Physiology Flashcards
Roles of the Pulmonary (Respiratory) system?
Roles of the Pulmonary (Respiratory) system
- *1) Regulate plasma levels of oxygen and carbon dioxide** (most important)
- *2) Regulate plasma pH**
3) Protect against inhaled pathogens
4) Provide an adequate surface for gas exchange with the external environment
5) Assure adequate alveolar air movement by alterations in rate and depth of ventilation
6) Support vocalization of sound
Why makes the interpleurral space?
Lungs have tendancy to collapse, ribs have tendancy to expand.
At rest, diaphragm is__________
relaxed
When inhaling, the diaphragm _________ and thoracic volume ________.
diaphragm contracts, thoracic volume increases
When exhaling, the diaphragm _______, and thoracic volume ________
relaxes, volume decreases
Does length of trachea, etc affect air resistance?
yes, but it’s a constant; unaffected by other things
[higher pressure gradient, higher flow
higher resistance, lower the flow]
read others on picture
what mediates bronchoconstriction?
parasympathetic neurons
histamines
leukotriens
what factors affect bronchodilation?
carbon dioside
epinephrine
(want to dilate lungs in fear rxn…)
what happens if intrapleural space is invaded? (pneumothorax)
lung collapses
VT=
tidal volume
normal volume of air displaced when breathing normally
about the same in men and women
What is ERV?
expiratory reserve volume
amount of air that can be expired from the lungs by deterined effort after normal expiration
greater in men than in women
IRV =
inspiratory reserve volume
additional amount of air you can breath in
What is inspiratory capacity?
IRV + VT
RV?
residual volume - can’t move it out of lungs
What is the difference between capacities and volumes?
capacities are sums of 2 or more volumes
What is eupnea?
normal quiet breathing
What is hypernea?
increases respiratory rate and/or vol. in response to increase metabolism
(like exercise)
What is hyperventilation?
increased respiratory rate and/or vol. without increased metabolism
(panic attack, blowing up a balloon)
What is Hypoventilation?
decreased alveolar ventilation
shallow breathing, asthma
what is Tachypnea
rapid breathing; usually increased respiratory rate with decreased depth
ie panting
what is dyspnea
difficulty breathing
various pathologies or hard exercise
what is apnea?
cessation of breathing
voluntary breath-holding, depression of CNS control centers
Define Hypoxic hypoxia
low arterial PO2
high altitude; alveolar hypoventilation, decreased lung diffusion capacity; abnormal ventilation-perfusion ratio
define anemic hypoxia
decreased total amount of O2 bound to hemoglobin
blood loss, anemia (low {Hb] or altered HbO2 binding); carbon monoxide poisoning
Define ISchemic hypoxia
reduced blood flow
heart failure (whole-bpdy hypoxia); shock (peripheral hypoxia) thrombosis (hypoxia in a single organ)
define histoxic hypoxia
failure of cells to use O2 because cells have been poisioned
cyanice and other metabolic poisons
What regulates ventilation?
**peripheral chemoreceptors **
located in carotid and aortic arteries
specilzed glomus cells
sense changes in PO2, pH, and PCO2
centeral chemoreceptors
changes in CO2
What happens when PO2 decreases?
carotid body oxygen sensor releases neurotransmitter
(K+ channels close, cell depolarizes, voltage-gated Ca2+ channel opens, Ca2+ enters, neurotransmitters undergo exocytosis, reach receptor on sensry neuron, cause aciton potential)
What monitors CO2 in cerebrospinal fluid?
central chemoreceptors
What are the “controlled variables” that influence pulmonary function?
plasma levels of oxygen, carbon dioxide, and pH - it responds to increases plasma PCO2 and decrease PO2
Negative feedback essential for homeostatic regulation
change in co2 or o2 invfluence
What are the roles of the Renal system?
Kidneys:
1) Regulate extracellular fluid volume and blood pressure
2) Regulate osmolarity
3) Maintain ion balance
4) Regulate pH
5) Excrete waste
6) Produce hormones
histology of the kidney:
list outside to inside?
capsule
then cortex
then medulla where the filtering part extend through medulla and cortex before filtering out thru ureters
What are the critical parts of the kidney?
