Blood-brain Barrier, Hypothalamus And Temperature Regulation Flashcards
(49 cards)
What is the blood-brain barrier (BBB)?
A highly selective barrier that separates circulating blood from the extracellular fluid surrounding brain tissue and the CNS
What are the pharmacological implications of the BBB?
It keeps the brain tissue separate from harmful pathogens, bacteria, and chemicals, maintaining a constant environment for the CNS
What substances can cross the BBB?
Lipid soluble substances, water, CO2, and O2
What does the BBB prevent from entering the brain or CSF?
Proteins
Fill in the blank: Water-soluble substances are generally not permeable, but some specific molecules may pass due to _______.
[carrier-mediated and active transport mechanisms]
What specific transporter is responsible for glucose transport across the BBB?
GLUT 1 transporter
What types of substances have specific transporters that can cross the BBB?
- Glucose
- Amino acids
- Hormones
Where are the areas in the brain that interact with blood vessels and are vulnerable to unwanted substance entry?
Capillaries and small vessels
What structures provide the BBB?
- Tight junctions between endothelial cells
- Thick basement membrane
- Astrocytes with feet-like projections
What is the role of astrocytes in the BBB?
They secrete substances that help decrease the permeability of endothelial cells
What are the general functions of the hypothalamus?
[General functions include regulation of homeostasis, temperature, hunger, thirst, sleep, and emotional activity]
What is the specific function of the hypothalamus in temperature regulation?
[Maintaining body temperature within a narrow range]
What can break down the BBB and increase the chances of infection within the brain?
Areas of damage, infection or inflammation
The blood-brain barrier (BBB) is a selective permeability barrier that protects the brain from pathogens and toxins.
What types of drugs face serious problems accessing the brain due to the BBB?
Non-lipid soluble drugs, protein antibodies, antibiotics
These substances are typically unable to cross the BBB effectively.
What is a current strategy to overcome BBB limitations for drug access?
Increase plasma concentration of smaller precursor molecules
Examples include L-dopa and 5-hydroxytryptophan, which can produce larger molecules like dopamine and serotonin.
What type of nanoparticles are being researched to carry drugs across the BBB?
Lipid-soluble nanoparticles
These may accumulate in specific regions of the brain.
What is associated with cancerous tumour growth that can breach the BBB?
New blood vessel growth
These vessels can be targeted by chemicals that bind to molecules associated with their growth.
Name some regions in or near the brainstem that have fenestrated capillaries.
Neurohypothesis of the pituitary, area postrema, subfornical region, organum vasculosum of the lateral terminalis
Collectively known as the circumventricular organs.
What do circumventricular organs allow to enter the general circulation?
Some hormones produced in the pituitary
They are sensitive to blood constituents like glucose and angiotensin.
Where is the hypothalamus located?
Below the thalamus, just above the brainstem
It is a deep and primitive part of the brain.
What are the hypothalamus’s primary functions?
Control of body homeostasis, regulation of vegetative functions
Includes temperature regulation, cardiovascular variables, feeding, body water regulation, and endocrine control.
How does the hypothalamus affect behavior?
Communicates with the limbic system and thalamus to the cerebral cortex
Important for states of alertness and emotion.
What size is the hypothalamus approximately?
About the size of an almond
Despite its small size, it has many varied functions.
What type of functions does the hypothalamus control that we do not need to think about?
Vegetative functions
These include involuntary processes such as heart rate and body temperature regulation.
