unit 9 - human physiology Flashcards
(181 cards)
1
Q
what is system integration
A
- coordination b/w systems to carry out function of life
- effective communication b/w components
- can involve two+ systems
2
Q
define emergence
A
components together can do more than individual components
3
Q
endocrine system
A
glands that release hormones
4
Q
nervous system
A
neurons that transmit nerve impulses
5
Q
what type of signal is hormone signalling
A
chemical
6
Q
what type of signal is nervous signalling
A
electrical <– by passage of cations across membranes
7
Q
how is signal transmitted in hormone signalling vs. nervous signalling
A
in bloodstream vs. in neurons
8
Q
destination of hormone signalling
A
widespread - everywhere where blood is supplied, but only some cells respond to it
9
Q
destination of nervous signalling
A
highly focused - to one specific neuron or group of effector cells
10
Q
effectors in hormone signalling
A
target cells in any type of tissues
11
Q
effectors in nervous signalling
A
muscles or glands
12
Q
responses to hormone signalling
A
- growth+development
- reproduction (gamete production and pregnancy)
- metabolic rate and heat generation
- solute conc in blood including glucose and salts
- mood, including stress, thirst, sleep/wakefulness and sex drive
13
Q
responses to nervous signalling
A
- contraction of a muscle (ex. locomotion, peristalsis, heart rate)
- response/secretion from a gland (ex. sweat/saliva, epinephrine secretion)
14
Q
speed of response of hormone signalling vs. nervous signalling
A
slower vs. very rapid
15
Q
duration of hormone signalling vs. nervous signalling
A
long time until hormone broken down vs. short unless nerve impulses are sent rapidly
16
Q
what system is used for transport
A
circulatory system transports water+carbon compounds and removes waste
17
Q
what is included in the nervous system
A
- brain
- spinal cord
- interneurons
18
Q
what is included in the peripheral nervous system
A
- motor neurons
- sensory neurons
19
Q
what does the brain do
A
- central integrating organ in body
- receives info from sensory receptors
- processes info leading to decision making and sending signals to body to respond
- stores info in long/short term memory
20
Q
what is the white matter in spinal cord
A
- myelinated axons
- carry signals thru brain and spinal cord facilitating communication
21
Q
what is the grey matter in spinal cord
A
- motor neurons + interneurons with many synapses (connections b/w nerve cells)
- synapses (info processing)
22
Q
unconscious processes
A
- occurs when awake/asleep
- involuntary
- gland secretions + smooth muscles contractions
- coordinated by brain/spinal cord
- ex. sweating
23
Q
conscious processes
A
- occurs when awake
- voluntary
- skeletal muscle contractions
- coordinated by cerebral hemispheres of brain
- ex. fanning self
24
Q
how do sensory neurons deliver info to brain
A
- detect changes in environment or body
- signals carried as nerve impulses along axons of sensory neurons
- brain receive info in specialized areas in cerebral hemisphere
25
how does the brain deliver info to motor neurons
- cerebral hemispheres play major role in control of striated muscles and glands
- signal travel as nerve impulses through dendrites in grey matter of cerebral hemispheres
- axons leads from cell body out of brain down spinal cord to specific striated muscle
26
what is a nerve
a bundle of nerve fibres enclosed in a protective sheath, varies in size
- contains both sensory and motor nerves
27
what occurs during the reflex arc
- involuntary response to stimulus
1. receptors/nerve ending sense stimulus
2. sensory neurons receive stimulus info and sends thru long axons in grey matter of spinal cord to interneuron
3. interneurons(CNS) process info, makes decisions super quick
4. motor neurons receive signal and pass to effectors if threshold reached
5. effector carries out response
28
what does the cerebellum do, what does it not do
does: fine-tune control of skeletal muscle contraction and balance, help with activities requiring motor memory
does not: make decisions
29
muscles in the gut
2 layers of smooth muscle tissue in walls of gut
outer: longitudinal muscle
inner: circular muscle
30
how does the CNS play a role in peristalsis in the digestive system
- muscles can exert continuous moderate force for short periods
- circular muscles: contract behind food, pushing it forward
- longitudinal muscles: contracts along food
- esophagus: peristalsis occurs only downwards in one continuous wave
31
function of neurons
- transmits nerve impulses (electrical signals)
32
structure of neurons
- cell body: cytoplasm and nucleus
- dendrites: short branched nerve fibres that receive info from other cells
- axons: long nerve fibres that transmit nerve impluses
33
define membrane potential
voltage difference across a cell membrane
34
what is membrane potential caused by?
