Hormones of Reproduction/ Chemical Control

These flashcards cover ( chapter 15 & 17)

How many parts does a Pituitary gland have?

Well we have two parts: Anterior and Posterior!

What does the posterior gland release? (The direct path)

Releases magnocellular neurosecretory cells:

• Vasopressin & Oxytocin

Path:

• Cells located in the paraventricular zone in hypothalamus

• Send axons to the pituitary stalk

• End up in the posterior pituitary, the neurohormones are released which go into the capillary bed( your bloodstream)

What does the Anterior gland release?

• The Origin: Parvocellular neurosecretory cells (the "small" ones).

• The Path: They stop early. They secrete "hypophysiotropic" hormones into the portal circulation (the private plumbing).

• The Result: Those hormones then tell the Anterior Pituitary cells to release things like ACTH, LH, or FSH,TSH,prolactin

Periventricular Zone

The innermost layer of the hypothalamus( next to third ventricle)

• contains the neurons that actually control the pituitary gland

Neurosecretory cells

These are specialized neurons that release hormones ( not neurotransmitters into the blood

• Magnocellular: Large cells that send axons way down into the posterior pituitary

• Parvocellular: smaller cells that release “trigger” hormones into the blood vessels of the anterior pituitary

Posterior Pituitary

• Releases Oxytocin & Vasopressin

  • Oxytocin: The ‘bonding’ hormone. Triggers uterine contractions and milk let-down.

  • Vasopressin: The ‘antidiuretic hormone.” It tells the kidneys to hold onto water ( preventing dehydration)

Anterior Pituitary

• Hypophysiotropic hormones: The middleman hormones sent from the hypothalamus to the anterior pituitary

• Hypothalamo-pituitary portal system: The specialized “private” plumbing of the blood vessels that carries hormones from the hypothalamus directly to the anterior pituitary

Kidney to Brain Loop

1. The kidney signals: The kidney releases an enzyme: Renin

2. The chemical chain: Renin creates a hormone in the blood called Angiotensin II

3. The Brain “tastes” the blood: essentially, our brain is protected by the blood-brain barrier, but there is a specific part called the subfornical organ that doesn’t have that barrier. it tastes the Angiotensin II in the blood.

Trigger: Dehydration: blood volume drops, and the salt concentration rises, resulting in less water to dilute salt.

Release: Vassopressin

Target: Kidneys, stop pumping water to the bloodline to pump it to the blood

Subfornical organ

A part of the brain that “tastes” the blood for Angiotensin II to trigger thirst

• Signals to the hypothalamus, “ Release more vasopressin.”

• Feeling of overwhelming thirst

Renin

An enzyme released by kidney when blood pressure is low

Angiotensin II

: A chemical created in the blood (triggered by Renin) that travels to the brain to make you feel thirsty and tells the pituitary to release vasopressin

CRH(corticotropin- Releasing Hormone)

Released by the hypothalamus to start the stress response

ACTH( Adrenocorticotropic hormone)

Released by the anterior pituitary: travels through the blood to the adrenal glands

Cortisol

The “stress hormone” released by the adrenal cortex. It provides negative feedback to the brain to shut the system down.

What hormone does the Hypothalamus (Parvocellular cells) release to initiate the stress response?

CRH( corticotropin-releasing hormone)

In response to CRH, what hormone does the Anterior Pituitary release into the general circulation?

ACTH

ACTH travels to the Adrenal Gland. Which specific part of the gland releases Cortisol?

The adrenal cortex

• cortical levels rise suppresses immune system: energy fights stress

• mobilize energy: dumps sugar/ energy into blood to fight or flight

How does Cortisol regulate the HPA axis once the stressor is gone?

Negative Feedback. Cortisol travels back to the Hypothalamus and Pituitary to inhibit further release of CRH and ACTH.

ACTH

releasing of acth

• Stimulates cortisol secretion by adrenal glands

Prolactin

Which stimulates the breast milk production

Thyroid-stimulating hormone ( TSH)

In thyroid

• Thyroid hormone secretion by thyroid gland causes thyroxin to be released, which increases the metabolic rate

  • Thyroxin: “work harder and faster” —> increase in metabolic rate as a sign to burn more fuel

Follicle-stimulating hormone (FSH)

In the gonads: causes ovulation and sex maturation

• Triggers sperm maturation in males and egg growth in females

Luteinizing hormone (LH)

Also located in the gonads as well! Which takes part in the ovulation

• triggers testosterone in males and ovulation/luteinization in females

Addison Disease

Adrenal glands degenerate because of too little cortisol: causing low blood pressure, abdominal pain, mood changes

Crushing’s Disease

Pituitary dysfunction: because of too much ACTH/cortisol: causing weight gain, immune supression, irritability, and memory loss

GNRH( Gonadtropin-releasing Hormone):

The hypothalamus “start button” for the reproductive system

Gonadotropins

The collective name for LH ( luteirzing hormone) and FSH(Stimulating Hormone)

Aromatase

The enzyme that converts testosterone into estradiol (estrogen)

Alpha fetoprotein

The “sponge” in fetal blood that binds maternal estrogen to protect the female brain from being masculinized

Organizational effects

Permanent Structural changes to the brain during development

Activation effects

Temporary, reversible changes in the brain/behavior in adulthood( like dendritic spine growth in the hippocampus)

AIS ( androgen insensitivity)

XY genotype; body cant see testosterone, female external appearance

CAH (Congenital Adrenal Hyperplasia)

• XX genotype; overexposed to adrenal androgens; masculinized external appearance.

