Unit 3 Exam

How does neural communication act?

Acts in short millimeter distances, milliseconds, in a very precise, all-or-none manner.

How does hormonal communication act?

Acts in long distances (up to meters), in longer time, diffusive, graded manner.

What type of communication occurs in bursts?

Hormonal communication has pulsatile secretion.

What are the structural types of hormones?

Peptide, monoamines, and steroid hormones.

Peptide Hormones

Made of amino acids (protein subunits)

Monoamines

Modified version of a single amino acid.

Steroids

Derived from cholesterol.

Which type of hormones binds to receptors on the surface of the cell and releases a second messenger inside the cell?

Protein and Amine hormones

Which type of hormones pass through the cell membrane and bind to receptors inside the cell?

Steroid hormones, as a transcription factor, binding to DNA and controlling gene expression.

Where in the brain structure does Neuroendocrine cells effect and what hormones does it release?

Produce and secrete hormones that affect the posterior pituitary, releasing vasopressin and oxytocin.

What biological effect does vasopressin (antidiuretic hormone) have?

Raises blood pressure, inhibits urine formation through water conservation.

What biological effect does oxytocin have?

Promotes reproductive and parenting behavior, uterine contractions, and mil letdown reflex.

In the mammary gland example, what encourages the posterior pituitary to secrete oxytocin?

Sensory signal → Somatosensory cortex → Hypothalamus → Neuroendocrine cells → Posterior pituitary which then releases oxytocin contracting mammary glands.

Endocrine Feedback Loop

Hypothalamus → Releasing (TRH) → Anterior pituitary → Tropic (TSH) → Thyroid gland → Thyroid hormones → Target cells

Purpose of releasing hormones

The hypothalamus secretes releasing hormones into blood vessels controlling pituitary’s release of tropic hormones.

Purpose of tropic hormones

The anterior pituitary makes tropic hormones which affect other endocrine glands. TSH stimulates thyroid.

Goiter

Swelling of the thyroid gland in the neck as a result of iodine deficiency. Too much TSH from anterior pituitary, the negative feedback loop is not working and no inhibition of the releasing hormone.

Congenital Hypothyroidism

Inadequate thyroid hormone production in newborn infants, too little TRH or TSH.

Cushing Disease

Psychiatric disorder resulting in fatigue and depression and caused by long term excess glucocorticoids.

What releasing hormone does the hypothalamus secrete to begin gonad hormone production?

Gonadotropin releasing hormone (GnRH)

GnRH stimulate the anterior pituitary to release what hormone?

Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH)

Effects of FSH + LH in males

The testes sense LH and produce and secrete the androgen, testosterone, and steroid. Also sensing FSH and produce sperm.

Effects of FSH + LH in females

Ovaries sense FSH stimulating the maturation of egg containing follicles and secretion of estrogens. LH stimulates follicles in the ovary to rupture releasing the egg and form a corpus luteum to secrete progesterone.

How do Oral Contraceptives work?

Negative feedback loop, inhibiting release of GnRH from hypothalamus stopping FSH and LH from releasing. Avoiding LH stimulate follicle in ovary and keeps it from releasing an egg.

What kind of effects affect genitalia maturation and growth and are lifelong?

Organizing effects, mostly occurring prenatally or shortly after birth.

What kind of effects come and go, but can be long lasting?

Activating effects, occurs at any time in life including breast growth, sperm production, muscle development, and hair growth and can be reversible. Common in increase in sexual interest.

Without SRY gene, what type of ducts develop further and what type shrink?

Mullerian ducts develop into the fallopian tubes, uterus, and vagina. The ,wolffian ducts shrink.

What hormone guides development of wolffian ducts and what hormone causes Mullerian ducts to shrink in males?

Testosterone promotes the development of wolffian ducts. The anti-mullerian hormone causes mullerian ducts to shrink.

What causes Klinefelter Syndrome?

Trisomy of sex chromosomes and have two female sex chromosomes but also male. Leads to conflicting genetic material resulting in small testes, osteoporosis, and poor hair growth.

During sexual activity, how do hormones influence women?

In non-human females, estrogen produced before ovulation promotes sexual behavior. If the female rat is sexual receptive, she is in Estrus. In humans, women do not have an estrus, but more likely to initiate sex at ovulation.

How do response curves differ between male and females during sex?

Males have a very standard response curve of excitement, plateau, orgasm, and resolution very similar to an action potential. Females have many different curves and can experience multiple orgasms.

What hormone is release at ejaculation? What drug treatment would block this?

Oxytocin is released at ejaculation. Naloxone drug treatment would block this and men report less pleasurable orgasm.

