Physio1 Flashcards
1
Q
What percentage of oxygen is required by the brain?
A
20% of O2 required
2
Q
How long does total cessation of blood flow lead to unconsciousness?
A
5-10 seconds
3
Q
How long can the brain survive without blood flow before damage occurs?
A
~ 5 minutes
4
Q
What are the three components of the skull?
A
- Brain tissue
- Blood
- CSF
5
Q
What is the normal range for arterial blood pressure (ABP) in autoregulation?
A
50 - 160 mm Hg
6
Q
What is the arterial blood pressure (ABP) level for a hypertensive patient?
A
180 mm Hg
7
Q
What is myogenic autoregulation?
A
Smooth muscle response to stretch by contraction
8
Q
How do arterioles respond to increased arterial blood pressure?
A
They dilate or constrict to maintain constant cerebral blood flow
9
Q
What happens to the vascular wall with increased ABP?
A
Stretch of the vascular wall occurs
10
Q
What is the effect of smooth muscle contraction on cerebral blood flow?
A
Decreases CBF back to its normal level
11
Q
What factors affect cerebral blood flow?
A
- Cerebral perfusion pressure (CPP)
- Radius of cerebral blood vessels
12
Q
Cerebral blood flow depends on changes in _______.
A
[cerebral perfusion pressure (CPP)]
13
Q
True or False: Metabolic autoregulation involves local changes in brain metabolites.
A
True
14
Q
What metabolic factors influence Cerebral Perfusion Pressure?
A
- CO2 concentration
- Hydrogen ions concentration
- O2 concentration
15
Q
What is the effect of hydrogen ions (H+) on cerebral blood flow?
A
H+ concentration leads to vasodilation.
16
Q
What happens when O2 concentration is low?
A
Cerebral blood flow is regulated to increase blood supply.
17
Q
What factors disturb the autoregulation of cerebral blood flow?
A
- Hypoxia
- Trauma
- Brain compression (tumors, hematoma, cerebral edema)
18
Q
What leads to an increase in Intracranial Pressure?
A
Any increase in brain tissue, blood, or CSF
19
Q
What are normal compensatory mechanisms for maintaining ICP?
A
- Absorption of CSF
- Production of CSF
- Displacement of CSF into spinal subarachnoid space
20
Q
True or False: An increase in brain tissue will decrease Intracranial Pressure.
A
False
21
Q
What is the role of metabolic autoregulation in cerebral blood flow?
A
It adjusts blood flow based on metabolic needs.
22
Q
What is the Cushing response?
A
A physiological response to raised Intracranial Pressure (ICP) characterized by hypertension and bradycardia
The Cushing response occurs when ICP exceeds mean arterial pressure (MAP).
23
Q
List three pathological conditions that can cause a rise in Intracranial Pressure (ICP).
A
- Hydrocephalus
- Meningeal diseases
- Choroid plexus tumour
24
Q
What is the role of baroreceptors in relation to ICP?
A
They help regulate blood pressure and can influence heart rate through vagus nerve stimulation.
25
What are the major types of stroke?
* Ischemic stroke
* Hemorrhagic stroke
26
What treatments are commonly used for strokes?
* Anticoagulants
* Antiplatelets
* Antihypertensives
* Angioplasty / stents
* Surgery
27
Why is the brain considered metabolically fragile?
* High rate of energy consumption
* Low glycogen storage
* Rapid cellular damage when ATP is depleted
28
Describe the dura mater.
Composed of two layers: periosteal (outer) and meningeal (inner).
29
What is the arachnoid layer known for?
It is spider web-like in appearance.
30
What is the function of the subarachnoid space?
It is filled with cerebrospinal fluid (CSF) and contains blood vessels supplying the brain.
31
Fill in the blank: The _______ is a delicate layer of the meninges that follows the convolutions of the brain.
Pia mater
32
What can raised ICP lead to in terms of cardiovascular responses?
Hypertension and tachycardia.
33
What happens during cerebral compression?
It can occur due to cerebral abscesses or other mass effects.
34
True or False: The brain has a high glycogen storage capacity.
False
35
What are the components of the arachnoid layer?
* Arachnoid membrane
* Arachnoid trabeculae
* Subarachnoid space
36
What are the roles of Cerebrospinal Fluid (CSF)?
* Buffer brain to prevent mechanical injury
* Nourish brain and carry chemical signals
* Exchange gases (O2, CO2), nutrients, and wastes
## Footnote
CSF is essential for maintaining homeostasis in the central nervous system.
