A&P Flashcards
What is homeostasis?
The maintenance of stable living conditions
Components of a feedback system
Stimulus, Controlled condition, Receptor, Control Centre, Effectors, Response
What does a negative feedback system do?
Reverses an effect
What does a positive feedback system do?
Enhances an effect
What are the different methods of measuring body temperature?
Oral, axillary, tympanic and rectal
What is core temperature?
The temperature of the deep tissues of the body.
Average core temperature
36.5-37.5°C
What is peripheral temperature?
The temperature of the blood flow through the vessels under the skin
Average peripheral temperature
18-36°C
Cyclic variations in normal temperature
0.25-0.5°C
Axillary temperature
Armpit. Usually 1°C lower than oral and up to 2°C lower than rectal. Least accurate.
Rectal temperature
Usually most accurate - especially best for infants.
Role of hypothalamus in regulating temperature
The hypothalamus checks our current temperature and compares it with the normal temperature of about 37°C. If our temperature is too low, the hypothalamus makes sure that the body generates and maintains heat.
Signs of a temperature
Increased heart rate, red face due to increased blood flow.
Tissue repair - normal vs. scar
New cells originate via cell division from the stroma, or the parenchyma. If parenchymal cells accomplish the repair, tissue regeneration is possible. However, if fibroblasts need to come in, then they synthesise materials that aggregate to form scar tissue, through a process called fibrosis.
Why is the endocrine system ductless?
It is quicker to dump hormones directly into the bloodstream
Technical term for generating heat
Thermogenesis
What do goosebumps do?
Trap air
Flow chart of temperature regulation
Stimulus decreases body temp –> Thermoreceptors –> Hypothalamus and anterior pituitary –> Vasoconstriction decreases heat loss through skin, Adrenal medulla releases hormones that increase cellular metabolism, skeletal muscles contract and cause shivering, thyroid gland release thyroid hormones which increases metabolic rate –> Response
What is heat?
A form of energy measured in calories
What is a calorie?
The amount of energy required to raise the temperature of 1g of water by 1°C.
Metabolic rate definition
The rate at which heat is produced from the catabolism of food
4 principle routes of heat loss
- Radiation
- Conduction
- Convection
- Evaporation
BMR
Basal Metabolic Rate
Where are baroreceptors located?
In the carotid sinus and its aortic arch.
How do baroreceptors detect pressure changes?
By responding to changes in the tension of the arterial wall
Flow chart of an injury
Injury –> Platelets release growth factors –> Neutrophils and macrophages engulf bacteria –> Epithelial + endothelial cells and fibroblasts produce growth factors –> Synthesis of extracellular matrix and new capillaries –> Fibroblasts orchestrate remodelling of scar by producing ECM, MMPs and TIMPs –> Mature scar
Which part of the brain connects the endocrine and the nervous system?
The hypothalamus
What is the response of the effector to the stimulus in a negative feedback system?
It inhibits the original stimulus
What does the adrenal medulla respond to?
Neural stimuli, not ACTH
What does innate immunity include?
External physical and chemical barriers provided by skin and mucous membranes. Also includes various internal defences such as antimicrobial substances, NK cells, phagocytes, inflammation and fever
First line of defence against pathogens?
Skin and mucous membranes.
Second line of defence against pathogens?
Internal defences
What does telomerase do?
maintains chromosome ends
4 main types of antimicrobial substances
interferons, complement system, iron binding proteins and antimicrobial proteins
What is inflammation?
Defensive response to tissue damage
Impact of fever
Intensifies effects of interferons, inhibits growth of some microbes and speeds up body reactions that aid repair
5 cardinal signs
Pain, redness, swelling, heat, loss of function
2 examples of commensal bacteria and their location
Staphylococcus aureus - mouth
Escherichia coli - gut
Flow diagram for inflammation
Tissue injury –> microbes enter –> release chemicals which are recognised by body –> initiates release of phagocytes –> blood vessels leak fluid into tissues, causing swelling
Difference between granular and agranular leukocytes
Granular contain granules that are visible under a light microscope after staining
Why don’t red blood cells contain a nucleus?
to increase surface area, allowing space for haemoglobin
What does the T in T cells mean?
