Question

Question 3 (10 points) Based on the Underhills' stress levels that night, which of the following represent long-loop negative feedback mechanisms that you would expect in this case? Select TWO CRH stimulates cortisol ACTH stimulates CRH Part 1 Cortisol inhibits ACTH ACTH inhibits CRH Cast of Characters . Sam Garrison - Detective • Roma and Clint Underhill - The hot couple • Kavita Dickson - EMR paramedics • Larry Gonzales - Policeman T3 and T4 inhibit CRH T3 and T4 inhibit TRH TSH stimulates T3 and T4 Cortisol inhibits CRH Friday, 7PM Roma and Clint Underhill had both had a long, stressful day. They were the owners of a successful real estate company and the strain of the current real estate market was getting to them. It had been an unusually cool day for June, with temperatures hovering around 14°C. On coming home, they decided to relax in their hot tub with some wine. While Roma changed from her work clothes, Clint said that he would join her in the hot tub after he took his blood pressure measurement: it read 122/86 mm Hg and his pulse was 72 beats per minute. He was happy: his physician recently told him he was at risk of chronic hypertension, so lower blood pressure was good news! To be sure it remained that way. Clint took one more furosemide pill that his physician had prescribed to help control his blood pressure. Question 4 (10 points) Alcohol also inhibits the release of anti-diuretic hormone (ADH). In the normal ADH endocrine reflex, dehydration stimulates neurons in the hypothalamus to produce ADH. ADH travels down the axons of the neurons to the posterior pituitary, where it is released into the blood. ADH binds to its cell-surface receptors on the kidneys to maintain water in the body, rather than being excreted in the urine. Based on this information, which of the following statements is/are TRUE? Question 1 (10 points) Based on the information given above, Clint's pulse pressure is mm Hg and his mean arterial pressure is Select all that apply. mm Hg ADH acts as the output signal in this reflex pathway For each blank: enter one number, no decimals..no units. Round up or down, as appropriate. ADH is a steroid hormone ADH acts primarily by increasing the transcription and translation of new proteins in the kidneys' cells Question 2 (10 points) Alcohol affects many physiological processes. For instance, acute alcohol consumption stimulates the release of corticotropin-releasing hormone (CRH) from the hypothalamus. Based on this information, which of the following event(s) would happen following wine consumption by the Underhills? The kidneys act as the sensor in this reflex pathway Select all that apply. Due to their alcohol consumption, the Underhills were more prone to dehydration. Release of adrenocorticotropic hormone (ACTH) from the adrenal cortex ADH has a relatively short half-life Release of adrenocorticotropic hormone (ACTH) from the anterior pituitary ADH is lipophobic Release of adrenocorticotropic hormone (ACTH) from the posterior pituitary Increased blood glucose levels Decreased blood glucose levels Increased synthesis and release of triiodothyronine (T3 hormone) Decreased synthesis and release of triiodothyronine (T3 hormone) Increased glucose release from the liver Decreased glucose release from the liver

Answer 1

Question 1

Pulse pressure denote the force generated by cardiac muscles during each contraction which is measured in millimeters of mercury.

The formula is,

Pulse pressure ( mm Hg )= Systolic blood pressure ^{$\large -$} Diastolic blood pressure( difference between systolic and diastolic blood pressure)

Clint's blood pressure = 122/86 mm Hg

Systolic blood pressure = 122

Diastolic blood pressure = 86

Thus, Pulse pressure = 122-86

=36 mm Hg

Mean arterial pressure is the average pressure measured in a individual's arteries during a complete cardiac cycle.

The formula is,

Mean arterial pressure(mm Hg) = Diastolic blood pressure x 2 + Systolic blood pressuresum

3

(Sum of doubled diastolic blood pressure and systolic blood pressure divided by 3 is approximate mean arterial pressure in mm Hg)

Clint's blood pressure = 122/86 mm Hg

Systolic blood pressure = 122

Diastolic blood pressure = 86

Mean arterial pressure = (86 x 2) + 122

3

=172 + 122

3

= 98 mm Hg

Thus the answer is, Clint's pulse pressure is 36 mm Hg and his mean arterial pressure is 98 mm Hg.

Question 2

Corticotropin releasing hormone(CRH) from the hypothalamus will stimulate the anterior pituitary to secrete adrenocorticotropic hormone(ACTH) which act on adrenal cortex to release cortisol. Cortisol breakdown the muscle protein into amino acids. These amino acids will be used by the liver for gluconeogenesis (synthesis of glucose from non carbohydrate compounds) thus cause increased glucose level in blood. Both CRH and cortisole inhibit the release of THyroid stimulating hormone(TSH) from the anterior pituitary and inhibit production of thyroid hormones. Cortisole directlely reduce the level of T3 by inhibiting the convertion of T4 to active form of T3 and also increse reverse coversion of T3 to T4, thereby decrese the level of T3 hormone.

Thus the answers are,

Release of adrenocorticotropic hormone from the anterior pituitary.

Increased blood glucose level.

Decrease synthesis and release of triiodothyronine (T3 hormone)

Increase glucose release from the liver

Question 3

Hormones released from the peripheral endocrine glands inhibit pituitary gland and/or hypothalamus secretions. This is known as long-loop negative feedback mechanism.

Under the stress, hypothalamus and pituitary secrete corticotropin releasing hormone(CRH) and adrenocorticotropic hormone(ACTH) respectively, thereby elevate cortisol level in the blood. Elevated cortisol level inhibits release of CRH from hypothalamus and ACTH from anterior pituitary.

Hence answers are,

Cortisol inhibits ACTH

Cortisol inhibits CRH

Question 4

In normal ADH endocrine reflex, dehydration or decreased blood volume etc. stimulates osmoreceptors (sensory receptor) that sent sensory input to the hypothalamic neurosecretory cells to release ADH. The ADH secreted from posterior pituitary act as an output signal to the effector kidney for the absorption of water .

ADH is made up of polypeptides, hence it is not a steroid hormone. ADH is highly water soluble (hydrophlic), so it has shorter half life(15-20 minutes) thus it is lipophobic in nature.

Since ADH binds to the cells surface recptors of the kidney, it is not participating in transcription and translation process of protein synthesis.

Acute alcohol intake distrupt the ADH endocrine reflex, inhibit the reabsorption of water by the kidneys causes dehydration.

So the answers are,

ADH act as the output signal in this reflex pathway

Due to their alcohol consumption, the Underhills were more prone to dehydration.

ADH has a relatively short half-life

ADH is lipophobic