human physiology Flashcards
a neuron
it is the main component of nervous tissue, an electrically excitable cell. they receive signals via the dendrites and soma and send out signals down the axon.
neuron structure
Soma: Cell body
Dendrites: Receives info
Axon: Transmits signals away from some to muscles or glands
Myelin sheath: Insulating the axon
Synapse: Junction where information is transmitted
soma
soma is the body of the neuron. it contains the nucleus. they are placed mostly in the brain and the spinal cord also nerve nodes
axon
a finer, cable-linked projection that can extend to 1 meter long. carried nerve signals away from the some. Many neurons have insulating sheaths of myelin around their axons
dendrite
cellular extensions with many branches. Branching is a multi-step biological process by which neurons form a new dendritic trees and branches to create new synapses.
synapse
- structure that permits a neuron to pass an electrical or chemical signal to another neuron
presynaptic part
is located on an axon and the post synaptic part on a dendrite
where do neurotransmitters bind to
neurotrasmitter binds to the receptors located in the plasma membrane of the postsynaptic cell
depolarization
an electrical change within a neuron from a negative charge to a positive charge.
cause: by a rapid rise in membrane
Sodium Na channels open
potassium K channels closed
Na and K pump closed
BEFORE: Na outside, K inside (inside -70mV)
AFTER: Na influx - they have come inside (inside +30mV)
repolarization
an electrical change within a neuron from a positive change to a negative change
cause: results from rapid sodium channel inactivation.
sodium channel closed
potassium channel open
Na and K pump closed
BEFORE: Na and K inside (+30mV)
AFTER: K efflux, they are coming out of there (inside: -80mV)
what is the resting potential in mV
-70
how does sodium potassium pump work
needs atp to pump, active translocation
three sodium iones oumped out of the cell\
two potassium ions pumped into the cell
acetylcholine
it is used as the neurotransmitter in many synapses
produced in the pre-synaptic neuron by combining choline, absorbed from the diet, with an acetyl group produced during aerobic respiration
it is loaded into vesicles and then released into the synaptic cleft during synaptic transimission
the receptors for acetylcholine in the post-synaptic membrane have a binging site to which it will bind. The acetylcholine only remains bound to the receptor for a short time, during which only one action potential is initiated in the post-synaptic neuron.
the choline is reabsorbed into the pre-synaptic neuron.
oscilloscopes
they are scientific instruments that are used to measure the membrane potential across a neuronal membrane
tas grafas kuris rodo depolarization and repolarization
hyperpolarization
a change in a cell’s membrane potential that makes it more negative
nerve impulses
action potentials that move along the length of an axon as a wave of depolarization
myelin
in a certain neruons the axon way be covered by a fatty white substance called myelin which functions as an insulating layer. Myelin is a mixture of protein and phospolipids that is produced by glial cells. The main purpose of the myelin sheets is to increase the speed of electrical transmission via saltatory conduction
synaose
a structure that permits a neuron to pass an electrical or chemical signal to another neuron. the Presynaptic part is located on an axon and the postsynaptic part is located on a dendrite
a chemical that kill insects
Neonicotinoid
natural hormones
proteins
steroids are made of
cholesterol - lipid
hormones
regulate the body’s homeostasis
thyroxin
is a hormone secreted by the thyroid gland in response to signals initally derived form the hypothalamus. The primary role of thyroxin is to increase the basal metabolic rate (amount of energy the body uses at rest) this can be achieved by stimulating carbohydrate and lipid metabolism via the oxidation of glucose and fatty acids.
hotter: temperature causes hypothalamus to inhibit thyroxin release ehich decreases metabolic reate of the body to reduce heat production (lower body temp)
colder: tempretarture cause hypothalamus to stimulate thyroxin release which increased metabolic rate fo the body to generate heat rising body’s temp.
thyroxin - thyroid gland - to regulate the body’s metabolism
hypothalamus stimulates the anterior pituitary stimulating the thyroid gland to release thyroxin - negative feedback - thyroxin when released sends signals to the hypothalamus to stop producing hormones stimulating the anterior pituitary
regulates metabolism, body temperature, growth and development
melatonin
a hromone produced by the pineal gland within the brain in response to changes in light. Light exposure to the retina is relayed via the suprachiasmatic nucleus (in the hypothalamus and inhibits melatonin secretion (for sleep)
melatonin - regulates the sleep-wake cycle, supports immune function
during bright light - inhibition of melatonin, during night - stimulates
triggers eyes, this triggers brain, pineal glands secret melatonin
leptin
a hormone produced by adipose cells that regulate fat stones within the body by suppresing apetite. Leptin binds to receptors located within the hypothalamus to inhibit apetite and thereby reduce food intake.
fat cells empty - no leptin signal to hypothalamis - we eat
fat cells full - leptin signals sent to hypothalamus - we don’t eat
leptin - secreted by the adipose (fat) cells, into the blood, passes through the brain, and attaches to the receptor of the hypothalamus, this sends signals about the information of the fat cells and the brain is able to regulate the need of food - negative feedback on brain because more hormone - less hunger
Homeostasis
a self-regulated process by which a living organism can maintain internal stability while adjusting to change external conditions.
glucose
it cannot be stored in the blood because of them disolving and water goes out of the cell. It is however stored in the liver and muscles. this stored form is called glycogen. Insulina nd glucogen molecule help maintain sugar levels.
glucagon
prevent sugar from dropping, and produced by the alpha cells found in the pancreas
target cells: liver and muscle cells
these cells release glucose into the blood and convert glycogen to glucose.
insulin
prevent sugar levels from rising too high, produced in the pancreas, it is a peptide hormone secreted by Beta cells of the pancreas.
targets liver an muscle cells
these cells absorb glucose from the blood and convert it to glycogen
glucose in plants is stored in
starch
homeostasis and negative feedback
for example when blood glucose levels are high - insulin is produced which lowers blood glucose.
diabetes form if
glucose is not regulated
diabetes is
a disroder that results from a high blood glucose concentration ocer a prolonged period.
type 1 diabetes
usually happens when the body attacks itself by mistake. It destroys beta cells that make insulin in the pancreas. it happens when figghtin infections. Treatment includes insulin injuctions, diet, exercise and counting carbohydrates, etc.
cannot be prevented
B-cells destroyed - autoimmune disease so insulin not secreted
consequences; thirst, frequent urination, fatigue, blurred vision, poorly healing wounds
benefit when avoiding stress, blood sugar monitoring and changes in diet, exercise
type 2 diabetes
often develop in people over age 45, cells respond poorly to insulin, there is insulin resistance and take less sugar, does not recognize it.
it rises the risk in people with obesity. managing it can HELP eating well and exercising.
causes: genetic, environmental or lifestyle factors (unhealthy diet)
can be prevented with lifestyle changes
consequences; thirst, frequent urination, fatigue, blurred vision, poorly healing wounds
benefit when avoiding stress, blood sugar monitoring and changes in diet, exercise
testis
produce sperm and testosterone
scrotum
hold testes at lower than core body tempreture
epididymis
store sperm until ejaculation
sperm duct / vas deferens
transfer sperm during ejaculation
seminal vesicle and prostate gland
screte fluid containting alkali proteins and fructose that is added to sperm to make semen
urethra
transfer semen during ejaculation and urine during urination
penis
penetrate the vagina for ejaculation of semen near the cervix
ovary
produce eggs, estrogen and progesterone
oviduct / fallopian tube
collect eggs at ovulation, provide a site for fertilization then move the embryo to the uterus
uterus
provide for the need of the embryo and then fetus during pregnancy
cervix
protect the fetus during pregancy and then dilate to provide a brith canal
vagina
stimulate penis to cause ejaculation and provide a birth canal
vulva
protect internal parts of the female reproductive system
how many chromosomes does an egg in the ovum have
23
how many chromosomes does the sperm have
23
how many chromosomes do a zygote and embryo have
46 chromosomes in 23 pairs
Y chromosome contain info about
only about male development
X chromosome contain info about
female development but human body too
SRY
a gene in Y chromosome that codes for a testis-determining factor (TDF) that causes embryo to form into testes
In absence of TDF protein (no Y chromosome) the embryonic gonads will develop into ovaries.
