Foundation Flashcards
What are the determinants of pulse pressure?
Stroke volume
Compliance of aorta
What may cause low pulse pressure?
Distended arteries
Low stroke volume
What does a low pulse pressure lead to?
Small waveform
What may cause a small amplitude and upstroke of the carotid arterial waveform?
Slow blood ejection
Low stroke volume
What causes a fourth heart sound audible at the apex?
Atrial kick caused by decreased ventricular compliance
Why do you produce an atrial kick?
Ventricles have higher pressure so atria have to contract harder to shut atrioventricular valve
What murmur does an aortic stenosis cause?
Systolic murmur
Why is an aortic stenosis louder on expiration?
During expiration, blood being pushed into systemic circulation and out of pulmonary circulation due to greater intrathoracic pressure
More blood flow through left side of heart > louder heart sounds
Why do right-sided heart sounds increase in volume on inspiration?
During inspiration bloodflow increases to venous and pulmonary circulations, because of less intrathoracic pressure > greater preload,
More blood flow through right side of heart
What are the changes to the cardiovascular system when a person stands up?
Force of gravity causes blood to pool in lower extremities > blood pressure initially decreases
Baroreceptor reflex acts to increase heart rate and contractility
What is the role of a finometer?
Measures real-time
- Blood pressure
- Heart rate
- Stroke volume
- Cardiac output
- Total peripheral resistance
How does nicotine act on the body?
Cholinergic receptor agonist
Acts on autonomic ganglia, skeletal muscle, and CNS
What are the side effects of nicotine use?
Tachycardia Mild increase in contractility Anxiety Tremors Nausea Sore throat Mouth irritation
How does caffeine act on the body?
Adenosine receptor agonist Phosphodiesterase inhibitor Acts on - Heart - Vasculature - Airways - Skeletal muscle - CNS
What are the side effects of caffeine use?
Tachycardia Mild increase in contractility Anxiety Tremors Sleeplessness
What is the definition of maximum resolving power?
Smallest distance between 2 points at which 2 points distinguishable
What is the difference between a transmitting electron microscope (TEM), and a scanning electron microscope (SEM)?
TEM = cross-sections SEM = scans surfaces
Why is fixation following removal of tissue from the body important?
Prevents autolysis and bacterial colonisation
How does formalin act as a fixative?
Chemically cross-links molecules to lock them in place
Describe the process of embedding
Fixed tissues gradually dehydrated in solutions of alcohol
Alcohol replaced with xylene
Why is paraffin embedding necessary?
To stiffen tissues > can be sectioned thinly
What occurs after the tissue is sectioned?
Sections rehydrated by passing through series of xylene and alcohol
Put on glass slides
Stained
Covered with coverslip
What does haematoxylin bind to?
Acidic/anionic compounds
What colour does the nucleus stain?
Blue/purple
What are tissues that stain with haematoxylin called?
Basophilic
What does eosin bind to?
Basic/cationic compounds
What colour does the cytoplasm and extracellular matrix generally stain?
Pink
What are tissues that stain with eosin called?
Eosinophilic
Define amphophilic
Stains with both eosin and haematoxylin
What cell components stain amphophilic?
Cytoplasm of cells producing lots of protein with abundant rough endoplasmic reticulum (RER)
What is the life span of platelets?
8-10 days
Where is red bone marrow contained in adults?
Axial skeleton and proximal femur
Where does foetal haematopoiesis mainly occur?
Foetal liver
How is cell production controlled in haematopoiesis?
Growth factors
Microenvironment
Able to respond to sudden demand for extra cells of particular type
What is the structure of collagen fibres?
3 polypeptide alpha chains which form triple helix
What are the three types of connective tissue fibres?
Embryonic connective tissue
Connective tissue proper
Specialised connective tissue
Where is type I collagen found?
Within connective tissue proper
Where is type II collagen found?
Cartilage
Intravertebral discs
Where is type III collagen found?
Reticular fibres
Where is type IV collagen found?
Basement membranes
Where is type VII collagen found?
In anchoring fibres that link basement membranes
Depending on how the section is cut, how may fibroblasts appear?
Round nuclei/long, thin nuclei
What is the role of reticulin fibres?
Provide delicate supporting framework in certain tissues; eg:
- Bone marrow
- Liver
Describe the structure of elastin
Central core of elastin
Surrounding network of fibrillin microfibrils
Why is ground substance frequently not seen on H&E sections?
Lost on preparation
What are the components of ground substance?
Glycosaminoglycans (GAGs) - Hyaluronic acid - Proteoglycans Glycoproteins - Fibronectin - Fibrillin - Laminin
What is extracellular matrix composed of?
Fibres and ground substance
What are the roles of extracellular matrix?
Mechanical support
Control of cell growth and differentiation
Scaffolding for cell proliferation
Synthesis and storage of various growth factors
What are the resident cells of the extracellular matrix?
