187 Questions
What resets NADH back to NAD+?
Citric Acid Cycle
Which enzyme is responsible for the creation of citrate in the Citric Acid Cycle?
Citrate synthase
What drives the reaction forward in the step involving aconitase in the Citric Acid Cycle?
Aconitate intermediate
In the Citric Acid Cycle, which enzyme produces NADH and CO2 during an exergonic reaction?
Alpha ketoglutarate dehydrogenase
Which enzyme in the Citric Acid Cycle involves substrate-level phosphorylation?
Succinyl CoA synthetase
What enzyme in the Citric Acid Cycle is attached to the inner mitochondrial membrane and serves as part of the Electron Transport Chain?
Step six enzyme
What is the consequence of uncontrolled type 1 diabetes mellitus on ketone bodies in the liver?
Build-up of ketone bodies
What is the relationship between insulin and glucagon levels?
Insulin and glucagon levels are inversely proportional
What is the effect of glucagon on glycolysis?
Glucagon inhibits glycolysis
Why does ketogenesis occur in uncontrolled type 1 diabetes mellitus despite high blood sugar levels?
The interplay between insulin and glucagon leads to ketogenesis
What is the effect of glucagon on gluconeogenesis?
Glucagon stimulates gluconeogenesis
What is the effect of glucagon on beta oxidation?
Glucagon stimulates beta oxidation
What are the three types of molecules that can be catabolized to feed into the Citric Acid Cycle (CAC)?
Glucose, fatty acids, and amino acids
Which molecule has an entry point via pyruvate to enter the Citric Acid Cycle?
Aspartate
What are the overall products of the Citric Acid Cycle?
3 NADH, 1 FADH2, 1 ATP, 2 CO2
Which coenzyme is used in the Pyruvate Dehydrogenase Complex (PDH complex) to pick up the acetyl group?
TPP
Which enzyme releases CO2 during the conversion of pyruvate to acetyl CoA in the PDH complex?
Pyruvate dehydrogenase
Which of the following represents the energy yield from one round of the Citric Acid Cycle?
6 NADH, 2 FADH2, 2 ATP
What is the end product of the last round of beta oxidation of an odd-numbered fatty acid?
1 acetyl CoA and 1 propionyl CoA
How many fewer ATP are produced from a propionyl CoA compared to an acetyl CoA?
2 ATP
What is the effect of a propionyl CoA entering the citric acid cycle?
It bypasses the production of 2 NADH
What is the deficiency in an MCAD deficiency?
Medium chain acyl dehydrogenase
How much less energy is obtained from the full beta oxidation of a 16:2 fatty acid compared to a 16:0 fatty acid?
4 ATP
Which fatty acid provides more energy after beta oxidation?
16:0
What is the result of low oxaloacetate levels in beta oxidation MCAD deficiency?
Decreased gluconeogenesis
Which treatment approach is recommended for infants with beta oxidation MCAD deficiency?
Frequent feeding
In peroxisomal beta oxidation, how are very long chain fatty acids (VLCFA’s) metabolized?
Shortened into medium and long chain fatty acids
What is the major difference between peroxisomal beta oxidation and mitochondrial beta oxidation?
Transportation of fatty acids into the mitochondria
Why is early identification crucial for infants with beta oxidation MCAD deficiency?
To prevent coma and death
Which metabolic pathway is impaired in beta oxidation MCAD deficiency leading to lethargy in infants?
Citric Acid Cycle
What is the primary purpose of triglycerides in the liver?
To combine with cholesterol, phospholipids, and proteins to make lipoproteins
What is the role of hormone-sensitive lipase (HSL) in adipose tissue?
To break down triglycerides to release free fatty acids and glycerol
What is the result of lipolysis in adipose tissue?
Release of fatty acid and glycerol-3-phosphate
Which hormones regulate hormone-sensitive lipase (HSL)?
