Endocrine System (chapter 13) Flashcards
what is homeostasis defined as?
tendency of a system to maintain internal stability
endocrine system (read)
slower rates, hormones, longer distances throughout the body
define intrinsic controls
controls regulate factors within a local environment (in an organ)
define exinstric controls
controls regulate factors coordinating body systems (initiated outside of an organ)
define feedforward
control signals sent to a part of the body or other system in order to prepare it for future motor activity or expected sensory input
define feedback
responses made after a change has already been detected
feedback is split into two categories, what are they?
negative and positive
negative feedback
causing a change to be minimized or stopped
positive feedback
increase the change or output
where is thyroxine produced? (hormone)
thyroid gland
what is the role of thyroid hormones in metabolism?
increasing the rate at which cells convert oxygen and calories into energy. they help control processes like growth, energy and temperature regulation.
what are T3 and T4?
T3: triiodothyronine
T4: thyroxine
what is the normal for blood sugar regulation?
80-120mg/100ml
what hormone is secreted when blood sugar is high
insulin
what is the role of insulin in blood sugar regulation?
insulin is secreted by the pancreas to allow glucose to enter body cells, returning blood sugar levels back to homeostasis
what happens when blood sugar is too low?
the pancreas secretes glucagon
what does glucagon do in the body?
glucagon breaks down glycogen stores into glucose, increasing blood sugar levels
what are glycogen stores and where are they found?
glycogen stores are stored glucose, found in the liver and large muscle groups
what are the two types of cells in the pancreas involved in blood sugar regulation?
- alpha cells: secrete glucagon
- beta cells: secrete insulin
what is the purpose for glucose in the body?
glucose will provide energy for the body cells
what is the difference between glucose and glycogen?
glucose: simple sugar in the blood
glycogen: stored form of glucose in liver and muscles
what are the two parts of the adrenal gland involved in the stress response?
the adrenal medulla (internal) and adrenal cortex (external)
what hormone is released in response to stress by the pituitary gland?
ACTH (adrenocorticotrophic hormone)
what does the adrenal medulla produce during short term stress?
epinephrine and norepinephrine
what hormone is affiliated with adrenaline?
epinephrine
list six effects of epinephrine and norepinephrine during short term stress
- increased heart rate
- increase blood pressure
- increased blood flow to heart and muscles
- increased breathing rate
- increase of blood glucose
- increased rate of cell resp.
what is produced by the adrenal cortex during long term stress?
mineralocorticoids such as aldosterone
what role does aldosterone play during long term stress?
helps kidneys reabsorb sodium and water which then maintains the blood pressure
where is the pituitary gland located?
base of the brain
where is hypothalamus located?
in the brain, below thalamus, and above pituitary gland
why is the pituitary gland referred to as the master gland?
it controls other glands and secretes multiple important hormones
what does the posterior pituitary gland do?
stores hormones
name two hormones stored in the posterior pituitary gland?
oxytocin and ADH (antidiuretic hormone)
what role does oxytocin play in the body?
oxytocin is involved in uterine contractions during childbirth and milk ejection during breastfeeding
what does ADH do?
helps to regulate water balance by promoting water reabsorption within the kidneys
what is the role of the anterior pituitary gland?
produces and secretes hormones
list six hormones secreted by the anterior pituitary gland?
- hgh (human growth hormone)
- tsh (thyroid stimulating hormone)
- fsh (follicle stimulating hormone)
- lh (luteinizing hormone)
- acth (adrenocorticotrophic hormone)
- prl (prolactin)
what is the function of the glucocorticoids?
help metabolize proteins and fats
how do glucocorticoids affect the immune system
suppress immune cell activity
what does HGH target and its function?
it targets heigh, bone and muscle developpement, and its function is to stimulate fat and sugar metabolism
what does TSH target and its function?
targets the thyroid gland, and its function is to control metabolism and affect energy and growth
what does ACTH target and its function?
it targets the adrenal gland and it controls the stress hormones
what does FSH target and its functions?
targets the ovaries and testes and its function is to produce ovarian follicle production and sperm maturation
what does LH target and its function?