37
What is produced by the choroid plexuses?
Cerebrospinal Fluid (CSF)
## Footnote
Choroid plexuses are specialized structures in the ventricles of the brain.
38
What occurs during Stage I of CSF formation?
Ultrafiltration of plasma occurs across the fenestrated capillary wall into the extracellular fluid (ECF) beneath the basolateral membrane of the choroid epithelial cell.
## Footnote
This process is essential for initiating CSF production.
39
What happens during Stage II of CSF formation?
Choroid epithelial cells secrete fluid into the venous system.
## Footnote
This secretion is crucial for the continuous production of CSF.
40
What is the net transfer involved in CSF production?
* NaCl
* NaHCO3
## Footnote
This transfer is fundamental for the ionic balance of CSF.
41
How does the choroid plexus condition CSF?
By absorbing K+.
## Footnote
This absorption helps maintain the chemical environment of CSF.
42
What mechanism is involved in CSF absorption?
Transcytosis
## Footnote
This mechanism ensures a one-way direction for CSF movement.
43
What is the relationship between CSF pressure and venous blood pressure?
CSF pressure is greater than venous blood pressure.
## Footnote
This difference is critical for the flow of CSF.
44
What are the chemical contents of normal CSF?
* Low level of blood cells
* Normal glucose levels
* Low protein levels
## Footnote
Abnormal levels can indicate various medical conditions.
45
What indicates hemorrhage in CSF?
Presence of red blood cells (RBC).
## Footnote
This can suggest bleeding in the central nervous system.
46
What does turbid CSF indicate?
An infectious process.
## Footnote
This turbidity can result from the presence of pathogens or inflammatory cells.
47
What does a yellow color in CSF suggest?
Excessive protein due to blood breakdown.
## Footnote
This can be a sign of a pathological condition.
48
What is the typical position for a lumbar puncture?
Lateral decubitus (L4-5) or sitting.
## Footnote
These positions allow for optimal access to the spinal canal.
49
What are the purposes of obtaining CSF samples?
* Cell count
* Protein levels
* Glucose levels
* Microbiology
* CSF pressure
* CSF removal
* Drug introduction
## Footnote
Each of these assessments provides critical information about the patient's condition.
50
What does a CSF cell count greater than 1000/µL indicate?
Bacterial infection (leukocytosis).
## Footnote
This is a significant indicator of infection in the central nervous system.
51
What is the normal glucose concentration in CSF relative to plasma?
60% of plasma glucose concentration.
## Footnote
This ratio is vital for assessing metabolic activity in the brain.
52
What conditions can lead to decreased glucose levels in CSF?
* Bacterial meningitis
* Tuberculous meningitis
* Neurosyphilis
## Footnote
These conditions can severely affect the brain's metabolism and require urgent medical attention.
53
What does intrathecal production of IgG indicate?
Intrathecal inflammation.
## Footnote
This finding can suggest various neurological disorders.
54
55
What is Hydrocephalus?
Excess water in the cranial vault
## Footnote
Hydrocephalus can lead to increased intracranial pressure.
56
What are the types of Hydrocephalus?
* Communicating Hydrocephalus
* Non-communicating Hydrocephalus
57
What characterizes Communicating Hydrocephalus?
No blockage in the CSF flow in ventricles; blockage occurs in subarachnoid spaces or arachnoid villi
## Footnote
This prevents normal absorption of CSF into venous sinuses.
58
What characterizes Non-communicating Hydrocephalus?
Blockage of CSF flow, commonly at the level of aqueduct or foramina of Luschka and Magendie
## Footnote
This type obstructs the flow within the ventricular system.
59
What is the common treatment for Hydrocephalus?
VP SHUNT or VA SHUNT
## Footnote
Shunts help to redirect excess CSF to relieve pressure.
60
What are some common types of shunts?
* Ventriculoperitoneal (VP)
* Ventriculoatrial (VA)
* Ventriculopleural (VPL)
* Lumboperitoneal (LP)
61
What does a Ventriculoperitoneal (VP) shunt connect?
Ventricles to peritoneal cavity
62
What does a Ventriculoatrial (VA) shunt connect?
Ventricles to right atrium of heart
63
What does a Ventriculopleural (VPL) shunt connect?
Ventricles to pleural cavity
64
What does a Lumboperitoneal (LP) shunt connect?
Lumbar spine to peritoneal cavity
65
What is the Blood Brain Barrier (BBB)?