Insulin, glucagon and epinephrine
What is the purpose of lipoproteins in the liver?
To carry fatty acids and cholesterol to tissues
What is the sequential process of lipolysis in adipose tissue?
TAG to DAG to MAG to glycerol
What is the primary purpose of lipoproteins in the liver?
Combining with fatty acids to make triglycerides
During lipolysis, what is the main function of hormone-sensitive lipase (HSL)?
Catalyze the breakdown of triglycerides into free fatty acids
What is the fate of free fatty acids (ffa's) released from adipose tissue during lipolysis?
Used for energy by the adipose and liver cells
Which enzyme is responsible for converting diacylglycerol (DAG) to monoacylglycerol (MAG) during lipolysis?
Hormone-sensitive lipase (HSL)
What is the function of lipoproteins in transporting fatty acids and cholesterol?
Deliver fatty acids and cholesterol to tissues
What is the primary role of Glycerol-3-P in the formation of lipoproteins for energy storage?
Converting glycerol into triglycerides
What is the first step in beta oxidation of fatty acids?
Activation of a fatty acid to a fatty acyl CoA
What is the purpose of the carnitine transport system in beta oxidation?
To transport fatty acyl CoA from cytosol to the matrix
How is the energy yield from beta oxidation determined?
By dividing the number of carbons by two to find # of acetyl-CoA
What is the role of a translocase in beta oxidation?
To transport acyl-carnitine across the inner mitochondrial membrane
What is the significance of fatty acyl CoA activation in beta oxidation?
Activating fatty acids provides energy equivalent to two ATP molecules
How do fatty acyl CoA's enter the mitochondria for beta oxidation?
By using a shuttle system involving carnitine
How many acetyl CoA molecules does a 16:0 fatty acid produce?
8 acetyl CoA
What is the total number of FADH2 molecules produced from beta oxidation of a 16:0 fatty acid?
7 FADH2
How many ATP molecules are produced from the beta oxidation of a 16:0 fatty acid, excluding those produced in the Citric Acid Cycle?
129 ATP
What is the total ATP yield from one acetyl CoA undergoing the Citric Acid Cycle?
12 ATP
How many ATP molecules are produced from 7 NADH molecules generated during the beta oxidation of a 16:0 fatty acid?
21 ATP
What is the end product of the first reaction in the Citric Acid Cycle?
Citrate
Which molecule is created after the preparatory step to connect glycolysis to the Citric Acid Cycle via the Pyruvate Dehydrogenase Complex?
Acetyl CoA
How does acetyl CoA enter the Citric Acid Cycle?
As a product from glycolysis
What does the Citric Acid Cycle produce directly?
ATP
Which molecule connects both glycolysis and beta oxidation to the Citric Acid Cycle?
Acetyl CoA
What is the enzyme responsible for combining acetyl CoA and oxaloacetate to form citrate in the Citric Acid Cycle?
Citrate synthase
What is the primary function of lipoproteins that contain triglycerides in the liver?
Transport fatty acids and cholesterol to tissues
Which of the following correctly represents an important function of free fatty acids released from adipose tissue during lipolysis?
Used for energy in the liver and adipose tissue
In the process of lipolysis, what enzyme is responsible for converting triglycerides to diacylglycerol and free fatty acids?
Adipose triglyceride lipase (ATGL)
What is the primary function of lipoproteins called VLDL in the context of lipolysis?
Transport fatty acids and glycerol to tissues
What happens to the excess glucose in the body regarding lipolysis?
Converted to fatty acids for storage in adipose tissue
Where in the mitochondria is the electron transport chain located?
Inner mitochondrial membrane
Which of the following is the final electron acceptor in the electron transport chain?
Oxygen
What is the function of the H+ gradient created by the electron transport chain?
Drives the production of ATP
Why does FADH2 generate less ATP compared to NADH in the electron transport chain?
FADH2 has lower energy electrons
Which enzyme is responsible for generating ATP using the H+ gradient in the electron transport chain?