- imbalance in net charge -> caused by ions and charged AAs
- cytoplasm (inside of neuron) usually more neg compared to extracellular fluid
35
define resting potential
membrane potential when the cell is not transmitting an impulse
36
what does the sodium-potassium pump do, where is it located?
- pumps 3 Na molecules out and 2 K in creating charge imbalance and concentration gradient
- type of active transport -> needs ATP
- loc. in cell membrane
37
diffusion caused by sodium-potassium pump
- pumped ions leak back across membrane by slow diffusion
- membrane 50X more permeable to K than Na, so K leakage is faster
- inc. difference b/w Na and K conc. gradients so inc. charge imbalance
38
define action potential
a rapid, temporary change in membrane potential of neuron
39
define depolarization (AP)
change in membrane potential from - to + caused by nerve impulse
40
define repolarization (AP)
change in membrane potential from + to -
41
what occurs during depolarization
- Na channels open, Na diffuses into neuron
- when threshold potential reached, depolarization reaches critical level where Na channels open, Na rushes in, full depolarization occurs
- reverses charge imbalance across membrane from -70mV to +30mV
42
what occurs during repolarization
- K channels open, K diffuses into neuron so that the inside of neuron is neg again
- k channels remain open until membrane potential is -70mV
43
how is resting potential achieved again after a nerve impulse
- when the concentration gradients are wrong, the Na/K pump resets it to -70mV
44
what occurs during action potential process
- depolarization
- repolarization
- undershoot then return to resting potential
- refractory period
45
all or nothing of action potentials
action potential either occurs fully or doesn't occur at all
46
what is the refractory period
time required until another action potential can occur
- prevents impulse from travelling wrong way
- prevents action potential from blending together, keeps them discrete events
47
how does the diameter of the axon affect the speed of an impulse
- humans: diameter of one nerve is ~1um and impulses travel ~1m/s
- some animals have larger diameters allowing for faster impulses bcus less resistance
- larger axons used to coordinate rapid rxns for survival
- ex. giant axons in squids have: d=500um, impulses are up to 25m/s
48
what is myelination and how does it affect the speed of a nerve impulse
- coating of fatty substance (myelin) forming myelin sheath, acts as insulator
- allows nerve impulses to jump from node to node <- faster, up to 100m/s
49
define synapse
fluid filled gap b/w 2 cells in nervous system ~ 20nm wide
50
[deleted]
51
how do signals move across synapse
in one direction
52
what does the presynaptic neuron do
- bring signal to synapse via action potential
53
define neurotransmitters
chemicals that carry signal across synapse
54
what does the postsynaptic neuron do
carries signal away from synapse via action potential
55
what occurs in the presynaptic neuron during synaptic transmission
- AP propagated along presynaptic nerve
- depolarization of presynaptic membrane (Ca diffuses in thru membrane channels)
- influx in Ca-> vesicles containing NTs fuse w/ presynaptic membrane
- NT release into synaptic cleft via exocytosis
56
what occurs in the postsynaptic neuron during synaptic transmission
- NTs diffuse across synapse
- NTs bind to receptors in postsynaptic membrane, ion channels open
- Ions diffuse into postsynaptic neuron -> membrane potential less neg
- if excitatory postsynaptic potential strong enough, triggers AP
- NTs rapidly broken down and removed from synapse
57
what is acetylcholine (ACh)
a neurotransmitter (NT) that sends signals b/w nerve cells and other cells
58
how is acetylocholine used when signalling b/w neurons
- binds to receptor in postsynaptic membrane (open Na channel)
- NA diffuses in -> excitatory postsynaptic potential
- ACh binds to receptor for short time, generates one AP