Protects the brain and maintains the environment
## Footnote
It regulates the entry of substances into the brain.
66
What is the composition of the Blood Brain Barrier?
* Continuous endothelium of capillary walls
* Thick basal lamina around capillaries
* Feet of astrocytes
67
What is a key function of the Blood Brain Barrier?
Acts as a selective barrier for water-soluble compounds and nutrients
## Footnote
It allows certain substances to pass while blocking others.
68
What types of substances can pass through the Blood Brain Barrier?
* Water-soluble nutrients/metabolites (glucose, amino acids)
* Uncharged/lipid-soluble substances (alcohol, caffeine, nicotine, heroin, anesthetics)
69
What connects the endothelial cells in the Blood Brain Barrier?
Continuous tight junctions
70
What is the importance of the tight junctions in the Blood Brain Barrier?
They make the capillaries relatively tight, regulating substance passage
## Footnote
This prevents unwanted substances from entering the brain.
71
True or False: The Blood Brain Barrier allows all substances to pass freely.
False
72
What type of diffusion allows small water-soluble molecules to pass through the BBB?
Paracellular (aqueous) diffusion
## Footnote
This process occurs through tight junctions in the blood-brain barrier.
73
What is transcellular (lipophilic) diffusion?
Diffusion of small inorganic molecules through the lipid plasma membrane of endothelial cells
## Footnote
Examples include O₂, CO₂, NO, and H₂O.
74
What triggers the transport of solutes like glucose or amino acids across a membrane?
Binding to a protein transporter
## Footnote
This process involves a conformational change in the protein to facilitate transport.
75
What energy source may be used for transporting compounds against a concentration gradient?
ATP
## Footnote
ATP provides the energy necessary for active transport mechanisms.
76
Name two factors that use receptor-mediated endocytosis at the BBB.
Insulin-like growth factors (IGF-I, IGF-II), angiotensin II
## Footnote
Other examples include atrial and brain natriuretic peptide (ANP, BNP) and IL-1.
77
What does adsorptive-mediated transcytosis (AMT) initiate with?
Uptake through clathrin-coated pits or caveolae
## Footnote
This is the initial stage of transcytosis at the BBB.
78
Is transcytosis at the BBB an energy-requiring process?
True
## Footnote
Transcytosis is ATP-dependent for both uptake and transport across endothelial cells.
79
What pathological states primarily affect the BBB?
BBB breakdown or disorder
## Footnote
These conditions mainly disrupt tight junctions in the BBB.
80
What is a common use of mitotic inhibitors?
Cancer chemotherapy
## Footnote
These drugs are used to inhibit cell division in cancer treatment.
81
82
What are microglia cells?
Microglia cells are the only immune cells in the CNS that originate from mesoderm.
## Footnote
Microglia are rapidly activated by injury to the brain and are the most effective antigen-presenting cells.
83
What is cerebral edema?
Cerebral edema is the accumulation of fluid within the cerebral parenchyma.
## Footnote
Types of cerebral edema include cytotoxic, vasogenic, hydrostatic, osmotic, and hydrocephalic.
84
What are the two types of astrocytes?
* Fibrous astrocyte: mainly in white matter, have long, thin, well-defined processes
* Protoplasmic astrocyte: mainly in gray matter, short and bushy processes
85
What percentage of total metabolic use does the brain account for during the resting stage?
The brain accounts for 15% of total metabolic use during the resting stage.
## Footnote
The brain has a metabolism that is several times that of non-nervous system tissue.
86
What is the primary energy requirement of the brain?
Most energy in the brain is used for ion regulatory functions.
87
What type of glucose transporters does the brain require?
The brain requires insulin-independent glucose transporters (GLUT).
88
How do astrocytes handle potassium?
* Na+/K+ ATPase cotransporter
* K+ channels
89
Fill in the blank: K+ is taken up by an astrocyte in a _______.
[region of high K+]
90
What role do astrocytes play in the glutamate-glutamine cycle?
Astrocytes are involved in the recycling of glutamate and glutamine.
91
What do glial cells contain that is important for myelination?
Glial cells contain most of the enzyme carbonic anhydrase within the brain.
92
What are the two proteins related to iron that glial cells contain?
* Ferritin (iron storage protein)
* Transferrin (iron transport protein)
93
What is the chemical reaction facilitated by carbonic anhydrase?
CO2 + H2O ↔ H2CO3 ↔ HCO3- + H+
