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UNLV / Kinesiology / KIN 224 / What is the role of pituitary gland?

What is the role of pituitary gland?

What is the role of pituitary gland?

Description

School: University of Nevada - Las Vegas
Department: Kinesiology
Course: Human Anatomy and Physiology II
Professor: Sean neiswenter
Term: Fall 2016
Tags: Anatomy & Physiology II
Cost: 25
Name: Chapter 18 Continued
Description: Notes from 09/08; Week 2
Uploaded: 09/10/2016
7 Pages 166 Views 2 Unlocks
Reviews


09/08


What is the role of pituitary gland?



Chapter 18 cont’d

Hypothalamic Control of the Anterior Lobe

• Releasing hormone and inhibiting hormone  

- only from the hypothalamus

• Endocrine and nervous system work together

- neither one controls the other

• Maintain very minimal fluctuation  

The Pituitary Gland

• Thyroid-stimulating hormone (TSH) 

- aka thyrotropin

- regulation 

• thyrotropin-releasing hormone (TRH)

- function 

• to stimulate the release of thyroid hormones from the thyroid gland • Adrenocorticotropic hormone (ACTH) 


How does the hypothalamus control the anterior pituitary?



- aka corticotropin

- regulation 

• the release in response to corticotropin-releasing hormone (CRH) from the  hypothalamus

- function 

• stimulates release of glucocorticoids by the adrenal cortex

→ secretes numbers of steroids

→ sugar metabolism

ex. cortisol  

• Follicle-stimulating hormone (FSH) 

- aka follitropin

- releasing hormone is gonadotropins

- regulation 

• release in response to gonadotropin-releasing hormone (GnRH) from the  hypothalamus


What are posterior pituitary hormones?



- function 

• promote follicle development and estrogen secretion in females, sperm  maturation in males

• Luteinizing hormone (LH) 

- aka lutropin

- releasing hormone is gonadotropins We also discuss several other topics like How to record the journal entry for the cost flow when you have two department?

- regulation 

• release in response of gonadotropin-releasing hormone (GnRH) from the  hypothalamus

- function If you want to learn more check out What was the purpose of the wade davis bill?

• promote ovulation and progesterone secretion in females, testosterone  secretion in males

• Prolactin (PRL)

- aka mammotropin

- not a tropin hormone

- “pro” – before

- “lactin” – lactate

- chemical messenger

- regulations 

1. prolactin – releasing factors from the hypothalamus stimulate production 2. prolactin – inhibiting hormone (PIH; dopamine) inhibits production - function 

• stimulate mammary gland development and milk production

** Levels of prolactin in blood are a part of negative feedback Don't forget about the age old question of What does it mean to be scientific?
If you want to learn more check out What are the main phases of database development?

- stimulate release of dopamine

• Growth hormone (GH) 

- aka somatotropin

- regulations 

1. stimulated by GH-RH from hypothalamus

2. release inhibited by growth hormone-inhibiting hormone

- function If you want to learn more check out What does chromosome inversion cause?

• stimulate cell growth and replication, stimulates production of somatomedins  by liver which promote AA uptake and protein synthesis  If you want to learn more check out What was ancient israel called?

- targets the liver

- secretes number of other messengers that lead to growth and development of  other tissues

** Figure 18-9

• Look over as good reference for pituitary hormones

• MSH 

- stimulate hormone

- no significant levels in adults

- important in kids

- seen in pregnant women and people with some diseases

- high levels in some patients cause over stimulation

The Posterior Lobe

• aka neurohypophysis  

• Separately develop from anterior love

• More nervous tissue

• Contains unmyelinated axons of hypothalamic neurons 

• Supraoptic and paraventricular nuclei secrete

- antidiuretic hormone (ADH) 

- oxytocin (OXT) 

• Does not synthesize, stores and secretes

Hormones of Posterior Lobe

• Antidiuretic hormone (ADH) 

- aka vasopressin

• “vaso” – vessel

• “pressin” – pressure

→ increase blood pressure

- reduces urination

- reduces water loss

- mechanism for preventing dehydration

- regulates blood solute concentration rises (less water) or blood pressure drops  (less volume)

- function 

• decrease water loss at the kidneys

• Oxytocin (OXT) 

- regulation 

• responds to sensory nerve stimulation

- function 

• tactile stimulation

• stimulate smooth muscle contraction in uterus, ductus deferens, and prostate  gland

→ Let down reflex 

- ejection of milk in females (forces milk from the gland)

- plays a role in bonding

**Positive Feedback

ex. Childbirth & breast-feeding

• The more oxytocin released during childbirth the more stretch of the uterus and  uterus cervix. When continuously done, more oxytocin gets released until the baby  is out

• Tactile stimulation causes oxytocin to be released (from baby suckling nipple).  Allows milk to be released. Will continue being released until baby lets go • Anything that affects hypothalamus can affect response

- anxiety, stress

• can prevent milk flow

- baby crying

• can trigger let down reflex

• can trigger lactation

• Plays through nervous system stimulation, anything that interferes gets fed through  emotions and mood

- can affect release of milk

The Thyroid Gland

• Inferior to thyroid cartilage

• 2 lobes connected by isthmus 

• Thyroid follicles

- spheres lined by simple cuboidal epithelium

• Follicular cells surround follicle cavity 

• Colloid contains thyroid hormones

- center of large follicle

• Hormones (2)

- Thyroxine (T4)

- Triiodothyronine (T3)

** Produced by follicular cells

Functions of Thyroid Hormones

• Target = most cells in body

• Derived from amino acids

• Binds to receptors inside cell

- cytoplasm (increases in available ATP)

