Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

203-T1 > Introduction to the endocrine system & HPA > Flashcards

Introduction to the endocrine system & HPA Flashcards

1
Q

How does the nervous system compare to the endocrine system?

A

NS- Allows very rapid, focused , precise communication

Endocrine- transmitters are released into carrier medium (blood) and rare that two organs are directly linked- usually CVS involvement (e.g. via blood pumping from heart)
-Sustained communication between group of cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the endocrine system?

What are hormones?

A

A system of ductless glands which secrete chemical messengers into the blood

Chemical messengers carried in blood that are able to act on cells processing the appropriate hormone receptors (target tissues). Each hormone can act on several target tissues.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Identify 5 endocrine organs

A 
Pineal gland
Hypothalamus
Pituitary gland
Parathyroid gland
Thyroid gland
Thymus
Adrenal gland
ancreas
Kidney
Ovary
Testes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is the pituitary gland found? Outline the anatomical structures found in and around it

A

Situated below the brain, encased in skull

Ant and post pituitary gland
Infundibulum (connection to hypothalamus)
Hypothalamus
Neurosecretory cells
Hypothalamico-hypophyseal tract
Hypothalamico-hypophyseal portal vessels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where are the thyroid and parathyroid gland found? Function?

A

In the neck

Important in control of metabolic rate and calcium homeostasis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Function of the pancreas

A

Secrete digestive enzymes directly into the GI tract (exocrine)

Also secretes insulin which regulated b/g and glucose utilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Shape and function of adrenal glands

A

Left- pyramidal
Right- semilunar

Medulla is concerned with stress response

Cortex with stress, sodium and glucose homeostasis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Function of the gonads (ovaries and testes)

A

Secrete female and male reproductive hormones respectively. Responsible for the development of secondary sexual characteristics and reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Consider the mechanism of hormone action at steroid hormone receptors

A

Lipid soluble hormone crosses the cell membrane

Binds to receptor (cytoplasmic or nuclear)

Hormone-receptor complex binds to hormone-response element of DNA

Influences gene transcription

! Receptor may be constitutively active

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Consider the mechanism of hormone action at G-Protein coupled hormone receptors

A

Receptor –> G-Protein–> Phospholipase C –>:

  • PIP2
  • DAG
  • IP3

DAG and IP3 act as secondary messengers and phosphorylate intracellular, regulatory protein to influence cellular activity (e.g. smooth muscle contraction)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Consider the mechanism of hormone action at Tyrosine kinase hormone receptors

A

Membrane bound enzyme is a single strand of protein (often dimerised)

1 hormone molecule binds to each receptor

Receptor acts as an enzyme to phosphorylate ‘tyrosine’ components of intracellular regulatory proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Outline the characteristics of peptide hormones

A
  • Chains of AA’s
  • High water solubility (susceptible to protease attack therefore not orally active and short half-life)
  • Cant cross cell membrane without carrier protein
  • Act on membrane-bound receptors (RAPID onset)
  • Short duration of action
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Outline the characteristics of steroid hormones

A
  • Poorly water soluble (transported in blood, bound to plasma protein)
  • Orally active
  • Crosses cell membrane to act on intracellular receptors (slow onset of action)
  • Long plasma 1/2-life
  • Long duration of action
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Function of the anterior pituitary gland

A

Control secretion of a hormone from a gland

It in itself secretes stimulating (TROPHIC) hormones

In turn, the secretion of a hormone by the ant.Pituitary is controlled by the hypothalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Consider the control of the endocrine system

The anterior pituitary acts on a gland to stimulate secretion of a hormone.

Complete the name of the gland and hormone for each SH:

  1. Thyroid stimulating hormone (TSH)
  2. Adrenocorticotrophic hormone (ACTH)
  3. Follicle stimulating hormone (FSH)
  4. Luteinising hormone (LH)
A
  1. Thyroid gland, thyroxine (T4)
  2. Adrenal cortex, cortisol
  3. Ovary, oestrogens
  4. Ovary, Progesterone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The hypothalamus secretes “Hormone 1 “ to stimulate secretion of “Hormone 2 “ from the ant.Pituitary gland

Which “Hormone 1” leads to the release of :

  1. TSH
  2. ACTH
  3. FSH
  4. LH
A
  1. Thyrotrophin releasing hormone (TRH)
  2. Corticotrophin releasing hormone (CRH)
  3. Gonadotrophin releasing hormone (GnRH)
  4. Growth hormone releasing hormone (GHRH)
17
Q

State the negative feedback function of the following hormones:

  1. Thyroid hormone
  2. Cortisol
  3. Oestrogens
A
  1. Acts to decrease secretion of TRH and TSH
  2. Acts to decrease secretion of CRH and ACTH
  3. Acts to decrease secretion of GnRH and FSH
18
Q

What is the consequence of negative feedback of [hormone]

A

Cyclic variation

Varies at different times of the day (Always note at which time hormone conc. is being measured. Cortisol should be measured at 9am- shift workers excluded, measured first thing when waking up)

19
Q

State 5 hormones secreted from the anterior pituitary gland

What is special about the destination of the R- hormones?