it targets ovaries and testies, initiates ovulation, formation of the corpus luteum and stimulates production of testosterone
what is the corpus luteum?
a mass of cells that forms in an ovary
what does PRL target and its function?
targets the breasts and controls and sustains milk production
what does oxytocin target and its function?
targets uterus and breasts and stimulates uterine contraction and stimulates secretion of milk
what does ADH target and its function?
targets the kidneys and controls the reabsorption of water
how does sexual reproduction differ from asexual reproduction?
sexual involves fusion of gametes creating new gene combinations leading to genetic diversity
why is genetic diversity important?
provides for evolution and natural selection, allowing for species to adapt and survive
what are the primary reproductive organs called and what do they produce?
- gonads (testes in males, ovaries in females), produce gametes and secrete sex hormones (testosterone, estrogen and progesterone)
what controls the onset of puberty?
- hypothalamus (releases GNRH, gonadotrophin-releasing hormone)
- anterior pituitary: releases FSH and LH
what is the role of FSH in males and females?
in males, FSH stimulates sperm production. in females it stimulates follicle developpement in the ovary
what is the role of LH in males and females?
in males, it stimulates testosterone production and sex organs. in females, it stimulates ovulation and follicle release
how is Fsh production regulated in males?
testosterone causes sertoli cells in testes to produce inhibin, which inhibits FSH production through negative feedback
how do estrogen and progesterone regulate the menstrual cycle?
at start of cycle, estrogen provides positive feedback, increasing LH secretion. after ovulation, estrogen and progesterone provide negative feedback, inhibiting the hypothalamus and pituitary.
what secondary sex characteristics influenced by estrogen and testosterone?
- hair growth
- genital maturation
- shoulder width and muscle mass increase (males)
- wider hips and fat distribution in butt and breasts (females)
how does testosterone affect the voice and skin in males?
enlarges the larynx and thickens vocal cords (deeper voice) and increases sebaceous gland activity leading to thicker secretions (acne, etc)
what mental changes are associated with testosterone during puberty? (males)
increased aggression and sex drive
what causes erections during sexual arousal?
trapping of blood in the corpus cavernosa due to parasympathetic stimulation, which dilates arterial supply and constricts venous outflow
what is the prepuce and what is its function?
the prepuce (foreskin) is a fold of skin that serves to protect and may be removed during circumcision
what is the glans penis?
the extended tip of the penis
what is the function of the corpus cavernosa?
it is erectile tissue that fills with blood to produce an erection
what is the corpus spongiosa?
it is soft erectile tissue that surrounds urethra
what does the urethra do in males?
carries sperm and urine, but never at the same time, as a sphincter controls urine excretion
what are the three sets of accessory glands that add secretions to semen?
prostate gland, seminal vesicle, and bulbourthral (cowpers) gland
what is the purpose of the bladder and ureters?
bladder stores urine, ureters transfers urine from the kidneys to the bladder
what is the function of the ductus deferens (vas deferens)
tube that carries sperm from the testes to the urethra
what is the ejaculatory duct?
connects the ductus deferens to the urethra
what is the epididymis?
a coiled tube attached to the testis where sperm complete their development
what functions of the testes
sperm production, and secretion of testosterone
what is spermatogenesis?
the production of sperm that begins at puberty and continues until death
where does spermatogenisis occurs?
seminifernous tubules of the testes
how do sperm mature and travel?
as sperm mature, they move down lumen of seminiferous tubules and from there, travel to epididymis for final maturation
what role do sertoli (nurse) cells play in spermatogenisis?
sertoli cells nourish the developing sperm in the seminiferous tubules
what hormones stimulate sperm production?
FSH, and testosterone
what are leydig (interstitial) cells and what do they produce?
leydig cells in testes produce testosterone, stimulated by LH
what is testosterone stimulated by?
