Final Flashcards
What is homeostatis
maintence of relatively constant conditions in the internal environment
what is negative feedback control in homeostatiss
- Negative because the response of the system is opposite in direction to the change that set in motion
Deviation away from its set point
describe steps negative feeback loop
- Sensors (input) > integrating centre (set of neural circuits in the brain or an endocrine gland) > compares regulated variable to set point > orchestrates response > output to the cells, tissues and organs
what is positive feedback control
- Same direction as the change that sets it in motion
e.g. of a tissu with gap juncitons?
cardiac
benefits of gap junctions
adjacent cells formed by connexins - connexon form channels that allow ions and small mocluels to pass direclty from one cell to another
juxtacrine communication?
direct contact btw cells - gap junctions
paracrine cellular communication?
short distance, immediate cellular environment, local coordiantin
autocrine cellular communication?
cell signals to self, self stimulation or self identitiy
endocrine cellular communication?
to distant sites, via hormones in the blood stream
what is an agonsit
ligands that binds to receptors and produces a biological response
e.g. of an agonist
E.G. morphine - opioid agonist used in the treatment of pain. Binds to mu opioid receptors in the spinal cord and brain and blocking pain signals from reaching consciousness. We have mu opioid receptors which prevent us from feeling pain under certain circumstances e.g. stress
what is an antagonist?
ligands that bind to receptors but do not produce a response - instead - they may compete with agonists for the receptor, decreasing the likelihood that the binding of agonist to receptor will occur and bring about a response
e.g. antagonist
E.g. naloxone - antagonist - binds to my opioid receptor 10x the strength of morphine - prevents morphine from binding there, reversing the effects of morphine
role of immune sstem
prevent infections and eradicate already estbalished infections
what does immunity refer to
bodys ability to recognise and eliminate microorgansims
what is innate immunity
intial protection agaisnt infection - blocks entry of microbes and eliminates those that do enter
what is adaptive immunity
specialised defence against infection
what are the phsyical and chemiCAL BARRIERS (immunity)
skin, respiratory system, stomach
how does the skin act as a barrier
sebaceous glands secrete sebum to inhibit bacterial growth
how does the respiratory system act as a barrier ( immunity)
mucus production which traps fogein particles that are inhaled
how does the stomach act as a barrier ( immunity)
HCI to kill ingested pathogens
what are the types of lymphoid cells
○ Natural killer cells - cells with abundant cytoplasmic granules, nonspecific defence against microorganisms
Lymphocytes - small cell with a large nucleus and very little cytoplasm, specific defence against a particular microorganism
cells in bone marrow
b cells
cells in thymus gland
t cells
what is ht ekey funciton of leukocytes
ability to migrate btw blood and tissue is key, important in detectign anitgens
e.g. of central lymphoid tissue
thymus galnd and bone marrow
e.g. peripheral lymphoid tissue
lymph nodes and spleen
what are the 4 types of nonspecific defence mechanism
○ Physical and chemical barriers
○ Inflammation
○ Interferons
Complement system
why are toll like receptors important
activate important signalling pathways that lead to activation of transcription factors
what is hte function of interferon regulatory factors
lead to transcription and secretion of type 1 interferon (IFN) which establishes an anti-viral state in the cell
whAt are inflammasomes
multi protien complexes that form in response to pathgoens - consists of a sensor and enzyme linked together by an adapter
function of RIG-like receptors
cystolic proteins that sense viral RNA,
funciton of cystolic DNA snesors (CDSs)
recognise DNA inthe cytoplasm, - DNA bidns to a DNA sensor called cGAS, which then activates a protein called STING, which eventually leads to the production of type 1 IFN
4 steps of phagocytosis
Macrophages have several receptors on the cell surface that can detect invading pathogens
1. Attachment: macrophages attaches to pathogen and recognises it as foreign
2. Internalisation: pathogen is engulfed into the cytoplasm into a vesicle called a phagosome
3. Degradation: phagosome fuses with lysosome (vesicle with digestive enzymes) and degrades pathogen
4. Exocytosis: debris is released from cell Important in limiting the initial spread of the pathogen
what are some fucntions of ISGs (interferon stimulated genes)
- Inhibit entry
- Inhibit viral replication
- Inhibit translation
- Inhibited release from cell
Enhance signalling pathways to produce more IFN
what is the complement system
A system consisting of approximately 30 proteins Upon activation there is a cascade of events (one protein activates another, which activates another etc.)