testes role
they produce testosterone to promote further development of male sex characteristics, it can affect all of the hormones
ovaries role
will produce estrogen and progesterone to promote the development of female sex characteristics
FSH function
from the anterior pituitary
stimulates follicular growth in ovaries
stimulates estrogen secretion from developing follicles
LH function
from the anterior pituitary
surge causes ovulation
promotes a release of an egg during ovulation
results in formation of corpus luteum (isskiria progesterona)
estrogen function
in the ovaries
thickens uterine lining (endometrium)
inhibits FSH and LH for most of cycle
stimulates FSH and LH release pre-ovulation
progesterone function
in the ovaries
thickens uterine lining (endometrium)
inhibits FSH and LH.
menstrual cycle short
recurring changes that occur within the female reproductive system to make pregnancy possible.
each menstrual cyckle lasts roughly one month (28days) and begins at puberty; ending with menopause.
which hormones control and coordinate the menstrual cyckle and how
pituitary hormones FSH and LH are released from the anterior pituitary gland and act on the ovaries to develop follicles
ovarian hormones estrogen and progesterone are released from the ovaries and act on the uterus to prepare for pregnancy.
menstrual cycle parts
follicular phase
- fsh stimulates growth of the follicles
- dominant follicle produces estrogen which enhibits fsh secretion to prevent other follicles growing (negative feedback)
ovulation
- midway through the cycle estrogen makes pituitary to secrete hromones (positive feedback)
LH causes the dominant follicle to rupture and release an egg
luteal phase
- follicle develops into a slowly degenerating corpus luteum
- this corpus luteum secretes high levels of progesterone
- estrogen and progesterone makes the uterus thicker to prepare for possible pregnancy
menstruation
- if fertilisation occurs the developing embyo makes the corpus luteum to make progesterone further a do.
- if fertilisation doesn’t occur corpus luteum eventually degenerates
- esterogen and progesteron levels drop and the endometrium cannot be longer maintained (sienele kuri padideja)
- it is then removed by menstrual blood
IVF MEANING
fertilization that occurs outside the body, suspends normal ovulation before using hormone treatments to collect multiple eggs
IVF process
- ovarian stimulation hormone therapy. the woman takes a drug each day usually as a nasal spray, to stop her pituitary gland secreting FSH and FH. secretion of estrogen and progesterone therefore also stops. This suspends the normal menstrual cycle and allows doctors to control the timing and amount of egg production in the woman’s ovaries
- egg picks up - superovulation
intramuscular injections of FHS and LH then are given daily for about ten days to stimulate follicles to develop. The FSH injections give a much higher concentration of this hormone than during a normal menstrual cycle and as a consequence for more follicles to develop than usual. - sperm preparation, egg fertilization
the extracted eggs are then incubated in the presence of a sperm sample from the male donor, the eggs are then analyzed under microscope for successful fertilization. - embryo development, embryo transfer
2 weeks prior to implantation, the woman begins to take progesterone treatments to develop the endometrium, healthy embryos are selected and transffered into the female uterus (or the uterus of a surrogate) multiple embryos are transferred to improve chances of successful implantation (hence multiple births are a possible outcome.)
why are hormones during IVF regulated?
completely regulated for IVF to be successful due to correct menstrual cycle part during the procedure.
homeostasis
is the maintenance of a constant internal environment within an acceptable pre-set range (e.g. temperature) despite the changes in the environment
hormones
chemical signals secreted by endocrine glands and carried in the blood to their target tissues or organs
gonads
reproductive organs that produce gametes (sex cells and hormones)
what mutations lead to cancer
mutation in a gene coding for cell growth and mutations in tumor suppressor genes that repress cell cycle progression
