27 Flashcards
Hypothalamus to anterior pituitary
Hypothalamic neurons release chemicals ( hormones ) into a blood portal connection to anterior pituitary gland cells
Hypothalamus to posterior pituitary
Hypothalamic neurons have long axons that extend into and terminate ( axon thermals ) in the posterior pituitary gland
The posterior pituitary gland: Where is the hypothalamus connected and explain in depth the posterior pituitary hormones
The hypothalamus is connected to the posterior pituitary by neurons
- cell bodies in the hypothalamus
- axon terminate in the posterior pituitary gland
Posterior pituitary hormones
- are made in hypothalamic neuron cell bodies
- travel down the axon to be stored in the axon terminal until required
- and then are released into the main bloodstream when an action potential depolarises the axon terminal
The posterior pituitary hormones
There are 2 types: Oxytocin and Anti-Diuretic hormone ( ADH )
What is Oxytocin
This is one of the posterior pituitary hormones
- water soluble
- stimulates milk release during breastfeeding an infant
- stimulated the contraction of uterine muscles during childbirth
What is Anti-Dluretic Hormone ( ADH )
- water soluble
- stimulates the kidney to reabsorb water when a person is dehydrated
- one of the hormones secreted during exercise and stress response
What is the posterior pituitary hormone initiated by
Baby sucking or dehydration
What stimulus is the anterior pituitary gland
Exercise
Puberty
Stress
The Anterior pituitary gland, where is the hypothalamus connect to
It’s connected to the anterior pituitary by a portal blood stream
- hypothalamic neurons secrete “releasing” or “inhibiting” hormones
-they travel via a blood portal system to the anterior pituitary and binds to membrane receptors on anterior pituitary cells
- this causes the anterior pituitary cells to release an anterior pituitary hormone
What are the 3 main anterior pituitary hormones
Growth hormone ( GH )
thyroid stimulating hormone ( TSH )
adrenocorticotropin hormone ( ACTH )
Explain the growth hormone
- water soluble
- stimulates the liver, skeletal muscle and adipose for fuel mobilisation
- stimulates the liver to release IGF-1 for growth
Explain the thyroid stimulating hormone (TSH)
- water soluble
- stimulates the thyroid gland to release thyroid hormones to increase basal metabolic rate
Explain Adrenocorticortropin hormone ( ACTH )
- water soluble
- stimulates the adrenal gland ( cortex ) to release CORTISOL in a daily pattern and during the stress response
What are the glands involved in cell metabolism
Hypothalamus
Pituitary Gland
Thyroid gland
What is the general pattern of hormone release from hypothalamus
- Stimulus: this is external or internal, so excersize, stress or changes in environment ect
- hypothalamus: this is when it’s releasing or inhibiting hormones, releasing hormones stimulate the anterior pituitary gland while inhibiting hormones suppress its activity
- anterior pituitary gland: Releasing hormones from the hypothalamus bind to receptors on anterior pituitary cells, prompting the release of specific pituitary hormones. These hormones then enter the bloodstream.
- target endocrine organ: The pituitary hormones travel to target endocrine organs, such as the thyroid gland, adrenal cortex, or gonads.
Upon stimulation by pituitary hormones, target endocrine organs release their hormones, often referred to as the “3rd hormone.” - target effectors - The hormones released by the target endocrine organs act on various effectors, such as tissues or organs, to exert their physiological effects.
Hypothalamic pituitary- thyroid axis
This is the process that stops when excersize stops or cold stress if removed
- stimulus- excersize and cold stress
- hypothalamus secretes - In response to the stimulus, the hypothalamus secretes Thyrotropin-Releasing Hormone (TRH).
- anterior pituitary gland - TRH stimulates the anterior pituitary gland to release Thyroid-Stimulating Hormone (TSH).
- thyroid gland secretes - TSH stimulates the thyroid gland to secrete thyroid hormones, primarily triiodothyronine (T3) and thyroxine (T4).
- target of thyroid hormone: all body cells - Thyroid hormones act on all body cells. Their effects include:
- Increasing the basal metabolic rate, regulating energy production and consumption.
- Stimulation of growth in fetus and during early childhood.
- Increasing mental alertness.
Thyroid gland location
- wraps around the trachea, just bellow the Adam’s apple
- on the anterior and lateral surfaces of the trachea
Hormones of the thyroid gland
- thyroid hormones (T3 and T4) - made by cells that line the follicles, to increase metabolic activity, growth, alertness
- calcitonin - minor hormone involved in Ca2+ homeostasis
Synthesis and storage and structure of thyroid hormones
T3 an pd T4
Structural and function units - thyroid follicles
Synthesis - thyroglobulin (TGB) is a protein made in thyroid follicles and contain tyrosine (Y) . Iodine enters cells lining and thyroid follicles and react with tyrosine ( Y ) in thyroglobulin (TGB)
= T3 = tyrosine with 3 iodine
= T4 = tyrosine with 4 iodine
Thyroid hormones ( T3 and T4 ) detach from iodised TGB as they are needed
- T3 and T4 travel in blood bound to a carrier protein
What is iodine necessary for
Part of our diet as it is required for production of thyroid hormone
Target cell activation by thyroid hormones ( T3 and T4 )
- they are made in advance and stored until required
- travels across the plasma membrane and it bounds to a carrier protein
- detaches from the carrier protein and enters the target cell
- thyroid hormone bind to the receptor in the nucleus
- specific genes are activated to transcribe messenger RNA ( mRNA )
- specific proteins are synthesised that lead to increased basal metabolic rate (BMR)
- response time: 45 minutes
What is the Basal metabolic rate
The energy the body requires for its most basic functions to sustain life
-heart beating
-blood circulation
-respiration
-thermoregulation
-cell production
-nutrient processing
Your BMR influenced by your sex, age, body type and size, food intake, activity and exercise levels
Effects of thyroid hormones on basal metabolic rate
Thyroid hormones increase the BMR by increasing
- thermogenesis ( body heat production)
- oxygen consumption and ATP production
- fat and protein breakdown
Thyroid hormone also have a complex unterstion with various organs to ensure that enough glucose is available for metabolic processes, without significantly disturbing plasma glucose homeostasis
What are the glands involved in growth and cell metabolism
Hypothalamus
Pituitary Gland
