Test 3 Flashcards
What is the endocrine system?
System of small organs called glands that release signalling molecules known as hormones.
What do hormones do?
Hormones influence growth, development and puberty, metabolism, and behaviour
What does the pineal gland release?
Melatonin
What does the adrenal gland release?
Cortisol, corticosterone, cortisone, aldosterone, androgens, estrogens, epinephrine, and norepinephrine
What does the pancreas release?
Glucagon and insulin
What does the testis release?
Androgens (testosterone)
What does the ovary release?
Estrogens and progesterone
What does the thyroid gland release?
Thyroid hormone, and calcitonin
What is the function of melatonin?
Reduces jet lag and promotes sleep
What are the functions of aldosterone?
-Increase sodium reabsorption by kidneys
-Increase potassium excretion by kidneys
What are the functions of androgens and estrogens?
Insignificant effects in adulthood, relative to secretion by gonads
What is the function of epinephrine and norepinephrine?
Fight if flight response to stress
What is the function of glucagon?
Increases blood glucose level
What is the function of insulin?
Decreases blood glucose level
What is the function of testosterone?
Develop male secondary sex characteristics
What is the function of estrogens and progesterone?
Develop female secondary sex characteristics
What are hormones?
Hormones are a type of chemical molecule that act as a signal to various cells of the body.
How do hormones travel in the body?
Most are secreted in the blood and travel throughout the body (endocrine).
-They only affect cells that have precise receptors
-Ultimately, hormones affect their target cells.
How many hormones have been discovered in the human body?
Approximately 50
How does hormone signalling work?
-Target cells have receptors
-Cells other than target cells lack the correct receptors and are unaffected by the hormone
-Once the hormone binds to its specific receptor, it triggers a specific reaction
What are the three types of interactions between hormones?
-Antagonistic
-Synergistic
-Permissive
What does antagonistic mean?
The effect on one hormone opposes that of another hormone
What does synergistic mean?
The response of a tissue to a combination of hormones is much greater than its response to either individual hormone
What doe permissive mean?
One hormone must be present for another hormone to exert its effects.
Which gland is the master gland of the endocrine system?
Pituitary gland
What is the relationship between the hypothalamus and the pituitary gland?
-The hypothalamus is part of the nervous system: it receives information from both internal and external environments
-It is also acting on the endocrine system by controlling the pituitary gland, which is the master gland of the endocrine system
-Targets and control the pituitary gland, which in turn influences numerous body functions via hormones
What body functions does the pituitary gland influences via hormones?
Body temperature
Hunger
Thirst
Fatigue
Childbirth
Emotions
Growth
Milk production
Salt and water balance
Sleep
Weight
Circadian cycles
Etc
How does the hypothalamus control the pituitary gland?
Cells in the hypothalamus secrete releasing and inhibiting hormones to the anterior pituitary.
Releasing and inhibiting hormones travel by way of the bloodstream to the anterior pituitary and cause it to modify secretion of its hormones.
What systems control homeostasis?
Nervous and endocrine systems
What are the steps in cortisol secretion?
- CRH (corticotropin-releasing hormones) is released by the hypothalamus and reaches the pituitary gland
- CRH stimulates the ACTH (adrenocorticotropic hormone) in the blood by the pituitary gland
- ACTH stimulates the cortex of the adrenal gland to stimulate the cortisol in the blood
- Cortisol is often associated with long-term stress (fight or flight response)
What does underproduction of cortisol cause?
Addison’s disease (yellow skin)
What does overexposure to cortisol cause?
Cushing’s syndrome (affects the distribution of fat and causes the typical accumulation of fluids in the face).
What system is the pancreas part of?
Endocrine system and digestive system
What are the function of the pancreas?
-Produces glucagon and insulin, antagonistic hormones that help maintain glucose homeostasis
-Produces digestive enzymes
What is the function of glucagon?
Triggers the formation of glucose from the energy reserve in liver: increase blood glucose levels
What is the function of insulin ?
Triggers the absorption of glucose from the blood by muscle cells and other tissues: decrease blood glucose levels.
What is diabetes mellitus?
Diabetes mellitus is perhaps the best-known endocrine disorder. It is caused by a deficiency of insulin or a decreased response to insulin in target tissues.
What is Type I diabetes?
Type I diabetes is insulin dependent. It is an autoimmune disorder in which the immune system destroys pancreatic beta cells.
Caused by the pancreas’ failure to produce enough insulin due to loss of beta cells.
What is Type II diabetes?
Type II is non-insulin-dependent. It involves insulin deficiency or reduced response of target cells due to change in insulin receptors.