A 
Growth hormone
FSH
LH
TSH
ACTH
Prolactin

These travel from hypothalamus into hypothalamicoadenohyphophyseal portal vessel and do not enter systemic circulation

20
Q

State 2 hormones secreted from the posterior pituitary gland
How do these two hormones compare?

Alternate name for posterior pituitary gland?
Function?

A

ADH
Oxytocin

Both peptide hormones, 9AA’s (7 identical–> overlap of activity)

Made by hypothalamic neurones (supraoptic nuclei and paraventricular nucleus)

Travel via hypothalamiconeurohypophyseal tract

Neurohypophysis
Post.PG converts these hormones into their active forms and stores.

21
Q

Consider ADH

When is it secreted?
Mechanism of action?
Disorder?

A

Secretion is influenced by plasma osmolarity

Stimulation of V2 receptors causes translocation of aquaporins to the membrane of the kidney tubule –> water reabsorption

Stimulation of V1 receptors causes vasoconstriction (THIS DOES NOT OCCUR AT PHYSIOLOGICAL CONCS)

Disorders of ADH secretion –> disorders of fluid balance

22
Q

Consider oxytocin

When is it secreted?
Mechanism of action?
How does synthesis differ at different times in a womans life?

A

Secretion stimulated by genital and nipple stimulation. Important in parturition (childbirth) as it causes contraction of SM of uterus aiding expulsion of child; and lactation (stimulated by sucking)

  • Continues stimulation of the cervix causes continued secretion and SM contraction of the myoepithelial cells in . breast during breast feeding
  • Not necessary for the initiation of a normal labour but oxytocin may be administered to induce labour

IP3 –> causes contraction of the smooth muscle of the genital tract (uterus) and breast

Synthesis increases during pregnancy, but there is a parallel increase in oxytokinase activity (to prevent premature contractions)

23
Q

How has the body adapted to the delay in lactation?

A

There is a delay between suckling and milk ‘let down’

Pavlovian reflex- begin secretion in response to baby crying
- inappropriate secretion in response to other children crying

24
Q

Function of prolactin?

Chemical structure?
Secretion?
Disorder?

A

Promote lactation and development of breast tissue
- Most important in women (post-puberty and during/after pregnancy) but also secreted in men

199 AA’s

  • Synthesised in lactotrophe cels of anterior pituitary
  • Secretion under hypothalamic control by means of Prolactin Release Inhibiting factor (DA); TRH stimulates prolactin synthesis
  • Secretion stimulated by mild stress, nipple stimulation, coitus

Hyperprolactinaemia in breastfeeding mothers decreases fertility

25
Q

Which cells synthesise TSH, ACTH and FSH?

A
  • Thyrotrophe cells
  • Corticotrophe cells
  • Gonadotrophe cells
26
Q

CLINICAL APPLICATION

Why is time of measurement of hormone relevant?

A

Diurnal rhythms (24 hour oscillations)

27
Q

CLINICAL APPLICATION

In chronological order, outline how you would identify an endocrine disorder?

A
  1. Analyse signs and symptoms
  2. Biochemical tests: TSH & FT4, Cortisol, LH & FSH, Prl, Testosterone/’periods”

(compare with basal levels)

  1. Is it the gland that is the problem or hypothalamus? REMEMBERL: cant measure hypothalamus activity directly
    e. g. Stimulate (ACTH) or suppress secretions (Dexmathsone suppression)
  2. Imaging
  3. Visual field tests (because optic chiasm lies above pituitary gland)
    - Bilateral hemianopia? (compression)
28
Q

Consider growth hormone

Where is it synthesised?
Control of secretion?
Mechanism of action?
Function?

A
  • Synthesised in somatotrophe cells of the anterior pituitary gland
  • Secretion controlled by GHRH (most important) and GHRIH (somatostatin)
  • Stimulated by low carbohydrates, fatty acids and AA’s
  • In some tissues, acts via 2nd messengers produced in liver
    e. g. Insulin-like GF-1, Insulin-like GF-2
  • Promote linear growth of adolescence by increasing protein synthesis and collagen deposition (mediated by nucleus)
  • FOETAL DEVELOPMENT IS RELATIVELY INDEPENDENT OF GH

203-T1 (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions