Physiology Flashcards
Catecholamines
Stimulation of our organs by the sympathetic nervous system.
Trigger “fight or flight” response.
What are some of the catecholamines?
noradrenaline (norepinephrine) and adrenaline (epinephrine)
Miosis
Narrowing the pupil
Constriction
Parasympathetic activation
Contraction of the sphincter muscle
Mydriasis
Dilation
Sympathetic activation
Dilator pupillae muscle contraction
Atropine blocks muscarinic receptors
Hypothalamus
a region of the forebrain below the thalamus which coordinates both the autonomic nervous system and the activity of the pituitary, controlling body temperature, thirst, hunger, and other homeostatic systems, and involved in sleep and emotional activity.
What does NO (nitric oxide) do to vascular smooth muscles?
Muscle relaxation and vasodilation
Parathyroid hormone and calcium
Classic negative feedback system.
The parathyroid hormone helps maintain an appropriate balance of calcium in the bloodstream and in tissues that depend on calcium for proper functioning.
Conservation of calcium by the kidneys.
In the bones, the hormone triggers the release of calcium stores from the bones to the blood leading to bone destruction.
In the intestines, the parathyroid hormone helps with vitamin D metabolism.
Forced Expiratory Volume 1
How much air is exhaled in one second (forced breath).
In healthy individuals, 80% of air is exhaled in the first second.
Good for diagnosing patients with obstructive lung disease
Where is calcitriol vitamin D made?
Kidney
Kep in mind
Steroid hormones vitamin D, thyroid hormone acting through nuclear DNA binding receptors.
or
Vitamin D had nuclear DNA binding transcription regulatory receptors.
Vitamin D receptor in the nucleus…
Binds VDREs
T4
major form of thyroid hormone made in the thyroid gland. It can be activated to T3.
Medulla
Most neurons responsible for respiratory regulation are in the medulla.
Some are in the pons (pneumotaxic control center).
What is the importance of the pneumotaxic
Control of respiratory rate and depth of breathing.
Curare
Competes with ACh for receptors.
It acts postsynaptically.
BoTox
Blocks release of ACh from presynaptic terminals
the neuron botulinum toxin interferes with SNARE proteins responsible for vesicular ACh release and results in flaccid paralysis of muscle exposed to the toxin, including the diaphragm.
What are the slowest fibers?
Unmyelinated C fibers.
Function - postganglionic autonomic fibers; pain and temperature.
Slow, chronic, aching pain.
Remember
The larger the diameter of an axon, the faster it will be.
Rod sodium channels are regulated by binding which of the following
cGMP
Growth hormone
Secreted by the anterior pituitary
Secretion stimulated by GHRH
Secretion inhibited by somatostatin.
Most effects of GH are mediated by IGF-1.
GH stimulates the release of IGF-1 from hepatocytes.
IGF-1 activated tyrosine kinase receptors on cells and stimulates cell division
Alpha motor neurons
they are the motor neurons that innervate the long muscle fibers that go full length
Gamma motor neurons
They innervate short muscle fibers
They innervate muscle spindle cells
Which neurotransmitter is used by alpha motor neurons?
Acetylcholine
What part of the brain controls the body temperature setpoint?
Hypothalamus
What is the hippocampus known for?
Memory storage
Why is GABA so popular as an inhibitory neurotransmitter?
type A GABARs
They are ligand-gated channels.
Which neuron is most likely to be an inhibitory neuron
Interneuron
Which of the following is most likely to cause an inhibitory post-synaptic potential?
GABA
Which ion channel is most commonly associated with hyperpolarization?
Chloride channel
Adrenergic receptors
G Protein-coupled
Troponin
key calcium-binding protein for regulating striated muscle contraction in smooth muscle.
What is the major excitatory transmitter?
Glutamate
involved in memory formation
Cell death if overstimulated
The nicotinic acetylcholine receptor is what type of protein?
Ligand-gated ion channel
Remember
Chronic hypertension is a leading cause of kidney failure.
Short-term: an increase in BP leads to an initial increase in GFR causing pressure diuresis (increased urine).