what is the classical pathway of the complement system
circulating antibodies to pathogen
what is the lectin pathway in the complement system
mannose-binding lectins bidnds to proteins on the surface of bacteria
what is the alternative pathway in compleemtn system
pathogen directly activate complement proteins
features of the adaptive immune system
memory,, speciifc, fiversity
what are the 2 major divisions of adaptive immune system
Humoral immunity
○ Mediated by B cells
- Cell-mediated immunity
○ Mediated by CD4+ helper T cells
○ and CD4+ cytotoxic T cells
what are some of the ways antibodies eliminate infections
- Neutralisation – antibodies bind to and block microbes from infecting a cell
- Agglutination – antibodies neutralise antigen and then clump together
Opsonisation – antibodies coat microbes (opsonisation) and promote their ingestion by phagocytes
- Agglutination – antibodies neutralise antigen and then clump together
compare autocrine and paracrine
autocrine - signal sent and received by presynaptic neuron
paracrine - signal from presynaptic neuron received on nearby postsynaptic neuron
what are ligand gated channels
ion channels that open or close in response to the binding of a chemical to a receptor or to the channel
what is a trophic hormone
a hormone that controls the secretion of other hormones
what is a stimulating hormone
increases the secretion of another hormone
what is an inhibiting hormone
decreases the secretion of another hormone
what is retrograde transport
from axon terminal to cell body
what is anterograde transport
from cell body to axon terminals
what are bipolar neurons
sensory neurons with 2 proections - axon and dendrite - funciton: olfaction and vision
what are pseudounipolar neurons
xon and dendrite projections appear as a single process that enstends in two directions BUT the dendrite is modified to function much like an axon
fucniton of glial cells
- Function: providing structural integrity to the nervous system and chemical and anatomical support that permits neurons to carry out their functions , supply nutrienrs, electrical insulation
function of astrocytes
- Transport nutrient from blood vessels to neurons
- Remove neurotransmitters (glutamate and GABA) released by neurons during synpatic transmission
- Regulate extracellular potassium concentrations
funciton of oligodendrocytes and schwann cells
- To form an insulating layer of myelin around the axons of neurons
- Myelin is: a greatly extended and modified portion of the cell membrane that wraps around the axon in spiral fashion
- Rich in lipid –> provides effective electrical insulation of the axon
- Oligodendrocytes - CNS -
Schwann cells - PNS
function of microglia
- Immune effect cells of the CNS
- Phagocytose cell debris following injury
- Brain development ad homeostasis
- Promote regrowth and remapping of damaged neural circuitry
Involved in neuronal and synaptic plasticity
how many Na+/K+ in and out in the ATPase pump
- 3 Na+ transported out of the cell
2 K+ transported into the cell
what hapens when Na+ flows into a cell
cell inside becomesmore positive
what is the current if K+ ions are flowing out of the cel
outward K+ current
what is the current if Na+ ions are flowing into the cell
inward Na+ current
if ion inside is greater than the ion outside how will ions diffuse?
ions will diffuse out
what is the eletrical driving force
acting on charged particles and has hte potential to cause those particles to move
what are cations
attracted by the negative change inside the cell, have an inward directed electrical driving force
what are anions
repelled by the negative membrane potential and have an outward directed electrical driving force
what does the electrochemical driving force determine?
- It determines the direction in which the ions move if they are allowed to cross the membrane spontaneously.
What occurs during ventricular filling?
Blood enters the relaxed atria and passes through the AV valves into the ventricles under its own pressure.
Why does venous return occur?
Because the pressure in the veins is greater than that in the atria.
What happens at the end of diastole?
the atria contract, driving more blood into the ventricles.
What is isovolumetric contraction?
A phase where all valves are closed, and no blood flows into or out of the ventricles despite contraction.
When does isovolumetric contraction end
When ventricular pressure is sufficient to force open the semilunar valves.
What occurs during ventricular ejection?
Blood is ejected into the aorta and pulmonary arteries, causing ventricular volume to fall.
What marks the beginning of diastole?
The closure of the semilunar valves after ventricular pressure falls below aortic pressure.
Describe isovolumetric relaxation.
