Hypothalamus

Explain the embryological origins of the hypothalamus and pituitary gland Recognize the many inputs and outputs to and from the hypothalamus Understand biological rhythms Know the two major ways that the hypothalamus and pituitary communicate Describe the important releasing and inhibitory hormones

Where is the hypothalamus locaeted

Under the thalamus on floor of the 3rd ventricl e

What is the embryological origin of anterior pituarory gland

• evagination of oral ectodermal cells (rathke pouch, from the mouth)

• Therefore true endocrine organ

Posterior Pituitary gland embryoogical origin

• neural crest ecotderm evagination. Nervous system origin, therefore has a storage function

What ways can the hypothalamus has different inputs

• Receptor sensin

• Indirectly via the blood (temp, osmotic pressure, hormones)

• indirectly via nerves

• 
  

what are the 6 hypothalami nuclei

Paraventrivular - oxytocin adh trh crh

Supraoptic - oxytocin and adh

suprachiasmatic - biological clock

lateral nucleaus - arousal adn hunger

arcuate - energy

mammillary - wakefullness

what are the 3 types of hypothalmi inputs and the 2 types of mechanisms for this..

• Receptors

• circulating hormones

• Indirect sensing (nerves, emotions, limbic system..)

Humoral and neural pathways…

What are the 3 types of hypothalamic inputs..

Thermoreceptors

Osmoreceptors

energy balance (hunger control)

How is thermoregulation controlled in the hypothalamus..

Anterior hypothalamus = Heat detection, therefore will cool you down.. (anterior means the front!..)

Posterior hypothalamus = Cool detection (christmas post) therefore will warm up the dog, peropheral vasoconstriction, goosebumps, shivering

How do osmoreceptors in the hypothalamus respond

• respond to dehydration

• (ADH hormone from supraoptic nucleaus in the hypothalamus, dehydration stimulates the thirst center lateral hypothalamus..)

How does the hypothalamus regulate energy balance..

• SENSES blood glucose..

• Leptin causes ‘fullness’

• Ghrelin ‘ hunger’

What are the 2 ‘food centres’ in the hypothalamus

Saitety centre - high glucose levels, stop eating

appetite centre - response to low glucose levels, stimulates eating

What are the hypothalmic regulations of feeding behaviours..

• afferent inputs to hypothalamus, glucostat cells. Glucosee utilization..

• CCK = chloecytokinin (pancreatic secretion and gall baldder contraction)

What is the 3 endocrine outputs of the hypothalamus

• biological clock

• pineal gland

• melatonin

Secretory neurons (adh + Oxytocin..)

Inhibitory AND stimulatory hormones..

How and where is the biological clock regulated..

Light sensed by retina + transmited in nerve pathways - hypothalamus..

bio clock nucleas = the SUPRACHIASMATIC NUCLEAS —> stimulates pineal gland to make melatonin

What are the 3 different types of rhythmns..

Circadian rhtym —> 24 hr period

ultrafradian —> more regularly than 24hr (e.g. cortisol)

Infradian —> longer than 24 hrs, e.g. oestrus cycles..

What is important to remember if measuring cortisol…

Higher in the morning, the high cortisol triggers waking.. should decrease by 30% in a healthy individual..

What are the 3 parts of the pituatory gland

Anterior - pars tuberalise + pars distalis (adenohypophysis)

Intermdiate - Pars intemdi

posterior - pars nervosa (neurohypothesis)

What does the posterior pituatory gland secrete

• adh + oxytoxin.. from son and pvn

• axons descend and terminate at the blood vessels.

What does the posterior pituatory gland act as

Storage site for the hormone,s as originally a collection of nerves…

where are hte 2 plexi in the anterior pituatory gland

hypothalamis neurone

primary plexus

hypophyseal portal veins

secondary plexu

For referance exaples of releasing hormone

W?hat do inhibitory hormones fo

stop hunger signals.. stop the signal all the hormones will reach specific target tissues..

What is TOnic vs episodic secretion

TOnic = constant = e.g. dopamines

episodic = pulsating release of hormone - e.g. cortisol..

What is tonic inhibition

releasen and inhibition and sitmulates them /..

4 lecture integreation

Neurohormones

Dual opposing roles..

conclusions