Endocrine Systems

1.  Endocrine
    A.  Release of hormone into bloodstream
    B.  Receptor on target cell
    C.  Types of hormones
        i. amino acid derivatives
        ii. peptides
        iii. proteins
        iv. steroids
    D.  Receptors
        i.  cell surface receptors
            a.  intracellular enzymatic changes
        ii. cytoplasmic receptors
            a.  changes in transcription and translation
    E.  Endocrine Tissues
        i.  adrenal gland
        ii. pancreas
        iii. thyroid gland, parathyroid gland
        iv. GI tract
        v.  brain
            a.  hypothalamus
            b.  pituitary gland
                1.  andenohypophysis
                 2.  neurohypophysis

2.  Hormones
    A.  adrenal gland
        i.  aldosterone
        ii. cortisol
        iii. epinephrine, norepinephrine
    B.  pancreas
        i.  insulin
        ii. glucagon
    C.  thyroid gland
        i.  T3, T4
    D. brain
        i.  hypothalamus
            a. TSH
            b. CRH (or CRF)
            c. GnRH
        ii. anterior pituitary
            a.  TSH
            c.  ACTH
            d.  FSH
            e.  LH
        iii. posterior pituitary
            a.  ADH
            b.  oxytocin

3.  Hormone Actions
    A.  Thyroid hormone
        i.  thyoid gland
            a.  follicle cells
            b.  thyroglobin
            c.  colloid
            d.  thyroxine (T3, T4)
            e.  iodine
        ii. stimulation by TSH
        iii. actions of T3, T4
            a.  neural development
            b.  metamorphosis of amphibians
            c.  increase synthesis of Beta receptors, incr response to Epi and NE
            d.  facilitates responses to GH (synergistic)
            e.  increase in BMR
                1.  increase in Na/K ATPase pumps
                2.  increase in O2 consumption
                3.  increase in heat production
        iv.  cytoplasmic receptors
            a.  changes in protein synthesis
        v.  imbalances
            a.  hypothyroidism
                1.  cretinism, mental retardation
                2.  weight gain, decr BMR
                3.  cold intolerance
            b.  hyperthyroidism
                1.  Grave's disease
                2.  exophthalamus
                3.  incr BMR
                4.  heat intolerance
                5.  incr HR and BP (hyperreactive to sympathetic stimulation)
            c.  goiter

    B.  Cortisol
        i.  produced in adrenal cortex
        ii. glucocorticoid (corticosteroid)
        iii. increases blood glucose
            a.  glucogenolysis
            b.  lipolysis
            c.  glucose sparing
        iv.  increases protein breakdown
        v.  inhibits immune system
            a. decrease inflammation
        vi.  protection against stress
        vii.  permissive for epinephrine and glucagon
        viii.  imbalances
            a.  hypersecretion
                1.  Cushing disease
                2.  fat redistribution
                3.  spindly limbs
                4.  poor wound healing
             b. hyposecretion
                1.  Addisons disease
                2.  increase in blood K, decrease in blood Na
                3.  low blood glucose
                4.  poor stress resonse
                5.  increased melanin
                6.  low BP

    D.  Growth Hormone
        i.  produced in pituitary
        ii. stimulated by GHRH
        iii. inhibited by SS
        iv. stimulates release of IGF-I
            a. increased long bone growth
            b. increased protein synthesis
            c. small increase in blood glucose
        v.  imbalances
            a. hypersecretion
                1. gigantism, acromegaly
                2. increased long bone growth
                3. thickening of bones
            b. hyposecretion
                1. dwarfism

    D.  Insulin
        i.  produced by pancreatic beta cells
        ii. stimulated by increase in glucose, fats, aa in blood
        iii. allows glucose uptake
        iv.  glycogen synthsis
        v.  fat storage in adipose tissue
        vi.  aa uptake and protein synthesis
        vii.  imbalance
            a.  hyposecrection
                1.  Diabetes mellitus
                        I.  juvenile
                        II.  adult onset
                        III. gestational

    E.  Glucagon
        i.  produced by pancreatic alpha cells
        ii. stimulated by fall in blood glucose
        iii.  glycogenolysis
        iv.  gluconeogenesis
        v.  lipolysis