- acetylocholinesterace in synapse breaks down ACh back into choline and acetyl group
- choline reabsorbed and turned back into ACh
59
define homeostasis
multicellular organisms regulating internal environment to keep it as close to optimal as possible
60
examples of homeostasis in human body
- blood glucose concentration
- blood osmotic concentration
- blood pH
- body temp
61
positive feedback loops in human body
- output of process amplifies process leading to more change "snowball effect"
- not common in human body as it promotes change rather than stability
- ex. increase of contractions during childbirth)
62
negative feedback loops to achieve homeostasis
- output of process dampens process leading to less change
- used to achieve balance and return to set point, keeping internal conditions within limits
- require a lot of energy but allows multicellular organisms to survive in extreme conditions
63
what is the hypothalamus
small region of the brain what plays major roles in integration of body systems
64
what are the endocrine system and nervous system controlled by
hypothalamus which links the nervous system to the endocrine system via pituitary gland
65
what does the pituitary gland do
- anterior lobe and posterior lobe secrete hormones into blood capillaries under directions of nuclei in hypothalamus
66
function of specialized "nuclei" cells
operates one or more specific control systems using info from a a variety of sources
- ex. blood glucose conc, osmolarity, blood temp, hormone conc
67
define osmoregulation
the monitoring of blood solute concentration
68
how does osmoregulation work
- blood solute conc monitored by hypothalamus
- influences release of antidiuretic hormone (ADH) by neurosecretory cells in hypothalamus
- axons transport ADH to pituitary gland to be secreted into capillaries
69
how does puberty work
- hypothalamus initiate by secreting GnRH
- stimulates secretion of LH and FSH by pituitary gland leading to production of testosterone (male), oestradiol and progesterone (female)
70
what is involved in blood glucose regulation
- kept within narrow limits, must balance glucose removed/added to blood
- set point ~5mmol/L
- regulated by insulin and glucagon <- secreted by cells in pancreas "isle of langerhans"
71
what must happen when blood glucose levels drop in order to maintain homeostasis
- pancreas detects it
- alpha cells make+secrete glucagon hormone which signals liver to convert stored glycogen into glucose which is then released into blood
- blood glucose levels increase
72
what must happen when blood glucose levels rise in order to maintain homeostasis
- pancreas detects it
- beta cells make+secrete insulin which allow skeletal muscle cells + liver to store glucose and convert it to glycogen
- blood glucose levels decrease
- insulin broken down by target cells which means secretion must be ongoing
73
what is diabetes, what does it do, what are the symptoms?
- consistently elevation blood glucose levels
- damages tissues+proteins
- prevents water reabsorption in kidneys
- symptoms: constant thirst/urination/tiredness/sugar cravings/glucose in urine
74
what occurs when someone has type 1 diabetes
- body cannot produce enough insulin because of destructions of beta cells by immune system
- autoimmune disease
- sudden onset
75
treatments for type 1 diabetes
- test blood glucose level regularly
- inject insulin when too high/before eating
- implant devices to release insulin
- stem cell treatment to create new beta cells (in development!)
76
what occurs when someone has type 2 diabetes
- cannot respond to insulin bcus lack of insulin receptors or glucose transporters on target cells
- slow onset
- risk factorsL unhealthy diets, prolonged obesity, genetic factors
77
treatments for type 2 diabetes
- frequent, smaller meals to avoid peaks of glucose
- avoid sugary foods
- eat food w/ low glycemic index and high fibre (slower digestion)
- exercise and weight loss to improve insulin uptake
78
what is thermoregulation? what is the body temp of humans?
