endocrine

• An endocrine gland is a gland which secretes hormones directly into the blood.
• The endocrine system is made up of glands that produce and secrete hormones. Hormones are chemical substances produced in the body to regulate the activity of cells or organs. These hormones regulate the body's growth, metabolism (the numerous physical and chemical processes of the body), and sexual development and function.
• Endocrine gland - Secretes product directly in blood

  Exocrine gland - Secretes product through duct
• Epithelia cover exposed surfaces and line internal cavities and passageways;

  they often contain secretory cells, or gland cells, scattered among the other cell types.

  
• Glands are derived from epithelia, but secretory cells predominate; there are two types:

  
• Exocrine glands secrete

  substances through ducts on to external surfaces or internal passageways that connect to the exterior. E.g Sweat glands

  Salivary glands

  Mammary glands

  Sebaceous glands

  
• Endocrine glands secrete hormones

  directly into the blood rather than through a duct.

  
• Endocrine System

  •System of glands

  •Hormones are transmitted via blood stream

  •Slow acting

  •Chemical response lasts longer

  
• Nervous System

  •Signals travel along neurons using neurotransmitters

  •Fast acting electrical action potentials

  •Often short-acting changes to the body

  
• Nervous system vs Endocrine system similarities

  ØRely on chemical messengers

  ØRespond to stimuli

  ØWork via feedback loops

  ØRegulate physiological activities to maintain homeostasis
• Hormones are chemical messengers secreted by endocrine glands. Different hormones affect different target organs. The bloodstream transports hormones from the glands to the target organs.
• Hormones stimulate certain life processes and inhibit others. Growth, reproduction, control of metabolic processes, sexual attributes, and even mental conditions and     

  personality traits are dependent on hormones.
• The Hypothalamus:

  A) Thalamus

  B) hypothalamus

  C) Infundibulum

  D) anterior Pituitary

  E) Posterior Pituitary

  
• The Hypothalamus:

  •Regulation of certain metabolic processes and other activities of the autonomic nervous system

  •Links nervous system to endocrine

  •Synthesizes and secretes RELEASING or INHIBITORY hormones -these in turn stimulate or inhibit the secretion of pituitary hormones.

  
• Hypothalamus = a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland (hypophysis).

  
• The Pituitary gland:

  •Lies below hypothalamus, suspended from underside of brain by a infundibulum.

  •Also referred to as the ‘hypophysis’

  •Size and shape of a pea

  
• The Pituitary gland:

  •Pituitary gland sits in the pituitary fossa (small depression in sphenoid bone).

  •This fossa = sella turcica (‘‘Turkish saddle’’)

  •Superior surface of the gland = covered by a reflection of dura mater (diaphragma sellae). This membrane has a central opening which allows passage of the infundibulum.

  
• The Pituitary gland:

  Pituitary gland = anterior pituitary and posterior pituitary

  
• The Pituitary gland:

  A) hypothalamus

  B) mammillary bodies

  C) median eminence

  D) Infundibulum

  E) optic chiasm

  F) anterior pituitary

  G) pars tuberalis

  H) pars intermedia

  I) pars distalis

  J) posterior pituitary

  K) infundibular stalk

  L) pars nervosa

  M) Hypophyseal fossa

  
• The Anterior Pituitary gland:

  The anterior lobe can be further divided into three parts:

  1)Pars anterior (aka pars distalis)

  2)Pars intermedia

   

  3)  Pars tuberalis

  
• The Posterior Pituitary gland:

  •Upon stimulation, posterior lobe secretes 2 hormones: ADH (controls blood osmolality) and oxytocin (involved in parturition and milk secretion).

  
• The Posterior Pituitary gland:

  The posterior lobe can be further divided into two parts:

  1)Pars nervosa

  2)Infundibulum

  
• The Posterior Pituitary: hypothalamic nuclei

  A) Anterior lobe of pituitary gland

  B) Posterior lobe of pituitary gland

  C) Hypothalamo- hypophyseal tract

  D) Supraoptic Nucleus

  E) Paraventricular Nucleus

  
• The Posterior Pituitary: hypothalamic nuclei

  Paraventricular Nucleus - Oxytocin

  Supraoptic Nucleus -

  Anti diuretic hormone (ADH) aka Vasopressin

  
• Blood supply to the pituitary gland:

  via the internal carotid artery

  A) superior hypophyseal artery

  B) inferior hypophyseal artery

  
• superior hypophyseal artery is the main artery that supplies the Hypothalamohypophyseal portal system.

  
• inferior hypophyseal artery main function is to pick up oxytocin and ADH from posterior pituitary and distribute it

  
• The Hypothalamohypophyseal portal system:

  A) Hypothalamus

  B) Median eminence

  C) Hypophyseal portal veins

  D) Inferior hypophyseal artery

  E) Superior hypophyseal artery

  
• The Hypothalamohypophyseal portal system

  1. Axon terminals of hypothalamic neurosecretory cells release hormones (RHs and IHs) into the hypothalamo-hypophysial portal system.
  2. The RHs and IHs travel in the portal system to the anterior pituitary.
  3. The RHs and IHs stimulate or inhibit the release of hormones from anterior pituitary cells.
  4. Anterior pituitary hormones leave the gland via the blood.

  
• The Hypothalamohypophyseal portal system:

  A) supraoptic

  B) paraventricular

  C) Inferior hypophyseal artery

  D) Pars nervosa

  E) dorsal medial

  F) ventral medial

  G) infundibular nuclei

  H) Median eminence

  I) Superior hypophyseal artery

  J) Hypophyseal portal veins

  K) Primary capillary plexus

  L) Pars distalis

  M) Secondary capillary plexus

  
• posterior pituitary gland - Hormones produced in the hypothalamus and released in the pars nervosa

  anterior pituitary gland - Stimulating (or inhibiting) hormones produced in the hypothalamus. Then Hormones produced in the pars distalis

  
• The Posterior pituitary gland releases:

  •Oxytocin

  •Antidiuretic Hormone (ADH)/ Vasopressin (used interchangeably)
• The Anterior pituitary gland releases:

  •Thyroid- Stimulating Hormone (TSH)

  •Luteinising Hormone (LH)

  •Follicle Stimulating Hormone (FSH)

  •Adrenocorticotropic Hormone (ACTH)

  •Prolactin

  •Growth Hormone (GH)

  Mnemonic:

  These Leave From Anterior Pituitary Gand
• The Anterior pituitary – Histology

  Acidophil - pink

  •GH (somatotrophic cells)

  •Prolactin (lactotrophic cells)

  
• The Anterior pituitary – Histology

  Basophil - purple

  •TSH (thyrotrophic cells)

  •ACTH (corticotrophic cells)

  •LH AND FSH (gonatotrophic cells)

  
• The Anterior pituitary – Histology

  Chromophobes - dont stain

  
• The Pineal Gland:

  •Small gland which produces melatonin

  •Helps modulate sleep

  •Receives vascular branches from the posterior cerebral artery

  
• Thyroid Gland:

  A) hyoid bone

  B) thyroid gland

  C) Laryngeal prominence

  D) Adams apple

  
• Thyroid secretes Triidothyronine (T3) & Thyroxine (T4)

  
• Thyroid Gland:

  A) right lobe

  B) isthmus

  C) left lobe

  D) pyramidal lobe

  E) Triidothyronine (T3)

  F) Thyroxine (T4)