Bio 2301 PRST

What two nerves work to produce the pupillary reflex?

- CN II (optic) and CN III (occulomotor)

Why is the pupillary reflex a consensual reflex?

A unilateral stimulus produces a bilateral response (light shined into either eye will cause both pupils to restrict)

Cause and effect sequence of increased cardiac output

Increased cardiac output -> increased BP -> decreased resistance

Cause and effect sequence of decreased cardiac output

Decreased cardiac output -> decreased BP -> increased resistance

Cause and effect sequence of increased resistance

Increased resistance -> increase BP -> decreased cardiac output

What pH, carbon dioxide, and respiratory rate changes would be expected after an infusion of an acid?

- As acids introduce hydrogen ions, it lowers blood pH

- The respiratory chemoreceptors would respond to the low pH with an increase in ventilation in an effort to bring the pH back up

- The increase in ventilation would case an increase in CO2 removal from the blood

- This is metabolic acidosis

Barbiturate abuse can suppress respiration. How would this affect blood pH and carbon dioxide levels?

- Decreased ventilation will cause CO2 to be retained

- Increasing blood CO2 will lower pH causing a respiration acidosis

- decreased resp. rate -> increased carbon dioxide -> decreased pH

How will plasma osmolarity change if the kidneys retain more sodium (assume that body water and other electrolytes are unchanged)?

As osmolarity is a ratio of solute concentration over solution volume, retaining more solute (sodium in this case) will increase the osmolarity

How will plasma osmolarity change if the kidneys excrete more water (assume that other electrolytes are unchanged)?

Loss of water decreasing the solution volume would increase the ratio of solutes to total solution volume and, therefore, increase osmolarity

Assume that the kidneys begin to retain more water than usual, but less sodium. How will this affect plasma osmolarity? How could aldosterone and ADH secretion be manipulated in order to induce this change?

- With less sodium and more water, the ratio of solute to solution volume would decrease, thereby decreasing osmolarity

- ADH increases collecting duct permeability allowing more water to be reabsorbed. Therefore, increasing ADH secretion could create the extra water retention described.

- Aldosterone drives sodium reabsorption at the kidneys. Therefore, reduced aldosterone secretion could cause the reduced sodium retention described

How can aldosterone and ADH secretion be adjusted in order to maximize water retention?

- Increasing both aldosterone and ADH secretion will maximize water retention

- The aldosterone increases sodium reabsorption creating a large osmotic gradient

- The ADH increases collecting duct permeability so that the water can freely follow the gradient

In addition to increasing aldosterone levels, how does the increase in renin that results during low blood pressure help to increase the blood pressure (hint: consider the effects of angiotensin II)?

- Renin causes the production of angiotensin II which constricts blood vessels

- Such vasoconstriction increases peripheral resistance and, therefore, tends to increase blood pressure

Describe the hormonal response to an increased osmolarity (as induced in Series 1)

ADH levels increase and aldosterone levels decrease in response to the increased osmolarity.

How do the changes in aldosterone and ADH secretion help correct the osmolarity problem?

- Increased ADH levels will increase water retention

- Decreased aldosterone levels will reduce sodium retention

- Expanding the amount of water in the body while reducing the amount of sodium will decrease the ratio of solutes to solution volume, thereby, reducing the osmolarity

Describe the hormonal responses to a decrease in osmolarity (as induced in Series 2)?

ADH levels decreased and aldosterone levels increased in response to the decrease in osmolarity

How do the changes in aldosterone and ADH secretion help to correct the osmolarity problem?

- Decreased ADH levels will increase water loss by the body

- Increased aldosterone levels will increase sodium retention

- With increased solute retention and decreased body water, the ratio of solute to total solution will increase, thereby increasing the osmolarity

How do the changes in aldosterone and ADH that occur during low blood pressure affect water reabsorption at the kidneys?

- The increases in ADH and aldosterone levels will maximize water retention

- The aldosterone will create a large osmotic gradient, while ADH allows water to freely follow that gradient

Explain the low urine potassium levels that developed during Series 1 as a consequence of increased sodium intake, and the high urine potassium levels during Series 2 as a consequence of decreased sodium intake.

- Many of the aldosterone sensitive active transport pumps which reabsorb sodium will co-transport potassium in the opposite directions. - Therefore, increased aldosterone secretion cause both increased sodium reabsorption, and increased potassium excretion.

- In Series 1, aldosterone levels decreased in response to the excess of sodium in the body. This decreased the counter transport of sodium and potassium.

- With less sodium reabsorption, there was less potassium excretion than usual, leading to the low urine potassium levels.

- In Series 2, aldosterone levels increased in response to the low blood sodium levels.

- As the active transporters were turned on to increase sodium retention, they excreted more potassium. This created the high urine potassium levels.

Since psychoactive drugs typically interact either with different receptors or enzymes, suggest at least three different ways in which drugs could alter communication between neurons.

- Acting as a agotnist or antagoist of the natural neurotransmitter

- Interfere with the functioning of the reuptake receptor leading to an accumulation of neurotransmitter in the synapse

- Could interfere with synaptic enzymes preventing digestion of the neurotransmitter leading to accumulation in the synapse

How would neurotransmitter levels be affected by an MAOI and how would this be different from an SSRI? (Include in your answer the specific neurotransmitter and how their levels in the synaptic cleft would change)

- MAOI medications, since they inhibit the enzyme monoamine oxidase, will caused increased levels or epi, norepi, seratonin, and dopamine at the synaptic clefts

- SSRIs will cause increased levels of serotonin at the synaptic cleft by preventing reuptake

How could that help alleviate the symptoms of depression?