Fibroblasts Myofibroblasts Macrophages Mast cells Mesenchymal stem cells Adipocytes
What are the types of wandering cells that may be found in the extracellular matrix?
Lymphocytes
Eosinophils
Plasma cells
Basophils
Which cells are responsible for the synthesis of extracellular matrix?
Fibroblasts
What are some examples of dense regular connective tissue proper?
Tendons
Ligaments
Aponeuroses
Where are the nuclei located in adipocytes?
Sometimes visible on edge of cells
Why does bone stain both pink and purple with a H&E stain?
Ground substance stains purple
Matrix largely collagen, so stains pink
What are the components of the extracellular matrix in the basement membrane?
Predominantly type IV collagen
Heparan sulphate
Structural glycoproteins
- Involved in linking integrins of epithelial cells to extracellular matrix
What are the differences between bacterial and higher-order cells?
Have no ER Nucleus not membrane bound No membrane-bound organelles 70S ribosomes, compared to eukaryotes (80S) Replicate by binary fission
What are the key components of bacteria?
Cytoplasmic membrane Cytoplasmic matrix Ribosomes Genome Cell wall
What is the difference between prokaryotic and eukaryotic ribosomes?
Prokaryotic: 50S + 30S = 70S
Eukaryotic: 60S + 40S = 80S
How can bacteria acquire new genes horizontally?
Plasmids Transposons Integrons Bacteriophages Pathogenicity islands
Describe a Gram positive cell wall
Plasma membane > thick peptidoglycan layer
Describe a Gram negative cell wall
Plasma membrane = inner membrane > thin peptidoglycan layer > periplasmic space > outer membrane
What is the structure of lipopolysaccharide (LPS)?
Lipid A attached to core polysaccharide, with repeating units of O-Ag attached
What is the main function of flagella?
Movement
What is the main function of fimbriae or pilli?
Attachment
What is the main function of capsules?
Short-term survival
What is the main function of endospores?
Long-term survival
What are flagella composed of?
Basal body
Hook filament made of flagellin protein
What are fimbriae composed of?
Pilin
What are endospores?
Specialised, resistant, dormant structures
What is the difference between sporulation and germination?
Sporulation = bacteria to spore Germination = spore to bacteria
What are the phases of bacterial growth?
Lag
Log
Stationary
Death
Define facultative anaerobes
Can grow with/without air
Define aerotolerant anaerobes
Can survive in oxygen but won’t grow
Define microaerophiles
Grow best in low oxygen concentrations
What is the set point?
Level at which variable varies upon
What is the comparator?
Acts to integrate sensory information > sends signal to effector
What is the effector?
Receives signal from comparator > makes change to variable
What is the diurnal variation in temperature?
0.6 degrees higher in late afternoon
What is the menstrual variation in temperature?
1 degree higher post-ovulation
Why is thermal energy balance crucial?
Metabolic enzymes have narrow operational temperature range
What controls body temperature?
Hypothalamus
What happens when ambient temperature is high, in terms of body temperature control?
Sweating occurs sooner
Sweat volume decreases
Sweat Na concentration decreases > retains fluid volume and electrolytes
What initiates the increase in set-point temperature during fever?
Pyrogens = endotoxins/cytokines
Induce synthesis of prostaglandin > raises set point temperature
What produces severe combined immunodeficiency (SCID)?
Defective common gamma chain
What is the hygiene hypothesis?
Increase in autoimmunity and allergies because of too clean environment
Immune system has to attack something, so attacks self and innocuous substances
What are the two arms of the immune system?
Innate
Adaptive
Does innate immunity form immunological memory?
No
Can innate immunity distinguish self from non-self?
Yes
What are the barrier tissues of innate immunity?
Skin
Mucosa
What are the soluble factors of innate immunity?
Complement
Cytokines and mediators
Antimicrobial peptides
What are the cell-associated factors of innate immunity?
Pattern recognition receptors (PRRs)
- Toll-like receptors (TLRs)
Cytokines and mediators
Antimicrobial peptides
What are the cells of innate immunity?
Granulocytes - Neutrophils - Eosinophils - Basophils Monocytes/macrophages Dendritic cells (DCs) Natural killer (NK) cells
What is the speed of adaptive immunity?
Slow
What is the specificity of adaptive immunity?
Highly specific
Does adaptive immunity for immunological memory?
Yes
What are the cells of adaptive immunity?
T cells
B cells
What are various types of T cells?
Th1 Th2 Th17 Tfh Cytotoxic T cells Semi-invariant T cells - NKT cells - MAIT cells Gamma-delta T cells
What are the fundamental principles of immune recognition?
Immunological recognition
Immune effector mechanisms
Immune regulation
Immunological memory
What do are some innate effector mechanisms?
Phagocytosis
Microbicidal agents
Complement
What bridges innate and adaptive effector mechanisms?
DC collects Ag
Transports Ag to local draining lymph node
Presents Ag to naive T cells
What are the three main functions of B cell immunity?
Neutralisation
Opsonisation
Complement activation