Reproductive Hormones
    A.  Male reproductive physiology
        i.  Testes
            a.  seminferous tubules - site of spermatogenesis
            b.  epididymus
       ii.  Spermatogenesis
            a.  Sertoli cells - stimulated by FSH
                1.  maintain developing spermatids
                2.  androgen binding protein
                3.  inhibin
            b.  Leydig cells - stimulated by LH
                1. testosterone
            c.  Sperm cells
                1.  Head region
                    I. acrosome
                2.  Tail region
        iii.  Control of reproduction
            a.  ANS (parasympathetic and sympathetic)
        iv.  Testosterone actions
            a.  fetal differentiation
            b.  spermatogenesis
            c.  secondary sex characteristics
                1.  facial hair
                2.  growth of larynx
                3.  fat distribution
                4.  long bone growth
                5.  muscle growth
                6.  male baldness
            d.  sex drive
        v.  Mechanism
            a.  alterations in transcription and translation
            b.  conversion by 5 alpha reductase to dihydrotestosterone
                1.  pseudohermaphrodites (no external male genitalia at birth, all internal)
            c.  conversion in brain into estrogen

    B.  Female reproductive physiology
        i.  Gonads
            a.  ovaries, fallopian tubes (oviduct), uterus, cervix, vagina
        ii. Reproductive Cycle - Follicular phase
            a.  GnRH stimulates release of FSH, LH
            b. development of follicles, emergance of primary follicle
            c.  granulosa cells (FSH sensitive)
                1. estrogen
                2.  inhibin
            d. theca cells (LH sensitive)
                1. androgens
            e. inhibition of FSH release
            f.  large increase in estogen
                1.  increase synthesis of GnrH receptors (LH releasing cells)
                2.  increase synthesis of FSH, LH receptors
            g.  LH surge - ovulation
        iii.  Reproductive Cycle - Luteal phase
            a.  corpus luteum
            b.  release of estrogen and progesterone
            c.  inhibition of FSH and LH
            d.  preparation of uterus
                1.  increase blood vessels
                2.  increase glycogen
                3.  inhibition of smooth muscle contraction
                4.  mucus in cervix
            e.  with no fertilization, corpus luteum degenerates
            f.  drop in estrogen and progesterone
            g.  shedding of uterine lining
                1.  smooth muscle contraction
                2.  vasoconstriction followed by vasodilation
        iv.  Estrogen
            a. secondary sex characteristics
                1.  mammary gland development
                2.  fat deposition
                3.  bone growth and maintenance
              b. also produced in fat tissue
       v.  Androgens
            a.  from adrenal cortex
                1.  sex drive
        vi.  Menopause
            a. lack of estrogen, progesterone
            b. osteoporesis
            c.  problems with temperature regulation
            d.  increased effects of androgens

    C.  Pregnancy
        i.  Fertilization
            a. formation of embryo
            b. trophoblasts
                1.  release of hCG
                2. maintenance of corpus luteum
            c. development of placenta
                1.  chorionic villi
                2.  maternal sinuses
                3.  fetal circulation via umblical cord
            d.  fetal physiology
                1.  unused organ systems
                2.  changes in circulation
                    I.  foramen ovale
                    II.  ductus arteriosus
        ii.  Maternal changes
            a.  triggered by increased levels of estrogen and progesterone
            b.  placental hormones
                1.  placental lactogen
                    I.  increased fat utilization by mother
                    II. stabilization of plasma glucose
                    III. stimulation of mammary gland development
            c.  physiological changes
                1.  increase blood volume
                    I. increase RBC synthesis
                    II. increase total blood volume - renin pathway
                2.  increase in CO
                    I.  increase HR, SV
                3.  decrease in TPR
                    I. increase blood flow to uterus, kidneys, skin
                4.  increase oxygen consumption
                    I.  increase in resp. rate
                    II. decrease in VC in last trimester
                5. increase ability for heat loss
                    I.  change in set point
                    II. increase in evaporative cooling
                6.  Naseau (morning sickness)
                    I.  high levels of hCG
        iii. Partuition
            a.  increase oxytocin receptors
            b. increase prostaglandin and oxytocin stimulation of smooth muscle
            c.  decrease progesterone