Nephrons:
short loops, long loops…filtrate passes through and is altered in various ways. After comes up into cortex, the tubule goes all the way thru the medulla and dumps nuron into renal pelvis
Bowman’s capsule is characterized by:
an inflow arteriole called the affarent arteriole. Remember they have ability to change their diameter (site of resistance). (If it constricts, less gets through, less filtration)
also has outflow arteriole - the efferent arteriole (if that constricts, forces more filtration.)
blood then goes into another capillary bed near the medulla - a portal where it particpates in absorbing the fluid that comes through the lopps and ducts.
180 L filtered a day.
What is the relationship between the urine production rate, the glomerular filtration rate, and the tubular reabsorption rate?
Urine Production Rate =
Glomerular Filtration Rate - Tubular Reabsorption Rate
Normal GFR = ~180 L/day
Normal Urine Rate = ~1-2 L/day
(highly variable depending on fluid intake)
What does the urinary excretion of a substance depend on?
on its filtration, reabsorption, and secretion
“clearance” = how much blood is cleared of a substance
What is special about glucose filtration?
it has special transporters to bring it back to blood - it’s reabsorbed, not gotten rid of
transporters can be overwhelmed (at 300 mg/100mL plasma) and sugar will spill over into urine - at the renal threshold
how does kidney control blood volume and blood pressure?
through sodium and water excretion
what are the Roles of the Gastro-Intestinal (Digestive) System?
1) Provide a connection with the external environment for ingesting nutrients and eliminating wastes
2) Regulate the secretory and motility processes involved in normal gut function
3) Assure that ingested nutrients are digested to absorbable forms
4) Provide an absorptive surface for nutrients (etc.) uptake
5) Protect against ingested pathogens
What must the volume of fluid entering the GI tract equal?
must equal the volume leaving
what are layers of the GI tract?
mucosa
submucose
muscles
What do the secretory cells of the gastic mucosa do?
read all
What do parietal cells secrete?
gastric acid (HCL into the lumen of the stomach) and intrinsic factor
what stimulates parietal cell to release HCL and intrinsic factor?
acetylcholine
gastrin
histamines
What do parietal secretions do?
HCL activates pepsin, kills bacteria
Intrinsic factor complexes with vitamin B12 to permit absorption
more on secretion of hydrochloric acid
Water is dissociated using carbonate anhydrase; bicarbonate goes out back end of cell, H H is actively pumped (using K+) out front end of cell into stomach.
proton pump inhibitors stop this from happen
(will also affect bone remodeling)
Where are nerves in the GI?
in the submucosal plexus and the myenteric plexus
How are long and short reflexes in the digestive system integrated?
it’s controlled by autonomic nervous system, but affected by somatic nervous system
Reflexes invovlving GI Peptides
Summarize motility, secretion, digestion, and absorption in different regions of the digestive system
*note: some absorption DOES happen in oral cavity
What are the 3 cells we’re interested in in the gut?
gastrin (stimulates acid secreation by acting on parietal cells; also act on D cellls - stimulate acid secretion by actin through histamine)
secretin (slows down gastric motiltiy and acid/enzyme secretion - turns off the gastric stage when acid reaches the intestines)
cholosytrokinin (?)
could treat hyperacidity by cutting the vegas nerve (it affects acidity; don’t do it any more)
GASTRIC STAGE BEGINS AS SOON AS FOOD ENTERS STOMACH
can small intestine handle the acid?
no, so chyme (mixed up food) inhibits gastric motility and secretion
INTESTINAL PHASE
gastric stage turned off when acid reached intestine.
Primary homeostatic roles of the CV system:
CV provides a mass transit system to move materials around body
total blood volume ~ 5L
Q =
deltaP/R
ie. flow = pressure difference/resistance
units of each = mL/time; mmHg1; mmHg x time/volume
bigger the delta P, the greater the flow.
radius of vessel determines resistance - smaller the vessel, higher the resistance to flow.
but with so many capillaries, the collective cross-sectional area is huge, and the collective resistance is low
What allows blood flow to individual systemic organs to be independently controlled?
arrangement of systemic organs individual circulations iin parallel
while that of pulmonary circulation and systemic circulation are arranged in series
What two factors control mean arterial pressure?