- surfaces of mitochondria

- nucleus

• Alters metabolism

• Increases

- energy utilization

- oxygen consumption

- growth and development

- temp in kids

** Metabolic Processes

• How they get across membrane

- cells have transport molecules so the hormone latches on and moves across it Plasma Proteins 

• Bind most thyroid hormone in blood

- about 0.3% of T3 and 0.03% of T4 are unbound

• Not getting cleared out or removed

• A lot of hormone put out, a tony amount of everything available - holds steady amount that is available for use

→ steady level, no fluctuation

Calorigenic Effect 

• Cells consume more energy = increased heat

• Increase in rate of cellular metabolism

- in children ???? heat

- in adults ???? burn calories

** Essential for normal growth/development in children

- iodine in environment

• lack of

→ developmental issues (children)

→ overgrown thyroid gland (adults)

- TSH isn’t negatively reduced through thyroid hormone (not enough  iodine)

C (clear) cells

• aka parafollicular cells

• Produce calcitonin (CT) in response to high Ca2+ levels in bloodstream - inhibits osteoclasts (targets bone)

• slows the rate of Ca2+ release from bone

- takes Ca2+ out of blood

- stimulates Ca2+ excretion by the kidneys

• into urine

• Work together to lower Ca2+ levels

Parathyroid Gland

• 4 glands

- embedded in the posterior surface of the thyroid gland

• Parathyroid hormone (PTH) 

- aka parathormone

- produced by parathyroid (chief) cells in response to low concentrations of Ca2+ • Antagonist for calcitonin

- blood calcium levels to increase

Effects of PTH

• 3 effects

1. stimulates osteoclasts (breakdown bone) and inhibits osteoblasts (growth of bone) • releases Ca2+ from bone

• reduces rate of calcium deposition in bone

2. enhances reabsorption of Ca2+ in kidneys  

• reduces urine volume

3. stimulates formation and secretion of calcitriol by the kidneys 

• targets kidneys as well

• Ca2+, PO43 absorption by digestive tract

• enhances PTH effects

• increased absorption and release of other hormones

Thyroid and Parathyroid

• Antagonistic relationship with same goal to maintain blood calcium levels ** Figure 18-3 

Possible essay question

• Negative feedback

Adrenal Glands

• Superior to kidneys

• 2 portions

• Adrenal cortex

- mostly cholesterol

- stores lipids

- manufactures corticosteroids 

• Adrenal medulla

- secretory activities controlled by sympathetic division of ANS

- produces epinephrine and norepinephrine

• “fight or flight”

• Neurological

• Hypothalamus controls directly through sympathetic stimulation  Cortex 

• 3 zones

-zona glomerulosa

-zona fasciculate

-zona reticularis

(all have different roles)

• zona glomerulosa

** think salt

- alter mineral concentration

- produces mineralocorticoids 

• steroid hormones that affect electrolyte composition of body fluids - outer level

• mineral composition

ex. aldosterone

→ stimulates conservation of Na+ and elimination of K+ 

- reabsorption of sodium from urine

• Presence of aldosterone

- sodium in, potassium out  

• zona fasciculate 

- produces glucocorticoids 

• sugar

• steroid hormone that affect (alter) glucose metabolism 

ex. cortisol

- makes you fat

- ACTH (anterior pituitary) stimulates secretion increase glucose synthesis and  glycogen formation in the liver  

• causes glucose to be synthesized by liver

- stimulate glucose – sparing in peripheral tissues

• cells stop using glucose as primary source of energy

• start burning fatty acids

→ lead to elevated glucose level for nervous system

- show anti-inflammatory effects

• when stressed

• inhibits white blood cells and other immune functions

→ causes cold sore

• stress hormone and takes over role of epinephrine once it is done • zona reticularis 

- minor role in adults

- produces androgens under stimulation by ACTH

• promotes bone and muscle growth as well as blood cell formation in women  and children 

     ex. mustache, chin hair

• excessive production of hair on females

- not important in adult men

• negligible

• men have testes for this purpose

- role in sex development

• especially in children and adolescents

→ signs of puberty

Adrenal Medulla 

• Contains 2 types of secretory cells

• One produces epinephrine (adrenaline)

- 75% to 80% of medullary secretions

• Other produces norepinephrine (noradrenaline)

- 20% to 25% of medullary secretions

Epinephrine and Norepinephrine

(common in asthma inhalers)  &  (“fight or flight” response)

• In skeletal muscles 

- mobilization of glycogen reserves, making sugar available for source of energy  - acceleration of glucose metabolism

• In adipose tissue 

- lipids are broken down and released into the bloodstream

• free fatty acids

- larger amounts of energy available

• In the liver 

- main storage of glucose

- glycogen molecules are broken down and glucose is released into the  bloodstream

- major storage of sugar in other tissues except skeletal (has own) • In the heart 

- increase in the rate and force of cardiac muscle contraction

• response

- increase blood pressure and movement of blood  

• In the lungs 

- allows more air flow

The Pineal Gland

• Pine cone shape

• Lies in posterior portion of roof of third ventricle  

• Contains pinealocytes

• Synthesize hormone melatonin

- made by pinealocytes

- role in sex, seasonality, sleep

• Functions 

- inhibits reproductive functions

• through negative feedback

• via FSH/LH

- protect against damage by free radicals

• antioxidant

- influence circadian rhythms

• photosensitive entrainment (tired at night)

• Decartes’

- seasonal affective disorder

• no melatonin shut off in places that are always light

ex. Alaska

- high in children

**stimulation of receptors of light causes pineal gland to be turned off

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