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bio 30 > Endocrine system > Flashcards

Endocrine system Flashcards

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Biology 101 flashcards
1
Q

What is the endocrine system?

A
  • A system of glands that secrete chemical messengers called hormones into the bloodstream
  • Messages carried by hormones travel slower than those carried by nerve impulses (bloodstream is slower than nervous system)
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2
Q

What are the similarities between the nervous and endocrine system?

A
  • Some nervous tissues (eg. hypothalamus, pituitary, adrenal glands) secrete hormones
  • Some chemical function as neurotransmitters and hormones
  • Both systems include positive and negative feedback loops
  • Often work hand in hand
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3
Q

Describe lipids vs. water soluble hormones:

A
  • Hormones lipid based are lipid - soluble
    • Can diffuse through cell membrane easily
    • Inside cell bind to receptors and often affect genes
  • Hormones that are protein based are water - soluble
    • Cannot diffuse across membrane
    • Bind to receptor on surface which sends message to inside of cell
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4
Q

Describe the negative feedback loops:

A
  • Need some way to “turn off” hormone production
  • Negative feedback - some way of stopping hormone release once certain level of hormone is reached or after desired effect eg. ADH
  • Also sometimes positive feedback loops to increase amount of hormone produced eg. during birth (oxytocin)
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5
Q

Describe tropic vs. non-tropic hormones:

A
  • Tropic - have endocrine glands as targets (eg. thyroid stimulating hormone (TSH —> thyroid)
  • Non - tropic - do not have endocrine glands as targets (eg. insulin —-> muscle, liver, fat cells)
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6
Q

Describe the hypothalamus:

A
  • Located at the base of the brain (a component of the brain)
    -Secretes hypothalamic releasing and inhibiting hormones
  • Produces ADH and oxytocin
  • Regulates anterior pituitary
  • Hormones travel down stalk to pituitary glands
  • Also uses natural impulses to communicate with pituitary
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7
Q

Describe the pituitary:

A
  • Located at the base of the brain (below hypothalamus)
  • Secretes hGH, TSH, ACTH, FSH, LH and PRL hormones
  • pituitary is divided into two lobes, posterior (smaller lobe) and anterior
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8
Q

Describe the posterior pituitary:

A
  • Part of the nervous system
  • Does not make any hormones
  • Oxytocin and ADH travel to pituitary via nerve portal
  • Posterior pituitary stores and releases these hormones
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9
Q

Describe the antidiuretic hormone (ADH):

A
  • Secretes from posterior pituitary
  • Acts on collecting duct of kidney to increase water reabsorption
  • Control based on osmotic pressure (quantity of salt vs. water) of body fluids
  • If fluid is too concentrated, hypothalamus signals posterior pituitary to release ADH
  • If fluid is to dilute, hypothalamus signals posterior pituitary to decrease ADH
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10
Q

Describe the anterior pituitary:

A
  • Produces and releases hGH, prolactin (PRL), TSH, ACTH, follicle stimulating hormone (FSH), leutenizing hormone (LH)
  • Blood vessel/nerve portal carries hormones from hypothalamus (releasing or inhibiting) - either stimulate or inhibit hormone release from anterior pituitary
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11
Q

Describe the human growth hormone (hGH):

A
  • Secreted from anterior pituitary
  • Stimulates growth and metabolism either directly or indirectly
  • Stimulates liver to release growth factors
  • Effects include:
    • Protein synthesis and cell division
    • Breakdown and release of stored fats
    • Results in growth of muscles, connective tissue and at the plates of long bones
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12
Q

Describe the thyroid-stimulating hormone (TSH):

A
  • Secreted from anterior pituitary
  • Causes the thyroid gland to secrete thyroxine
  • Operates on negative feedback loop
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13
Q

Describe the adrenocorticotropic hormone (ACTH):

A
  • Secreted from anterior pituitary
  • When body senses danger, hypothalamus signals release of ACTH by the way of a releasing hormone
  • ACTH stimulates cortisol release from adrenal cortex
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14
Q

Describe the thyroid:

A
  • Located around trachea just below larynx
  • Produces T3, thyroxine (T4) and calcitonin
  • Iodine is needed to make T3 and T4
  • Stimulated by TSH from anterior pituitary
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15
Q

Describe thyroxine (T4):

A
  • Produced and released in the thyroid
  • Increases metabolism of CHOs, fats and proteins
  • Increases rate of cellular respiration of individual cells (especially those of the heart, skeletal muscles, liver and kidney)
  • Influences organ and tissue development in children
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16
Q

Describe the T4 negative feedback cycle:

