BIOM2011 (2021) Exam MCQs Flashcards
What is The major difference between ion channels and ion pumps is
their specificity for moving particular ions
How many milliseconds are between the peak of an action
potential and the peak of the cytoplasmic Ca2+ transient during excitation-contraction coupling
in mammalian skeletal muscle (at normal body temperature)?
20 ms
What can A potential five-fold increase in cardiac output in a person going from a resting state to one of
intense exercise suggests that
both the stroke volume and pacing rate of the heart must have increased
At high heart rates (e.g. 150 bpm), why do the ventricles still fill with blood
because filling is accomplished in early diastole
What is the major difference between skeletal and cardiac type excitation-contraction coupling?
a physical coupling of the voltage sensor and Ca2+ release channel in skeletal muscle, and a chemical coupling in cardiac muscle
What occurs During tetani in skeletal muscle
there is a fusion of the cytoplasmic Ca2+ transient and force responses that may be complete or incomplete
Does the hypothalamus receive both neural and humoral inputs
yes
What is the correct pairing of a hypothalamic neurohormone and the
anterior pituitary hormone it regulates
gonadotrophin releasing hormone and luteinising hormone
What stimulates Growth hormone release
Starvation, deep sleep, exercise and high plasma amino acid
What activates Janus Kinase 2
activated by phosphorylation
Compare oxytocin and prolactin
Prolactin acts on alveolar epithelial cells via a G protein-coupled receptor and cyclic AMP
What positively regulates vasopressin
solute concentration of extracellular fluid
What negatively regulates vasopressin
blood volume
What does vasopressin do in the kidneys
decreases water excretion in the kidneys
What lateral intercellular junction complexes are calcium dependent?
tight junctions and gap junctions
Where would you find ciliated epithelial cells in large quantities?
ventricles of the brain and the lining of the trachea
What cell type in the epidermis is responsible for pigmentation of the skin?
melanocyte
Both the Na+/K+ pump and the SGLT require energy to function, but they get this energy from different sources. Specifically, where does the Na+/K+ pump get the energy from, and what kind transport is this considered to be
ATP hydrolysis; primary active transport
What kind of cells in the intestine produce defensins and what is the function of these proteins?
Paneth cells; defensins are antimicrobial peptides
What chemical modification of claudins induces conformational changes in tight junctions to increase paracellular permeability?
phosphorylation
Solutes are transported across the membranes of the collecting ducts in the kidney via two distinct cell types, principal cells and intercalated cells. What solutes do these cells transport
Principal cells transport sodium and potassium ions, while intercalated cells secrete and absorb acid or bicarbonate
Which has a slower conduction velocity, unmyelinated or myelinated axons
Unmyelinated axons have slower conduction velocity than myelinated axons
What are 2 amine neurotransmitters
Noradrenaline and Serotonin (5-HT)
What are the characteristics of the dendrites of neurones
They’re variable in length, branched and unmyelinated
You measure a current of 100 picoamperes (100 x 10-12 A) moving across a neuron’s membrane when you change the neuron’s membrane potential by 10 millivolts (10 x 10-3 V). Which of the following answers gives the resistance of the neuron’s membrane to current movement?
10 megaohms (1 x 10^7 ohms)
What happens in long-term potentiation (LTP) of synaptic transmission
LTP causes changes in postsynaptic NMDA receptor number and phosphorylation
What mechanism is involved in clearance of released neurotransmitters from the synaptic cleft?
re-uptake into surrounding glial cells by specific transporters
Where are Neuropeptide neurotransmitters and Amine neurotransmitters made
cytoplasm of the synaptic terminal
Where are Neuropeptide neurotransmitters made
cell body Golgi apparatus
How are Neuropeptides are transported
along the axon to the synaptic terminal in vesicles
What are Primary sensory neurons
afferent neurons which can detect sensory stimuli and relay the information to the brain
What does lateral inhibition do
limits the interference of overlapping receptive fields
Hair Cells characteristics
Hair cells are polarised and respond to one direction of movement, Hair cells transduce mechanical energy to electrical signal and Hair cells are tuned to a specific frequency of stimulation
Can muscles in the eye flatten the lens and why
Yes, to change its focal length
Which is more sensitive to light, cones or rods
Rods are more sensitive to light, however, cones are most sensitive to one of three different colours (green, red or blue).
How is colour perceived
The ratio of responses between cones of different types
How is Sound transduction is achieved
via mechanically-gated cation channels, which open and close depending on the direction of bending
When a physician tests the knee-jerk, which types of neurons and pathways are involved?
mechanoreceptor neurons, interneurons, and efferent neurons in a reflex arc
During an immune response to viral infection in the lung, where would naive T cells would most likely be activated
The lymph node
On repeat exposure to a pathogen, a patient is identified with high circulating levels of IgM antibody specific for the pathogen. What is most likely to cause this
IgM being the most appropriate response
Within inflamed tissues, what molecule directly results in chemotaxis of immune cells?
complement
Many years ago, William Coley found that injection of bacterial extracts would often clear
many types of tumour. This technique was most likely successful because
the activation of dendritic cells was enhanced by the bacterial extracts
What immune component is primarily involved in the development of serum sickness
IgG