Long-term: damages the glomeruli eventually destroying it (reduced GFR).
Baroreceptos reflexes - sit to stand
Reduced activity of baroreceptors - reduced parasympathetic stimulation - increased sympathetic stimulation - increased cardiac output and vascular resistance and increased blood pressure.
Va/Q ration
Va = Alveolar ventilation
Q = blood flow
Ratio of fresh air delivered to alveoli to the amount of blood flowing past those alveoli through the pulmonary capillaries.
When a person is standing, gravity pulls blood towards the bottom of the lungs meaning higher perfusion at the bottom of the lungs. Very low perfusion at the top of the lungs - all due to gravity.
What autonomic subclass division is responsible for sweating?
Sympathetic nervous system.
Skin has nerves that mediate vasodilation and increased blood flow to the surface of the body.
Cholinergic post-ganglionic fibers of the sympathetic division mediate which of the following?
Cutaneous vasodilation.
Which neurotransmitter is used by the sympathetic nervous system to send signals to target tissues?
Norepinephrine.
95% of shympathetic postganglionic axons are going to be using norepinephrine,
Remember
Most of the clotting factors are present in the bloodstream, proteins like prothrombin, fibrinogen, clotting factor X are present in the bloodstream all waiting to be activated.
Tissue factor is found on the walls of blood vessels.
What is the natural pacemaker of the heart?
The SA node (sinoatrial node).
Found at the junction of the crista terminalis in the upper wall of the right atrium and the opening of the superior vena cava.
During AV block
The atria contract at a faster rate than the ventricles. The ectopic pacemaker cells in the back of the AV node take over to keep the ventricles contracting in the patient like this has fewer funny channels so the ventricles don’t depolarize as quickly.
Anything that isn’t the SA node (normal pacemaker) is called an ectopic pacemaker
During ventricular systole
Isovolumetric contraction starts and mitral valve closes, then aortic valve opens, rapid ejection reduced ejection, the aortic valve closes.
During ventricular systole
Isovolumetric relaxation, rapid ventricular filling, mitral valve opens
During regulation of respiration, low oxygen is detected by
cells in the carotid bodies.
Feed-forward regulation
during exercise
It is normally good at anticipating respiratory demands.
The nervous system apparently learns through experience how to anticipate demand even before oxygen levels start to drop.
Remember!
Va = alveolar ventilation (fresh air delivery)
Q = blood flow to alveoli
Hypoxemia: partial pressure of oxygen in arteries is below 85 mm Hg
Low VA/q due to chronic obstructive lung disease: blocked airways
In general patients with COPD will have low ventilation-perfusion ratio
The aortic valve opens at the start of
The ejection phase
What is the first phase of ventricular systole?
Isovolumetric contraction
Which of the following would decrease blood flow to the intestine?
Norepinephrine from sympathetic neurons.
Bed rest causes
reduced blood volume.
Experienced by astronauts as well.
Curiosity
Physiologists believe that it is the level of CO2 in the body that provide the major signal to the brain stem for regulating
respiratory muscle activity.
Hering-Breuer
It is thought when you are near full capacity when you are taking a deep breath when these sensors in the lungs are activated noticing the stretch from the stretch that was caused to the lungs
The Hering–Breuer inflation reflex, named for Josef Breuer and Ewald Hering, is a reflex triggered to prevent the over-inflation of the lung. Pulmonary stretch receptors present on the wall of bronchi and bronchioles of the airways respond to excessive stretching of the lung during large inspirations.
J Receptors
In the alveoli
The stimulation of the J-receptors causes a reflex increase in breathing rate and is also thought to be involved in the sensation of dyspnea, the subjective sensation of difficulty breathing.
These cells are activated by physical engorgement of the pulmonary capillaries or increased pulmonary interstitial volume.
Cough reflex
respond to foreign matter or chemical stimuli
Cheyne-Stokes breathing is
alternating hypo- and hyperventilation.
It is an unusual pattern of breathing typically seen in a pulmonary disease patient that is having patient adequately ventilating their lungs. CO2 builds up causing the patient to hyperventilate
Obstructive sleep apnea
loss to muscle tone in upper respiratory airways
reduced upper airway muscle activity during sleep
O2 goes down and CO2 goes up
Overweight patient. Excess neck fat can be more risk.