Decreases in norepi and serotonin have been suspected in depression so increased levels of these neurotransmitters in the synaptic cleft will cause enhanced communications between neurons

Which would be expected to have more side effects, an MAOI or an SSRI, and why?

- MAOI because they influence levels of more things than SSRIs

- Side effects are increased BP, especially when taken along any other medication that increases BP like nasal decongestants which cause vasoconstriction

What effect does epinephrine/norepinephrine have on the alpha receptors of the iris of the eye or the skeletal muscle vasculature?

- Iris: Contraction of the radial muscle and mydriasis (dilation of pupil)

- On skeletal muscle vasculature they cause vasoconstriction which can increase BP

What would be the result in each of those places if the alpha 1 receptors were blocked? That explains why you can often tell which types of medication people are taking by looking at their pupils!

If alpha 1 receptors were blocked there would be constriction of the pupils and vasodilation in the muscles causing a drop in BP

Many illegal drugs are sympathetic agonists. What would the pupils of someone taking such sympathomimetic drugs look like?

Dilated pupils

Where the beta 1 and beta 2 receptors found and what are the results when they are activated?

- Beta 1: found on the heart, increase heart rate and strength of contraction

- Beta 2: found on skeletal muscle and bronchioles, cause vasodilation, increased strength of muscle contraction, and bronchodilation

Since the alpha 1 receptors were blocked by a medication in the above patient, how would an injection of epinephrine affect the blood vessels and blood pressure (ignore the effect on the heart and focus on changes in vascular tone)?

Vasoconstriction effect caused by alpha 1 receptors is prevented so injection of epi would cause vasodilation, which would cause a decreased in TPR and a decrease in BP

A patient with normal strength displays a waddling gait and maintains a wide stance in order to stay upright. When seated quietly the patient's muscles are quiet. The patient has great difficulty when asked to touch an index finger to the nose. A Romberg test could not be performed as the patient was unable to balance reliably with feet together even with eyes open.

Ataxia and an intention tremor indicated this subject has a cerebellar lesion

A patient with normal strength displays a resting tremor in the left arm. The tremor diminishes when the arm is in motion (such as when the patient is reaching for something, or when the patient is asked to touch finger to nose). [note: in the real world the character of the tremor and its rate would be important. for our purposes, however, we have only considered one source of resting tremor]

A resting tremor indicates a basal ganglia lesion

A patient with normal strength complains of unusual clumsiness lately. The patient displays a positive sign during the Romberg test (sways with eyes closed). With the patient lying down, a physician moves the big toe up and down. The patient is asked to identify dorsiflexion and plantarflexion of the toe without looking. The patient responds "What's dorsoflexion?" Subsequently the patient is asked if the big toe is up or down. The patient is unable to correctly identify the position of the toe.

Since the subject is unable to sense the position of his limbs in space, he is suffering from a proprioceptive deficit

Another patient with normal strength complains of dizziness. Blood pressure (sitting and standing), blood hemoglobin levels, and blood oxygen levels are all determined to be normal. The patient displays a positive sign during the Romberg test (sways with eyes closed). Unlike the patient above, this patient has no difficulty sensing the position of limbs and digits in space. When asked to describe the feelings of dizziness, the patient explains that it feels like they have been spinning on a carnival ride.

The spinning sensation tends to cooroborate this as a deficiency in the vestibular systems which detects head rotation

Name three hypothalamic hormones that normally stimulate and one that normally inhibits prolactin (PRL) secretion

- Stimulate: VIP, TRH, ocytocin

- Inhibit: dopamine

In the case of a hypothyroidism induced by a hyperprolactinemia (as in the case of the mother with the pituitary adenoma), what would the levels of PRL, TRH, TSH, and thyroid hormones be? (high, low, normal)

- Prolactin levels high

- THR, TSH, and thyroid homone levels would be low

An agonist of what hypothalamic hormone might be valuable in treating the above condition?

Dopamine agonist

In the case of a hyperprolactinemia induced by a non-functioning thyroid, what would the levels of PRL, TRH, TSH, and thyroid hormones be? (high, low, normal)

- Thyroid levels would be high

- TSH, TRH, and prolactin would be low

Administration of what hormone could be valuable in treating the above condition?

Thyroid hormones

A patient has increased respiratory rate, confusion, disorientation, and smelly breath. What blood chemistry values for pH, carbon dioxide, bicarbonate, and oxygen would one expect in this patient when the patient was brought into the ER? (normal, low, high)

- The patient is experience metabolic acidosis

- pH: low

- CO2: low

- Bicarbonate: low

- Oxygen: at least normal

How would the respiratory and renal systems be helping to compensate for the pH effectsof the ketone body production?

- Respiratory: increasing ventilation to try and get rid of excess CO2/H+ ions and raise the pH

- Buffers: weak bases of the buffers would be reaction with excess H+

Renal: excreting H+ and retaining bicarbonate to raise pH

Patient begins hyperventilation. What form of pH imbalance was this latter patient experiencing and how is the pH imbalance related to the hyperventilation?

- Respiratory alkalosis

- The hyperventilation is the cause of the increase in pH

What levels of blood pH, carbon dioxide, bicarbonate, and oxygen would be expected in this patient? (normal, low, high)

- pH: high

- CO2: low

- Bicarbonate: low

- Oxygen:normal