- control of body temp
- temp of ppl change depending on time of day/year
- typically 37C
79
how is body temp monitored
- by thermoreceptors which are free nerve endings of specialized sensory neurons
- sensory inputs from peripheral/central thermoreceptors to hypothalamus
- initiates response if hypothermia or hyperthermia
80
types of thermoreceptors
- there are cold and warm receptors
- peripheral thermrec. are located near skin to sense outside temp
- central thermrec. located in body to sense core temp
81
how is the temp maintained in the body
- generated by metabolism which can be increased or decreased by signals from hypothalamus
- muscles contract to release heat
- subcutaneous adipose tissue (insulation) prevents heat loss
- brown adipose tissue generated heat at rapid rate
82
vasoconstriction as a bodily response to cold
- constriction of arterioles in skin
- less blood flow to skin preventing heat loss
83
shivering as a bodily response to cold
- muscles contract involuntarily to cause movement to generate heat
84
uncoupled respiration as a bodily response to cold
- when energy from mitochondria doesn't produce ATP but rather heat
- brown adipose tissue has a lot of mitochondria (gives it the brown colour)
- mitochondria oxidizes fat and converts all energy to heat
85
hair erection as a bodily response to cold
- thick coat allows air b/w hairs which atcs like thermal insulator
- erector muscles move hairs to increase insulating effect
86
vasodilation as a bodily response to heat
- circular muscles relax, arterioles dilate
- more blood flow to skin encouraging heat loss
87
sweating as a bodily response to heat
- sweat secreted by glands in skin <- controlled by hypothalamus
- water is evaporated, solutes remain, giving salty taste
- water has high latent heat of vapourization, cooling effect
88
affect of secretion of melatonin on sleep patterns
- affects circadian rhythms
- depends on cells (suprachiasmatic nuclei (SCN)) in hypothalamus as cells follow daily rhythms even when grown in labs
- secreted from pineal gland
- ganglion cells in retina detects light, signals SCN timing of duck/dawn to adjust melatonin secretion
89
define circadian rhythms
the 24 hour sleep-wake pattern
90
what do high levels of melatonin do
- cause drowsiness, allows one to sleep through night
- contributes to dec in body temp and dec in urine production at night
91
what do low levels of melatonin do
encourages waking in the morning
92
how does epinephrine (adrenaline) work
- know as fight or flight hormone, get body ready for physical activity
- secreted by adrenal glands, controlled by brain
- binds to adrenergic receptors in plasma membrane of target cells
93
how does epinephrine (adrenaline) affect blood supply
- inc blood supply to skeletal muscles
therefore inc O2/glucose supply which allows for more production of ATP via cell respiration
94
how does epinephrine (adrenaline) affect muscle and liver cells
muscle: convert glycogen to glucose for cell respiration
liver: convert glycogen to glucose to go into blood
95
how does epinephrine (adrenaline) affect bronchi and ventilation rate
- bronchi: dilate for easier ventilation
- vent. rate: increased for larger volume of air
96
how does epinephrine (adrenaline) affect arterioles
to muscles/liver: dilate for more blood flow as they're crucial
to gut/kidneys/skin: constrict for less blood flow
97
what is the sinoatrial (SA) node
group of cardiac muscle cells in wall of right atrium (natural pacemaker)
98
how does the sinoatrial (SA) node work
- receives signals from cardiovascular centre of brain
- signals reach pacemaker via sympathetic nerve(to inc HR) or vagus nerve (to dec HR)
99
function of baroreceptors
monitor blood pressure in walls of aorta/carotid arteries
- low BP triggers faster HR to bring BP up
high BP triggers slower HR to bring BP down
- negative feedback loop
100
function of chemoreceptors
monitor blood O2 conc and pH (CO2 levels) in aorta.carotid arteries
- low O2/pH triggers inc HR to inc blood flow for more O2 and removal of CO2
- high O2/pH triggers dec HR
101
how do chemoreceptors affect ventilation rate
- chemoreceptors monitor blood pH in aorta/carotid arteries
- low pH (high CO2) triggers inc in VR which will dec CO2 conc in alveoli
- allows for more diffusion of CO2 from capillaries to lungs, increasing pH
102
how is ventilation rate controlled
- regulated by respiratory centres in brainstem as it is main way to regulate blood pH
- brain signals muscles used to inhale, when lungs expanded, detected by stretch receptors to stop inhale
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how can chemoreceptors also monitor O2
- monitor O2 conc in blood flowing to head
- low O2 levels send signal to respiratory centre in brain triggering inc VR
