Ch 5 - Endocrine

Question 1

peptide hormones

Answer 1

• made of amino acids
  
  • derived from posttranslational modification of larger polypeptides
  • then sent to golgi to modify and activate the hormone
  • exocytosed
• charged, must bind to extracellular receptor
• first messenger - triggers second messenger
• signaling cascade that allows for amplification at every step
• rapid but short lived response
• water soluble and do not require carrier in blood

Question 2

Second messengers

Answer 2

• common second messengers - cyclic adensosine monophosphate (cAMP), inositol triphosphate (IP3), Ca 2+
• bind peptide to receptor triggers activation or inhibition of an enzyme
• enzyme raises or lowers level of second messenger
• second messenger binds to intracellular targets
• such as kinase that can phosphorylate transcription factors and effect gene expression
• slow or rapid effect on the cell

Question 3

steroid hormones

Answer 3

• derived from cholesterol
• produce by gonads and adrenal cortex
• easily cross cell membrane
• intracellular receptors or intranuclear
• steroid hormone - receptor complex has conformational change and receptor binds DNA to increase or deccrease transcription
• dimerization - conformational change, pairing of 2 steroid-receptor complexes
• slower, longer effects than peptides
• require blood carrier protein
  
  • some carriers are specific and others are not
  • increasing carrier leads to more production of the hormone because less free hormone

Question 4

amino acid derivative hormones

Answer 4

• less common than peptides and hormones
• catecholamines - epi, norepi
  
  • bind to G protein coupled receptors
• thyroid hormones - bind intracellularly
• triiodothyronine, thyroxine
• made from amino acids with modifications

Question 5

hormone targets

Answer 5

• direct hormones - secreted and act directly on target tissue
• tropic hormones - intermediary before action
  
  • originate in brain and anterior pit. gland
  • GnRH and LH - do not directly effect body
    
    • stimulate production of another hormone

Question 6

hypothalmus

Answer 6

• bridge endocrine and nervous
• receive input and then control pituitary gland via tropic hormones
• negative feedback
• conencted to ant. pituitary vis the hypophyseal portal system
• GnRH — FSH and LH
• GHRH — Growth hormone (GH)
• TRH — Thyroid stimulating hormone (TSH)
• Corticotropin releasing factor (CRF) — Adrenocorticotropic hormone (ACTH)
• prolactin inhibiting factor (PIF) decreases prolactin secretion
  
  • PIF is dopamine

Question 7

axes (hormone control)

Answer 7

• three organ systems that regulate hormone levels
• ex. hypothalmus - pituitary - adrenal axis
• ex. hypothalamus - pituitary - overian axis
• hormone receptors in pituitary and hypothalus for negative feedback regulation

Question 8

Hypothalamus control over posterior pituitary gland

Answer 8

• no tropic hormones
• neuron from hypothalamus, axons down pituitary stalk to post. pituitary
• control oxytocin and ADH (vasopressin)

Question 9

Tropic hormones from Ant. Pit.

Answer 9

• FSH and LH stimulated by GnRH and act on gonads
• Adrenocorticotropic hormone (ACTH) stimulated by cortiotropin releasing factor (CRF) adn acts on the adrenal cortex
• Thyroid stimulating hormone (TSH) due to thyroid releasing hormone (TRH) acts on the thyroid

Question 10

Direct hormones of Ant. Pit.

Answer 10

• prolactin - stimulate milk production in mammary glands
  
  • dopamine decreased prolactin secretion
• endorphins - decrease pain perception
• growth hormone - prevent glucose uptake in tissues not growing
  
  • stimulate breakdown of fatty acids
    
    • increase glucose availability
  • stimulated by GHRH from hypo.
  • gigantism and dwarfism - excess or deficiency in childhood
  • acromegaly - excess as adult. effects hands, feet, head

Question 11

posterior pituitary gland

Answer 11

• contains nerve terminals of neurons with cell bodies in hypothalamus
• receive and store ADH from hypothalamus
  
  • ADH secreted in response to low blood volume (baroreceptors) or increased blood osmolarity (osmoreceptors)
  • increase permeability of collecting duct in nephron
    
    • retention of water
• receive and store oxytocin from hypothalamus
  
  • secreted during childbirth
  • secretion stimulated by suckling
  • positive feedback loop - promote uterine contraction

Question 12

Thyroid

Answer 12

• controlled by thyroid stimulating hormone
• sets basal metabolic rate - triiodothyronine (T₃) and thyroxine
• calcium homeostasis - calcitonin

Question 13

basal metabolism

Answer 13

• Triiodothyronine (T₃) and thyroxine (T₄) produced by iodination of tyrosine
  
  • occurs in follicular cells of thyroid
  • make energy production more or less efficient
• increase hormones - increase cellular respiration
  
  • more protein and fatty acid turnover
• negative feedback loops
• hypothyroidism - iodine deficiency or inflammation of thyroid
• hyperthyroidism - excess thyroid hormone