LH
how many sperm are produced daily?
over 300,000,000
what is the structure of a sperm cell and what are its parts
acrosome (head), contains enzymes to penetrate egg, nucleus, contains DNA, midpiece, contains mitochondria to provide energy for flagellums whip like motion, and flagellum (tail), propelling the sperm
what is semen composed of?
contains sperm and secretions from accessory glands for nourishment and protection against acidic environment of the vagina
what is the purpose of mitochondria in sperm cells?
to produce energy for the flagellum to propel the sperm being the tail of the sperm
what are the external genitalia of the female reproductive system?
include clitoris, labium majora, and labium minora
what is the function of the ovaries?
the ovaries store and produce ova (eggs)
what is oogenisis?
during ovulation, a mature egg is released from ovary into the oviduct (fallopian tube)
what is the corpus luteum, and what happens to it if pregnancy does not occur?
the corpus luteum is a solid mass of tissue that forms in an ovary after ovulation. if pregnancy does not occur, it leaves after 10 days
what is the oviduct (fallopian tubes) and its function?
the oviduct is a tube that carries the egg to the uterus and is usually the site of fertilization
what are fimbriae?
fimbriae are thread-like projections that sweep over the ovary to carry the egg into the oviduct after ovulation
describe the uterus and its funtion
the uterus (womb) is a pear shaped, muscular organ where the fertilized ovum embeds and grows during pregnancy
what is the endometrium?
the endometrium is the lining of the uterus, rich in blood vessels, which shed during menstruation if pregnancy does not occur
what is the cervix?
the cervix is a muscular band at the base of the uterus that prevents premature delivery and only dilates during childbirth
what is the vaginas function?
the vagina connects the uterus to the outside world. it is the site of sperm deposition, the birth canal, and protects against bacterial invasion
where does development of the ova occur?
initial development occurs in the ovary, and final occurs in the fallopian tubes
how does female ova production differ from male sperm production?
woman are born with all ova producing cells they will ever have, every spermatogonia produces 4 sperm, whereas oogonium produces 1 ovum (the rest become polar bodies)
what is the role of polar bodies during oogenesis?
polar bodies sacrifice themselves to provide more cytoplasm for the one ovum produced
what are the key stages of oogenesis?
- oogonium (2n) undergoes mitotic division
- becomes a primary oocyte
- starts meiosis (at prophase 1 until ovulation)
- completion of meiosis, forms the secondary oocyte and first polar body
- entry of sperm triggers completion of meiosis ll producing the ovum and second polar body.
at what point does meiosis ll complete in oogenesis?
meiosis ll is completed only when sperm entry occurs
what happens to the oogonium during differentiation?
the oogonium (2n) differentiates into a primary oocyte and begins meiosis l
what happens during ovulation?
the secondary oocyte is released from the ovary into the fallopian tube and awaits fertilization
what hormone triggers the development of a primary oocyte and surrounding granulosa cells?
FSH
what happens to the two cells produced during oocyte development?
one of the two cells dies and becomes a polar body
what forms around the oocyte during its maturation?
a fluid filled cavity forms around the oocyte
what happens to the follicle after ovulation if implantation does not occur?
the follicle breaks down and the corpus luteum forms. if no implantation occurs, the corpus luteum breaks down into a scar called the corpus albicans
what is the corpus luteums function?
the corpus luteum secretes hormones, including progesterone, to prep for possible implantation
what is menstruation?
the normal monthly shedding of blood and tissue from the lining of the uterus (womb) when pregnancy does not occur
what are the 4 phases of the menstrual cycle?
- menstrual (flow phase)
- follicular phase
- ovulation
- luteal phase
what happens during the menstrual (flow phase)? (days 1-5)
shedding of endometrial lining, triggered by decrease in ovarian hormones, particularly progesterone, stimulates FSH and LH, the corpus luteum degenerates the forming corpus albicans, low hormone levels can cause headaches, cramps, nausea, and mood changes
what happens during the follicular phase (days 6-13)
governed by estrogen released by developing follicle (stimulated by FSH), endometrial lining thickens due to estrogen, FSH increases initially but is lowered by negative feedback from estrogen, the follicle matures
what happens during ovulation? (day 14)
estrogen and LH levels peak, follicle erupts releasing ovum into fallopian tube, the female bodies temperature peaks, which can be used for contraception or to aid impregnation
what happens during luteal phase (days 15-28)
corpus luteum develops and secretes progesterone and estrogen (stimulated by LH), progesterone inhibits further ovulation and uterine contraction, endometrial lining thickens further, preparing for pregnancy, progesterone and estrogen inhibit LH release, breakdown of corpus luteum leads to breakdown of endometrium, starting mentstration
what is male infertility?