ATP synthase
How do the ATP molecules generated by ATP synthase move to the cytosol?
Active transport
What is the function of thermogenin in brown fat cells during non-shivering thermogenesis?
Promoting the release of heat rather than ATP production
What is the role of brown fat in babies, hibernating animals, and cold-adapted animals during non-shivering thermogenesis?
Generating more heat than normal metabolism
What is the primary function of ATP synthase in the electron transport chain during non-shivering thermogenesis?
Facilitating the movement of H+ back into the matrix
Which protein allows for the uncoupling of the electron transport chain by translocating H+ back to the matrix in brown fat cells?
Thermogenin
What is the purpose of the Glycerol Phosphate shuttle in the context of energy production?
To transfer reducing equivalents from cytosolic NADH into the mitochondria
What is the ultimate fate of FADH2 produced via the Glycerol Phosphate shuttle?
Directly enters the Electron Transport Chain
Which compound is involved in the regeneration of NAD+ from NADH in the mitochondrial matrix during glycolysis?
Dihydroxyacetone phosphate (DHAP)
Why does using the Glycerol Phosphate shuttle for NADH transport lead to the generation of one less ATP compared to other shuttles?
The FADH2 produced is less efficient in ATP synthesis
Which enzyme plays a crucial role in converting dihydroxyacetone phosphate (DHAP) to glycerol 3-phosphate during the Glycerol Phosphate shuttle?
Glycerol 3P Dehydrogenase
Which statement accurately describes the involvement of FADH2 within the Glycerol Phosphate shuttle system?
FADH2 participates in the shuttle of electrons between glycolysis and the mitochondria
Which molecule can connect to the Citric Acid Cycle via pyruvate?
Alanine
Which amino acid can enter the Citric Acid Cycle via fumarate?
Phenylalanine
Which amino acid can connect to the Citric Acid Cycle via alpha-ketoglutarate?
Arginine
Which amino acid can feed into the Citric Acid Cycle via oxaloacetate?
Aspartate
What is the purpose of the two shuttle systems described in the text?
To allow NADH from the cytosol to contribute to energy production in the mitochondria
Which organelle poses a barrier for NADH to enter during glycolysis under aerobic conditions?
Mitochondria
Which system converts NADH to FADH2 to allow its entry into the ETC?
Glycerol Phosphate Shuttle
Which molecule is used to convert oxaloacetate to malate in the Malate Aspartate shuttle?
Aspartate
What is formed when oxaloacetate is converted back to aspartate in the shuttle system?
Oxaloacetate
In the Malate Aspartate shuttle, what is regenerated when aspartate is converted back to oxaloacetate?
NADH
What is the purpose of a phosphate translocate symporter in the inner mitochondrial membrane?
Move phosphate groups into the mitochondrial matrix
Why does NADH produced during glycolysis not enter the Electron Transport Chain (ETC) in red blood cells or under anaerobic conditions?
It can't enter the ETC as red blood cells lack mitochondria or under anaerobic conditions
What happens to lactate after being converted back to pyruvate in the liver?
It is used for gluconeogenesis
Which of the following is NOT a catabolic pathway that produces indirect energy intermediates feeding into the ETC?
Gluconeogenesis
What is the role of the Adenine nucleotide translocate antiporter in the inner mitochondrial membrane?
Exchange ATP for ADP
Why is it important for the NADH produced during glycolysis in red blood cells or under anaerobic conditions to be regenerated into NAD+?
For the conversion of lactate back to pyruvate
Which symptom is commonly associated with astrocytomas due to the 6th cranial nerve palsy?
Double vision
What is a key factor contributing to the worse prognosis of Grade IV astrocytomas?
Hemorrhage and necrosis
Which of the following is NOT considered a sign of increased intracranial pressure related to brain tumors?
Hypothalamic impairment
What is the median survival for Grade II astrocytomas?