Thymus
What does the B in B cells mean?
Bursa
Which cells are formed from a myeloid stem cell?
Erythrocytes, platelets, leukocytes
Which cells are formed from lymphoid stem cells?
T, B and NK cells
What does adaptive immunity mean?
The production of specific types of cells or antibodies to destroy a particular antigen. Involves B and T cells.
Two types of adaptive immunity
Cell mediated and antibody mediated
Cell mediated immunity
Doesn’t use antibodies. Cytotoxic T cells directly attack invading antigens and phagocytes are activated.
Antibody mediated immunity/humoral
B cells transform into plasma cells, then secrete antibodies
Clonal selection
Lymphocyte proliferates and differentiates in response to specific antigen, forming a clone of cells that can recognise the same antigen.
What is an antigen?
Any substance the body recognises as foreign
Which 2 types of cells does clonal selection lead to?
Effector and memory
Effector cells
carry out immune responses that result in the destruction/inactivation of the antigen.
Memory cells
do not participate in initial immune response, but if antigen reappears in future, will quickly respond by proliferating and differentiating into more effector and memory cells.
Effector cells include…
active helper T cells, active cytotoxic T cells and plasma cells
Memory cells include…
memory helper T cells, memory cytotoxic T cells and memory B cells.
Naturally acquired active immunity
After exposure to microbe, antigen is recognised by B cells and T cells and costimulation leads to the antibody secreting plasma cells, cytotoxic T cells and B and T memory cells
Naturally acquired passive immunity
Transfer of IgG antiboies from mother to foetus aross placenta or of IgA antibodies via breastmilk.
Artificially acquired active immunity
antigens introduced during vaccination stimulate cell mediated and antibody mediated immune responses, leading to the production of memory cells. Antigens pretreated to be immunogenic but not pathogenic, meaning they will trigger an immune response but not cause illness.
Artificially acquired passive immunity
IV injection of immunoglobulins
What are interferons?
a group of signalling proteins made and released by cells in response to the presence of viruses
What do interferons do?
Boost immune response and regulate the action of several genes which control the secretion of cellular proteins affecting growth
What does the complement system do?
enhances the ability of antibodies and phagocytic cells to clear microbes, promote inflammation and attack the pathogen’s cell membrane
Iron binding proteins
carrier proteins needed for the proliferation and maturation of immune cells
Antimicrobial proteins
contain sites that target specific microbial macromolecules.
What do the smaller antimicrobial proteins do?
disrupt structure and function of microbial cell membranes
What is chemotaxis
the movement of an organism in response to a chemical stimulus
What do immune cells use chemotaxis for?
to circulate between vascular and lymphatic systems and to migrate from the blood to the site of infection
IgA - where is it? what does it protect against?
Found in mucous, saliva, tears and breast milk. Protects against pathogens
IgD - where is it? what does it do?
part of B cell receptor, activates basophils and mast cells
IgE - what does it do?
protects against parasitic worms and responsible for allergic reactions
IgG - how does it travel?
secreted by plasma cells in blood, crosses from mother to foetus via placenta
IgM - where is it? what does it do?
may be attached to surface of B cell or secreted into blood. Responsible for early stages of immunity.
What is a mast cell?
a cell filled with basophil granules
Frank-Starling law
the greater the force of contraction during systole, the more forcefully it will contract
How does ANS affect force of contraction?
