Endocrine

What system works together?

Nervous & Endocrine System

Nervous System

Short-term, very specific responses (very direct/fast)

Endocrinology

Study of hormones and endocrine glands

Endocrine System

Long termed, general responses, relies on duration rather than speed

What does endocrine system release?

Chemicals called hormones

Hormones

-Produced by endocrine cells located in glands (NO DUCTS ductless if it does its called EXOcrine)

-hormone enter blood(move through the whole body) binds to specific target cells that have hormone receptors causes a response

Main endocrine organs

Primary function is to make hormones

• pituitary gland

• Hypothalamus

• Thyroid gland

• Adrenal gland

• Pineal gland

• Parathyroid gland

• Pancreases

Secondary Endocrine Functions

Secondary function makes hormones but has other primary functions

• Heart (pumps heart)

• Thymus (immunity)

• Adipose tissue

• Digestive tract

• Kidneys (produce urine)

• Gonads (Testes, Ovaries)

Endocrine cells are of

Epithelial origin

Classes of Hormones

• Amino acid-based hormones

• Steroids - derived from cholesterol

Target Cells

• Influence only specific tissues

• A hormone can have different effects on different target cells

3 types Release of Endocrine

Humoral, Neural, Tropic Hormones(hormonal)

Humoral

• Simplest of endocrine control mechanisms

• Secretion direct response to changing ion/nutrient levels in blood very direct

Neural

Sympathetic never fibers stimulate cells in the adrenal medulla (norepinephrine or epinephrine)

-released by neural input (neurons response)

Tropic Hormones(hormonal)

Certain hormones signal secretion of other hormones

(Hormone released by another hormone)

Pituitary Gland

• Secrets 9 major Hormones

• Attached to Hypothalamus by the infundibulum

2 basic divisions of the pituitary gland

• Anterior lobe (adenohypophysis)

• Posterior lobe (neurohypophysis)

Anterior Lobe

• Makes and secretes 7 different hormones

• Thyroid-stimulating hormone(THS): Produce by thyrotropic cells secrete thyroid hormone

• Adrenocorticotropic hormone(ACTH): stimulate adrenal cortex

• Gonadotropins: FSH & LH

• Melanocyte-stimulating hormone(MSH): Appetite suppression

• Prolactin: stimulates milk production

• Growth Hormone: Stimulates body growth

Hypothalamus

Controls secretion of anterior lobe hormones BY:

• Releasing hormone

• Inhibiting hormone: turn off secretion of anterior lobe hormones

Hypothalamic Control of hormone secretion from anterior lobe

• Releasing hormone , travel to hypophyseal portal veins to 2nd capillary plexus

• From there the anterior lobe hormones enter circulation & trial to target organs

Posterior Lobe

• axons make up hypothalamohypophyseal tract

• Does not make hormones

• Releases 2 peptide hormones:

  -Antidiuretic hormone (ADH)

  -oxytocin

ADH (vasopressin)

• Made in supraoptic nucleus

• Targets kidneys to reabsorb water

• Increase blood volume/pressure (distal convoluted tube)

Oxytocin

• Induces smooth muscle contraction of reproductive organs, ejects milk during breast-feeding, and signals contraction if the uterus during childbirth

Thyroid Gland

Produces 2 hormones:

• Thyroid hormone (TH) - T3 & T4 (temperature regulation)

  -Calcitonin

• TRH maintains body temp by increasing T4 & T3 concentrations

Parathyroid Glands

• Parathyroid Cells: produce parathyroid hormone (PTH)

• Increase blood concentration of Ca 2+

Adrenal (Suprarenal) Gland

2 endocrine gland in 1:

• Adrenal Medulla: cluster of neurons; derived From crest, part of sympathetic nervous system

• Adrenal Cortex: bulk of gland; derived from somatic mesoderm

(All adrenal hormones help the body cope with stress, danger, terror ‘fight or flight response’)

Medullary Chromaffin Cells (Adrenal Medulla)

• modified postganglionic sympathetic neurons

• Secrete amine hormones epinephrine & norepinephrine (enhances “fight or flight” response)

Adrenal Cortex

Cortex: composed of 3 layers (zone)

• Zona glomerulosa: in spherical clusters

• Zona fasciculata:in parallel cords (has lipoid droplets)

• Zona reticularis: in a branching network

Adrenal corticosteroids has 2 what main classes?

Mineralocorticoids

• Aldosterone: secrete in response to decline in blood volume/pressure (terminal of renin-angiotensin mechanism)

Glucocorticoids

• Cortisol: main type;

  -secreted by zona fasciculate & zona reticularis (helps body deal w/ stressful situations)

Pineal Gland

Secrete melatonin

Pancreas

Endocrine cells & regulatory Pancreatic islets

• Alpha cells: secrete glucagon (Raise Blood sugar)

• Beta cells: secrete insulin (Lower Blood sugar)

• Delta cells: secrete somatostatin; inhibit secretion of insulin & glucagon

• PP cells: secret pancreatic polypeptide

Thymus

Site at which T lymphocytes arise from precursor cells

Stimulate by thymic hormones: Thymopoietin & Thymosin

Gonads

Male: Interstitial cells→secrete androgens, primarily testosterone Formation of sperm

Female: Ovaries→ estrogen, progesterone; prepares the uterus

Kidneys

Secrete renin (cells of the juxtaglomerular)

The skin

Modified cholesterol molecules convert to precursor of vitamin D

The Heart

Atria contain atrial natriuretic peptide (ANP)

Type 1 diabetes

• Develops suddenly before age 15

• Autoimmune response destroy beta cells

Type 2 diabetes

• Adult onset, after age 40

• Cells have lowered sensitivity to insulin

• Controlled by dietary changes & regular exercise

Graves’ disease

• Common type of hyperthyroidism

  (Nervousness, weight loss, sweating, rapid heart rate)

Myxedema

• Adult hypothyroidism

• Antibodies destroy thyroid issue

• Low metabolic rate & weight gain

endemic goiter

Lack of iodine in diet

Cretinism

Hypothyroidism in children (thick tongue)

Cushing’s syndrome

Hypersecretion of glucocorticoid

Addison’s disease

Hyposecretory disorder of adrenal cortex