Important brain areas for reproductive behavior in both sexes

Experience activation in the medial amygdala (sex, smell, aggression, and emotions) and medial preoptic area (sexual performance).

What brain areas for sex are important for males?

The sexually dimorphic nucleus. In MPOA (INAH3), lesions here cause impairment while stimulation cause enhancement. 2-3x larger in men with size related to activity. Size also depends on prenatal exposure to testosterone.

What structure is especially important for women in sex?

Ventromedial hypothalamus, important for receptivity to make advances.

During orgasm, which part of the brain do you see light up in males and females?

VTA activated in males, making orgasm very pleasurable and even addicting. Females, deep cerebellar nuclei but decreased orbitofrontal cortex activity.

What motivates sexual behavior?

Dopamine for men, increasing dopamine produces erection then ejaculation. Giving a dopamine agonist would not interfere with sexual activity, unlike other drugs.

What impair sexual ability?

Serotonin

How are brains of males and females different?

Males have greater asymmetry and larger right hemisphere, have less gyrification as well. Females have a larger corpus callosum which has cognitive skills.

Social Influence Hypothesis

Home environment or early seduction causes homosexuality.

Biological Hypothesis

Something in a person’s biology helps to determine sexuality. Early childhood gender nonconformity and feel different early on, preferring to be around other-sex companions.

When you compare hormonal levels between homosexuals and heterosexuals, what do you find?

Same testosterone between people, if there is a difference it would occur prenatally.

What brain structures are usually different in straight vs. gay men?

Homosexual men, smaller INAH3 and larger anterior commissure like in heterosexual female brains, larger SCN with more vasopressin-secreting cells.

Which group has better verbal ability?

Females due to high estrogen levels which is associated with decreased spatial ability, but have enhanced speech and manual skill tasks.

Brain connections in males

Better connected from front to back and are better at concentrating on one task.

Brain connections in females

Women are better connected from left to right usually making them better at multitasking.

Which group as better visual spatial ability?

Males due to testosterone which increases growth of right hemisphere but males low in testosterone have impaired spatial ability.

Homeostasis

Maintenance of a stable, balanced internal environment.

Main homeostatic mechanism

Negative Feedback Systems

If you deviate from _______, compensatory action begins.

Set Point, body tries to compensate and keep things balanced.

Motivation

Factors initiate, sustain, or direct behavior

Physiological Motivation Drive

Homeostatic Systems, I’ll eat when I’m hungry, I’ll drink when I’m thirsty.

2 systems involved in thermoregulation

Preoptic Area and Lateral Hypothalamus

Preoptic Area

Part of hypothalamus where lesions result in impaired physiological response. (sweating, constriction/dilation of blood vessels, respiration)

Lateral Hypothalamus

Lesions result in loss of behavioral regulation of temperature. (shivering and heat-seeking/avoiding behaviors)

Hypovolemic Thirst

Thirst stimulated by low or loss of extracellular/intravascular (water) volume. Outside cells have less water and have low blood pressure, Baroreceptors detect drop and Arteries constrict to raise BP but concentration does not change.

Function of Vasopressin release due to Hypovolemic Thirst

Released from posterior pituitary, blood vessel constriction, less blood flow to bladder, more water retention.

Function of Renin release due to Hypovolemic Thirst

Released from kidneys when blood volume decreases, plays major role in Angiotensin cascade.

Angiotensin Cascade

Angiotensinogen (in blood) → Renin (from kidneys) → Angiotensin 1 → Converting Enzyme → Angiotensin 2 → Aminopeptidase → Angiotensin 3

Effects of Angiotensin 2

Blood vessels constrict → Circumventricular organs trigger drinking → Vasopressin is released → Aldosterone is released

Organs that help resolve hypovolemic thirst

Subfornical Organ, angiotensin 2 acts here to signal to other brain sites (ex. POA) to initiate drinking.

Osmotic Thirst

Thirst stimulated by high extracellular solute concentration. Water can leave the cell, but salt cannot. When water leaves the cell, the cell shrinks.

Neurons that respond to rise in blood osmotic pressure

Osmosensory neurons that are found in anterior hypothalamus (OVLT) and cause the posterior pituitary to release Vasopressin.

Organ that helps resolve osmotic thirst

OVLT

Principal energy source

Glucose, body uses glycogenesis to convert glucose to glycogen for storage.

Another form of energy brain is willing to use

Fat, only if brain is starving and no other glucose left. Lipids and fat tissue are generally for longer-term storage of energy.

Glycogen

Body makes this through glycogenesis to convert glucose into this for short-term storage in the liver. Glycogenesis involves the use of insulin.

