause oxygen release

Why can't hemoglobin have extremely high affinity for oxygen?

If affinity too high, oxygen would not unload
Tissues would not receive oxygen

What are the CO2 removal ways

Dissolved into plasma

Some react with hemoglobin

Converted into HCO3

carried in RBC

What is CO2

Waste product that produces H+ which gives it a toxicity

What is the equation?

CO2 + H2O —> H2CO3 —> H+ + HCO3

what is the purpose of Carbonic anhydrase (CA)

it catalyzes the reaction to form carbonic acid

What is the chloride shift?

Movement of bicarbonate (HCO₃⁻) out of red blood cell
Chloride (Cl⁻) moves into cell
Maintains electrical neutrality

Why does bicarbonate leave the red blood cell?

CO₂ converted to carbonic acid
Carbonic acid dissociates into H⁺ and HCO₃⁻
Bicarbonate builds up in cell and diffuses out

What moves into the red blood cell during chloride shift?

Chloride ions (Cl⁻) move into cell
Balances charge when bicarbonate leaves

Where does chloride shift occur?

Occurs in tissues
CO₂ enters red blood cells
Converted to bicarbonate for transport

What happens during reverse chloride shift?

Occurs in lungs
Bicarbonate enters red blood cell
Chloride leaves cell
CO₂ formed and exhaled

inspiration movement

diaphragm contracts downward and the thoracic cavity is larger

expiration movement

diaphragm relaxes and the recoil drives air out, passively

respiratory rhythm is generated in the

Medulla Oblongata

purpose of carotid bodies

monitor oxygen supply to the brain

What happens to PCO₂ when ventilation decreases?

PCO₂ increases

What happens to H⁺ when PCO₂ increases?

H⁺ increases

What happens to pH when H⁺ increases?

pH decreases

What do peripheral chemoreceptors detect?

Changes in H⁺ concentration

What happens when chemoreceptors detect increased H⁺?

They signal the medulla

What does the medulla do in response to increased H⁺?

Increases ventilation

Front:
What happens to CO₂ when ventilation increases?

CO₂ decreases

What happens to pH when CO₂ decreases?

pH increases toward normal

What is the normal pH for blood

7.35- 7.45

how is pH maintained

Through Lungs- CO2 and kidneys- bicarbonate

Acidosis

When plasma H+ increases, pH below 7.4

Alkalosis

When plasma H+ decreases, pH above 7.4

decrease in CO2 means

increase in H+ concentration

Hypoventilation

Low pH, acidosis, high CO2

Hyperventilation

High pH, alkalosis, low CO2

secretion

The body adds something into urine.

reabsorption

The body takes something back into the bloodstream.

What are the 2 sets of capillaries

Glomerular and peritubular

Glomerular

filtration

Peritubular

reabsorption of filtrate to blood supply

Gain of pH

Generation of H+ from CO2

gain H+ due to loss of HCO3 in diarrhea and urine

Loss of pH

Loss of H+ in vomit and urine, hyperventilation

Compensation- FULL

pH is normal

Compensation- NOT

other variables are normal

Compensation- PARTIAL

acid/alk each hold a variable, pH NOT normal.

Parts of a nephron

1 - Renal corpuscle

2 - proximal convoluted tubule

3 - loop of henle

4 - distal convoluted tubule

5 - cortical collecting duct

Glomerular filtration

Efficient and passive process, moves through the nephron k

reabsorption is

filtrate (nephron —> kidney)

What happens during glomerular filtration?

Plasma filtered into tubule

What is the next step after glomerular filtration?

Proximal convoluted tubule reabsorption

What is heavily reabsorbed in the proximal tubule?

Glucose and organic nutrients

What else is reabsorbed in the proximal tubule?

Water and many ions

How much reabsorption occurs in the proximal tubule?

About 65%

How is sodium reabsorbed in the nephron?

Active transport

How is water reabsorbed in the nephron?

Osmosis following sodium

What happens in the descending loop of Henle?

Water reabsorbed

Is the descending loop permeable to solutes?

No, only water

What happens in the ascending loop of Henle?

Solutes reabsorbed

Is the ascending loop permeable to water?

no :(

What happens after the loop of Henle?

Distal tubule regulation

Which parts are hormonally regulated?

Distal tubule and collecting duct

What does vasopressin (ADH) do?

Increases water reabsorption

Where does ADH act?

Collecting duct

What does more vasopressin cause?

More water retained, less urine

sodium reabsorption

Na and Cl combine to make salt that will drive the reabsorption of water

Na is reabsorbed by

primary active transport

The descending loop of henle is

impermeable

the ascending limp is

permeable

What is the countercurrent multiplier?

Interaction between ascending and descending loop creating concentration gradient

What leaves the descending limb?

Water

what leaves the ascending limn

solutes

Result of countercurrent multiplier?

hypertonic renal medulla

thirst is triggered by

increase in plasma osmolality and decrease in extracellular fluid

more vasopression (ADH) =

more aquaporings = more water retained = less water secreted