: All valves are closed, and the volume of blood in the ventricles remains constant as they relax.
What initiates heart contractions?
Pacemaker cells that spontaneously generate action potentials, primarily in the SA and AV nodes.
What is the role of conduction fibers in the heart?
They quickly conduct action potentials generated by pacemaker cells through the myocardium.
What allows efficient transmission of action potentials in cardiac muscle?
Gap junctions that connect all cardiac muscle cells.
How do the left and right ventricles differ?
The left ventricle has a thicker wall to pump blood at higher pressure throughout the body.
What do blood vessels do in the cardiovascular system?
hey regulate blood pressure and distribute blood to various parts of the body.
What is the epimysium?
Connective tissue that surrounds the body of the muscle.
What does the endomysium do?
It is a thin sheath of connective tissue that encases muscle fibers.
What are myofibrils?
: Structures that contain the fibers’ contractile machinery, composed of thick and thin filaments.
What is a sarcomere?
The fundamental unit of myofibrils that repeats over and over, bordered by Z lines.
What are thick and thin filaments made of?
Thick filaments are made of myosin, and thin filaments are made of actin and regulatory proteins (tropomyosin and troponin).
What is the role of tropomyosin in muscle contraction?
It blocks myosin-binding sites on actin when muscles are at rest.
What is the function of troponin?
: It binds to actin, tropomyosin, and calcium, facilitating muscle contraction by exposing myosin-binding sites on actin.
Describe the structure of myosin
Myosin molecules are dimers with long tails and protruding heads; the heads bridge the gap between thick and thin filaments
What is the sliding-filament model?
model explaining that muscle contraction occurs as thick and thin filaments slide past each other without changing in length.
What occurs during the binding phase of the cross-bridge cycle?
Myosin in its energized form binds to actin in the presence of calcium.
What triggers the power stroke in muscle contraction?
The release of Pi from the ATPase site on the myosin head upon binding to actin.
What is rigor in the context of muscle contraction?
The tightly bound state of myosin and actin when ADP is released from the myosin head.
What initiates the unbinding of myosin and actin?
the binding of a new ATP molecule to the ATPase site on the myosin head.
What happens during excitation-contraction coupling?
An action potential triggers the release of calcium from the sarcoplasmic reticulum, initiating muscle contraction
Describe the function of T tubules
They allow rapid transmission of action potentials from the muscle fiber’s surface to its interior.
What is the sarcoplasmic reticulum?
A fluid-filled system of membranous sacs that encircle each myofibril and store calcium ions.
What is the formula for Mean Arterial Pressure (MAP)?
MAP = Cardiac Output x Total Peripheral Resistance (TPR)
What determines cardiac output?
Cardiac output is determined by heart rate (HR) and stroke volume (SV).
What is heart rate (HR)?
HR is the number of contractions of the heart per minute.
What is stroke volume (SV)?
SV is the volume of blood pumped from each ventricle per beat.
How is cardiac output expressed?
Cardiac output is expressed in liters per minute.
What is Starling’s Law?
: It states that an increase in venous return leads to a greater force of contraction in the heart, ensuring that stroke volume matches venous return.
What is preload
Preload is the end-diastolic pressure that stretches the walls of the ventricles to their greatest dimensions
What effect does afterload have on stroke volume?
An increase in afterload (the pressure the heart must work against) decreases stroke volume.
What is the role of the autonomic nervous system in cardiac output?
The autonomic nervous system regulates both heart rate and stroke volume through intrinsic and extrinsic factors.
How does the sympathetic nervous system affect ventricular contractility?
It increases contractility by releasing norepinephrine, leading to stronger and faster contractions.
What is the function of arterial baroreceptors?
They sense changes in arterial pressure and regulate heart rate and vascular resistance.
How do sympathetic nerves influence blood vessels?
They control vascular resistance in arterioles and influence venomotor tone in veins.
What is the role of the cardiovascular control center in the medulla oblongata?
It orchestrates cardiovascular responses by processing sensory input and coordinating autonomic outputs.
What are the functions of arterioles in the cardiovascular system?
They regulate and distribute blood flow and control total peripheral resistance.
What is Laplace’s equation?
It explains why larger vessels need thicker walls to withstand blood pressure, while capillaries can have thin walls.
