BIOM2011 (2022) Exam MCQs Flashcards
The human eye can focus on an object through a part of the eye or the whole eye
The whole eye can change shape on demand to accommodate the focus needs
How is the frequency of sound encoded in the cochlea
place coding, the position of the responding hair cells depends on the frequency
An efference copy is the copy of what
motor commands sent to predict sensory feedback
Why is colour vision lacking in the dark
Due to reduced visual pigments being more sensitive to colour
What is happening in hair cells’ signal transduction
Mechanosensitive K+ channels are opening or closing
How do sensory receptors inhibit neighbouring receptors
By improving the signal to noise ratio
What are Primary sensory neurons
They are afferent neurons which can detect sensory stimuli and relay the information to the brain
What’s The major difference between ion channels and ion pumps
their specificity for moving particular ions
If the closure of the K+ channels of the sino-atrial node slowed down, the effect on the baseline phase of the cell’s action potential would be
The baseline would depolarize more slowly to threshold
At high heart rates (e.g., 150 bpm), the ventricles still fill with blood because
filling is accomplished in early diastole
A potential five-fold increase in cardiac output in a person going from a resting state to one of intense exercise suggests what
both the stroke volume and pacing rate of the heart must have increased
What are some (four) effects of the parasympathetic nervous system on the heart
Slowed closure of K+ channels, decrease inward Ca2+ current, weakened atrial contraction and slowed pacemaker activity
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
Which immune component is primarily involved in the development of serum sickness
IgG
During an immune response to viral infection in the lung, what naïve T cells would most likely be activated
lymph node
On repeat exposure to a pathogen, a patient is identified with high circulating levels of IgM antibody specific for the pathogen. This is most likely caused by
lack of isotype switching
Within inflamed tissues, which of the following molecules would directly result 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 are the mechanisms for clearance of released neurotransmitters from the synaptic cleft?
re-uptake into surrounding glial cells by specific transporters, simple diffusion in extracellular space, rapid breakdown by specific enzymes and endocytosis of unchanged neurotransmitter
Can electric and chemical neurotransmitters be modulated in many ways
Electrical neurotransmission can be modulated in many ways, and chemical neurotransmission has limited mechanisms for modulation
In neuronal axons where are Voltage-gated sodium channels concentrated at
nodes of Ranvier
What are the dendrites of neurons
where most neurotransmitters are received by neurons
What is the correct relationship between current (I), voltage (V), and resistance (R)
V = I x R; Ohm’s Law.
What does Long-term potentiation of synaptic transmission require
NMDA receptor activation, calcium ion influx, and protein kinase activation
Where are growth hormone receptors found in the body
They’re found in most tissues in the body
How is growth hormone regulated
By GH releasing hormone and somatostatin via G-protein coupled receptor signalling
What mechanism is involved in mediating the increased prolactin secretion during lactation
Increased tyrosine hydroxylase activity and expression
What is the pairing of hypothalamic releasing factor and anterior pituitary gland hormone
thyrotrophin-releasing hormone and thyroid-stimulating hormone.
Why do oxytocin levels increase during birth
due to a positive feedback loop between the uterus and hypothalamus
What is oxytocin
is a small peptide hormone
What does oxytocin promote in lactation
promotes breast milk ejection for the suckling infant
What can stimulate the release of growth hormone
Exercise, low blood fatty acid concentrations, low circulating insulin like growth factor 1 concentrations and high plasma amino acid levels
What are the precursors that polymerize to form the keratin network on the surface of the epidermis?
keratohyalin and eleidin
What motor protein is responsible for the movement of cilia?
dynein
What is the cell type in the epidermis responsible for sensing touch and temperature
The Merkel cell
Within the intestinal epithelium, regeneration and cellular identity of the different types of epithelial cells is mediated by induction of which signalling pathway
Wnt and Notch signalling pathways
What kind of cells produce mucin and what is the function of this substance
goblet cells; to create a layer that traps external particles
Which hormone produced in the hypothalamus is responsible for increasing water resorption in the kidney and what is the mechanisms of action for this increased water permeability
vasopressin; it causes aquaporin to recycle to cell surface allowing more water molecules to enter the cells
What respiratory epithelia region is lined with simple squamous epithelial cells?
The alveolus