5-6 years
What is the most common symptom found in astrocytomas due to the worsening of the tumor in the morning?
Headache
Where are ependymomas most frequently found in children?
Near the 4th ventricle
What is the typical cellular appearance of oligodendrogliomas?
Similar to normal oligodendrocytes
What is a common feature of meningiomas when found in the brain?
Attached to the dura
Which primary brain tumor arises from the ependymal cells of the ventricular system?
Ependymomas
What distinguishes brain metastases from other primary brain tumors?
Secondary tumors from other parts of the body
What characterizes the growth of meningiomas during pregnancy?
Highly aggressive growth
What is a distinguishing feature of medulloblastomas in terms of location?
Limited to the cerebellum
Which of the following is a common sign of meningiomas due to compression of specific brain structures?
Focal neurological deficits
What tends to differentiate ependymomas in adults from those found in children?
Location in the cerebellum
Which primary site commonly metastasizes to the brain, leading to brain metastases?
Lung
What percentage of childhood CNS tumors arise in the posterior fossa?
70%
Which brain tumors are among the deadliest of cancers due to their aggressiveness and poor differentiation?
Astrocytomas
What is the most common grade range for astrocytomas?
Grade II - IV
Where do 70% of brain tumors tend to arise in adults, according to the text?
Above the tentorium cerebelli
What is the primary source of brain tumors that lead to extensive destruction because of difficulty in isolating them from normal brain tissue?
Astrocytomas
What is the approximate rate of intraspinal tumors in the population?
1 to 2 per 100,000
What is the defining characteristic of major neurocognitive disorders?
Progressive impairment of cognitive function
What is a common feature in many neurodegenerative disorders?
Protein aggregates resistant to degradation
Which term describes the daily activities used to measure one's ability to live independently?
Instrumental activities of daily living (IADLs)
What distinguishes early mild neurocognitive disorder from major neurocognitive disorder?
Limited activities of daily living impairment
Which neurons are selectively affected in neurodegenerative disorders?
One or more groups of neurons
What is a common clinical feature associated with neurocognitive disorders?
Impairment in ADLs
What is the main function of APP?
Being a receptor for an unidentified ligand
What is the role of Presenilin 1 and presenilin 2 in Alzheimer's disease?
Regulating neuronal calcium levels
What risk factor for Alzheimer's disease is associated with increased risk primarily in homozygous individuals?
Apolipoprotein E4
What function does the infectious theory of Alzheimer's disease suggest for APP?
Virus receptor
Which genetic factor is suggested to have a more significant causative role in Alzheimer's disease compared to Apolipoprotein E4 positivity?
Presenilin mutations
What is one of the proposed functions of APP in Alzheimer's disease?
Innate immune system component
What distinguishes delusions from normal beliefs?
Compatibility with reality
Which cognitive functions are orchestrated by the prefrontal cortex?
Executive functions
What is a common type of hallucination associated with psychosis?
Visual
Which executive function involves selecting and focusing on information relevant to a task?
Attention allocation
Which feature characterizes frontotemporal dementias in terms of behavior?
Apathy
What type of dementia is associated with Parkinson's disease and visual hallucinations?
Parkinson's disease dementia
Which grade of astrocytoma exhibits greater anaplasia?
Grade IV
Which brain region is grade I astrocytoma more commonly found in?
Cerebellum
What is a typical feature of grade I astrocytoma when compared to other grades?
Lack of necrosis
What gene is often excessively activated in grade I astrocytomas?
BRAF
Which of the following is a commonly-used name for grade III astrocytomas?
Anaplastic astrocytoma
What cellular morphology is typically seen in grade IV astrocytomas?
Abnormal cellular morphology
Which skin infections are caused by HHV-6 and HHV-7 in children?
Benign skin infections
What happens to the insulin resistance patient's receptors due to genetic and lifestyle factors?
