Endocrine System (2/25/2025)

Can different Hormone interact together

• Synergistic

  • hormones work together to produce greater effecr

• Permissive

  • 1st hormone allows action of 2nd hormone (Need A for B to work)

• Antagonistic

  • one hormone causes opposite effect of another

Types of Hormone based on solubility

• Soluble hormones

  • peptides or small proteins

  • can’t pass through phospholipid bilayer

  • Must bind to protein receptors on the cell membrane

  • cell signaling/signal cascade

• Insoluble hormones

  • sterioid hormones

  • lipid soluble

  • can pass through phospholipid bilayer

  • Bind to receptor molecules inside the cytoplasm / nucleus

    • can activate processes like transcription

Calcium Ion 2nd Messenger System

• Phospholipase C is the second messenger for the calcium system

  • oxytocin

  • antidiuretic hormone

  • epinephrine

• Involves a G protein

• G protein activates phospholipase C enzyme

Pituitary Gland and Hypothalamus

• Hypothalamus controls the pituitary glang (the master of the master)

• The pituitary glands have two parts:

  • Posterior pituitary (neurohypophysis): composed of unmyelinated neurons

  • Anterior pituitary (adenohypophysis)

Anterior and Posterior lobes

• Anterior lobes is dervived from oral ectodem and is epithelial in origin

• Posterior lobe dervies from the neural ectoderm

• Hypothalamus interacts with the anterior PG lobe

  • Hypothalamus hormones travel via primary capillary plexus to the portal vein, which carry them into the anterior pituitary

Summary

• Anterior lobe PG → Thyroid gland → Thyroid hormone (secretion)

  • TRH: Thyroid releasing hormone

  • TSH: Thyroid stimulating hormone

• Posterior lobe PG

  • Can’t produce any hormone

  • Stores oxytocin and ADH hormones produced by Hypothalamus until fire by a nerve signal from hypothalamus also

  • Stores it until Hypothalamus uses it

  • Made up of nerves, part of the nervous system

• Hypothalamus is also nerve, part of the nervous system

• Pituitary system diseases can be treated by stem cells

Endocrine System Pt 2. (2/27/2025)

General

• Will cover the thyroid, parathyroid, adrenal, pancreas, pineal, gonads, thymus gland

• Anterior lobe of the pituitary gland (PG) can produce the hormone, the posterior can only store two hormones (oxytocin and ADH: anti-diuretic hormone)

• The posterior and hypothalamus are more closely related because both come from nervous tissue

• There are 4 to 3 glands in the human body

• There are mechanisms: nervous system, hormonal ingratiation, humoral

• Short term stress is good because it motivates you to work hard

Hypothalamus Hormones and Impacts on PG

• Ventral hypothalamus hormones

• Secreted Hormones (from hypothalamus)

  • Thyrotropin releasing hormone (TRH)

  • Growth hormone releasing hormone (GHRH)

  • Growth Hormone Inhibiting hormone

  • Cortico-tropin Releasing Hormone (CRH)

  • Gonadotropin releasing hormone (GnRH)

  • Polactin releasing hormone (PRH)

  • Prolactin inhibiting hormone (PIH)

Growth Hormone

• More so in babies as they are still growing

• Get more growth hormone if you’re asleep by 10 or 10:30 as this when it’s more active

• Body grows better when you’re asleep

• Food has affect on the growth hormone (more amino acids, glucose, and fatty acids, the better)

• Stress has impact on growth hormone: decreases it (short term stress is good, but long term stress (chronic stress) is bad)

  • Chronic stress is controlled is by the cortisone

Thyroid Gland and Hormones

• @ the front of the neck, under the voice box

• Butterfly shaped: 2 lobes lie around the trachea)

• Produce thyroid hormone

• Has 2 different endocrine cell popns:

  • Parafollicular (or C) spindle cells: produce calcitonin

    • Calcitonin target = skeleton, stimulates Ca uptake and osteoblasts; lower blood [Ca]

    • regulation: hurmoral: high bid [Ca] stim. parafollicular cells release calcitonin

    • More prevalent in children than in adults

  • Follicular cells: secrets T3 and T4 hormones

    • thyroid follicular epithelial cells make the thyroid gland

    • derived from the endodermal foregut

    • T4 inactive (and circulating) form; (2 tyrosine plues 4 iodines)

    • Tissues take up T4 and turn it into T3

    • Tri-iodo-thyronine (T3) active (and circulating) form, (2 tyrosines plus 3 iodines)

Secretion

• Chronic secretion: maintaince of relatively constant concentration of hormone

  • ex. thyroid hormone

• Acute secretion: hormone regulation

  • Ex. epinephrine (adrenaline: fight or flight)

• Cyclic secretion: hormone regulation

  • ex. female reproductive hormones (woman release of ova)

Thyroid Hormones

• VIP in regulating the metabolism (basal metabolic rate)

• Thyroid dysfunction cal lead to:

  • Obesity or obesity-related diseases: like metabolic syndrome. hypertension, hyperglycemia

  • Myxe-derma/Hypothyroidism:

    • decrease in basal metabolic rate, puffy eyes, edema

    • uptake of iodine

  • Grave’s Disease/Hyperthyroidism

    • high basal metabolic rate, weight loss, eyeballs protrude due to edema

    • can remove thyroid and replace hormones (total thyroid-ectomy (TTx)

Parathyroid Glands and Hormones

• 4 nodular structures

• located behind the thyroid gland

• Regulates Ca lvls by increasing Ca lvls when low in blood through its action on the bones, kidneys, and intestine

  • Bones: Ca stores in the bones into the blood stream

  • Kidneys: reduces loss of Ca ions in urine and stimulates vitamin D in the kidneys

  • Intestine: increases Ca absorption from food via effects on vitamin D metabolism

Adrenal Gland and Hormones

• Sits on top of each kidney

• Two parts: cortex and medulia

• Adrenal cortex has three distinct parts:

  • Zona glomerulosa (outermost): produces five hormones but most important is aldosterone

  • Zona fasciculata (middle): produces cortisol which controls bad stress

  • Zona reticularis (innermost): produces androgen and estrogen which controls female menstrual cycle

  • Each zona produces steroid hormones from the precursor cholesterol

• Corticosteroids = steroid hormones produced in the adrenal cortex and are of 2 types:

  • Mineralocorticoids

    • e.g Aldosterone

    • balances Na: also bicarbonate

  • Glucocorticoids

    • produced in the the zona fasciculata and reticularis

    • ex. cortisol, cortisone, and corticosterone

    • effects: gluconeogensis, mobilizes fat, proteins are broken down by ATP, resistance to stress, and anti-inflammation

  • Congenital adrenal hyperplasia

    • a genetic disorder

    • the gene (21-hydroxylase) makes enzymes needed to produce cortisol and aldosterone is not working properly

    • Results in the accumulation of cortisol precursors which can be converted into testosterone

Pancreas and Regulation of Blood Sugar Lvl

• Dual function: exocrine and endocrine cell types

  • Exocrine produces enzymes, while endorcrine produces hormones

• Diseased relating to blood sugar

  • Diabetes

    • Type 1: insulin is not produced

    • Type 2

    • Three Ps

      • Poly-uria: excess urine

      • Poly-dipsia: thirsty

      • Poly-phagia: strong eating drive; hungry

    • Type 2 has normal amount of insulin but not enough receptors