MAP = CO x TPR
MAP Imean arterial pressure) is the controlled variable, and it equals cardiac output times total peripheral resistance.
if either of those two goes up, MAP will go up
blood flow pathway:
inferior vena cava & superior vena cava
right atrium
tricuspid valve
right venticle
pulmonary valve
pulmonary artery
lungs
pulmonary veins
left atrium
mitral valve
left ventricle
aortic valve
aorta
body
What are the 2 determinants of cardiac output?
CO = HR x SV
cardiac output = heart rate (beats per minute) time stroke volume (volume per beat)
Which vascular segment has the greatest effect on total peripheral vascular resistance?
ARTERIOLES
What happens during ventricular systole?
ventricular diastole?
systole pumps;
diastole fills
what makes hearts beat…
pacemaker cells in SA node set heart rate (spontaneous firing)
action potential slow down going throu AV node…
smooth muscle contractions in arterioles can change their diamter - what effect does that have on pressure?
what nerves control this?
if increases diameter, TPR goes down
sympathetic nerves - when bear comes in, start running, arterioles dialete, TPR goes down
What controls arterolie pressure?
Arterial baroreceptor
(stretch receptors) signal medulla, resulting in alertion of sypathetic and parasympathetic nerves
pressure in arteries is determined by CO and TPR - sympathetic activity works to increase arterial pressure
when bp goes down, receptors fire less, telling medulla that bp is low
Where is the MAP established?
in the medullary cardiovascular center.
Increases or decreases in MAP from set point start compensatory resopnses
What happens when you stand up?
venous pressure in lower legs goes up
this decreases central veouns pressure
decrease blood returning to heart
makes CO fall
drops MAP
causes decreased firing of arterial baroreceptors
Medullary Cardiovascular Center - sees blood pressure drop: slows down the heart by removing parasympathetic and adding sympathetic, Increase contractice force of heart (contracting veins and arteries), increase stroke volume, all counteract fall in BP and return it to normal
Define physiology:
study of how the various parts of the body work together to achieve optimal functiono capacity of the body
What is homeostasis?
we have an open system, need constancy, mechanisms are required to maintain this constancy
regulating systems that determine homeostatic state consist of a # of cooperating mechanisms acting simultaneously or successively.
Name the major physiological roles of the organ systems
Integumentary
Musculoskeletal
Respiratory
Digestive
Urinary
Reproductive
Circulatory
Nervous and Endocrine
Immune
they’re all aimed at controlling certain variables
Integumentary (defends/protects/holds/together/heat exchange)
Musculoskeletal
Respiratory (gas exchange)
Digestive (take in and break down nutrients)
Urinary (control salt/water in body)
Reproductive
Circulatory (mass transport system)
Nervous and Endocrine (allow to interact with environment, though do not specifically condition blood itself)
Immune (protects from outside environment)
What is the difference between teleological and mechanistic approaches to understanding physiological processes?
Teleological asks WHY
Mechanistic asks HOW
what is a controlled variable?
must be kept in a very narrow range
like arterial blood pressure, blood glucose…
What is a set point?
point the controlled variable needs to be at
What is steady state?
may be change, but no net change
What is a negative feedback system?
acts to maintain control variable at set value…
like MAP: if it goes DOWN, detected by detector, contacts medulla, medula sends out signals thru nersoi st that tel heart and blood vessels to bring it back up
What is a positive feedback system?
acts to reinforce a change in a variable, accelerates the change, leads to an explosion and breakdown of homeostatic system
What are the essential components for a neural reflex?
signal, sensory receptor, afferent neurons, integrating center, efferent neurons, effector organs (like a muscle or a gland)
What are the essential components for a hormonal reflex?
same as neural, but it is humoral signals being carried by chemicals in the blood instead of neural connections
What is the difference between endocrine
neurocrine
paracrine
autocrine?
- endocrines (hormones), carried in the blood to distant target cells
- neurocrine (neurotransmitters), released from nerves acting on neighboring cells
- paracrines (local chemical messengers) that acting on neighboring cells
- autocrines (locally secreted chemical messengers that act on the secreting cell)
