short qs Flashcards
List a total of 5 essential roles of the L-type Ca2+ channel in the heart for excitability and
initiating Ca2+ release from sarcoplasmic reticulum
1.Initiation of action potentials
2.Regulation of contractility
3.Pacemaker activity
4.Excitation-contraction coupling
5.Regulation of heart rate and rhythm
you are on the last stretch of a rollercoaster, the cart goes downhill, makes a hard turn to the left before braking and stopping for you to get down. Describe which parts of the vestibular system are stimulated, and how they are stimulated during each stage:
a. Downhill
During the downhill portion of the rollercoaster, the otolith organs (utricle and saccule) of the vestibular system are primarily stimulated. The otolith organs sense linear acceleration and gravity-related forces. As the rollercoaster moves downhill, the otolith organs detect the change in linear acceleration and gravity, signaling the body’s downward movement.
you are on the last stretch of a rollercoaster, the cart goes downhill, makes a hard turn to the left before braking and stopping for you to get down. Describe which parts of the vestibular system are stimulated, and how they are stimulated during each stage:
Hard turn to the left
During the hard turn to the left, the semicircular canals of the vestibular system are stimulated. The semicircular canals are responsible for detecting angular acceleration and rotational movements. When the rollercoaster makes a sharp left turn, the fluid inside the left semicircular canals moves, stimulating the sensory hair cells, and signaling the brain about the rotational movement.
you are on the last stretch of a rollercoaster, the cart goes downhill, makes a hard turn to the left before braking and stopping for you to get down. Describe which parts of the vestibular system are stimulated, and how they are stimulated during each stage:
braking and stopping
During the braking and stopping phase, both the otolith organs and the semicircular canals may be stimulated. The braking forces and the sudden stop can lead to changes in linear acceleration and deceleration, which stimulate the otolith organs. Additionally, the sudden stop and change in rotational movement might also lead to stimulation of the semicircular canals.
You are walking down the street and hear the low rumble of your neighbour putting out their
wheelie bin, describe the mechanism by which your brain can locate the direction the sound is coming from (along the horizontal plane/azimuth)
The brain can locate the direction of the sound along the horizontal plane (azimuth) through a process called binaural hearing. This mechanism relies on the comparison of sound information received by both ears. The time delay and intensity difference between the sound arriving at each ear provide vital cues that the brain uses to determine the direction of the sound source. The auditory pathways in the brain analyze these binaural cues, allowing us to perceive the direction from which the sound is coming.
Ca2+ release during excitation-contraction coupling is terminated by different means in skeletal and cardiac muscle. How is termination of Ca2+ release regulated in skeletal and cardiac muscle cells?
the termination of Ca2+ release during excitation-contraction coupling is regulated by the SERCA pump in both skeletal and cardiac muscle cells, while cardiac muscle cells also utilize the NCX to remove Ca2+ from the cytoplasm and aid in muscle relaxation
Describe the steps involved in neurotransmitter release from a synapse and generation of a
postsynaptic excitatory postsynaptic current.
1.Action potential arrival: An action potential reaches the presynaptic terminal, depolarizing the membrane.
2.Calcium influx: Depolarization opens voltage-gated calcium channels, allowing calcium ions to enter the presynaptic terminal.
3.Neurotransmitter release: Calcium triggers the fusion of synaptic vesicles with the presynaptic membrane, releasing neurotransmitters into the synaptic cleft.
4.Neurotransmitter binding: Neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic membrane.
5.Ion channel activation: The binding of neurotransmitters opens ligand-gated ion channels, typically permitting the influx of positively charged ions like sodium (Na+) or calcium (Ca2+).
6.Excitatory postsynaptic current (EPSC): The influx of positive ions depolarizes the postsynaptic membrane, generating an EPSC, which increases the likelihood of an action potential in the postsynaptic neuron.
Consider this hypothetical scenario: a person is born with a mutation in the prolactin receptor that results in severely reduced (only 20% of normal) signalling via the Jak/STAT signal transduction pathway.