- can override blood pH and CO2 response to ensure brain has sufficient O2
104
define disease
a particular illness with characteristic symptoms
105
what can cause disease
- genetic: alleles one has
- environment: chemicals/radiation
- pathogen: a micro-organism that causes disease
106
how do pathogens cause disease
- passed from one person to another
- enter organism, multiply once inside, causes harm
- often highly specialized, have a narrow range of hosts
107
define zoonosis + factors
- disease that can be transferred from animals to humans naturally (some pathogens can use many species as host)
- global health concern
- factors: ppl living close to livestock, displacement of animals through habitat disruption
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innate vs. adaptive immunity
innate: responds to broad categories of pathogens, doesn't change during organism's life (ex. phagocytes)
adaptive: responds in specific way to particular pathogen, builds up memory of pathogens (ex. antibody producing lymphocytes) <- more effective
109
skin as primary defence against pathogens
- outermost layer, provides physical barrier
- tough layer of dead cells containing a lot of keratin (protein)
- sebaceous glands release sebum to maintain low pH on skin, inhibits bacterial/fungal growth
110
mucous membrane as primary defence against pathogens
- thin, softer skin that secretes mucous (stick solution of glycoproteins)
- traps pathogens and harmful particles (swallowed or expelled)
- antiseptic properties
111
importance of blood clotting
- cascade of rxns each producing catalyst for the next
- prevents entry of pathogens via open wounds
- prevents blood loss and low BP
112
steps of forming blood clot
1. skin cut, bleeding
2. platelets cluster at site, temp plug
3. platelets release clotting factors, triggers clotting process
4. clotting factors produce enzyme thrombin
5. thrombin converts fibrogen in blood to insoluble fibrin
6. fibrin forms mesh in cuts, traps more platelets and blood cells
7. clot is gel, turns hard when meets air
113
what are phagocytes
- specialized WBCs that target any non self cells
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how do phagocytes work
- squeeze thru pores of capillaries to sites of infection
- engulf pathogens by endocytosis and digests them using enzymes from lysosomes
- creates pus
115
define lymphocytes, what do they do?
WBCs rounded nucleus and small amount of cytoplasm circulating in blood and lymphatic system
- large # in lymph nodes, produces antibodies
116
define antibodies
large proteins that help destroy pathogens
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structure of antibodies
hypervariable region: recognizes+binds to specific molecules on pathogen
constant region: helps body fight pathogen by making it more recognizable to phagocytes to engulf them
- prevents viruses from entering host cells
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immune system produces one/many diff antibodies, individual lymphocyte can produce one/many antibodies
many, one
119
how does the number of lymphocytes in body change
- normally have small # of each specialized lymphocyte cus we have so many
- when infect, needed lymphocytes will multiply and work tgt to create large volumes of antibodies
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how do antigens trigger antibody production
- antigen molecules stimulate immune response
- hypervariable region of antibody binds to antigens depending on shape/chemical properties
- bind is irreversible
121
define antigens
molecules located on surface of pathogens
122
how do we fight off pathogens (general process)
1. macrophage ingests pathogen and displays its antigens
2. helper T-cell specific to antigen activated by macrophage
3. B-cell specific to antigen activated by proteins from helper T-cell
4. B-cell divides repeatedly to produce antibody-secreting plasma cells
5. antibodies produced by clones of plasma cell are specific to antigen of pathogen, helps destroy it
123
how are helper T-lymphocytes/cells activated
- have antibody-like receptor in plasma membrane to help it bind to macrophage
- helper T-cells are specific to 1 antigen and bind w/ + activated by macrophage
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what do activated helper T-cells do
- bind to B-lymphocytes
- B-cells are specific to one antigen and are activated by helper T-cells via binding + signalling protein
125
what do activated B-cells do
- don't immediately create antibodies as there are too few to make enough and don't have the needed organelles yet
- divide by mitosis to make clones + grow large ER +golgi apparatus and ribosomes
- allows for rapid production of antibodies
126
what are plasma b-cells
