Animal Physiology Flashcards
What is another name for the fed state that occurs after a meal is consumed?
Absorptive state
What happens to good glucose in the body?
it is used for lipogenesis
When the level of the glucose pool falls below normal, which of the following tissues is still able to access glucose from the plasma?
Brain
What are the main molecules used for gluconeogenesis?
Amino acids
Which pathway is the opposite of gluconeogenesis?
Glycolysis
Question content area
Part A
A patient has a gene mutation that does not allow hormones to stimulate the activity of enzymes in the fed state. Based on push-pull control, which do you expect?
More glucose and less glycogen, because insulin cannot activate enzymes
A student is fasting for religious reasons. Which would you expect?
Increased glycogenolysis and increased lipolysis
What is the ultimate fate of proteins in the fasted state?
Deamination of amino acids in the liver
target cells do not respond normally to insulin.
type 2
no insulin is produced
type one
glucose levels remain higher than normal
both type one and type two
Insulin is produced by the __________ cells of the pancreas.
beta
Why is glucose present in the urine of people with diabetes mellitus?
Insulin target cells are not able to take in the glucose from the blood, resulting in hyperglycemia and saturation of kidney glucose transporters.
in the fasted state, which hormone combination would occur?
Higher glucagon and lower insulin
How does the binding of insulin to its receptor stimulate glucose uptake from the bloodstream?
It stimulates insertion of GLUT4 transporters in the cell membrane.
Which is a difference between the reflex loops for insulin and glucagon?
One stimulates installation of glucose carriers in target cell membranes, and the other does not.
What causes most cases of type 1 diabetes mellitus?
Antibodies and leukocytes destroy beta cells.
Information coming into the central nervous system is transmitted along ________ neurons.
afferent and sensory
Exocrine glands, smooth muscles, and cardiac muscles are controlled by the
autonomic division
the enteric nervous system is a network of neurons that functions in controlling
digestion
in general the nervous system is made of which two cells
1. motor
2. neurons
3. sensory
4. glia
5. associative
2 and 4
Arrange the following events in the proper sequence:
1. Efferent neuron graded potential reaches threshold and fires an action potential.
2. Afferent neuron graded potential reaches threshold and fires an action potential.
3. Target organ responds.
4. CNS reaches decision about response.
5. Sensory receptor detects change in the environment.
5,2,4,1,3
The region where the axon terminal meets its target cell is called the
synapse
Where do most action potentials originate?
Initial segment
What opens first in response to a threshold stimulus?
Voltage-gated Na Superscript + channels
What characterizes depolarization, the first phase of the action potential?
The membrane potential changes from a negative value to a positive value.
What characterizes repolarization, the second phase of the action potential?
Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV.
What event triggers the generation of an action potential?
The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV.
What is the first change to occur in response to a threshold stimulus?
Voltage-gated Na Superscript + channels change shape, and their activation gates open.
What type of conduction takes place in unmyelinated axons?
Continuous conduction
An action potential is self-regenerating because __________.
depolarizing currents established by the influx of Na Superscript + flow down the axon and trigger an action potential at the next segment
Why does regeneration of the action potential occur in one direction, rather than in two directions?
The inactivation gates of voltage-gated Na Superscript + channels close in the node, or segment, that has just fired an action potential.
What is the function of the myelin sheath?
The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals.
What changes occur to voltage-gated Na Superscript + and K Superscript + channels at the peak of depolarization?
Inactivation gates of voltage-gated Na Superscript + channels close, while activation gates of voltage-gated K Superscript + channels open.
In which type of axon will velocity of action potential conduction be the fastest?
Myelinated axons with the largest diameter
What does the Goldman-Hodgkin-Katz equation take into account that the Nernst equation does NOT?
the permeabilities of the ions
Which is the correctly written Nernst equation?
61/z × log [ion] Subscript out / [ion] Subscript in
The resting membrane potential results from
uneven distribution of ions across the cell membrane and differences in membrane permeability to ions.
he rising phase of the action potential is due to
Na Superscript + flow into the cell only.
The falling phase of the action potential is due mainly to
K Superscript + flow out of the cell only.
Choose the items that are correctly matched.
activation gate - opens during depolarization
The absolute refractory period of an action potential
ensures one-way travel down an axon, allows a neuron to ignore a second signal sent that closely follows the first, and prevents summation of action potentials.
In the membrane of a resting nerve cell, when chemically gated Cl Superscript - channels open,
Cl Superscript - ions enter the cell.
Which will best increase the conduction rate of action potentials?
Increase the diameter of the axon, increase the resistance of the axon membrane to ion leakage.
Which does NOT influence the time necessary for a nerve impulse to be conducted by a neuron?
whether axon is sensory or motor
If the resting axon’s membrane becomes more permeable to potassium ions,
it will take a stimulus of larger magnitude to initiate an action potential.