Fewer receptors
What role does insulin play in inhibiting lipids in the liver?
Inhibits lipolysis
Which of the following is a long-term effect seen in type II diabetics?
High levels of glucose and free fatty acids
What is a significant relationship between insulin resistance and Alzheimer's Disease?
Insulin resistance increases the risk of AD
How do HHV 6 and 7 viruses interact with the central nervous system (CNS)?
Migrate into the CNS and remain dormant
What is a distinguishing feature of Grade III astrocytomas compared to Grade II?
Presence of larger cells
Which genetic mutation is associated with excessive signaling through the PI3K pathway in astrocytomas?
PTEN inactivation
How do Grade IV astrocytomas, such as glioblastoma multiforme, differ from Grade II astrocytomas?
Rapid growth and prominent hemorrhage
What is a hallmark feature of glioblastoma multiforme among adult brain tumors?
Worst prognosis with rapid growth
Which genetic mutation is more commonly found in Grade IV astrocytomas, contributing to its aggressiveness?
P53 inactivation
What is the primary difference in growth pattern between Grade II and Grade III astrocytomas in the brain?
Grade II demonstrates invasion of surrounding brain tissue
Which type of dementia is characterized by a faster decline in comparison to Lewy body dementia?
FTDs
What is a common feature that distinguishes vascular dementia from Alzheimer disease?
Depression and psychosis
Which of the following is NOT a common symptom associated with vascular dementia?
Memory loss
What pathology is characteristic of vascular dementia?
Small vessel changes due to arteriolosclerosis
In patients with vascular dementia, what feature distinguishes the progression from Alzheimer disease?
Step-wise progression corresponding to vascular insults
What are the two general types of cells/structures innervated by efferents in the ANS?
Visceral Organs and Glands
Where do the parasympathetic motor outputs originate from?
Brainstem and Sacral Spinal Cord
What are the two types of ganglia in the ANS transmission?
Sympathetic and Parasympathetic Ganglia
What do preganglionic neurons in the SNS do after entering the sympathetic trunk?
Synapse within the trunk at the same level
Where do the postsynaptic neurons in the ANS transmission project to?
Target tissues and organs
Which structure is closer to the spinal cord in the ANS transmission?
Presynaptic Neuron
Where do the neuronal cell bodies for myelinated preganglionic neurons in the parasympathetic nervous system reside?
Sacral spinal cord
In the sympathetic nervous system, where do myelinated preganglionic fibers synapse on ganglia?
Inside the sympathetic trunk
Which part of the autonomic nervous system controls voluntary (or reflex) actions in the head/neck region?
Cranial nerves
Where are the neuronal cell bodies for non-myelinated postganglionic neurons in the parasympathetic nervous system located?
Terminal ganglia
Where do non-myelinated post-ganglionic fibers originate in the sympathetic nervous system?
Paravertebral or prevertebral
Which type of ganglia are common to the parasympathetic nervous system?
Terminal
Where do postganglionic fibers exit to join a sympathetic trunk and travel to their target?
Gray rami communicantes
What type of nerve is formed by the fibers passing through the trunk and synapsing on a ganglion?
Postganglionic nerve
At what spinal levels do preganglionic fibers synapse on paravertebral ganglia for sympathetic innervation to the heart and lungs?
Thoracic
Which splanchnic nerve is correctly matched with its target and ganglion?
Lumbar/sacral splanchnic - distal colon to bladder, rectum, genitalia, lower abdominal organs - inferior mesenteric
Which atypical receptor type is activated by NE leading to increased calcium signaling?
Alpha-1 adrenergic receptor
Which signaling molecule is involved in inhibiting Adenylate Cyclase and reducing cAMP levels?
G-protein Gi
Which paravertebral ganglia are involved in sympathetic innervation to the skin and blood vessels?
Superior cervical
In which type of shock would activating beta-2 receptors be beneficial?