How do vasopressin and angiotensin II affect blood pressure?
Both cause vasoconstriction, increasing total peripheral resistance and mean arterial pressure.
What happens to vasopressin secretion when arterial pressure falls?
Vasopressin release is enhanced to help increase mean arterial pressure.
What is internal respiration?
The use of oxygen within mitochondria to generate ATP, producing carbon dioxide as a waste product.
What is external respiration?
The exchange of oxygen and carbon dioxide between the atmosphere and body tissues, involving pulmonary ventilation, gas exchange, and transport via blood.
What is the conducting zone of the respiratory tract?
The upper part of the respiratory tract that conducts air from the larynx to the lungs; it includes structures like the trachea and bronchi.
What is the respiratory zone?
The lower part of the respiratory tract where gas exchange occurs, characterized by the presence of alveoli
What is the primary structure of the alveoli?
The wall consists primarily of type I alveolar cells overlying a basement membrane, facilitating gas exchange
What is the pleura?
A membrane lining the interior surface of the chest wall and exterior surface of the lungs, consisting of visceral and parietal layers
Describe the process of inspiration
Diaphragm and external intercostals contract, causing air to flow into the lungs.
Describe the process of expiration
Diaphragm and external intercostals relax, causing air to be forced from the lungs.
What determines intra-alveolar pressure (Palv)?
The quantity of air molecules and the volume of the alveoli.
What is transpulmonary pressure?
The difference between intra-alveolar pressure and intrapleural pressure (Palv - Pip).
What is lung compliance?
The ease with which the lungs can expand under pressure; higher compliance means less work is needed for breathing.
What role does pulmonary surfactant play?
It decreases surface tension in the alveoli, increasing lung compliance and reducing the work of breathing
What is airway resistance?
he resistance of the entire airway system, primarily determined by airway radius; as radius decreases, resistance increases.
What is a pneumothorax?
A condition where air enters the pleural space, leading to lung collapse and impaired gas exchange
What distinguishes a tension pneumothorax?
It acts as a one-way valve, allowing air to enter but not escape, leading to increased pressure and compromised function of the lungs.
What is the normal ventilation-perfusion ratio in healthy lungs?
Approximately 1, indicating that ventilation is matched with perfusion.
How much oxygen and carbon dioxide do body cells consume and produce at rest?
Approximately 250 mL of oxygen consumed and 200 mL of carbon dioxide produced per minute.
What is the significance of pulmonary circulation’s low resistance?
It allows efficient gas exchange with a pressure gradient of only 15% of systemic circulation, enabling a cardiac output of 5 L/min for both sides of the heart.
What is the role of partial pressure in gas exchange?
Gases diffuse down their own partial pressure gradients; oxygen diffuses from alveoli to blood, and carbon dioxide diffuses from blood to alveoli.
How is oxygen transported in the blood?
Oxygen is transported dissolved in blood (1.5%) or bound to hemoglobin (98.5%).
How is carbon dioxide transported in the blood?
Carbon dioxide is transported dissolved in blood (5-6%), bound to hemoglobin (5-8%), or as bicarbonate ions (86-90%
What role does carbonic anhydrase play in gas exchange
It catalyzes the reversible reaction converting carbon dioxide and water into carbonic acid, which dissociates into hydrogen ions and bicarbonate.
What is the chloride shift?
The movement of chloride ions into erythrocytes and bicarbonate into plasma; the reverse occurs when bicarbonate ions move into erythrocytes in exchange for chloride.
: What is the normal pH range for extracellular fluid?
The normal pH is 7.4 (7.38-7.42).
What happens when arterial blood pH is below 7.35?
It indicates acidosis, which can repress the central nervous system.
What are the consequences of blood pH above 7.45?
It indicates alkalosis, increasing nervous system excitability, potentially leading to muscle seizures and convulsions
How does the respiratory system contribute to acid-base balance?
Through chemical buffering (hemoglobin and bicarbonate) and regulation of arterial PCO2.
How does hemoglobin act as a buffer?
Hemoglobin can bind or release hydrogen ions, helping to prevent blood pH from becoming too acidic
What happens to hydrogen ions when bicarbonate concentration increases?
Hydrogen ions bind to bicarbonate to form carbon dioxide, helping to maintain pH balance.
What is respiratory acidosis?
