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MCAT Biology and Biochemistry > Endocrine System > Flashcards

Endocrine System Flashcards

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1
Q

How does hormones function?

A

They’re released into the bloodstream where they travel to distance targets and act on cells.

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2
Q

Peptide hormones v. Steroid hormones

A

Peptide hormones- composed of amino acids. They’re polar and so can travel freely in the bloodstream and binds to receptors on membrane which causes a signaling cascade.
- Each step of the cascade results in amplification of that signal ( activating more targets).
- Results are quick but short lived.

Steroid hormones- derived from steroids and are nonpolar so they need carriers to moved through the bloodstream. They can easily diffuse through the membrane and act on intracellular or intranuclear receptors. This complex serves as transcription factors for proteins.
- Results take longer but but are longer lived due to having to make proteins from scratch.

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3
Q

Amino- acid derivative hormones

A

Derived from modifications to amino acids. There properties vary with some having properties of peptide hormones and some having properties of steroid hormones.

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4
Q

Tropic hormones v. Direct hormones

A

Tropic hormones act on endocrine tissues which means they release signals that cause the release of hormones from nonendocrine tissues.

Direct hormones act of nonendocrine tissues to directly release hormones.

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5
Q

What serves as the bridge between the nervous system and the endocrine system?

A

The hypothalamus

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6
Q

Positive v. Negative Feedback

A

Positive feedback is when products acts back on the pathway to increase it’s own production.

Negative feedback is when products act back on the pathway to inhibit it’s own production.

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7
Q

HPAA

A

Hypothalamic - pituitary - adrenal axis.

Axis that results in the release of hormones into the bloodstream.

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8
Q

What’s the primary hormone involved in the parasympathetic NS? Sympathetic NS?

A

Acetylcholine ( Ach) for parasympathetic NS.

Norpinephrine, epinephrine, and cortisol for sympathetic NS.

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9
Q

Name the signaling cascade involving adenylate cyclase.

A

Gi or Gs acts on adenylate cyclase. If stimulatory adenylate cyclase converts ATP to CAMP which goes on to act on PKA. PKA activates CREB which goes on and acts on transcription factors.

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10
Q

Difference in effect between peptide hormones and steroid hormones.

A

Peptide hormones are quick acting but effect is shortly lived while steroid hormones take longer to act but the effects are longer.

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11
Q

Which hormone exhibits positive feedback?

A

Oxytocin

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12
Q

What hormones act on the gonads?

A
  • GnRH is released from hypothalamus which causes the release of FSH and LH from anterior pituitary.
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13
Q

Which hormones are responsible for growth of bone and muscle?

A

GHRH is released from hypothalamus while GH is released from anterior pituitary and acts on muscle and bone.

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14
Q

What causes the released of and what effect does TSH have?

A

TRH is released from hypothalamus while TSH is released from the anterior pituitary. TSH acts on thyroid glands to release T3 and T4 which controls metabolism.

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15
Q

Which hormones act on the adrenal glands?

A

CRH is released from hypothalamus which acts on anterior pituitary to cause release of ACTH. ACTH acts on adrenal glands.

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16
Q

Prolactin inhibiting factor ( PIF)

A

It’s dopamine. Works to inhibit prolactin.
When baby is breast feeding PIF is stopped allowing prolactin to release inhibition of prolactin causing more milk production.

17
Q

Which hormones are released from the posterior pituitary?

A

Oxytocin- causes milk ejection, bonding behavior, uterine contraction during birth.

ADH ( vasopressin)- causes increase in B.P. by increasing reabsorption of water. Caused by increased plasma osmolarity and increased solutes in blood.

18
Q

Role of endorphins

A

Decreases the perception of pain

19
Q

How does GH works in bone and muscle growth?

A

It increases glucose availability to those structures while increasing fatty acid metabolism in other tissues ( in order to create more free glucose).

20
Q

What happens when GH is too high or too low during puberty?

A

If it’s too high than you get gigantism. If it’s too low you get dwarfism. The epiphyseal growth plates close during puberty.

21
Q

Acromegaly

A

Overgrowth of small bones such as in the hands and feet.

22
Q

Which hormones are released from the thyroid gland? Which cells releases these hormones?

A
  • It releases T3 and T4 which sets the basal metabolic rate.
  • Releases calcitonin which decreases blood calcium levels by decreasing excretion from the kidneys while increasing absorption of calcium in gut and stores it in bone.
  • follicular cells releases T3 and T4 while C-cells releases calcitonin.
23
Q

Parathyroid gland

A

Causes the releases of PTH which works to increase blood calcium levels. Does this by causing the opposite effects of calcitonin.

24
Q

Hypothyroidism v. Hyperthyroidism

A

Hypothyroidism - decrease thyroid function caused by inflammation or low iodine.

Hyperthyroidism- increases thyroid function caused by tumor or overstimulation.

25
Q

What are the two parts of the adrenal gland?

A

Adrenal cortex and the adrenal medulla

26
Q

What hormones are released from the adrenal glands?

A

Corticosteroids which consists of 2 classes:
- glucorticosteroids- cortisol and cortisone which are released during times of stress. Increases glucose production while decreasing protein synthesis to provide a ready source of fuel.

  • Mineralcorticosteroids- aldsteron which increases reabsorption of salt and water in the convuluted tubule and collecting so that it raises B.P.
27
Q

What hormones are released from the adrenal medulla?

A

Norepinephrine and epinephrine which serves a role in the sympathetic NS.

28
Q

What controls the release of aldosterone?

A

The renin- angiotensin- aldosterone system.

  1. Renin is released from the juxtaglomerular cells of the kidneys which serves to cleave angtiotensinogen ( released from the liver), this results in angiotensin I.
  2. Angiotensin I is cleaved by ACE ( Angiotensin converting enzyme) into angiotensin II.
  3. Angiotensin II acts on target tissues involved in water and salt reabsorption.
29
Q

Which structure releases cortical sex hormones?

A

Adrenal gland

30
Q

Which cells of the pancreas are involved in endocrine functions?

A

Islets of langerhans.

  • Alpha cells secrete glucagon which causes release of glucose when in a fasting state.
  • Beta cells- secrete insulin which is released when our blood glucose is high such as after a meal.

Delta cells- releases somtatostatin which inhibits both insulin and glucagon.

31
Q

Diabetes mellitus

A

A condition characterized by hyperglacemia. Occurs in two types:

Type I- autoimmune diseases that attacks beta cells of the islet.

Type II - partially inherited and partially environmental and is characterized by the insensitivity of receptors to insulin.

32
Q

Polyuria/ polydipsia

A

-Both are present in diabetes patients, glucose interferes with water reabsorption in kidneys so it stays in kidneys and attracts water in the kidneys.
- Polyuria is excessive urination.
- Polydipsia is excessive thirst

33
Q

How does the hypothalamus controls the circadian rhythm.

A

Contains the SCN ( suprachiasmatic nucleus) which responds to changes in light. If decreased light it causes increased release of melatonin from the pineal gland. If it’s more light it’s the opposite effect.

34
Q

Up-regulation v. Down-regulation

A
  • Up-regulation- increase in the numbers of receptors.
  • Down-regulation- decrease in the numbers of receptors.
35
Q

Erythropoietin

A

Released by the kidneys and stimulates bone marrow to create erythocytes.

36
Q

Role of ANP ( atrial natriuretic peptide)

A

When pressure of the atrial walls are increased, ANP is released to increase sodium excretion in the kidneys ( therefore water) which decreases the pressure.

37
Q

Thymosin

A

Released by the thymus which is involved in T- cell development and differentiation.

MCAT Biology and Biochemistry (20 decks)

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