Based on your understanding of the regulation of prolactin, what would you expect as an
outcome in this individual in terms of
A. prolactin concentrations in blood, in a non-lactating state
A. Prolactin concentrations in blood, in a non-lactating state:
In a non-lactating state, the severely reduced signaling via the Jak/STAT signal transduction pathway in the prolactin receptor mutation would likely result in higher-than-normal prolactin concentrations in the blood. The reduced signaling would lead to impaired negative feedback regulation, causing the body to produce and release more prolactin to compensate for the decreased effectiveness of the signaling pathway.
onsider this hypothetical scenario: a person is born with a mutation in the prolactin receptor that results in severely reduced (only 20% of normal) signalling via the Jak/STAT signal transduction pathway.
Based on your understanding of the regulation of prolactin, what would you expect as an
outcome in this individual in terms of
B. milk production in the mammary gland, in a lactating state
B. Milk production in the mammary gland, in a lactating state:
In a lactating state, the severely reduced signaling via the Jak/STAT signal transduction pathway in the prolactin receptor mutation would likely result in significantly reduced milk production in the mammary gland. Prolactin is a key hormone responsible for stimulating milk production, and the impaired signaling pathway would hinder the proper induction and maintenance of lactation, leading to a decreased ability to produce milk
Difference between, gap junctions, adherens junctions and desmosomes
Gap junctions: Allow direct communication and exchange of ions and small molecules between adjacent cells. Formed by connexins and facilitate electrical and metabolic coupling.
Adherens junctions: Provide mechanical strength and adhesion between cells. Formed by cadherin proteins, linking the actin cytoskeletons of adjacent cells.
Desmosomes: Offer strong adhesion and resistance to mechanical stress. Composed of desmoglein and desmocollin proteins that connect the intermediate filaments of neighboring cells.
Describe the individual roles of MHC I in antigen presentation, in addition to the adaptive immune cells that recognise these MHC molecules and the function of those cells
MHC I (Major Histocompatibility Complex Class I):
Role in antigen presentation: MHC I molecules present endogenous antigens (usually from intracellular pathogens like viruses) to cytotoxic CD8+ T cells. The antigens are derived from proteins processed within the cytosol of the host cell.
Adaptive immune cells: Cytotoxic CD8+ T cells recognize MHC I molecules presenting antigens and become activated.
Function of activated cytotoxic CD8+ T cells: Activated CD8+ T cells target and destroy infected or abnormal host cells, playing a crucial role in cell-mediated immunity and eliminating intracellular pathogens.
Describe the individual roles of MHC II in antigen presentation, in addition to the adaptive immune cells that recognise these MHC molecules and the function of those cells
MHC II (Major Histocompatibility Complex Class II):
Role in antigen presentation: MHC II molecules present exogenous antigens (usually from extracellular pathogens like bacteria) to helper CD4+ T cells. The antigens are taken up, processed, and presented by antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells.
Adaptive immune cells: Helper CD4+ T cells recognize MHC II molecules presenting antigens and become activated.
Function of activated helper CD4+ T cells: Activated CD4+ T cells help orchestrate immune responses by releasing cytokines that regulate other immune cells, enhancing antibody production, and assisting in the activation of cytotoxic CD8+ T cells.
Name three antibody isotypes that dominate a secondary immune response and describe a
unique feature of each isotype
- IgG:
Unique feature: IgG is the most abundant antibody isotype in the bloodstream, making up about 75-80% of total antibodies in the body. It is highly versatile and can cross the placenta, providing passive immunity to the developing fetus. - IgA:
Unique feature: IgA is primarily found in secretions such as saliva, tears, colostrum, and mucosal surfaces, providing a crucial first line of defense against pathogens that enter the body through these routes. - IgE:
Unique feature: IgE is involved in allergic responses and plays a role in defending against parasitic infections. When IgE binds to allergens or parasites, it triggers the release of inflammatory mediators from mast cells and basophils, contributing to allergic reactions or defense against parasites.