Increased insulin levels lead to _______, whereas increased glucagon levels lead to _______

More glycogen production and less glucose; more glucose production and less glycogen

Guevedoces

Deficiency in enzyme 5-a-reductase which is needed to convert testosterone into dihydrotestosterone. Children raised as females and around 12, testosterone surge leads to growth of penis.

Human Sexual Response - Male

Primary activation was in ventral tegmental area, produces dopamine (in midbrain) to NA, pleasure cortical system emotion centers

Human Sexual Response - Female

Activation of deep cerebellar nuclei and inhibition of orbitofrontal cortex

Leptin

Produced by adipocytes (fat cells) and secreted into bloodstream. Deficit results in false-low report of body fat, causing animals to overheat. Obese rats and people are resistant on this.

Weight loss cause to leptin levels

Decrease it, leading to hypothalamus signaling your body to increase food intake and use less energy.

Weight gain cause to leptin levels

Increase it, food intake will go down and use more energy.

Ghrelin

Released by stomach endocrine cells, appetite stimulant rising during fasting and drops after eating.

If full after eating food, do you have high or low ghrelin and leptin levels?

Low ghrelin levels, high leptin levels

Diabetes Insipidus

Vasopressin is not produced- kidneys send more urine to the bladder, resulting in chronic thirst, and preventing bladder from releasing.

Disorder some obese people have with a problem with peripheral signals

Prader-Willis Syndrome. Abnormal elevated ghrelin levels and eat as if they were starving. Eat as much as they can, even if rotten food from the trash. “Do you have a lock in your fridge?”

Area in brain where lesions cause overeating

Ventromedial Hypothalamus. lesioned rats overate till obese. Stability and new set point is made at heavier weight, therefore, force feeding stops and drop back to new set point rather than healthy set point.

Area in brain where lesions would cause refusal to eat

Lateral Hypothalamus. Stop eating and stabilize weight at new lower level due to new, lower set point. Anorexics possibly have lower set point.

NPY/AgRP neurons produce neuropeptide Y and agouti-related peptide:

Stimulate appetite and lower metabolism. Weight gain leptin inhibits NPY neurons and stimulates POMC neurons.

POMC

POMC/CART neurons produce pro-opiomelanocortin and CART: inhibiting appetite and raise metabolism.

VMH lesions destroy:

Anorexigenic Paraventricular Nucleus (PVN)

LH lesions destroy:

Orexigenic Lateral Hypothalamus (LH)

High calorie diets cause ______ and _______

Hypothalamic scarring and microglial activation

Overeating leads to hypothalamic inflammation, which:

Inhibits neurogenesis, resetting set point

Izzy died of heart failure and obesity. How did he reach 757 lbs?

Possible leptin deficiency or VMH lesion and high set point from weight gain.

Effective treatments for obesity

Eat less, modify behavior to avoid temptation to pig out, and exercising. Cannabinoid receptor antagonist as well but blocking it leads to suicidal thoughts. Treating it as an addiction by reducing D2 and decreasing prefrontal metabolism, and gastric bypass surgery.

Reason as to why diets fail

Basal metabolic rate falls to prevent losing weight and body works against diet. Body will work to maintain set point even if too high. Eating less, burns energy. Cutting 100 then more every 2 weeks and exercising can increase the likelihood of losing weight.

Basal Metabolic Rate

Energy required to fuel brain/body and maintain body temperature. Women who fail to lose weight is due to low bmr, spontaneous activity can help increase bmr.

Gastric Bypass Surgery

Ghrelin is reduced and PYY and GLP-1 is increased, reducing mortality and has health benefits.

Anorexia Nervosa

Refusal to maintain body weight, fear of weight gain, body image disturbance, amenorrhea, and restricting or binge-eating/purging type.

Bulimia

Recurrent binge eating with recurrent inappropriate, compensatory behavior. Goes on for 2x/week for 3 months, thinning of bones, brittle hair and nails, drop in body temperature, low blood pressure, slow breathing and pulse.

Teenage girls have ______ and _______.

Larger insula; larger orbitofrontal cortex (OFC)

Treatments for Anorexia or Bulimia

Serotonin is low, treating it as a mood disorder. Antidepressants and anti-schizophrenic drugs and Dopamine could help.

GLP-1

Agonists injection, secreted from small intestine and suppresses appetite, enhances satiety, delays gastric emptying, enhances glucose dependent insulin secretion, and inhibits glucagon release. This is used to manage obesity and type 2 diabetes but also to lose weight.

George is sleep deprived and only able to sleep from 5 AM - 1 PM

Delayed Sleep Phase Syndrome

Importance to sleep

Helps learn consolidation, gives body time to rest, safety precaution in animals and helps us learn.

Type of rhythm humans have

Diurnal - active during the day.

Type of rhythm animals have

Nocturnal - active during the night.