Anaphylactic shock
Which G-protein activates Adenylate Cyclase leading to increased cAMP levels?
Gs
What is the effect of activating Alpha-1 adrenergic receptors?
Activates PLC
Why is EpiPen® primarily carried by people with allergies?
To counteract breathing difficulties
What is the mechanism of an 'anticholinesterase' drug in increasing ACH responses?
Inhibiting the enzyme that breaks choline ester bonds
Which type of agonist would be most useful in treating anaphylactic shock to counteract vasodilation and bronchoconstriction symptoms?
Alpha 1 and beta 2 agonist
Which of the following is an action of 'anticholinergic' substances?
Inhibits ACH responses
To enhance ACH responses, one might use a drug with what mechanism?
Inhibits acetylcholinesterase
Which response is accurate regarding the better treatment choice between NE and E in anaphylactic shock?
E has strongest beta-2 effect for bronchodilation
Which enzyme is inhibited by anticholinesterase drugs to prevent the degradation of acetylcholine?
Acetylcholinesterase
Study Notes
Lipids Part 3b Prelearning: Beta Oxidation
Fatty Acid Activation
- Activation of a fatty acid to a fatty acyl CoA + CoASH
- Fatty acid + ATP → Fatty acyl CoA + CoA + AMP + PPi
- Uses one ATP molecule, but equivalent of two ATP's worth of energy
- Hydrolysis to AMP and PPi first, then PPi hydrolysis
Carnitine Transport System
- Required for fatty acyl CoA's to enter the mitochondria
- Involves:
- Transferase (cytosol) to transfer fatty acyl from CoA to carnitine carrier
- Translocator to move acyl-carnitine across inner membrane and move free carnitine out
- Transferase (matrix) to transfer fatty acyl from carnitine back to CoA
Beta Oxidation Sequence
- Fatty Acyl CoA → CAC for energy
- Fatty Acyl CoA → 2 carbons shorter Acetyl CoA + FADH2 + NADH
Energy Yield
- Determine number of acetyl CoA by dividing number of carbons by two
- Determine number of cycles by subtracting one from number of acetyl CoA
- Each acetyl CoA yields 3 NADH, 1 FADH2, and 1 GTP (equivalent to 12 ATP)
Citric Acid Cycle
- Also known as Krebs cycle or TCA cycle
- Final common pathway for catabolism/oxidation of glucose, fatty acids, and amino acids
- Produces 3 NADH, 1 FADH2, and 1 ATP (via GTP)
CAC Entry Points
- Glucose, fatty acids, and amino acids can feed into CAC
- Specific entry points for:
- Glucose: Pyruvate → Acetyl CoA
- Fatty acids: Acetyl CoA
- Amino acids: various
Lipids Part 3a Prelearning: Lipolysis
Lipolysis
- Breakdown of TG's to release free fatty acids and glycerol
- Takes place in adipose tissue and liver
- Fatty acids used for energy, glycerol used for gluconeogenesis
Hormone Regulation
- Hormone-sensitive lipase (HSL) regulated by glucagon, insulin, and epinephrine
Lipogenesis
- Storage of fatty acids as TG's in liver and adipose tissue
- Additional purpose of TG's in liver: combine with cholesterol, phospholipids, and proteins to make lipoproteins
Citric Acid Cycle Part 1a Prelearning: Intro to CAC with connections to beta oxidation and glycolysis
CAC Connections
- Glycolysis: pyruvate → acetyl CoA → CAC
- Beta oxidation: fatty acid → acetyl CoA → CAC
- Amino acids: various → acetyl CoA → CAC
CAC Overview
- Energy-producing pathway found in mitochondria
- Produces NADH, FADH2, and ATP (via GTP)
Check Your Knowledge
- Fatty acid activation: requires one ATP
- Carnitine transport system: required for fatty acyl CoA's to enter mitochondria
- Beta oxidation: yields acetyl CoA, NADH, and FADH2
- Citric acid cycle: final common pathway for catabolism/oxidation of glucose, fatty acids, and amino acids
- Lipolysis: breakdown of TG's to release free fatty acids and glycerolHere are the study notes for the text:
- Non-Shivering Thermogenesis*
- Newborn babies, hibernating animals, and cold-adapted animals need to generate more heat than is produced by normal metabolism
- They have lots of brown fat, which is brown due to a large number of mitochondria
- Brown fat contains thermogenin, a protein that uncouples the Electron Transport Chain (ETC) by translocating H+ back to the matrix, producing heat instead of ATP
- Electron Transport Chain (ETC)*
- Located in the mitochondrial inner membrane
- Comprised of four complexes (I, II, III, IV) and two electron carriers (Coenzyme Q and Cytochrome C)
- Produces ATP through chemiosmosis
- Glycerol Phosphate Shuttle*
- A shuttle system that generates 1 less ATP than the malate-aspartate shuttle
- Converts NADH to FADH2 in the intermembrane space
- Citric Acid Cycle (CAC)*
- Also known as the Krebs cycle or tricarboxylic acid (TCA) cycle
- Occurs in the mitochondrial matrix
- Acetyl-CoA is fed into the cycle, which produces 2 CO2, 3 NADH, 1 FADH2, and 1 GTP
- Amino acids can feed into the CAC through various entry points
- Catabolism of Molecules*
- Three types of molecules that can feed into the CAC:
- Glucose (via pyruvate)
- Fatty acids (via beta-oxidation)
- Amino acids (via various entry points)
- Beta-Oxidation*
- Occurs in the mitochondrial matrix
- Produces FADH2 and NADH, which enter the ETC
- Each round produces 1 acetyl-CoA, 1 FADH2, and 1 NADH
- Communication Between Catabolic Pathways*
- The three catabolic pathways (glycolysis, beta-oxidation, and CAC) produce indirect energy intermediates (NADH and FADH2) that feed into the ETC to generate ATP.
- Astrocytomas*
- A type of brain tumor that can occur in adults and children
- Can be benign or malignant
- Classified into four grades (I-IV), with grade IV being the most aggressive
- Oligodendrogliomas*
- A type of brain tumor that occurs in adults
- Found in the cerebral hemispheres, often in the white matter areas
- Cells resemble normal oligodendrocytes and are often surrounded by a capsule
- Signs and symptoms are typical of slowly increasing intracranial pressure
- Prognosis is generally better than that of astrocytomas
- Ependymomas*
- A type of brain tumor that arises from ependymal cells in the ventricular system
- Frequently block the central canal or are near the 4th ventricle in kids
- Can produce lots of CSF, causing communicating or noncommunicating hydrocephalus
- Prognosis is generally poor
- Meningiomas*
- A type of brain tumor that arises from meningothelial cells
- Attached to the dura, often in the cerebral hemispheres
- Pathological findings include rounded masses with a dural base that compress underlying brain tissue
- Prognosis is generally good
- Medulloblastomas*
- A type of brain tumor that occurs in children and adults
- Rapidly growing and highly anaplastic
- Can metastasize widely, including to the cauda equina
- Can obstruct CSF flow, causing hydrocephalus
- Prognosis is generally good with radiation therapy### Astrocytomas
- Grade II and III astrocytomas are more common in adults and are usually found above the tentorium in the cerebrum, but can also be found in the cerebellum or medulla.
- Grade II astrocytomas have poorly differentiated cells that invade surrounding brain tissue.
- Grade III astrocytomas have similar characteristics to Grade II, but with more mitotic figures and larger cells.
- Mutations associated with astrocytomas include:
- PTEN inactivation, leading to excessive signaling through the PI3K pathway.
- Increased EGF or PDGF receptor activity or expression.
- P16, p14, or p53 inactivation.