Stimulation increases force, inhibition decreases force
Effect of increased nerve impulses from vagus nerves (parasympathetic)
decreased heart rate
Effect of increased nerve impulses from cardiac accelerator nerves (sympathetic)
increased heart rate and contractility
Effect of increased nerve impulses from vasomotor nerves (sympathetic)
vasoconstriction
Perfusion definition
the passage of fluid through the circulatory system or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue
Signs and symptoms of altered perfusion
dyspnoea, cough, chest pain, tachycardia, hypotension, cyanosis, changes in arterial blood gases, changes in ECG and biochemistry, confusion and anxiety, oedema, finger clubbing
How does the movement of fluids and solutes out of capillaries into the interstitial fluid occur?
via filtration which is driven by blood hydrostatic pressure
What assists the return of venous blood from the foot to the right atrium?
a system of valves within the veins
What percentage of the fluids in the body are extracellular?
33%
What percentage of the fluids in the body are intracellular?
67%
What percentage of extracellular fluid is made up of interstitial?
80%
What percentage of extracellular fluid is made up of plasma?
20%
Components of average daily water gain and their amounts
Metabolic water - 200mL
Ingested foods - 700mL
Ingested liquids - 1600mL
Components of average daily water loss and their amounts
GI tract - 100mL
Lungs - 300mL
Skin - 600mL
Kidneys - 1500mL
Dehydration pathway - decreased flow of saliva
Dehydration –> decreased flow of saliva –> dry mouth and pharynx –> stimulates thirst centre in hypothalamus –> increases thirst –> increases water intake –> increases body water to normal level and decreases thirst
Dehydration pathway - Increased blood osmotic pressure
Dehydration –> increased blood osmotic pressure –> stimulates osmoreceptors in hypothalamus –> stimulates thirst centre in hypothalamus –> increases thirst –> increases water intake –> increases body water to normal level and decreases thirst
Dehydration pathway - decreased blood volume
Dehydration –> decreased blood volume –> decreased blood pressure –> increased renin release by kidneys –> increased angiotensin ll formation –> stimulates thirst centre in hypothalamus –> increases thirst –> increases water intake –> increases body water to normal level and decreases thirst
Mechanism and effect of thirst centre in hypothalamus
Stimulates desire to drink leading towater gain if thirst is quenched
Mechanism and effect of angiotensin ll
stimulates secretion of aldosterone which reduces loss of water in urine
Mechanism and effect of aldosterone
By promoting urine reabsorption of Na+ and Cl- ions, increases water reabsorption via osmosis
Mechanism and effect of ANP
promotes natriuresis, elevated urine excretion of Na+, Cl- ions with water
Mechanism and effect of ADH
promotes insertion of water channel proteins into plasma membranes of cells in collecting ducts of kidneys, causing water permeability to increased and more water to be absorbed
Order of layers of artery from inside out
Endothelium, basement membrane, internal elastic lamina, smooth muscle, outer layer
Order of layers of vein from inside out
Endothelium, basement membrane, smooth muscle, outer layer
Layers of capillary
Endothelium and basement membrane
Filtration in capillary exchange
Fluid moves from high pressure in capillary bed to low pressure in tissues
Reabsorption in capillary exchange
Fluid moves from high pressure in tissues to low pressure in capillary bed
Two types of pressure involved in capillary exchange
Hydrostatic and osmotic
Blood hydrostatic pressure
force exerted by blood confined in blood vessels and heart chambers
Capillary hydrostatic pressure
force of blood on capillary walls –> drives fluid out of capillaries into tissue fluid
How does fluid move out of the capillary into ISF?
As fluid leaves capillary, hydrostatic pressure in ISF rises. Capillary hydrostatic pressure is higher than IFHP so fluid moves from capillary to ISF.
How is fluid drawn from tissue back into capillary?
Plasma proteins in blood can’t move across semi permeable capillary cell membrane so they remain in the plasma, meaning blood has a higher colloidal concentration and lower water concentration than tissue fluid so attracts water. Blood colloidal osmotic pressure is higher than IFCOP.
Capillary exchange
Net filtration occurs near the arterial end of the capillary since capillary hydrostatic pressure (CHP) is greater than blood colloidal osmotic pressure (BCOP). There is no net movement of fluid near the midpoint since CHP = BCOP. Net reabsorption occurs near the venous end since BCOP is greater than CHP.
