Endocrine refined Flashcards
Endocrine glands
- Function
- Vascularity
- Function: secrete hormones directly into the bloodstream upon stimulation
- Vascularity: highly vascularised
The three arrangements of endocrine tissue
1- Endocrine organ
2- Distinct clusters of cells within an organ
3- Individual cells scattered throughout an organ
Major hormone products of the hypothalamus
- RH and IF
- Examples
- Releasing hormones and inhibiting factors
- E.g. CRF, GnRH, GHRH, TRH, dopamine
Major products of the posterior pituitary (2)
- Anti-diuretic hormone (ADH)
- Oxytocin
Major hormone products of the anterior pituitary (6)
- ACTH
- GH
- P
- FSH
- LH
- TSH
- Adrenocorticotrophic hormone (ACTH)
- Growth hormone
- Prolactin
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
- Thyroid stimulating hormone
Major hormone products of the thyroid gland (3)
- Thyroxine (T4)
- Tri-iodothyronine (T3)
- Calcitonin
Major hormone product of the parathyroid gland
- Parathyroid hormone
Major hormone products of the adrenal gland (2)
- Adrenaline
- Cortisol
Major hormone products of the pancreas (2)
- Glucagon
- Insulin
Major hormone products of the gonads (3)
- Progesterone
- Oestrogen
- Testosterone
Modes of hormone action
- Autocrine and Paracrine
- Endocrine and Neuroendocrine
- Autocrine and Paracrine: Local diffusion
- Endocrine and neuroendocrine: Circulation
Chemical nature of hormones is related to …. (5)
- How they are….
- Nature of the H….
- Ability to b…..
- degradation
- How they are synthesised
- Nature of the hormone receptor they bind to
- Ability to bind to other proteins (e.g. transport proteins)
- How they partition in tissues
- How they are degraded
Steroid hormone examples:
- Prog…
- Gluco…
- Mineral…
- And….
- Oest…..
- Progestagens
- Glucocorticoids
- Mineralocorticoids
- Androgens
- Oestrogens
Non-steroid hormones
- Poly…
- Glyco…
- Eico….
- Pep….
- Ami….
- Polypeptides
- Glycoproteins
- Eicosanoids
- Peptides
- Amines
Hypothalamus-pituitary axis:
- Interface between central nervous system and endocrine system
Hypothalamus-pituitary axis controls homeostatic regulation of (7)
- S and I F
- R
- G and D
- W/E B
- E B/A C
- T
- S/W
- Stress and immune function
- Reproduction
- Growth and development
- Water/electrolyte balance
- Energy balance/appetite control
- Thermoregulation
- Sleep/wakefulness
Hypothalamus, anatomical boundaries:
- Anterior: OC
- Posterior: MB
- Superior: T
- Inferior: ME
- Anterior: Optic chiasm
- Posterior: Mammillary bodies
- Superior: Thalamus
- Inferior: Median eminence
Hypothalamus structure: (2)
- Divided into anatomical nuclei
- Contains hypothalamic neurosecretory cells
Action of the hypothalamus: (2)
- HNC R P F AT A to C
- I NI F BS, LS a HA, W R A
- Hypothalamic neurosecretory cells release peptides from axon terminals adjacent to capillaries
- Integrates neural inputs from brainstem, limbic system and hypothalamic areas, which regulate activity
Pituitary (hypophysis): two gland in one
- Posterior lobe: under DIRECT control
- Anterior lobe: under INDIRECT control
Tissue of the posterior lobe:
- Neural tissue: axons and nerve terminal endings of neurosecretory cells
Tissue of the anterior lobe:
- Glandular tissue: cells controlled by releasing hormones, delivered via hypophyseal portal system
Vascular supply of the pituitary gland:
- Anterior
- Posterior
- Drainage: CSS/IPS
- Anterior lobe: primary portal plexus transports releasing hormones to the secondary plexus
- Posterior lobe: a single plexus
- Drainage: cavernous sinus superior / inferior petrosal sinus
Anterior pituitary lobe: hormones secreted (6)
Hormones with trophic action
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
- Adrenocorticotrophic hormone (ACTH)
- Thyroid stimulating hormone (TSH)
- Growth hormone (GH)
- Prolactin
Hormones with trophic action:
- They go on to regulate a third hormone
“Tripartite” neuroendocrine system:
- The idea that 3 separate hormones are involved in a system
1. Releasing hormone
2. Tropic hormone
3. Hormone (hits target cells)
Tripartite neuroendocrine system is prominent in control of major glands e.g. (3)
- Thyroid gland
- Adrenal gland
- gonads (ovary/testis)
What controls biorhythms?:
- The hypothalamic suprachiasmatic nucleus (SCN), the body’s master clock
Role of the hypothalamic SCN: (2)
- Partial control on …. Of …. Release from rhythm generators in the SCN
- Partial control on pulsatile patterns of hormone release from rhythm generators in the SCN
- E.g. paraventricular nucleus receives circadian input from SCN, regulating hypothalamus-pituitary-adrenal (HPA) axis activity and cortisol release
Polyuria:
Polydipsia:
- Excessive production and passing of urine
- Excessive thirst
What causes polyuria:
- In uncontrolled diabetes mellitus, osmotic diuresis (glucosuria) causes increased passive water loss
Principles of metabolic regulation:
- The flow of metabolites through pathways must be regulated to maintain homeostasis
- Homeostasis occurs when metabolite concentrations are at a steady state
Reasons why the levels of required metabolites may vary: (3)
Hint:exercise
- To increase the rate of glycolysis during exercise
- To reduce the rate of glycolysis after exercise
- To increase the rate of gluconeogenesis after exercise
What is the Km of a reaction:
- Rates are more sensitive to concentration near or below their Km
Km variation in glucose transporters:
- Different tissues have different glucose transport proteins present.
- The Km for each GLUT type varies due to its tissues function
GLUT1:
- Tissue/organ:
- Km
- Red blood cells
- 3 mM
GLUT 2:
- Tissue/organ
- Km
- Liver, pancreas
- 17 mM
GLUT3:
- Tissue/organ
- Km
- Brain
- 1.4 mM
GLUT4:
- Tissue/organ
- Km
- Muscle, adipose tissue
- 5 mM
Contact-dependant signalling:
- A cell-surface-bound signal molecule binds to a receptor protein on an adjacent cell, no molecules are released
Paracrine signalling:
- Paracrine signals are released by cells into the EF, acting as a local mediator
Cell surface receptors:
- Most signalling molecules….
- instead, they bind to …..
- Most signalling molecules are large and hydrophilic, they can’t cross the plasma membrane.
- Instead, they bind to cell-surface receptors which generate intracellular second messenger signalling molecules
Intracellular receptors:
- Some small hydrophobic…. pass through the target cells plasma membrane binding to ….
- That regulate, for example…..
- Some small hydrophobic extracellular signalling molecules pass through the target cells plasma membrane, binding to intracellular receptors.
- That regulate, for example, gene transcription
Apoptosis:
- A form of cell suicide that occurs when a cell does not receive the necessary signals to survive
Timescales of a cell’s response
- Fast
- Slow
- Fast: processes that rely on altered protein function; movement, secretion and metabolism
- Slow: processes that rely on altered protein synthesis; differentiation, growth and division
Ion-channel-coupled receptors:
- Signal molecules…..
- Causing a change in……
- Thus, a chemical change…..
- Signal molecules (acetylcholine) cause the receptors to open in response to binding,
- causing a change in the electrical potential across the membrane
- Thus, a chemical signal is transducer into an electrical signal