- IDH mutations, which produce 2-hydroxyglutarate, a metabolite that dysregulates epigenetic signaling in glial cells, leading to excessive activation of the RAS pathways.
Grade IV Astrocytomas (Glioblastoma Multiforme)
- This is the most common brain tumor in adults and has the worst prognosis.
- Characteristics include:
- Prominent hemorrhage and necrosis.
- Rapid growth.
- Tendency to invade adjacent tissue more than other types.
- Common mutations include p53 and EGFR.
Frontotemporal Dementia (FTD)
- FTDs involve progressive inability to form words or use language.
- Characteristics include:
- Constant, non-fluctuating course with rapid decline.
- More common in younger patients.
- Frequency decreases with age, while AD becomes more common.
Vascular Dementia
- Caused by multiple small infarcts (often affecting gray matter of the cortices) or hypertension (often affecting white matter).
- Common cause of dementia, second only to Alzheimer disease.
- Clinical presentation varies based on pattern of injury.
- Characteristics include:
- Depression and psychosis can be prominent features.
- Agitation can be dangerous to both the patient and the caregiver.
- Lack of motivation is common.
- Gait abnormalities are common, including gait apraxia.
- Lateralizing signs, such as increased tone/reflexes, often present.
- Progresses in a step-wise fashion, corresponding to discrete vascular insults.
MMSE (Mini-Mental State Examination)
- Assesses:
- Orientation.
- Short, recent, and remote memory.
- Sustained concentration.
- Executive functions.
- Recognition.
- Registration.
- Sequencing and organization.
- Comprehension.
- Perceptual-motor skills.
Autonomic Nervous System (ANS)
- Innervates:
- Smooth muscle.
- Cardiac cells.
- Glands.
- Divided into sympathetic and parasympathetic nervous systems.
- SNS:
- Myelinated pre-ganglionic fibers are shorter.
- Neuronal cell bodies are located in T1-L2 spinal levels.
- Synapse on ganglia inside or outside of the sympathetic trunk.
- Ganglia are paravertebral or prevertebral.
- Non-myelinated post-ganglionic fibers are longer.
- PaNS:
- Myelinated pre-ganglionic fibers are longer.
- Neuronal cell bodies are located in brainstem or sacral spinal levels.
- Synapse on ganglia outside of the sympathetic trunk.
- Ganglia are terminal or near the target.
- Non-myelinated post-ganglionic fibers are shorter.
Sympathetic Nervous System (SNS)
- Innervates:
- Heart.
- Lungs.
- Skin.
- Blood vessels.
- Preganglionic fibers synapse on paravertebral ganglia at different spinal levels.
- Paravertebral ganglia involved include:
- Superior cervical.
- Middle cervical.
- Inferior cervical/stellate.
Receptors and Neurotransmitters
- Nicotinic receptor: acetylcholine, N/A, ionotropic receptor, sodium channel opening.
- α1 adrenergic receptor: NE, Gq, activates PLC, IP3, DAG, increased calcium.
- α2 adrenergic receptor: NE, Gi, inhibits AC, decreased cAMP.
- β1 adrenergic receptor: E, Gs, stimulates AC, increased cAMP.
- β2 adrenergic receptor: E, Gs, stimulates AC, increased cAMP.
- M1 muscarinic receptor: acetylcholine, Gq, activates PLC, IP3, DAG, increased calcium.
- M2 muscarinic receptor: acetylcholine, Gi, inhibits AC, decreased cAMP.
Anaphylactic Shock
- Treatment involves:
- Alpha 1 agonist to counteract vasodilation.
- Beta 2 agonist to alleviate bronchoconstriction.
- Best choice is an alpha 1 and beta 2 agonist, such as epinephrine (E).
Test your knowledge on beta oxidation by identifying enzymes for saturated and unsaturated fatty acids, calculating the ATP production difference for each double bond, and understanding the process for odd-numbered fatty acids. Learn about key steps and energy production in beta oxidation.
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