Caused by an insulin resistance. The insulin resistance contributes to high glucose levels in the blood.
What does the pineal gland do?
It secretes melatonin.
- Regulates day and night cycle.
-Receives input from visual system.
-Release of melatonin is triggered by darkness.
-Thought to be involved in seasonal affective disorders as overproduction of melatonin causes lethargy, sleep envy, and cravings.
-Light therapy inhibits secretion of melatonin.
What do feedback mechanisms do?
-Feedback mechanisms regulate the secretion of hormones.
What is the most popular feedback mechanism for hormones?
-Negative feedback mechanism, whereby the increased blood level of the hormone inhibits its further release is the most common feedback.
Give an example of a hormone regulated by a positive feedback mechanism.
Oxytocin production stimulates its own production.
Explain the positive feedback that occurs when a mother is giving birth.
- The head of the baby stretches the cervix of the mother’s uterus.
- In response to the stretching, nerve impulses are sent to the hypothalamus.
3.The hypothalamus signals the posterior pituitary gland to release oxytocin. - The posterior pituitary gland releases oxytocin which travels in the blood to muscles of the uterus.
- The uterus responds to oxytocin by contracting more vigorously.
Then,
- Uterine contraction increase dilation of the cervix, which stimulates further release of oxytocin, which stimulates even more frequent and vigorous contractions.
OR
At birth, stretching of the cervix lessens and the positive feedback cycle is broken.
What gland produces FSH and LH hormones?
Pituitary gland
What is the function of the seminal vesicle?
Produces secretion to nourish and protect sperm cells
What is the function of the prostate?
Produces secretions to nourish and protect sperm cells.
What is the function of bulbourethral gland?
Produces secretions to nourish and protect sperm cells.
What is the function of epididymis?
Sperm storage and maturation
What is the function of testis?
Produces sperm and testosterone.
What is the function of vas deferens?
Transport sperm from the epididymis to the urethra
What is the function of the urethra?
Transports semen during ejaculation, also transports urine at other times.
What is the function of the erectile tissue of the penis?
Fills with blood during sexual arousal, causing erection of the penis.
What is the function of the penis?
The organ of sexual intercourse that delivers sperm to the female reproductive tract.
What is the function of the glans of the penis?
The region at the tip of the penis that is rich in sensory nerves for sexual arousal.
What is the sperm route in a man?
- Testis
- Epididymis
- Vas deferens
- Urethra
- Seminal Vesicle
- Prostate gland
- Bulbourethral gland
What is the uterine wall?
Muscle layers that stretch to accommodate the developing baby; contract during childbirth to deliver the baby.
What is the cervix?
The opening of the uterus that extends into the vagina.
What is the function of the uterus?
Houses and nourishes the developing baby (the embryo and later the fetus until birth).
What is the endometrium?
The lining of the uterus that is built up and lost each months as menstrual flow; the usual site of fetus implementation.
What is the vagina?
A muscular tube that receives the penis during sexual intercourse; the birth canal.
What is the oviduct?
One of the two ciliated tubes that conduct the egg (or the embryo if fertilization occurred) toward the uterus; the usual site of fertilization.
Where is oxytocin sent?
Smooth muscle in uterus and mammary glands.
What gland releases oxytocin and ADH?
Posterior pituitary gland
What produces oxytocin and ADH?
Hypothalamus
What gland secretes FSH and LH?
Anterior pituitary gland
Where are FSH and LH sent?
Ovaries and testes
What called the reproductive organs?
Gonads
What are three major categories of steroid hormones?
- Androgens (testosterone)
- Estrogens (estradiol)
- Progestins (progesterone)
What steroid hormone is most common in males?
Testosterone
What steroid hormones are most common in females?
Estrogen and progesterone
What organ synthesizes testosterone?
Testes
What does testosterone do ?
-Promote development and maintenance of male sex characteristics but also impacts behaviour
-Androgens produced early in development determine whether a fetus develops as a male or a female
-Testosterone causes increase in muscle and bone mass
-Testosterone is often taken as a supplement for muscle growth
What is the proportion of testosterone among women?
On average, the adult male produces about twenty to thirty times the amount of testosterone compared to an adult female.
True or false. Women’s ovaries primarily produce testosterone from which estrogen is then made.
True
What produces estrogen?
Mainly placenta and ovaries (smaller amounts are produced by the liver, adrenal glands, and the breasts).
What are the functions of estrogen?
-Estrogen helps to maintain body temperature.
