Unit 2 - Chpts. 23, 26, 22, 8 Flashcards
Where does synthesis of thyroid hormones occur?
Thyroid follicles
In Graves’ disease, antibodies bind to TSH receptors leading to
increased T3/T4 and decreased TSH and TRH
Primary hypothyroidism caused by a lack of iodine in the diet leads to
decreased T3/T4 and increased TSH and TRH
Patients with hyperthyroidism experience heat intolerance. What mechanism would explain this?
The production of ATP is increased resulting ni more exothermic reactions taking place
In a hypophysectomized rat, which of the following would you expect to find?
Decreased levels of T3 and T4
What hormone “turns off” Growth Hormone?
Somatostatin
What digestive system hormone sends a signal to the hypothalamus to produce GHRH?
Ghrelin
What does GH indirectly impact?
The liver which produces Insulin-like growth factors, leading to cartilage growth
What are some stimulatory factors for GH release?
Sleep
Stress (only a little)
Exercise
Hormones of puberty
What are some inhibitory factors for GH release?
Obesity
Senescence
Somatostatin
GH (negative feedback)
Increased IGF (negative feedback)
Increased glucose
Increased fatty acids
What are the actions of GH?
Increase lipolysis and gluconeogenesis, decrease glucose uptake by muscle –> increases blood glucose
Which of the following statements about growth hormone is incorrect?
a) Cortisol released in response to stress inhibits the release of GH
b) Hypersecretion of GH in children causes gigantism
c) Hyposecretion of GH in children can be treated with bovine GH
d) Hypersecretion of GH in adults causes acromelaly
c) Hyposecretion of GH in children can be treated with bovine GH
GH is species specific
True or False: Thyroid hormones play a permissive role in tissue and bone growth
True
What stimulates protein synthesis and provides energy?
Insulin (glucose)
Role of osteoblast
produce enzymes and osteoid (build bone)
Role of osteoclast
secrete acid that dissolves calcified matrix (catabolize bone)
What is the most common form of calcium phosphate?
Hydroxyapatite
Role of parathyroid hormone
1) Mobilizes calcium from bone
2) enchances renal reabsorption of calcium
3) indirectly increases intestinal absorption of Ca2+
Signs of hypo calcium?
Muscle cramps
Convulsions and seizures
Tingling and numbness
Hyperactive bowels
Brittle hair/nails
Signs of hyper calcium
Muscle weakness
Constipation
Hypertension
Polydipsia
Polyuria
Lethargy, coma
Increased levels of phosphate ions in the boddy would likely accompany ____?
Bone loss during osteoporosis
Concerning calcium homeostasis, what is the correct relationship?
Osteoblasts build bone, osteoclasts catalyze its reabsorption
3 sets of sex organ structures?
1 - internal
2 - external
3 - gonads (ovaries and testes)
What are bipotential gonads?
gonad that could develop into either the ovaries or testes depending on presence of SRY gene
Which ducts belong to the male system?
Wolffian ducts (mullerian duct regresses)
Which ducts belong to the female system?
Mullerian ducts (wolffian duct regresses)
What hormone causes the Mullerian duct to disappear?
Anti-Mullerian hormone (produced by testes)
What causes the Wolffian ducts to disappear?
Absence of anti-mullerian hormone
What structures arise from the Mullerian duct in the female system?
Fallopian tube
Uterus
Upper part of vagina
What structures arise from the Wolffian duct in the male system?
Seminal vesical
Vas deferens
Epididymis
What do the genital tubercle, uretheral folds and grooves, and labioscrotal swellings form in the female system?
Genital - Clitoris
Uretheral - Labia minora, opening of vagina and urethra
Labioscrotal - labia majora
What do the genital tubercle, uretheral folds and grooves, and labioscrotal swellings form in the male system?
Genital - Glans penis
Uretheral - Shaft of penis
Labioscrotal - Shaft of penis and scrotum
What do interstitial cells secrete?
Testosterone
What do sertoli cells secrete?
anti-mullerian hormone
Pathway for GnRH in males
1) GnRH –> LH –> interstital cells of leydig –> testosterone
2) GnRH –> FSH –> sertoli cells (sastenacula) –> anti-mullerian hormone, sperm
Stem cell for sperm
Spermatogonia
Stem cell for eggs
Oogonium
Sex determination during development depends on the presence of
SRY gene
Testosterone is required for testicular development
False
Which is true for an individual with Turner’s Syndrome (X0)?
Embryo develops in a female, female reproduction function is impaired
How does the amount of DNA in the first polar body compare to that in the second polar body?
2x as much
What organ stores sperm?
Epididymis
What accessory glands contribute to secretions to semen?