4 functions of electrolytes broken into ions
- control osmosis of water between fluid compartments
- help maintain acid-base balance
- carry electrical current
- serve as cofactors for optimal activity of enzymes
Sodium ions in fluid
most abundant extracellular ions. Involved in action potentials, muscle contraction and fluid and electrolyte balance`
What is Na+ balance controlled by?
aldosterone, ADH, ANP
Chloride ions in fluid
major extracellular anions. Play role in regulating osmotic pressure, and forming HCl in gastric juice
What is Cl- balance controlled by?
processes that increase or decrease kidney reabsorption of Na+
Potassium ions in fluid
most abundant cations in intracellular fluid. Play key role in establishing the resting membrane potential in neurons and muscle fibres, contribute to regulation of pH
What is K+ balance controlled by?
aldosterone
Calcium ions in fluid
principally extracelllular cations. function in blood clotting, neurotransmitter release and muscle contraction.
What is Ca2+ balance controlled by?
parathyroid hormone and calcitriol
Oedema - what is it? Causes?
accumulation of excess interstitial fluid. Caused by heart failure, kidney disease, inadequate lymphatic systems or weakness/damage in leg veins
Renin-angiotensin-aldosterone system
kidneys convert prorenin to renin and secrete it into bloodstream. Plasma renin converts angiotensinogen to angiotensin, which is then converted to angiotensin ll. This causes vasoconstriction, leading to increased BP. Also stimulates aldosterone which causes renal tubules to increase reabsorption of sodium and water into blood while causing excretion of K+. This increases volume of ECF and increases BP.
Pressure of breathing at rest
diaphragm relaxed, so alveolar pressure = atmospheric pressure and there is no air flow
Pressure changes during inhalation
diaphragm contracts, chest cavity expands and alveolar pressure drops below atmospheric pressure.
Pressure changes during exhalation
diaphragm and external intercostals relax. Chest and lungs recoil, chest cavity contracts and alveolar pressure increases above atmospheric.
Negative feedback of breathing
stimulus –> controlled condition decreases pH –> central chemoreceptors in medulla / preipheral chemoreceptors in aorticand carotid bodies –> dorsal respiratory group in medulla oblongata –> muscles of inhalation + exhalation contract more forcefully and frequently –> response
Blood pressure formula
Cardiac Output x Peripheral Resistance
Cardiovascular disorders that can alter perfusion
Hypertension (In CYP causes may include renal disease, congenital cardiac disease) Diseases of the heart CYP -Congenital Heart Disease (CHD) Coronary Heart Disease (CHD) Heart failure (acute or chronic) Myocardial infarction (Ischaemic heart disease) Valve insufficiencies Cardiogenic shock Pericarditis Sinus Node Dysfunction
Cardiovascular disorders that can alter perfusion
Hypertension (In CYP causes may include renal disease, congenital cardiac disease) Diseases of the heart CYP -Congenital Heart Disease (CHD) Coronary Heart Disease (CHD) Heart failure (acute or chronic) Myocardial infarction (Ischaemic heart disease) Valve insufficiencies Cardiogenic shock Pericarditis Sinus Node Dysfunction
Cause for abrupt increase in ventilation at start of exercise
due to neural changes that send excitatory impulses to inspiratory area of medulla oblongata
Cause for more gradual increase in ventilation during moderate exercise
due to chemical and physical changes in bloodstream
Haemoptysis
coughing up blood
Lung compliance
a measure of the lung’s ability to stretch and expand
Compliance is affected by…
the amount of elastic tissue in the lung and the amount of surfactant
What is lymphatic tissue a specialised form of?
reticular connective tissue
What do lymph nodes do?
filter all fluids that pass through them and filter into the thoracic duct
Where is the thoracic duct located?
along the aorta
3 functions of immune system
- drains excess interstitial fluid
- transports dietary lipids
- carries out immune responses
role of lymphatic capillaries
absorb ISF and pass lymph to affarent vessels
role of affarent lymph vessels
carry lymph from lymph capillaries to lymph nodes
role of efferent lymp vessels
carry lymph from nodes to ducts
When is interstitial fluid called lymph?