- essentially plasma cells
- cells that have grown + differentiated for antibody production
- final form, creates lots of antibodies and secretes into body
127
can you get immunity from pathogens thru antibodies and plasma b cells
- antibodies can provide immunity for only for few weeks/months
- plasma B-cells that make antibodies only last for short time, antigens gone after infection passes, cannot produce more B-cells
128
how can one develop immunity from pathogens
- most B-cells produced by mitosis become active B-cells but some become memory B-cells
- remain inactive until same pathogen infects body again -> activates+ responds rapidly
129
what is immunity from pathogens dependent on
1. still having antibodies
2. have memory B-cells to make antibody quickly
130
how does transmission/infection of HIV occur
- only thru exchanges of body fluids from infected to uninfected person
- ex. sex w/o condom (causes abrasions to mucus membrane)
- sharing hypodermic needles
- transfusion of infected blood
- childbirth + breastfeeding
131
what does HIV do to a person
- destroys helper T-cells, cannot produce antibodies
- in early stages, immune system makes antibodies against HIV as rate in loss of helper T-cells vary
- w/o treatment, antibody production too low, even common illnesses are dangerous
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what is AIDS
- conditions caused by HIV combined in a person
- most advanced stage of HIV, when immune system is badly damaged
133
define syndrome
collection of several diseases and conditions existing together
134
how does HIV work to infect an individual
- retrovirus that has genes made with RNA
- uses reverse transcriptase to produce DNA copies of its genes after entering host cell
- integrated in host cell's DNA, becoming permanent part of their genetic material
135
currents ways to slow down effects of HIV
- antiretroviral drugs inhibit reverse transcriptase, slowing/preventing damage to immune system
- other drugs also target enzymes virus uses to insert DNA into host
136
define antibiotic
chemical that inhibits growth of microorganisms (mainly bacteria)
137
what do antibiotics do
- block processes like transcription, translation, DNA replication that occur in prokaryotes but not eukaryotes (ex. kills bacteria but not human cells)
138
how do antibiotics work
- viruses rely on hosts for transcription/translation
- if these processes are targeted, host cell will die, virus will die
- antibiotics don't work directly on viruses!
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where does antibiotic come from
- discovered in saprotrophic fungi that competes against saprotrophic bacteria
- they secrete antibacterial antibiotics to inhibit bacterial competitors
140
intramuscular injection vs. subcutaneous injection
into muscle vs under skin
141
how to vaccines work to achieve immunization
- contains pathogen antigens or nucleic acids that make antigens
- stimulates primary immune response by activation of B-lymphocytes and T-lymphocytes, production of plasma cells, antibody production
- memory cells produced for long-term immunity, secondary immune response
142
define herd immunity
significant proportion of population have contracted disease or have been vaccinated (immune)
143
how does herd immunity affect spread of disease
- slows, as keeps on encountering people who are immune
- new outbreak of disease should disappear
- individuals w compromised immune systems and cannot be vaccinated are unlikely to contract disease
144
how to calculate percentage of people who must be immune for herd immunity
(1-1/R) x 100%
R = average # of people one person infects
145
function of testes
to produce sperm and testosterone
146
function of scrotum
holds testes at lower than core body temp
147
function of epididymis
stores sperm until ejaculation
148
function of sperm duct
transfers sperm during ejaculation
149
function of seminal vesicle and prostate gland
secrete fluid containing alkali, proteins and fructose that is added to sperm to make semen
150
function of urethra
transfers semen during ejaculation and urine during urination
151
function of penis
penetrates the vagina for ejaculation of semen near the cervix
152
function of ovary
produces eggs, oestradiol and progesterone
153
function of oviduct
collects eggs at ovulation, provides a site for fertilization then moves the embryo to uterus
154
function of uterus
provides for the needs of the embryo and foetus during pregnancy
155
function of cervix
protects foetus during pregnancy and then dilates to provide birth canal
156
function of vagina
stimulates penis to cause ejaculation and provides birth canal
157
function of vulva
protects internal parts of female reproductive system
158
define menstrual cycle, what is it