An increase in blood acidity due to elevated CO2 levels, often occurring during hypoventilation.
What is respiratory alkalosis?
A decrease in blood acidity due to reduced CO2 levels, often occurring during hyperventilation or at high altitudes.
What is one primary function of the renal system related to plasma ionic composition?
Regulation of plasma ionic composition by excreting specific ions (e.g., Na+, K+, Ca2+) in urine.
How do the kidneys regulate plasma volume and blood pressure?
By controlling the rate of water excretion in urine, impacting total blood volume and blood pressure.
What role do the kidneys play in regulating plasma osmolarity?
The kidneys adjust the rate of water excretion relative to solutes to control plasma osmolarity.
How do the kidneys help regulate blood pH?
By regulating bicarbonate and hydrogen ion concentrations in the plasma.
What metabolic waste products do the kidneys remove from the plasma?
Urea, uric acid, food additives, drugs, and pesticides.
What is a secondary endocrine function of the kidneys?
Secretion of erythropoietin (stimulates red blood cell production) and renin (regulates blood pressur
What is the significance of vitamin D3 activation in the kidneys?
It regulates blood calcium and phosphate levels.
What are the components of the nephron?
Renal corpuscle, proximal convoluted tubule, nephron loop, distal convoluted tubule, and collecting system.
What is glomerular filtration?
The bulk flow of protein-free plasma from glomerular capillaries into Bowman’s capsule.
What is reabsorption in the renal system?
The selective transport of molecules from the renal tubules back to the interstitial fluid and then to the bloodstream.
How is secretion defined in renal physiology?
The selective transport of molecules from peritubular fluid to the lumen of renal tubules.
What does excretion refer to in the renal system?
The elimination of materials from the body in the form of urine.
What is the glomerular filtration rate (GFR)?
The volume of plasma filtered per unit time, approximately 125 mL/min.
What forces drive glomerular filtration?
Hydrostatic and osmotic pressure gradients across the walls of glomerular capillaries.
What is myogenic regulation?
A mechanism that helps maintain constant GFR despite changes in blood pressure by adjusting the diameter of afferent arterioles.
What is tubuloglomerular feedback?
A process where changes in GFR affect tubular fluid flow past the macula densa, leading to adjustments in afferent arteriole resistance.
What is the formula for the amount excreted by the kidneys?
Amount excreted = amount filtered - amount reabsorbed + amount secreted.
How is the filtered load calculated?
Filtered load = GFR × plasma concentration of the solute.
How can the GFR be measured?
Using a substance like inulin that is freely filtered but not reabsorbed or secreted.
What are the normal GFR values?
Approximately 125-150 mL/min or 180 L/day.
What is the equation for water balance in the body?
Input + production = utilization + output.
What role do the kidneys play in fluid and electrolyte balance
The kidneys regulate fluid and electrolyte balance, as well as acid-base balance.
What is normovolemia?
The normal state of blood volume in the body.
What condition occurs when water intake exceeds water loss?
Positive fluid balance, leading to hypervolemia.
What is hypovolemia?
A state where water loss exceeds water intake, resulting in decreased plasma volume.
How does plasma volume affect blood pressure?
Increases in plasma volume increase mean arterial pressure, while decreases lower it.
How do changes in plasma osmolarity affect water movement?
Changes in osmolarity affect water movement between intracellular and extracellular fluid compartments.
What percentage of sodium and water is reabsorbed in the proximal tubule?
70%
What is the relationship between sodium reabsorption and water reabsorption in the proximal tubule?
Solute and water reabsorption are coupled and occur iso-osmotically.
What triggers the reabsorption of water in the distal tubule and collecting duct?
Antidiuretic hormone (ADH).
What are aquaporins?
Water channels in the plasma membrane that facilitate water reabsorption in the kidneys.
What components make up extracellular fluid (ECF)?
Blood and interstitial fluid.
What regulates plasma sodium levels?
Reabsorption of sodium in the renal tubules.
: How does sodium balance affect blood pressure?
Changes in sodium chloride (NaCl) content affect ECF volume and blood pressure.
what is the renin-angiotensin-aldosterone system (RAAS)?
A hormonal system that regulates blood pressure and fluid balance in response to low blood pressure or low sodium levels.
How do baroreceptors function in blood pressure regulation?
hey detect changes in blood pressure and trigger responses to maintain it.