Question 14

calcitonin

Answer 14

• C-cells produce calcitonin
• decreases blood calcium levels
  
  • increase Ca excretion
  • decrease Ca absorption from gut
  • increase Ca storage in bone
• High blood Ca stimulates calcitonin secretion

Question 15

Parathyroid glands

Answer 15

• posterior of thyroid
• parathyroid hormone (PTH)
• antagonistic to calcitonin - raises blood Ca
  
  • decrease excretion of Ca, increase gut absorption, decrease bone storage (increase resorption)
• plasma Ca rises - PTH secretion decreases
• PTH effects phosphorus homestasis
  
  • resorb from bone and reduce resorption in kidney (promote excretion)
• PTH activates vit. D
  
  • need to absorb Ca and P from gut
• Overall PTH has great effect on Ca and less effect on P

Question 16

adrenal cortex

Answer 16

• adrenal glands on top of kidneys
• adrenal cortex secretes corticosteroids
  
  • glucocorticoids
  • mineralocorticoids
  • cortical sex hormones

Question 17

Glucocorticoids

Answer 17

• regulate glucose levels
• cortisol and cortisone
• raise blood glucose - increase glucoeogenesis
  
  • decrease protein synthesis
• decrease inflammation and immune response
• controlled by adrenocorticotropic hormone (ACTH)
• Corticotropin releasing factor (CRF) promotes ACTH - protmotes glucocorticoids

Question 18

Mineralocorticoids

Answer 18

• salt and water homeostasis
• aldosterone - increase Na reabsoprtion and water folloers
  
  • no change in osmolarity
  • decrease K and H+ reabsorption (promote excretion)
  • controlled by renin-angiotensin-aldosterone system
    
    • decrease BP - juxtaglomerular cells secrete renin
    • renin cleaves angiotensinogen to make angiotensin I
    • angiotensin I convert to angiotensin II by angiotensin-converting enzyme (ACE) in lungs
    • angiotensin II stimulate adrenal cortex to secrete aldosterone
    • rise in blood pressure decreases jux. cell activity and renin
  • angiotensin II - vasoconstrit and increase HR

Question 19

Cortical sex hormones

Answer 19

• adrenal cortex
• androgens and estrogens
• females more dependent on adrenal production

Question 20

Adrenal medulla

Answer 20

• inside the adrenal cortex
• epi and norepi
• made of nerve cells
• epi - increase glycogen to glucose and basal metabolic rate
• both increase HR and blood flow to skeletal muscles
• cortisol increases catecholamines release

Question 21

Pancreas

Answer 21

• exocrine - secrete directly into ducts. ex. digestive enzymes
• endocrine - islets of Langerhans are hormone producing cells
  
  • alpha cells - glucagon
  • beta cells - insulin
  • delta cells - somatostatin

Question 22

glucagon

Answer 22

• secreted while fasting
• glucose low - glucagon stimulate
  
  • protein and fat degradation
  • glycogen to glucose
  • new glucose via gluconeogenesis
• GI hormones increase glucagon
• Glucagon release inhibited by high glucose

Question 23

Insulin

Answer 23

• antagonistic to glucagon
• secreted when high glucose
• induce muscles and liver to take up glucose and store as glycogen
• stimulate anabolic processes
• hypoglycemia - low blood glucose, excess insulin

Question 24

Counterregulatory hormones

Answer 24

• hormones that raise blood glucose
• glucagon
• epinephrine
• glucocorticoids
• growth hormone

Question 25

Diabetes Mellitus

Answer 25

• hyperglycemia - excess glucose in blood
• excess glucose in filtrate in nephron - overwhelm reabsoprtion ability and glucose in urine
  
  • osmolarity effect and excess water excreted (increase urine volume)
• polyuria - frequent urination
• polydipsia - increased thirst
• Type I - insulin dependent
  
  • autoimmune destroy beta cells - little insulin produced
  • require insulin injections
• Type II - non insulin dependent
  
  • receptor resistance
  • partly inherited … mostly environmental

Question 26

Somatostatin

Answer 26

• inhbitor of insulin adn glucagon secretion
• stimulated by high glucose and AA conc
• produced by hypothalamus, secreted by pancreas
• also decreases growth hormone secretion

Question 27

Gonads

Answer 27

• testes secrete testosterone in respone to LH and FSH
  
  • sexual difference during gestation and 2nd sex characteristics
• ovaries - estrogen and progesterone in resposnse to gonadotropins
  
  • estrogen - develop female reproductive system durign gestation. Development of 2nd sex characteristics

Question 28

Erythropeietin, Atrial natriuretic peptide, thymosin

Answer 28

• erythropoietin - stimulate bone marrow to increase production of erythrocytes
  
  • in response to low oxygen
• atrial natriuretic peptide - heart releases to regulate salt and water balance
  
  • released when atrium stretched
  • promote excretion of salt and therefore water
  • antagonistic to aldosterone
• thymosin - released by thymus, develop T cells and differentiate