Hypophysis (pituitary)

Name another hormone that stimulates GH secretion

- Ghrelin

Dopamine inhibits which adenohypophysis hormone

- PRL by Lactrotropes

Major cells of the adenohypophysis

- chromophils - chromophobes

Name 3 Basophils and their product

- corticotrope: adrenocorticotropic hormone (ACTH) and beta lipotropin - Gonadotrope: follicle stimulating hormone (FSH) and luteinizing hormone (LH) - Thyrotrope: thryotropic hormone (TSH)

Follicle-stimulating hormone (FSH) stimulate

- development of ovarian follicles and spermatogenisis

Location of pars intermedia

- pars distalis and pars nervosa

adenohypophysis is developed from

An outpocketing of the oral ectoderm, which forms a structure called Rathke's pouch

Milk ejection reflex consists of

Neuronal afferent limb and hormonal efferent limb

Pituicytes

Non-neuronal cells that do not produce hormones, that have tropic and support role

Gigantism

Overproduction of growth hormone before closure of bone epiphyses causes unusual proportional growth

Functions of oxytocin

- Causes contraction of smooth muscle cells in myometrium of pregnant uterus - Causes contraction of myoepithelial cells in the lactating mammary gland

List the releasing and inhibiting hormones from the hypothalamus

- Growth hormone releasing hormone (GHRH) - Somatostatin - Dopamine - Corticotropin-releasing hormone (CRH) - Gonadotropin- releasing hormone (GnRH) - Thyrotropin- releasing hormone

Gonadotropin-releasing hormone (GnRH) stimulates which adenohypophysis hormone

- LH and FSH by gonadotropes

Name the two hormones found at the Neurohypophysis

- Oxytocin - Antidiurectic hormone

Types of cells found at the neurohypophysis

- Pituicytes - Unmyelinated axons

Name the 2 acidophils (type of chromphil cells) and their product

- Somatrope: growth hormone (GH) - Lactrotrope: prolactin (PRL)

Name two hormones that also stimulate PRL secretion via Lactrotropes

- TRH and Vasoactive inhibitory peptide (VIP)

Of the two lobes, which can produces its own hormones and which receives hormones produced from the hypothalamus

- adenohypophysis calls make their own hormones - neurophypohysis receives hormones from the hypothalamus

Chromophobes

- another cell type found in the adenohypophysis - small cells, occur in clusters, heterogenous population

Hypophysis is composed of two lobes

- anterior (adenohypophysis) - posteriors (neurohypophysis)

Name the cells found in Pars intermedia

- basophils and chromophobes

Growth hormone-releasing hormone (GHRH) stimulates which adenohypophysis hormone

- growth hormone by somatotropes

Somatostain inhibits which adenohypophysis hormone

- growth hormone by somatotropes

Describe hormonal efferent limb

- hypothalamic terminal axons release oxytocin into neurohypophysis. Then travels to the mammary gland via blood cause the myoepithelial cells to contract, enhancing milk ejection.

Two major mechanisms for adenohypophysis regulation

- hypothalamus produces stimulating or inhibitory hormones that affect hormone production of basophils or acidophils - negative feedback; product of target organs inhibits hormone production by acidophils and basophils

Functions of antidiuretic hormone (ADH)

- increases blood pressure by acting on vascular smooth muscle - promotes fluid resorption at the collecting ducts in the kidney

Neurohypophysis is supplied by

- inferior hypophyseal artery

What happens to Rathkes pouch during development

- it fragments into small cysts called Rathkes cysts which remain in pars intermedia

luteinizing hormone (LH) stimulates

- maturation of ovarian follicles and androgen secretion by testis

Location of the primary plexus of the hypothalamo-hypophyseal

- median eminence and infundibular processes

Via H&E, how do the neurohypophysis and adenohypophysis differe

- neurohypophysis is pale staining - adenohypophysis is dark staining

Describe direct innervation of hypothalamus

- neurons from hypothalamus extend into the neurohypophysis, where they secrete hormones into the blood to travel to target organs

