Brain Bee Chapter 10: The Body in Balance

What is Homeostasis?

Your body’s tissues and organs try to stay in balance or a steady state

Daily circadian rhythms are coordinated by what?

Daily rhythms are coordinated by the suprachiasmatic nucleus or SCN (a tiny group of neurons in the hypothalamus)

How do suprachiasmatic nucleus neurons turn signals on and off during the day and night?

This on-and-off activity is controlled by two sets of proteins made by your body’s clock genes

How do suprachiasmatic nucleus neurons adjust to day and night cycles?

Using signals from light sensitive cells in the retina

What does the paraventricular nucleus (PVN) do?

It sends signals o organs to release orexin and melatonin.

Long-term circadian disruptions can lead to what?

Lead to weight gain, insomnia, depression, and cancer

Hormones cause changes in what?

Cause changes in metabolism, growth, and behavior

Brain regions that control hormone release are called what?

The neuroendocrine system

What regions manages many hormones?

The Hypothalamus has connections to the Pituitary gland and manages many hormones

What happens when the Hypothalamus send axons into the posterior pituitary?

When activated these neurons release vasopressin and/or oxytocin into the blood stream

• Vasopressin: helps kidneys retain water

• Oxytocin: triggers uterine contractions during labor and milk when nursing

How many hormones does the anterior pituitary gland produce?

The anterior pituitary produces seven hormones

What are the characteristic functions of the hormones produced by the pituitary gland?

5 are trophic hormones that stimulate specific endocrine glands

2 act on non-endocrine tissues like the growth hormone and prolactin

How can Hormone release be regulated from the Hypothalamus?

Through negative feedback loops

What is one example of a negative feedback loop that regulates hormones? What are its characteristic functions?

One example is the three-hormone-cascade controlling reproduction:

• GnRH from the hypothalamus stimulates the anterior pituitary

• The anterior pituitary releases LH and FSH

• LH and FSH make the gonads produce sex hormones and mature eggs or sperm

How do males regulate hormone release?

Negative Feedback Loops reduce GnRH, LH, and FSH

How do females regulate hormone production?

During Menstruation, low estrogen and progesterone also FSH to rise, which causes egg to mature and the increase of estrogen, which triggers ovulation. Then high sex hormones  again reduce GnRH, FSH, and LH, restarting the cycle

Hormones that aren’t controlled by the Pituitary gland are controlled by what?

Tissues

What are examples of hormones that aren’t released by the Pituitary gland?

Leptin: Released by fat cells to stop and trigger eating

Ghrelin: Released by an empty stomach to stop and trigger appetite

When does the Stress Response happen?

It happens whenever there is a threat to the body’s balance

What does the stress response coordinate?

Coordinates voluntary and involuntary nervous systems, muscles, and metabolism to protect the body

What is the characteristic function of the Voluntary nervous system?

Prepares muscles for fight or flight

What is the characteristic function of the Involuntary nervous system?

Directs oxygen and nutrients to those muscles

What are the characteristic functions of the Sympathetic branch?

Releases epinephrine and makes heart beat faster so that adrenaline can reach those muscles faster

What are the characteristic functions of the Parasympathetic branch?

Reduces blood blow to other organs

What are the characteristic functions of glucocorticoids and give an example of one:

Glucocorticoids act on many tissues and prepare body for danger

• They increase sugar release to bring energy for muscles

• Increase attention and learning

• They stop processes that aren’t necessary like growth until the threat is over

An example of a glucocorticoid is cortisol

What happens to your body with Chronic stress?

• It causes muscle atrophy:  muscles to shrink

• Makes more fat and increases blood sugar levels

• Increases diabetes

• atherosclerosis (hardening of the arteries) and increases heart attacks

• Lowers the bodies ability to fight infection

What happens to your brain with Chronic stress?

• Slows neuron growth in hippocampus and decreases memory

• Weakens pathways related to decision making

• Speeds up age related decline

• Sleep problems

What happens to future generations if a pregnant woman faces Chronic Stress?

• If a pregnant woman has high levels of glucocorticoids, those hormones can harm the babies development

• stressors like starvation may prepare fetus for tough conditions, but it can lead to obesity and overweightness if child grows up in food rich environment