After it passes into the lymphatic vessels
What is the spleen and where is it located?
the largest single mass of lymphatic tissue in the body. Located between the stomach and the diaphragm.
What types of tissue does the spleen contain?
white pulp and red pulp
White pulp
lymphatic tissue where B and T cells carry out immune responses
Red pulp
blood filled sinuses where worn out blood cells and platelets are removed - red blood cells broken down into biliverdin and bilirubin
Splenectomy
removal of spleen
What cells does a lymph node contain?
B cells, T cells, plasma cells, dendritic cells, macrophages
Lymphatic nodules
egg shaped masses of lymphatic tissue that are not surrounded by a capsule
How does lymph flow around the body?
Lymphatic capillaries merge to form large lymphatic vessels which drain into the thoracic duct and the right lymphatic duct. Thoracic duct empties fluid into left internal jugular and left subclavian veins, right lymphatic duct empties into right internal jugular and right subclavian veins, then back to blood.
Flow diagram of lymphatic filtration
Extra fluid in body tissues –> lymphatic capillaries absorb fluid and pass on to –> affarent lymphatic vessels which pass to –> lymph nodes which contain lymphocytes that attack and break down pathogens –> lymp fluid carries waste through efferent lymphatic vessels to –> blood stream –> liver or kidneys remove waste from blood –> passed out of body
Biliverdin
green bile pigment responsible for greenish colour in bruising. Converted to bilirubin via chemical reduction
BIlirubin
orange-yellow substance in bile. Higher levels can indicate a liver problem (can cause jaundice). Oxidised back to biliverdin.
How does photo therapy work?
Light waves are absorbed by the skin and blood. Oxides bilirubin so that is can easily dissolve in water.
How does fluid move from the blood system to the lymphatic system?
Fluid accumulates in interstitial space is tissues after leaking through the cardiovascular capillaries, then leaks through mini valves at the junction of the endothelium into lymph capillaries.
What are the major lymphoid tissues?
Primary - thymus and bone marrow
Secondary - lymph nodes, tonsils, and spleen
What are primary lymphoid organs?
where lymphocytes are formed and mature.
What are secondary lymphoid organs?
sites where lymphocytes interact with each other and nonlymphoid cells to generate immune responses to antigens.
Where are the major lymph nodes?
tonsils, adenoids, armpits, neck, groin and mediastinum.
Parts of the urinary system top to bottom
kidney, ureter, ovary, bladder, uterus, urethra
Functions of the kidneys
- regulate ion levels in blood
- regulate blood volume and BP
- regulate blood pH
- produce hormones
- excrete wastes
Path of blood flow in kidneys
renal artery –> segmental arteries –> interlobal arteries –> arcuate arteries–> cortical radiate arteries –> afferent arterioles –> peritubular capillaries –> cortical radiate veins –> arcuate veins –> interlobar veins –> renal vein
Flow of fluid through a cortical nephron
Glomerular capsule –> proximal convoluted tubule –> descending limb of nephron loop –> ascending limb of nephron loop –> distal convoluted tubule (drains into collecting duct)
Glomerular filtration
In glomerulus, blood plasma and dissolved substances get filtered into glomerular capsule
Tubular reabsorption
all along renal tubule and collecting duct, water, ions and other substances get reabsorbed from the renal tubule into peritubular capillaries and into the blood
Tubular secretion
all along renal tubule and collecting duct, waste substances get secreted from peritubular capillaries into the renal tubule and go onto form urine
Transportation of urine
Urine produced by nephrons drains into minor calyces, which join to become major calyces that unite to form the renal pelvis. From here, urine drains first into the ureters and then into the bladder where it is discharged from the body though the urethra
How many layers do the ureter walls consist of? What are they?