Prostate gland and Bulbourethral gland
What is the role of the sertoli cell in spermiogenesis
secrete proteins to support
What type of junctions are present in the lumen of the seminiferous tubule and what role do they play?
Gap junctions between sertoli cells to provide developing sperm with nutrients
Role of blood testis barrier?
Keeps immune cells out
What is a spermatid?
a haploid cell that is not yet a sperm, develop into spermatozoa
What is the acrosome?
Allows sperm to get to egg by erroding part part of cell wall
Role of mitochondrial spiral in sperm?
help provide energy for flagella to move
Why does semen need buffers?
to neutralize acidic environment of vagina
What is unique about the production of GnRH?
It is pulsitile
What is Androgen-binding protein and what role does it have?
Produced by sertoli cells, keeps testosterone cells at a steady state, can bind to excess testosterone to keep it in the seminiferous tubules
Pathway of erection
Testosterone –> sexual arousal –> increase in parasympathetic signaling to penis –> increased nitric oxide release –> arterial and trabecular smooth muscle relaxation –> arterial dilation –> increased arterial blood flow and pressure & decreased blood flow out –> increased intracevernosal pressure –> increased penile rigidity –> erection
What are the 3 erection tissues?
Corpora cavernosa
Cavernosal artery
Corpus spongiosum
Developing spermatozoa are nourished by
sertoli cells (aka nurse cells)
In the erection reflex, stimulation of parasympathetic neurons causes vasodilation so erectile tissues in the penis shaft receive increased blood flow
True
After leaving the seminiferous tubule, spermatozoa enter the ___
epididymis
Pathway of spermatozoa
Seminiferous tubule –> epididymis –> vas deferens –> urethra
Why do anabolic steroids cause testes to shrink, making males temporarily infertile?
FSH secretion decreases
In males, what is the main target for FSH?
Sertoli cells
What does LH stimulate in males?
testosterone production
What are the 2 layers of the endometrium?
Basal layer (stem)
Functional layer (thicken)
What type of tissue is the myometrium made of?
smooth muscle
Where do cramps come from?
Cramps are the result of the myometrium contracting and pinching off the spiral ateries (the functional layer of the endometrium)
What are Granuloso cells?
make the enzyme aromatase, converts androgens to estrogen and inhibin (estrogen inhibits FSH and GnRH, inhibin inhibits FSH)
Pathway of an egg
Primordial follicles –> primary follicle –> secondary follicle –> early tertiary follicle –> dominant follicle w/oocyte –> ovulated oocyte –> Corpus luteum –> regressing corpus luteum
What pathway does LH use to make estrogen?
Secondary messengers (cAMP)
3 phases of ovarian cycle
Follicular cycle, ovulation, luteal phase
3 phases of uterine cycle
Menses, proliferative phase, secretory phase
What happens when ovulation occurs?
Estrogen, which had hit a peak, starts to decline and progesterone and inhibin start to increase.
How long is the secretory phase?
always 14 days
What hormone is high right before ovulation?
LH
FSH does peak but nowhere near the amount LH hits
Which hormone stimulates uterine contraction?
Oxytocin
A 42-year-old female has a total hysterectomy and bilateral oophorectomy (removal of both ovaries). What effect would this have on her hormone levels?
increase FSH and LH, decreased estrogen and progesterone
Which hormones control the ovairan and uterine cycles?
Inhibin, estrogen, progesterone, GnRH, FSH, and LH
What occurs during menstration?
The endometrium sloughs its surface layer (aka functional layer)
What occurs during the proliferative phase of the menstrual cycle?
A new uterine lining forms
Which of the following affects female reproductive function?
a) nutritional status
b) stress
c) changes in day-night cycle
d) all
d) all
In general, anything and everything can affect the female reproductive cycle
During which phase of ovarian cycle is estrogen lowest?
a) early follicular phase
As it moves down the fallopian tube, an egg ____
is moved by Fallopian tube cilia and muscular contractions
On average, a menstrual cycle is ___ days
28
What is the definition of contraception?
no fertilization occurrs (sperm and egg do not meet for whatever reason)
Oral contraceptives act by
decreasing FSH and LH release from the pituitary and decreasing GnRH release from the hypothalamus
What are some examples of contraceptive methods?
Oral pill
Vaginal ring
IUD
Condom
What is NOT considered a method of contraceptive
Mifepristone (abortive pill, means fertilization has already occurred)
What hormones does the pancreas secrete?
insulin and glucagon
what do beta cells secrete?
insulin
What do alpha cells secrete?