-Estrogen may delay memory loss
-Estrogen helps to regulate parts of the brain that prepare the body for sexual and reproductive development
-Estrogen helps to regulate the liver’s production of cholesterol, thus decreasing the build-up of plaque in the coronary arteries
-Estrogen stimulates the maturation of the ovaries
-Estrogen stimulates the start of a woman’s menstrual cycle - an indication that a girl’s reproductive system has matured
-Estrogen stimulates the maturation of the vagina
-Estrogen helps maintain a lubricated and thick vaginal lining.
-Estrogens are responsible for the maintenance of the female reproductive system and the development of female sex characteristics. It also influences behaviour and even physiological characteristics such as cholesterol production.
How does sex hormones regulation functions?
-Both estrogens and androgens are controlled by neuroendocrine feedback regulations.
-Hypothalamus controls the anterior pituitary hormones, which control the hormone production from the gonads.
-High concentration of sex hormones such as testosterone circulating in the blood negatively feed-back to reduce circulating levels of pituitary hormones (FSH and LH), which reduces the amount of testosterone.
How does FSH help control sperm production?
-FSH stimulates the seminiferous tubules to become more sensitive to testosterone (increases sperm production)
-As the seminiferous tubules produce more sperm, they also increase production of inhibin (this inhibits the hypothalamus and the production of FSH)
-As inhibin levels fall, FSH production increases
How does male reproductive strategy differs from the females?
The reproductive strategy of the male is to produce millions of sperm and deliver them to the female reproductive system. The female gamete production is more costly, and production is limited to one per month *
*All the ovules are already present in the ovaries at birth, but meiosis is not complete. Only one (or sometimes a few) will complete meiosis every month.
Why are the testes held outside the body cavity in the scrotum?
It allows for temperature regulation.
Where is the sperm produced?
Testes
Where does the sperm mature?
Epididymis
What happens in the uterus during the menstrual cycle?
- Menstrual phase: (days 1-5) as the corpus luteum in the ovary degeneratesm, estrogen levels drop causing menstruation (shedding of the endometrial lining)
- Proliferative phase: (days 6-14) as a new follicle starts growing, estrogen levels increase causing endometrium thickening.
- Secretory phase: (day 14 until first day of menstruation) the ovaries secret estrogen and progesterone, causing more thickening and maintenance of the endometrium.
What happens in the ovaries during menstrual cycle?
- Follicular phase: (days 1-14) FSH stimulates the development of the ovary
- Luteal phase: (days 14-28) LH triggers ovulation (day 14) and then the formation of the corpus luteum which secretes estrogen and progesterone.
How many chromosomes does a zygote have?
23 chromosomes from sperm and 23 from ovum
How are the levels of estrogen and progesterone during pregnancy?
Progesterone and estrogen levels are maintained high enough to prevent shedding of the uterine lining and to inhibit the pituitary gland releasing hormones that would cause the growth and release of another ovule.
How are the levels of estrogen and progesterone kept high during pregnancy?
The embryo secretes an hormone (human chorionic gonadotropin) that maintains secretion of progesterone and estrogen by the ovaries. Also, placenta secretes progesterone and estrogen to maintain pregnancy.
How do most oral contraceptives work?
Most oral contraceptives contain a synthetic progesterone and estrogen to inhibit FSH and LH the would cause the growth and release of an egg.
What does intersex mean?
Humans with ambiguous genitalia.
What are the effects of psychoactive drugs?
They alter communication between neurons. A psychoactive drug alters one mood or emotional state.
What do stimulants do?
Stimulants excite the central nervous system and tend to increase the # of AP (arterial pressure).
What do hallucinogenic drugs do?
They alter sensory perception.
What do sedatives do?
Sedatives depress the central nervous system and tend to decrease the arterial pressure.
What do opiates do?
Opiates reduce pain.
What does alcohol do?
Depresses the central nervous system.
What does marijuana do?
The psychoactive ingredient of marijuana is THC.
THC mimic anandamide, a natural neurotransmitter that alters mood, memory, pain, appetite, etc.
It also stimulate the release of dopamine in the reward pathway.
How can psychoactive drugs alter the communication between neurons?
- Stimulating release of neurotransmitters
- Inhibiting release of NTs
- Preventing the removal of NT
- Mimicking effect (agonists)
- Inhibiting effect (antagonists)
What is drug dependence?
-By using psychoactive drugs, an individual may develop some level of psychological or physical dependence on the drug
-Can no longer function normally without the drug
What is drug tolerance?
-Occurs when a person’s body requires higher and higher doses of a drug to generate a response
What is drug tolerance?
-Occurs when a person’s body requires higher and higher doses of a drug to generate a response
What is cross tolerance?
Occurs when tolerance to one drug results in a lessened response to another (usually similar drugs)