3 - transitional mucosa on inside, smooth muscle in middle and an outer layer of areolar connective tissue
Urinary bladder - what is it? What does it do?
hollow muscular organ in pelvic cavity posterior to pubic symphysis. Stores urine prior to mictuition
Mictuition
urinating
Describe the walls of the bladder
Mucosa contains transitional epithelium and rugae. Muscular layer consists of 3 layers of smooth muscle called detrusor muscle. Outer coat is a fibrous covering.
What is responsible for the yellow/amber colour of urine?
Urochrome and urobilin
What is urochrome?
a pigment produced from the breakdown of bile
What is urobilin?
a pigment produced from the breakdown of haemoglobin
What diets affect the pH of urine?
High protein increases acidity, vegetarian increases alkalinity
What does albumin in urine indicate?
increase in permeability of filtering membranes
What does glucose in urine indicate?
diabetes
What do red blood cells in urine indicate?
acute inflammation of urinary organs
What do white blood cells in urine indicate?
infection in the kidneys or other urinary organs
What do ketone bodies in urine indicate?
diabetes or anorexia due to too few carbohydrates
What does bilirubin in urine indicate?
liver damage or disorder
What does urobilinogen in urine indicate?
anemia, hepatitis, jaundice
What do ureters do?
transport urine from kidneys to bladder. As bladder fills, it expands and compresses the ureters to prevent backflow
What do rugae in kidneys do?
allow bladder to expand as it fills
What does the peritonum in kidneys do?
helps hold bladder in place
What does the internal urethral sphincter do?
it is an involuntary smooth muscle - opens and closes urethra
What does the external urethral sphincter do?
It is a voluntary skeletal muscle - opens and closes urethra
What is the external urethral orifice?
the opening of the urethra to the outside
What is the urethra?
a small tube leading from the bladder to the outside
What does urine consist of?
95% water, urea (ammonia and CO2), chloride, sodium, potassium and creatinine
pH of gastric juice
1.2-3
pH of vaginal fluid
3.5-4.5
pH of urine
4.6-8.0
pH of saliva
6.4-6.9
pH of semen
7.2-7.6
pH of cerebrospinal fluid
7.4
pH of bile
7.6-8.6
pH of blood
7.35-7.45
Why is the pH of blood so tightly controlled?
as proteins are sensitive to pH
What do buffer systems do?
temporarily bind H+, removing the highly reactive, excess H+ ions from solution but not from the body
3 types of buffer systems in the body
protein buffer system
carbonic acid-bicarbonate buffer system
phosphate buffer system
Kidney excretion of H+
slowest but only way for most acids.
cells of renal tubules secrete H+ which is then excreted in the urine.
What is H+ usually replaced with when excreted via kidneys?
Potassium which organs are very sensitive to
Acidosis and CNS
causes depression of CNS
Alkalosis and CNS
causes overexcitability of CNS
Protein buffer system
Proteins are made up of amino acids, which contain positively charged amino groups and negatively charged carboxyl groups. The charged regions of these molecules can bind hydrogen and hydroxyl ions, and thus function as buffers.
Carbonic acid-bicarbonate buffer system
CO2+H20H2CO3H+ + HCO3-
Phosphate buffer system
It consists of dihydrogen phosphate ions as the hydrogen ion donor ( acid ) and hydrogen phosphate ion as the ion acceptor ( base ) . If additional hydroxide ions enter the cellular fluid, they are neutralised by the dihydrogen phosphate ion
Effects of ageing on fluid and electrolyte balance
impaired thirst perception; decreased glomerular filtration rate; alterations in hormone levels, including ADH, ANP and aldosterone; decreased urinary concentrating ability; and limitations in excretion of water, electrolytes and acid.
What is the role of the somatic nervous system?
voluntary control of body movements via skeletal muscles
What is the role of the autonomic nervous system?
mostly involuntary and regulates bodily functions e.g. HR, digestion, RR. Sympathetic controls fight or flight response.
What is the role of the enteric nervous system?
governs functions of GI tract