Glucagon
What do delta cells secrete?
somatostatin
In what state does insulin dominate?
the fed state, or post absorptive
In what state does glucagon dominate?
the fasting state
In what order does blood flow through the Islet of Langerhans?
delta –> alpha –> beta
delta: can inhibit beta and alpha cells if range is good
alpha: if glucose is low, will release glucagon and inhibit beta cells
beta: if glucose is high, will release insulin and inhibit alpha cells
What relationship do insulin and glucagon have?
Antagonistic
How is glucose stored?
Short term = glycogen
Long term = fat
What factors stmiulate insulin secretion?
Increased plasma glucose
Increased plasma amino acids
Feed forward effects of GI hormones
Parasympathetic activity
What roles does adipose tissue have when exposed to insulin?
Increase glucose uptake
Increase rate of lipogenesis
Decrease rate of lipolysis
What roles does the liber have when exposed to insulin?
Decrease rate of gluconeogenesis
Increase rate of glycogen synthesis
Increase rate of lipogenesis
What roles do striated muscles have when exposed to insulin?
Increase rate of glucose uptake, glycogen synthesis, and protein synthesis
What does Hexokinase II do?
Attaches a phosphate group to glucose, trapping glucose in the cell
Primary target of glucagon?
the liver
What factors stimualte the release of glucagon?
low blood glucose
increased plasma amino acids
How is glucose transport different in the liver compared to all other cells?
Glucagon does not activate hexokinase II, so glucose can leave liver if needed
Type 1 diabetes
insulin deficiency from autoimmune destruction of beta cells
Type 2 diabetes
insulin resistant diabetes
During the absorptive state in a person at rest, ___
the liver forms glycogen
What is TRUE about fasted-state metabolism?
It is catabolic
Maintains plasma glucose for the brain
Leads to formation of ketone bodies
Promotes gluconeogenesis
The amount of insulin secreted in response to intravenous glucose is ___ insulin secretion in response to oral glucose
less than
Generally, insulin and glucagon are released by opposing stimuli and have opposing effects. However, both hormones are released by the stimulus of increased blood amino acids because ___?
glucagon prevents hypoglycemia following a pure protein meal
Which is NOT a main target for insulin action?
reneal glucose reabsorption
Which is NOT true about type 2 diabetes mellitus?
caused by beta cell destruction
Patients with diabetes inject insulin rather than taking it as a pill because
oral insulin is broken down in the digestive tract
What two organs make up the CNS?
Brain and spinal cord
What is a pseudounipolar neuron?
have a single process called the axon. Dendrite fused with the axon. Type of sensory neuron
What is a bipolar neuron?
2 relatively equal fibers extending odd the central cell body. Type of sensory neuron
What is an anaxonic neuron?
Have no apparent axon, type of interneuron
What are the two types of multipolar neurons?
a) Multipolar neurons of interneuron type are highly branched but lack long extensions
b) Multipolar neurons of efferect type have 5-7 dendrites, each branching 4-6 times. Single long axon, may branch several times and end at enlarged axon terminals
What is a synapse?
region where an axon terminal communicates with its postsynaptic target cell
What are the two types of axonal transport?
1) Anterograde - soma to synaptic knob
2) Retrograde - synaptic knob to soma
What type of neural cells are found in the CNS?
Ependymal cells
Astrocytes
Microglia cells
Oligodendrocytes
What type of neural cells are found in the PNS?
Schwann cells
Satellite cells
Role of ependymal cells?
Line ventricals
Cerebrial spinal fluid
Create barriers between compartments
Source of neural stem cells
Role of astrocytes?
Source of neural stem cells
Support cell
Completely surround capillaries, protecting against toxins and pathogens
Role of microglia cells?
Modified immune cells
Act as macrophages
Role of Oligodendrocytes?
creates myelin sheath
in CNS, it has many projefctions taking care of axons (repair)
Role of Schwann cells?
create myelin sheath
Secrete neurotrophic factors
Role of satellite cells?
Support cell bodies
Stimulant for growth, repair, and recycle
True or False: if the cell body dies, the neuron dies
True
True or False: if the axon is severed, the neuron dies
False
Steps of neuronal repair?
- Axoplasm leaks and seals damaged end, attached segment of axon swells
- Schwann cells release chemical signals alerting of tissue damage
- degeneration of distal axon segment, myelin sheath unravels, cellular debris removed
- Schwann cells secrete neurotrophic factors to keep cell body alive and encourage axon regeneration
Steps of membrane potential
1 Open leaky K+ channel
2 K+ exits cell (efflux)
3 Anions left behind, inside of cell becomes negative
4 Some K+ goes back in, flow now in and out
5 New equilibrium reached, outward drive = inward drive, resting membrane potential reached
What is the Nerst equation used for?
