S8 L1 - HPA and Growth Hormones Flashcards
- *Hypothalamus-Pituitary Axis**
- Provides a major link between…
- Where does the pituitary gland sit?
- Describe the anatomy/layout of the HPA
- Origin of anterior and posterior pituitary gland?
- Other name for anterior and posterior pituitary gland
- Provides a major link between…
The hypothalamus and pituitary gland form a complex functional unit that serves as the major link between the endocrine and nervous systems
- Where does the pituitary gland sit?
Sella turcica
- Describe the anatomy/layout of the HPA and Origin of anterior and posterior pituitary gland? Other name for anterior and posteiror pituitary gland
pic
- *Posterior pituitary gland:**
- What does it secrete?
- Where are these hormones made (really speicific names)?
- How does this work (in relation to hypothalamus)?
- *Anterior pituitary gland:**
- How does this work to release hromones?
- How is it different from posterior pituitary gland?
Posterior pituitary gland
- What does it secrete?
Oxytocin and ADH
- Where are these hormones made (really speicific names)?
Supraoptic and paraventricular nuclei of the hypothalamus
- How does this work (in relation to hypothalamus)?
Oxytocin and ADH are transport down the nerve cell axons to the posterior pituitary. They are released from posterior pituitary into the general circulation to act on distant tagerts
*The posterior pituitary gland does not synthesise these hormones. It just releases them
Anterior pituitary gland
- How does this work to release hormones?
Hormones synthesised in hypothalamus are transported down axons and stored in median eminence before release into hypophyseal portal system.
• These hormones stimulate (or inhibit) target endocrine cells in the anterior pituitary gland (neurocrine function).
• Endocrine cells of anterior pituitary secrete a variety of hormones into the bloodstream to act on distant target cells (i.e. endocrine function).
• Anterior pituitary hormones also effect neighbouring cells (autocrine and paracrine function)
Which hormones are produced in the hypothalamus for release from the posterior pituitary? What are the roles of these hormones?
- *OT** Oxytocin (Milk let down and uterus contractions during birth)
- *ADH** Antidiuretic hormone (also called vasopressin) - Regulation of body water volume)
- *Anterior pituitary summary**
- With trophic hormones (produced by hypothalamus)
- With hormones produced by the anterior pituitary gland
Graham-Linda Found Their Alice Picking
- *Anterior Pituitary:**
- Tropic hormones list and state their function
- Hormones produced by the anterior pituitary list and state their function
Tropic hormones: These have direct effects on the release of anterior pituitary hormones
TRH Thyrotropin releasing hormone (PRH)
Prolactin releasing hormone = TRH (minor +ve control on prolactin) PIH Prolactin release-inhibiting hormone (Dopamine)
CRH Corticotropin releasing hormone
GnRH Gonadotropin releasing hormone
GHRH Growth hormone releasing hormone
GHIH Growth hormone-inhibiting hormone (Somatostatin) (RH= releasing hormone, IH = inhibitory hormone)
Hormones produced by the anterior pituitary:
TSH Thyroid stimulating hormone - Secretion of thyroid hormone from thyroid gland
ACTH Adrenocorticotropic hormone - Secretion of hormones from adrenal cortex
LH Luteinising hormone - Ovulation and secretion of sex hormones FSH Follicle stimulating hormone - Development of eggs and sperm
PRL Prolactin - Mammary gland development and milk secretion
GH Growth hormone - Growth and energy metabolism. Stimulates IGFs
Example of the HPA, leading to the release of cortisol…
- *Endocrine**
- 4 ways to control growth
- Define: Hypertrophy, hyperplasia, atrophy, necrosis, apoptosis
Endocrine
- 4 ways to control growth:
Genetics, nutrient, environment, hormones
- Define: Hypertrophy, hyperplasia, atrophy, necrosis, apoptosis
pic
- *Growth hormone**
- Type of hormone and structure
- What tropic hormone stimulates it, what tropic hormones inhibits it?
- What receptor does GH act on?
- What does GH promote it’s effect via (some…)
- Which organs have GH receptors?
- Control of GH secretion (other things e.g. lifestyle…)
- Type of hormone and structure:
Protein, 191 amino acids, it has a signal peptide that needs to be cleaved before folding
- What tropic hormone stimulates it, what tropic hormones inhibits it?
•Stimulated by hypothalamic GHRH
•Inhibited by hypothalamic Somatostatin (GHIH)
- What receptor does GH act on?
Janus kinase receptors
- What does GH promote it’s effect via (some…)
leads to increase IGF levels, IGF has lots of effects… (next flashcard)
- Which organs have GH receptors?
Liver and skeletal muscles
- Control of GH secretion (other things e.g. lifestyle…)
pic
HPA of growth hormones…
- Another name for IGF
pic
IGF - insulin-like growth factors (Somatomedins)
How does GH exert it’s effects on cells?
-> Janus Kinase receptor
Role of Growth Hormone
- *IGF**
- Receptors
- Two types of IGF
- Role
- *Role of Growth Hormone:
- **GH stimulates long bone growth length & width prior to epiphyseal closure and Width after epiphyseal closure
IGF:
Receptors:
IGFs act through IGF receptors, not GH receptors
Types of IGF:
2 IGFs in mammals (IGF1 and IGF2)
• IGF2 mainly involved in fetal growth
• IGF1 major growth factor in adults
Role:
• IGFs stimulate both bone and cartilage growth
• Cell growth (Hypertrophy)
• Cell number (Hyperplasia)
• Increase in the rate of protein synthesis
• Increase in the rate of lipolysis in adipose tissue
- *Role of Both - In adults GH and IGFs help maintain:**
- muscle and bone mass
- promote healing and tissue repair as well as modulating metabolism and body composition.