A
  • TSH stimulates thyroid to produce T4
  • Elevated levels of T4 signal pituitary to stop producing TSH (both indirectly through hypothalamus and directly)
  • If T4 does not get produced (sometimes due to lack of iodine) TSH continues to stimulate thyroid (results in goiter)
17
Q

Describe calcitonin:

A
  • Produced and secreted by thyroid
  • Stimulates CA2+ (calcium) uptake by bones from blood when blood calcium levels get to high
  • Minor role in calcium regulation in humans
18
Q

Describe the parathyroid glands:

A
  • Four small glands attached to thyroid
  • Produces and releases parathyroid hormone (PTH)
19
Q

Describe the parathyroid hormone (PTH):

A
  • Produced and secreted by parathyroid glands
  • Responds to low blood calcium levels
  • Breaks down bones
  • Stimulates kidneys to reabsorb calcium from urine
  • Activates vitamin D (stimulates absorption of calcium from food)
20
Q

Describe high blood calcium levels:

A
  • Calcitonin hormone involved
  • Secreted from thyroid
  • Stimulates transfer of calcium from blood to bones
21
Q

Describe low blood calcium levels:

A
  • PTH hormone involved
  • Secreted fro parathyroid
  • Stimulates bone breakdown
  • Stimulates calcium absorption from urine
  • Activates vitamin D
22
Q

Describe the adrenal glands:

A
  • Located on top of kidneys
  • Inner layer is adrenal medulla
  • Outer layer is adrenal cortex
23
Q

Describe the adrenal medulla:

A
  • Inner portion of adrenal glands
  • Consider nervous tissue
  • Involved in short term stress response
  • Produces/secretes epinephrine and norepinephrine
24
Q

Describe epinephrine and norepinephrine:

A
  • Release signal directly (by neurons) from hypothalamus
  • Prepare body for fight or flight response by:
    • Increasing metabolism
    • Increase breathing rate
    • Increase heart rate
    • Increase blood flow to heart and muscles
    • Pupil dilatation
  • Acts quickly because it is stimulated by the nervous system
  • Because they are hormones, effects last longer than nervous stimulation
  • Remember norepinephrine is also a neurotransmitter
25
Q

Describe the adrenal cortex:

A
  • Outer portion of adrenal gland
  • Produces and secretes the following (involved in the long-term stress response):
    • Glucocorticoids (increase blood sugar)
    • Mineralcorticoids (increase blood pressure)
    • Gonadocorticoids (supplement hormones produced by gonads)
    • All of the above are made from cholesterol
26
Q

Describe cortisol:

A
  • A glucocorticoid
  • Release stimulated by ACTH (from pituitary)
  • Longer-lasting then epinephrine
  • Natural anti-inflammatory
  • raises blood glucose levels
    • Promotes breakdown of muscle
    • Protein converted to glucose by liver
    • Prompts breakdown of fat cells
27
Q

Describe aldosterone:

A
  • A mineralocorticoid
  • Stimulates kidneys to increase absorption for sodium from urine
  • Increases blood pressure
28
Q

Describe the pancreas:

A
  • Located below stomach
  • Attached to small intestine by duct
  • Exocrine functions - secretes digestive enzymes
  • Endocrine functions – performed by islets of Langerhans (clusters of endocrine cells in the pancreas)
29
Q

Describe the islets of langerhan:

A
  • Two types of cells:
    • Beta cells - secrete insulin
      • Decreases blood glucose levels
    • Alpha cells - secrete glucagon
      • Increases blood glucose
30
Q

Describe insulin:

A
  • Secreted by beta calls of pancreas
  • Decreases blood glucose levels
  • Acts on receptors of target cells - makes them more permeable to glucose (especially muscle and liver cells)
31
Q

Describe diabetes mellitus:

A
  • Body does not respond to insulin or produce enough insulin
  • Blood sugar levels are significantly higher
  • Cells starve - results in fatigue
  • Body breaks down fats and proteins in attempt to get energy
  • Large volumes of glucose-rich urine produced
  • Complications include blindness, kidney failure, nerve damage and gangrene
  • Alpha cells may also be degenerate
32
Q

Describe glucagon:

A
  • Secreted by alpha cells of pancreas
  • Stimulates liver to convert glycogen back to glucose
33
Q

Describe type 1 vs. type 2 diabetes:

A
  • Type 1 - immune system destroys beta cells, insulin is not produced
    • Also called insulin dependent
    • Usually diagnosed in childhood
  • Type 2 - Insulin receptors on cells stop responding to insulin
    • Adult - onset
    • 90% of diabetes
    • Can result in type 1
34
Q

Describe diabetes insipidus:

A
  • Caused by lack of ADH
  • Water isn’t reabsorbed from urine
  • Results in increased urine volume, excessive thirst
  • No change in blood sugar

bio 30 (17 decks)

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