Predicts the membrane potential that a single ion would produce if the membrane were permeable to only that ion
What is the Goldman-Hodgkin-Katz equation used for?
Calculates membrane potential that results from contribution of all ions that can cross the membrane
What is the resting membrane potential primarily determined by?
K+ conc. gradient
Cells permability to K+, Na+, and Cl-
What is depolarization?
When the cell’s RMP becomes more positive/less negative
What is hyperpolarization?
When the cell’s RMP becomes more neagtive
Between the activation gate and the inactivation gate, which one is faster?
activation gate is faster
If the ECF K+ concentration increases from 3 mM to 5 mM, what happens to the resting membrane potential of cells?
It becomes less negative
Would a cell with a resting membane potential of -70mV depolarize or hyperpolarize if the cell became more permeable to Ca2+?
Depolarize
Would a cell with a resting membrane potential of -70mV depolarize of hyperpolarize if the cell became less permeable to K+?
Depolarize
What are some characteristics of graded potential?
Has variable strength
Used for short distance communication
What are some characteristics of action potentials?
Very brief, large deploarizations
Rapid signaling over long distances
All or nothing stimulus
What is the local current flow?
a wave of deploarization that moves through the cell
Subthreshold graded potential?
Graded potential starts above threshold, but decreases in strength as it travels until it is below the threshold at the trigger point
Suprathreshold graded potential?
Stronger stimulus at same point on cell bod creates a graded potential still above threshold when is reaches the trigger point
If a cell was to increase its Na+ entry, would it depolarize or hyperpolarize?
depolarize
If a cell was to increase its Cl- entry, would it depolarize or hyperpolarize?
hyperpolarize
If a cell was to increase its K+ exit, would it depolarize or hyperpolarize?
hyperpolarize
If a cell was to increase its Ca2+ entry, would it depolarize or hyperpolarize?
depolarize
Absolute refractory period
due to voltage-gated Na+ channels resetting, cannot generate an action potential no matter the stimulus strength
Relative refractory period
occurrs after absolute refractory period, stimulus must be greater to cause new action potential
Ouabain, a specific inhibitor of the Na+K+ ATPase pump, is applied to a neuron. What effect will this have on the next action potential fired by that neuron?
There will be no effect
What causes the repolarization phase of the action potential?
K+ exiting the cell through voltage-gated ion channels
Which is TRUE about one of the two gates in Na+ channels in axons?
The closing of the inactivation gate stops the depolarization during an action potential
What are two factors that increase speed of action potential?
Larger diameter and more myelin sheath
(myelin sheath higher priority than diameter)
Which of the following would have the fastest conduction?
a) Myelinated axon, diameter 20 mm
b) Unmyelinated axon, diameter, 20 mm
c) Unmyelinated axon, diameter 200 mm
a) Myelinated axon, diamter 20 mm
Which of the following would have the slowest conduction?
a) Myelinated axon, diameter 20 mm
b) Unmyelinated axon, diameter, 20 mm
c) Unmyelinated axon, diameter 200 mm
b) unmyelinated axon, diameter 20 mm
What do electrical synapses have?
gap junctions, create bi-directional flow of electrochemical gradient
What type of receptors does norepinephrine and epinephrine have?
Adrenergic (alpha and beta), located in smooth and cardiac muscles and glands
Pathway for synthesis and recycling of Acetylcholine
1 - ACh made from choline and acetyl CoA
2 - In synaptic cleft, ACh rapidly broken down by the enzyme acetylchoinesterase
3 - Choline is transported back into axon terminal by cotransport with Na+
4 - Recycled choline is used to make more ACh
Hormones derived fro trytophan
Serotonin
Hormones derived from histidine
Histmine
Hormones derived from tyrosine
Dopamine, Norepinephrine, Epinephrine
How does a single stimulus create a long lasting effect?
Amplitude cannot change to make response more severe, so frequency changes to release a constant amount of neurotransmitter
Release of a transmitter requires
an action potential and Ca2+ entry into the cell
An excitatory postsynaptic potential is
depolarizing the next cell
An inhibitory postsynaptic potential is
hyperpolarizing the next cell
Spatial summation
2 or more neurons fire simultaneously, have an additive effect (like 50 people screaming fire at once)
Temporal summation
One neuron repeatedly firing graded potentials that overlap, having an additive efffect (like one person screaming fire over and over)
Assume the postsynaptic neuron ha a resting membrane potential of -70mV and a threshold of -55mV. If the inhibitory presynaptic neuron creates an ISPS of 5mV and the 2 excitatory presynaptic neurons have EPSPs of 10mV and 12mV, will the postsynaptic neuron fire an action potential?
yes