- cycles of changes in uterus and ovary regulated by hormones
- occurs from puberty to menopause
- each time it occurs, there's a change of pregnancy
159
what phases occur during ovarian cycle and uterine cycle
follicular phase then luteal phase
160
what occurs during the follicular phase during ovarian cycle
- group of follicles develop in ovary
- egg stimulated to grow in each follicle
- most developed follicle releases egg in oviduct during ovulation
- other follicles degenerate
161
what occurs during the luteal phase during ovarian cycle
- follicle that release egg becomes corpus luteum
- if no fertilization, corpus luteum breaks down , ovary returns to follicular phase
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what occurs during follicular phase during uterine cycle
- menstruation (days 1-7)
- endometrium starts to thicken again
163
what occurs during luteal phase during uterine cycle
- endometrium thickens, increased blood supply to prepare for implantation
- if no embryo, thickening breaks down, shedded during menstruation
164
what are the hormones FSH and LH in menstrual cycles
- FSH (follicle-stimulating hormone) and LH(luteinizing hormone)
- protein hormones produced by pituitary gland
- binds to FSH and LH receptors in follicle cell membranes
165
what are the hormones oestradiol and progesterone in menstrual cycles
- ovarian steroid hormones
- produced by wall of follicle and corpus luteum
- influences gene expression and development in the uterus + body
166
what happens to hormone levels during days 1-4 of the follicular phase
- FSH increases to stimulate follicle development
167
what happens to hormone levels during days 5-14 of the follicular phas
- FSH and follicle stimulate oestradiol release, stimulating endometrial thickening
- oestradiol stimulates more FSH receptors on follicles, more oestradiol released (+ feedback)
- oestradiol levels peak, inhibits FSH secretion (- feedback), stimulates LH
- peak in LH stimulates ovulation, egg released
- when corpus luteum develops, secretes oestradiol and progesterone
168
what happens to hormone levels during days 14-28
- progesterone levels increase at start (from corpus luteum)
- inhibits FSH and LH by pituitary gland (- feedback)
- if no fertilization, progesterone and oestradiol levels drop, triggering menstruation of LSH release
169
how does sperm and egg meet during fertilization
- receptors in plasma membrane of sperm detect chemicals from egg -> directional swimming
- egg surrounded by layer of follicle cells and glycoproteins
- sperm pushes past cells, absorb glycoprotein to reach egg
- first sperm to bind to egg plasma membrane fertilizes egg
170
what occurs after fertilization
- layer of glycoprotein outside of egg hardens preventing more sperm
- sperm tail doesn't penetrate or is broken down inside zygote
- sperm mitochondria may penetrate but is destroyed
- nuclei remain separate into first mitosis when nuclear membranes break down
171
causes of infertility in females
- ova not maturing/being released
- abnormality in uterus prevents implantation
- blocked fallopian tubes
- antibodies in cervical mucus impair sperm
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causes of infertility in males
- unable to achieve erection or normal ejaculation
- low sperm count or abnormal sperm
- blocked vas deferens (sperm duct)
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step one of IVF treatment (down-regulation)
- shut down menstrual cycle for 2 weeks by stopping secretion of pituitary and ovarian hormones
- better control/timing of egg production
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step two of IVF treatment (superovulation)
- collects multiple eggs from woman
- high doses of FSH are injected over 7-12 days to stimulate development of multiple follicles
175
step three+four of IVF treatment
- when follicles reach 15-20mm an injection of hCG (human chorionic gonadotropin) is given to start maturation process
- after 36 hours, 8-12 follicles collected from ovaries using micropipette and ultrasound
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step five of IVF treatment
- prepared eggs (removed from follicles), combined with 50k-100k sperm and incubated at 37C
177
step six of IVF treatment
- if fertilized, multiple embryos placed in uterus after 48 hours
- women takes progesterone for 2 weeks before implantation to maintain endometrium
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oestradiol trend during menstrual cycle
peaks at 14 days and near end of 28 days
179
progesterone trend during menstrual cycle
peaks near end of 28 days
180
FSH trend during menstrual cycle
peaks near start of cycle and at 14 days
181
LH trend during menstrual cycle
large peak at 14 days