It can impinge the airways.
High altetude respiration
causes hypoxia-induced hyperventilation due to the reduced atmospheric pressure and partial pressure of oxygen.
What is altered when respiration acclimatizes to high altitudes?
Sensitivity of chemosensory neurons
What is the normal compensation for metabolic acidosis?
Hyperventilation - it will remove more CO2 from the blood than usual and that helps bring the blood pH back closer to normal
What happens when you don’t have enough iodine?
Prevents the production of thyroid hormone.
The body realizes thyroid hormone is not being produced enough causing more release of TSH.
What does TSH (thyroid-stimulating hormone) do?
Stimulates the production of thyroid hormones and the growth of the thyroid gland
GI secretions
Stomach: acid, pepsin
Pancreas: bicarbonate, digestive enzymes
Liver: major secretions - bicarbonate, bile acids)
Intestines: bicarbonate. Anywhere down the line of the intestines, it can realize too much acidity in the body thus releasing bicarbonate to neutralize it.
Brush border enzymes
Enzymes of the epithelial apical membrane:
mostly in upper jejunum
lactase, sucrase, maltase
enteropeptidase - an enzyme of the brush border. It activates trypsin which activates chymotrypsinogen into chymotrypsin
What initiates intestinal slow waves (jargon for depolarization)?
Interstitial cells of Cajal
What is the role of Cholecystokinin in the GI tract?
To stimulate secretion of bile
Cholecystokinin is released from the small intestine when you are digesting a meal
It induces satiety.
Increase rate of pancreatic fluid.
Which of the following is a substrate for enteropeptidase?
Trypsinogen
Leydig cell
They produce testosterone. Testosterone can migrate into the bloodstream or diffuse through nearby membranes (basement membrane) or into Sertoli cells.
Small population
Where is testosterone converted into estrogen (estradiol)?
Sertoli cells
What converts testosterone to estradiol?
Aromatase is an enzyme that catalyzes the rate-limiting step of testosterone and androstenedione conversion into estradiol and estrone
Which of the following promotes breast development and inhibition of full lactogenesis?
Progesterone
Cytochrome P450
Major enzyme type of the endoplasmic reticulum in hepatocytes.
plays a key role in the metabolism of drugs and other xenobiotics
VO2
The velocity or the rate at which we can take up oxygen and deliver to our skeletal muscle tissues.
Exercise-induced changes to skeletal muscle
Acidification (pH can reach 6.8)
Increase skeletal muscle cell oxidative capacity
What protein normally helps prevent edema?
Albumin
Starlin curve
Curve shifts up and to the right. The venous return has to match cardiac output
chronotropic effect
Speeding heartbeat
Just know
Stimulation of the Beta1-adrenergic receptors in the heart results in positive inotropic (increases contractility), chronotropic (increases heart rate), dromotropic (increases rate of conduction through AV node) and lusitropic (increases relaxation of myocardium during diastole) effects.
Two sources of blood that can reach the liver
Portal circulation and hepatic arterioles
Cholinergic postganglionic fibers of the sympathetic division mediate which of the following?
Cutaneous vasodilation
Just know
In the board’s exam, if you are asked about refilling or about the ejection phase, do not fall for the word ISOVOLUMETRIC as it means NO CHANGE IN VOLUME
The aortic valve opens during
ventricular systole
Most warm sensation is carried by which nerve type?
Unmyelinated C fibers
Most cold sensation is carried by which nerve type?
Myelinated fibers
What core body temperature causes damage to the brain and cells of the body?
41.3 degrees Celcius or 106 degrees F.
28 degrees C
At what external temperature do we start sweating?
ABove 85 degrees F
what does pepsin do?
chief digestive enzyme in the stomach, which breaks down proteins into polypeptides.
What converts pepsinogen (inactive form) into pepsin?
HCL
Where are pepsinogens produced?
Pepsinogens are synthesized and secreted primarily by the gastric chief cells