What happens during a hemorrhage concerning blood volume and pressure?
Decreased blood volume leads to lower venous pressure, decreased stroke volume, and a drop in mean arterial pressure.
What role does angiotensin II play in blood pressure regulation?
It acts as a vasoconstrictor and stimulates aldosterone release to increase sodium and water reabsorption.
What stimulates the release of erythropoietin during low blood pressure?
Decreased oxygen supply to the kidneys due to reduced blood flow.
How do the kidneys influence extracellular fluid composition?
By regulating the output of water and electrolytes.
What is a major difference between the renal and gastrointestinal systems?
The renal system maintains normal extracellular fluid composition, while the gastrointestinal system absorbs all nutrients consumed, regardless of need.
What is the primary function of the gastrointestinal system?
To allow cells of the body to utilize ingested food.
What is absorption in the context of the GI system?
The uptake of products of digestion, water, and electrolytes across the wall of the GI tract.
What is defecation?
The removal of indigestible material and bacteria from the body in the form of feces.
What is motility in the GI tract?
The controlled relaxation and contraction of smooth muscle for mixing, movement of food, and defecation.
What are the two major divisions of the gastrointestinal system?
The gastrointestinal tract and accessory glands.
What are the four distinct layers of the GI tract wall
Mucosa, submucosa, muscularis externa, and serosa.
What is the role of the mucosa in the GI tract?
It lines the lumen and includes absorptive, exocrine, and endocrine cells.
What does the submucosa contain?
Connective tissue, larger blood and lymphatic vessels, and the submucosal plexus.
What is the function of the muscularis externa
Responsible for motility; it consists of an inner layer of circular muscle and an outer layer of longitudinal muscle.
What is the serosa?
The outermost layer of the GI tract wall, providing structural support and secreting lubricating fluid
Where does most digestion occur in the gastrointestinal system?
In the small intestine.
What factors contribute to digestion in the small intestine?
Delivery of chyme, mixing and movement through the intestine, pancreatic enzymes, bile, and exposure to digestive enzymes.
What anatomical features of the small intestine enhance absorption?
Its structure maximizes exposure of enterocyte luminal membranes to digestive products.
How is nutrient absorption facilitated in the small intestine?
Through specialized solute transporters and adequate blood and lymph flow.
Why is sexual reproduction important?
It promotes genetic diversity, repair of damaged DNA, and sexual selection.
What benefits does genetic diversity provide?
Increased immune diversity and greater adaptability to environmental changes.
What are the roles of male hormones?
Development of male sex organs, regulation of sperm production, sexual functions, and secondary sexual characteristics.
Define gender identity.
A personal sense of one’s own gender, distinct from the sex assigned at birth.
What is sexual orientation?
A person’s attraction to men, women, both, another gender, or neither.
What is the difference between transgender and cisgender?
Transgender individuals have a gender identity that differs from their sex assigned at birth, while cisgender individuals’ gender identity aligns with their assigned sex.
What does intersex mean?
Individuals with sex characteristics that do not fit typical definitions of male or female.
What factors can lead to intersex traits?
Genetic conditions, hormone exposure during development, and variations in sex-determining genes.
How does sex determination occur in embryos?
It depends on the presence of the SRY gene on the Y chromosome, determining whether gonads develop into testes or ovaries.
What is gender transition?
The process of living according to one’s gender identity rather than the gender assigned at birth
What steps might be involved in gender transition?
hanging clothing, appearance, name, pronouns, and potentially undergoing hormone therapy or surgeries.
What effects does testosterone therapy have on transgender men?
Enlargement of the clitoris, facial hair growth, increased muscle mass, and deepening of the voice.
What effects does hormone therapy have on transgender women?
Breast tissue growth, body fat redistribution, reduced muscle mass, and thinning body hair.
Define non-binary
A gender identity that does not conform to the male/female binary and may exist outside or between these categories.
: How do non-binary individuals differ from intersex individuals?
Non-binary individuals typically do not have atypical sex anatomy, whereas intersex individuals do
What challenges do non-binary individuals often face?
Greater mental health challenges and discrimination compared to the broader transgender population.
What is the importance of recognizing non-binary identities?
Understanding and respect for non-binary identities can lead to better support and acknowledgment of their experiences.