Describe indirect innervation of hypothalamus

- neurons release hormones into venus portal system to adenohypophysis. There the production of hormones via cells of the anterior pituitary is regulated. Then those hormones are secreted into blood and to their target organs

Protein that oxytocin and ADH associate with in granules

- neurophysins

The two hormones that neurohypophysis receives from hypothalamus

- oxytocin - vasopressin (Antidiuretic hormone)

Location of the secondary plexus of the hypothalamo-hypophyseal portal system

- pars distalis

Three parts of the neurohypophysis

- pars nervosa - infundibular process - median eminence

Thyrotropic hormone (TSH)

- stimulates synthesis of thyroid hormones, T3 & T4

Describe the neuronal afferent limb

- suckling stimulates afferent nerve endings in the nipple, impulses travels to hypothalamus

The main blood supply for the primary plexus of the hypothalamo-hypophyseal portal system

- superior hypophysis artery

What type of axons can be found in neurohypophysis

- unmyelinated axons, whose cell bodies are found in the hypothalamus

Chromaphils have __________ acidophils and ________basophils

2 acidophils - somatrope - lactrotrope 3 basophils - corticotrope - gomadotrope - thyrotrope

Herring bodies

Accumulation of secretory granules in the nerve terminals and neuronal axon. Characteristic of neurohypophysis.

At which part of the adenohypophysis, would we find the most cells

Pars distalis

Brain endocrine axis consist of

Pituitary gland and hypothalamus

Growth hormone stimulates

Production of insulin-like growth factor (IGF-1) by liver cells. When secreted they target muscle and bone to produce growth

Adrenocorticotropic hormone (ACTH) stimulates

Synthesis of glucocorticoids and gonadocorticoids by adrenal cortex

Thyrotropin-releasing hormone (TRH) stimulates which adenohypophysis hormone

TSH by thyrotropes

What is a portal system?

blood flows through two capillary beds that's are connected in series before returning to the heart

Acromegaly

overproduction of growth hormone after epiphyses closure causes enlarged hands and feet

Three parts of the adenohypophysis

pars distalis, pars intermedia, pars tuberalis

The hypophysis is another name for

pituitary gland

Graces disease

Autoimmune disease where receptors are produced against TSH receptors and promotes the affects of TSH hormone. Over production of T3 and T4 hormones

location of hypophysis

Base of the brain. In a small depression of the sphenoid bone, Sella turcica (Turkish saddle)

Rathke cysts is lined by

Cuboidal cells

Insufficiency or absence of ADH results in

Diabetes insipidus

Hypothalamus contributes to homeostasis via

Direct and indirect innervation

T/F. Neurohypophysis does not receive direct innervation from hypothalamus

False, recieves direct innervation from hypothalamus

T/F Hypothalamo-hypophyseal portal system is an arterial portal system

False. It is a venous portal system. The primary and secondary capillary plexus are connected via hyphyseal portal vein

T/F. Similar to neurohypophysis, the adenohypophysis receives direct innervation from hypothalamus

False. It receive indirect innervation

T/F. Lactrotropes similar to other cell types store their excess secretory granules within their cytoplasm until stimulated to release

False. Lactrotropes secretory granules are destroyed by lysosomal enzymes via crinophagy

arterial portal system

First capillary bed (primary plexus) is connected to another capillary bed (secondary plexus) via arteries

Venous portal system

First capillary bed (primary plexus) is connected to another capillary bed (secondary plexus) via vein

Compared to the blood brain barrier, the plexus have

Highly permeable fee started capillaries

The blood supplied to adenohypophysis is known as

Hypothalamo-hypophyseal portal system

The neurons found between hypothalamus and neurohypophysis make up the

Magnocellular neurosecretory system

Prolactin hormone stimulates

Mammary gland development and lactation.

neruohypophysis develops from

Neuroectoderm in the floor of the diencephalon. Maintains its connection via infundibulum

Corticotropin-releasing hormone (CRH) stimulates which adenohypophysis hormone

- ACTH by corticotropes