How would the absolute refractory period be affected if voltage-gated sodium channels remained inactivated?
longer than normal
When comparing action potentials to graded potentials, an/two important distinguishing characteristic/s is/are
graded potentials can undergo summation and the rate of action potentials is limited by the refractory period.
The primary problem in hyperkalemia is that
neurons are easier to excite because their resting potential is closer to threshold and neurons respond too quickly to smaller graded potentials.
What would happen to the membrane potential if a resting cell suddenly became more permeable to Ca Superscript ++?
it would depolarize
What triggers exocytosis of synaptic vesicle contents from an axon terminal?
The opening of voltage-gated Ca Superscript 2+ channels
Which is the main inhibitory neurotransmitter in the brain?
GABA
The inhibitory neurotransmitters of the CNS act by opening ________ channels.
only Cl Superscript -
Which is NOT a known drug effect on synaptic function?
change the type of neurotransmitter found in the synaptic vesicle
When more action potentials arrive at the axon terminal, how are neurotransmitters affected?
More molecules are released into the synapse.
The following are steps involved in transmission at the cholinergic synapse:
1. Chemically gated ion channels on the postsynaptic membrane are opened.
2. Calcium ions enter the axon terminal.
3. An action potential depolarizes the axon terminal at the presynaptic membrane.
4. Acetylcholine is released from storage vesicles by exocytosis.
5. Acetylcholine binds to receptors on the postsynaptic membrane.
The correct sequence for these events is
3,2,4,5,1
Which type of receptor would bind acetylcholine and be found in skeletal muscle?
Nicotinic cholinergic
An excitatory postsynaptic potential (EPSP)
depolarizes a neuron, increasing the likelihood of an action potential.
A patient had a trauma that damaged an endocrine gland, causing decreased hormone secretion. Which of the following would you expect?
Decreased negative feedback and decreased cellular responses
Which of the following is the best example of negative feedback?
Thyroid hormone (TH) released into the bloodstream causes increased cellular metabolism and increased body temperature, inhibiting TH release.
Endocrine pathologies can occur through excess secretion, inadequate secretion, and what other mechanism?
Abnormal target cell response
The endocrine gland that is modified sympathetic ganglia is the
adrenal medulla.
Cholesterol is the starting material for the synthesis of
progesterone, aldosterone, and estradiol.
Cortisol has which effects?
suppresses the immune system and influences brain function
Without cortisol’s permissive effect on ________, an animal would die.
glucagon
Melanocortins includes one or more of the following
ACTH and MSH
Increased cortisol would NOT cause which of the following?
increased ACTH levels
The common precursor for all steroid hormones is __________.
cholesterol
Which of these following would be a cause of secondary hypercortisolism?
A cancerous tumor secreting ACTH
A patient has a disease that destroys cells that secrete cortisol. Which of the following would you expect to find?
Increased CRH and increased ACTH
The effects of thyroid hormone on peripheral tissue include
increased adrenergic effects in the heart
C cells of the thyroid gland secrete __________.
calcitonin
Which of the following is the site of dysfunction in someone who has excessive TSH and excessive thyroid hormones but low TRH?
Anterior pituitary
Parathyroid hormone
increases the level of calcium ion in the blood.
stimulates osteoclast activity.
increases the rate of calcium absorption.
decreases the rate of calcium excretion.
All of these answers are correct.
all of the above
Which of the following is an action of growth hormone?
Increased insulin-like growth factor secretion
Which statement most accurately describes how the sex of a human embryo is determined?
Embryos with the SRY gene become male; embryos without the gene become female.
A baby is born with female external genitalia but has male internal genitalia. After running a few tests, you discover that the levels of 5-a reductase are normal. Which of the following statements best describes a condition that might have caused this?
The developing testis produced too little testosterone during development.
Which statement is true about gamete formation?
Human females are thought to be born with all the primary gametes they will ever have.
Which hormone released from the hypothalamus regulates gonad function?
Gonadotropin-releasing hormone
What is unique about GnRH secretion patterns from the hypothalamus?
GnRH is secreted in a pulsatile manner.
Testosterone are produced by the __________in testes
interstitial cells of Leydig
In males, what is the target of FSH, and what effect does it have?
Sertoli cells; production of paracrine factors
The first phase of the ovarian cycle is the __________ phase.
follicular
What is the third phase of the ovarian cycle called, and what occurs during this time?
Luteal phase; transformation of a ruptured follicle into a corpus luteum
Which hormone is the most important regulator of endometrium proliferation during the follicular phase?
estrogen
What causes the LH surge that occurs during the late follicular phase?
Increasing progesterone and high estrogen increase pituitary responsiveness to GnRH.
The role of the corpus luteum is to secrete __________.
progesterone and estrogen
In the follicular phase of the ovarian cycle, the ovary is
maturing a follicle.
In the late follicular phase of the ovarian cycle, the level of LH secretion is ________ the level of FSH secretion.
greater than
The enzyme responsible for converting androgens to estrogens is
aromatase
To which method of contraception does a contraceptive sponge belong?
barrier