the inability to impregnate a female, caused by various factors
what are the main causes of male infertility?
low sperm count, poor sperm mobility, hormone imbalance, drugs alc smoking, blockage in reproductive tract
what causes low sperm count in males?
low testosterone or blockage in the reproductive tract
what role does sperm morphology play in male infertility?
abnormal sperm (eg malformed head) may prevent the sperm from penetrating the egg, leading to infertility
how does a hormone imbalance affect male fertility?
low testosterone or conditions like klinefelters syndrome can impair sperm production and lead to infertility
is male infertility the same as impotence?
no male infertility is the inability to impregnate, while importance is the inability to obtain or maintain an erection
what is female infertility?
female infertility is the inability to conceive, caused by factors affecting ovulation or reproductive tract
whats a common cause of female infertility?
failure to ovulate, blockage of reproductive tract
what might cause a blockage in the female reproductive track?
- infection
- scarring
- cervical mucus at the cervix
whats the avg. age for menopause?
50
how is menopause defined?
end of menstruation, caused by diminishing estrogen from the ovaries
what hormonal changes occur during menopause?
- emotional change
- hot flashes
- stoppage of breasts and genital organs
- thinning of skin and bones
- increased cancer susceptibility
what is andropause?
decrease in testosterone in males, starting around the age of 40
what are some symptoms of andropause in males?
- fatigue
- depression
- loss of muscle and bone mass
- drop in sperm production
what is the first step of fertilization?
a sperm cell reaches the jelly like coating surrounding the egg
what do sperm cells release to penetrate eggs jelly like coating
sperm cells release enzymes that digest a path through coating
what happens after sperm cell digests a path through the coating?
the sperm moves closer to the plasma membrane of the egg
what happens when a sperm cell enters the egg?
the sperm nucleus and egg nucleus fuse, completing fertilization
what are the phases of human development?
fertilisation, embryonic (first 8 weeks), fetal (week 9 until birth), then birth of the baby
the fused egg and sperm is now a fertilised egg, what is this called? how many chromosomes?
zygote, with 46 chromosomes
if two eggs are fertilised by two different sperm, what does this mean?
fraternal twins
what is the scientific name for fraternal twins?
dizygotic twins
if one egg is fertilised by one sperm but during development splits into two, what is this called?
identical twins
what is the scientific name for identical twins?
mono-zygotic twins
what happens when their is an incomplete separation of an egg?
Siamese twins (connected)
what happens within 30 hours of fertilisation?
zygote divides by mitosis, forming two new cells
how does the zygote continue to divide after initial division?
the two cells divide to form 4, then again to form 8
what is the term for cell division without cell enlargement
cleavage
what is the purpose of cleavage during early development?
increase the number of cells without increasing the overall size of the embryo
what is the zygote called at the 16 cell stage of division when reproducing?
morula
when does the morula reach the uterus, and what does it form?
morula reaches uterus 3-5 days after fertilisation and forms a hallow, fluid filled pouch called a blastocyst
what are the 4 distinct germ layers of blastocyst?
- trophoblast/chorion: implants into endometrium and forms part of the placenta
- allantois: provide blood vessels for the placenta and forms foundation of umbilical cord
- amnion: forms the amniotic sac to protect the embryo/fetus
- yolk sac: forms digestive tract and produces the first blood cells but has no nutritive function
what happens by the 5th-7th day after fertilisation
blastocyst attaches to endometrium in a process called implantation
what hormone does the chorion secrete, and what is its function?
secretes HGC which maintains corpus luteums production of estrogen and progesterone to prevent menstruation
what forms fetal portion of the placenta?
chorion
what is role of amnion?
amnion forms amniotic sac which protects embryo/fetus from impact, temp change, infection, and dehydration
function of allantois
provides blood vessels for placenta and forms foundation of the umbilical cord
what is role of yolk sac in human development?
yolk sac forms digestive tract, produces first blood cells and serves no nutritive function
what does the inner cell mass of blastocyst develop into?
into embryonic disc, which becomes developing embryo