Turner Syndrome (XO)

• Missing one X chromosome; female phenotype but often requires hormone therapy.

Klinefelter Syndrome (XXY)

•  Extra X chromosome; male phenotype but may have lower testosterone.

Autonomic Nervous System

A system of Central and Peripheral nerves that innervate the internal organs, cardiovascular system, glands

• Consists of: Sympathetic, parasympathetic, and enteric divisions

Sympathetic Division

A division that regulates the FOUR F’s (fight, flight, fright, sex)

• Receive input from preganglionic sympathetic fibers

• Projects Ganglionic fibers to target organs and tissues

• Preganglionic: Release ACH

• Postganglionic: NE or aCh

Parasympathetic Division

Maintains the independent function that doesn’t need direct communication to constantly

• Maintain heart rate, respiratory, metabolic, digestive functions

• Peripheral axons emerge from brainstem/sacral spinal cord

  • both preganglionic and postganglionic: release Acetylcholine

Autonomic Ganglia

Autonomic ganglia are clusters of neuronal cell bodies located outside the Central Nervous System (CNS) that serve as the critical "relay stations" for the Autonomic Nervous System.

Postganglionic Nueron

This is the neuron that carries the signal from the relay station all the way to the target organ.

• Location of Cell Body: Always located outside the CNS, inside an autonomic ganglion.

• Path: Its axon travels from the ganglion to the specific target tissue (smooth muscle, cardiac muscle, or glands).

• Neurotransmitter: This depends on which "division" of the ANS is active:

  • Parasympathetic: Releases Acetylcholine (ACh).

  • Sympathetic: Usually releases Norepinephrine (NE) (except for sweat glands, which use ACh).

Receptor: Hits Muscarinic or Adrenergic receptors on the organ to produce a slow, coordinated effect.

Preganglionic Neuron

This is the neuron that carries the signal out of the brain or spinal cord.

• Location of Cell Body: Always inside the Central Nervous System (in the brainstem or the spinal cord).

• Path: Its axon exits the CNS and travels to an autonomic ganglion (a cluster of nerve cells in the periphery).

• Neurotransmitter: It always releases Acetylcholine (ACh).

• Receptor: The ACh binds to Nicotinic (nAChR) receptors on the next neuron to trigger a fast signal.

Sympathetic Chain

A specialized string of connected autonomic ganglia that runs parallel to the spinal column

• Process: It allows preganglionic fibers to “hop” up or down the chain to coordinate a body-wide, simultaneous sympathetic response

Interoception

The ‘inward sense’ of the body. It is the process by which the nervous system sense the internal state of the body

• Most interoception is unconscious, but it is vital to maintain visceral homeostasis and overall sense of well-being

Enteric Division

Often called the “little Brain',’ which is a semi- autonomous network of neurons embedded in the lining of the esophagus, stomach and intestines.

• process: it contains its own sensory and motor neurons ( myenteric and submucous plexus) to control digestion independently, though it can be overridden by the real brain during high stress

Nucleus of the Solitary Tract

A key integration center located in the medulla

• process: it collects all the interoceptive (sensory) information from your internal organs and works with the hypothalamus to coordinate appropriate autonomic output

The Diffuse Modulatory Systems of the Brain

Collectively, these are small collections of neurons in the brainstem that use a single neurotransmitter to regulate vast assemblies of neurons across the entire brain

Diffuse Modulatory System

Locus Coeruleus

A tiny “blue spot” in the pons that is the primary source of NE for the brain

• Function: it is most active during new, unexpected stimuli and functions to increase ‘brain responsiveness” and arousal

Raphe Nuclei

Nine clusters of neurons along the midline of the brainstem that releases serotonin ( 5-HT)

• function: They are most active during wakefulness and we are crucial for regulating sleep-wake cycles, mood, and emotional behavior

Basal Forebrain Complex

A group of cholinergic (ACh) nuclei ( including the Basal Nucleus of Meynert) that provides the “spark” for the cereberal cortex and hippocampus

• These are among the first cells to die in Alzheimer’s Disease which is why they are so linked to memory and cognitive details

Empathogen

A class of psychoactive drugs(specifically MDMA) that produce feelings of social connection, love, and empathy

• Process: It works by binding to the serotonin transporter (SERT) and putting it into “reverse.” causing the neuron to flood the synapse with serotonin