Lab 2 - Brain Flashcards
What do the brain and spinal chord develop from?
ectodermal neural tube
What are the four major parts of the brain?
brain stem, cerebellum, diencephalon, and cerebrum
What is the brain stem?
Consists of the medulla oblongata, pons, and midbrain and is continuous with the spinal chord
Is the diencephalon superior or anterior to brain stem?
superior
What does the diencephalon consist of?
thalamus, hypothalamus, and epithalamus
What area of the brain is the largest?
cerebrum
What are the brains protective coverings?
Cranium and cranial meninges
Cranial meninges are continuous and share names with what?
spinal meninges
What are the layers of cranial meninges?
dura mater, arachnoid mater and pia mater
The dura mater is what layer of the cranial meninges?
outer
The arachnoid mater is what layer of the cranial meninges?
middle
The pia mater is what layer of the cranial meninges?
inner
Difference between cranial dura mater and spinal dura mater?
the cranial dura mater has two layers; the spinal dura mater has only one
What are the two dura mater layers called?
Periosteal (outer) and minengeal (inner) layer
Role of the dura mater layers (dural layers)?
The dural layers around the brain are fused together except where they separate to enclose the dural venous sinuses (endothelial-lined venous channels) that drain venous blood from the brain and deliver it into the internal jugular veins. Also, there is no epidural space around the brain.
What is cerebrospinal fluid?
is a clear, colourless liquid composed primarily of water that protects the brain and spinal cord from chemical and physical injuries. It also carries small amounts of oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia.
Where does cerebrospinal fluid continuously circulate through?
cavities in the brain and spinal cord and around the brain and spinal cord in the subarachnoid space (the space between the arachnoid mater and pia mater)
Total CSF in adults?
80 to 150 mL
What molecules are found in CSF?
CSF contains small amounts of glucose, proteins, lactic acid, urea, cations (Na+, K+, Ca2+, Mg2+), and anions (Cl− and HCO3−); it also contains some white blood cells.
What are ventricles in relation to CSF?
CSF filled cavities in the brain
How many ventricles are there?
1 lateral ventricle (per side) separated by membrane septum pellucidum and the third ventricle is a narrow slitlike cavity along the midline superior to the hypothalamus and between the right and left halves of the thalamus. The fourth ventricle lies between the brain stem and the cerebellum.
3 main CSF functions?
mechanical protection, homeostatic function, circulation
what is mechanical protection of the CSF?
CSF serves as a shock-absorbing medium that protects the delicate tissues of the brain and spinal cord from jolts that would otherwise cause them to hit the bony walls of the cranial cavity and vertebral canal. The fluid also buoys the brain so that it ‘floats’ in the cranial cavity.
What is homeostatic function of CSF?
The pH of the CSF affects pulmonary ventilation and cerebral blood flow, which is important in maintaining homeostatic controls for brain tissue. CSF also serves as a transport system for polypeptide hormones secreted by hypothalamic neurons that act at remote sites in the brain.
What is CSF’s role in circulation?
CSF is a medium for minor exchange of nutrients and waste products between the blood and adjacent nervous tissue.
Where is the majority of CSF produced?
Choroid plexuses (network of capillaries in the walls of ventricles), with epidymal cells around it joined by tight junctions which secrete substances flowing through the choroid plexus.
What do ependymal cells surrounding the choroid plexus do?
Selected substances (mostly water) from the blood plasma, which are filtered from the capillaries, are secreted by the ependymal cells to produce the cerebrospinal fluid.
what creates the blood-cerebrospinal barrier?
tight junctions between ependymal cells, materials entering CSF from choroid capillaries cannot leak between these cells; instead, they must pass through the ependymal cells.
blood–cerebrospinal fluid barrier permeability ?
Semi-permeable: certain substances to enter the CSF but excludes others, protecting the brain and spinal cord from potentially harmful blood-borne substances.
Where is CSF reabsorbed?
arachnoid villi (fingerlike projections in the arachnoid mater)
The cerebral cortex has three main areas:
sensory, motor and association areas
Sensory areas:
receive sensory information and are involved in perception, the conscious awareness of a sensation
Motor areas:
control the execution of voluntary movements
Association areas:
deal with more complex integrative functions such as memory, emotions, reasoning, will, judgement, personality traits, and intelligence
Sensory areas are usually found:
behind central sulci (posterior)
What is found in the forebrain?
superficial (cortex, corpus callosum, parieto-occipital sulcus, calcarine sulcus, primary visual corex), basal ganglia, diencephalon
What is cortex?
grey matter thrown into ridges (gyri) and folds (sulci)
Corpus callosum is what?
A white matter tract carrying information between the hemispheres
what is the parieto-occipital sulcus?
a very deep sulcus that crosses the posterior part of the hemisphere and divides the internal occipital lobe from the parietal and internal temporal lobes
What is the calcarine sulcus?
The calcarine sulcus (or calcarine fissure) is an anatomical landmark located at the caudal end of the medial surface of the brain of humans and other primates.
Where is the primary visual cortex found? What is its role?
Centred on the calcarine sulcus in the occipital lobe (bottom front), receives visual information and is involved in visual perception
Basal ganglia are found where in the forebrain?
buried deep within each hemisphere
Diencephalon in the forebrain hold what?
The thalamus, hypothalamus, pituitary gland, third ventricle
What does the thalamus do?
relays almost all sensory input to the cortex
What does the hypothalamus do?
controls internal body functions and the autonomic nervous system
Where is the pituitary gland and what is it controlled by?
attached and controlled by the hypothalamus (always torn off when brain is removed from the skull)
What is in the midbrain?
Superior/inferior colliculi, cerebral aqueduct, cerebral peduncles
What do the superior and inferior colliculi of the midbrain do?
found at roof of midbrain, minor role in controlling eye movements and movements related to auditory stimuli
Cerebral aqueduct is found where?
narrow passage linking the 3rd and 4th ventricles (thick as a matchstick)
What do cerebral peduncles do and what are they made up of (midbrain)?
carry info between cerebral cortex and the spinal chord (corticospinal fibres) and cortext to pons (corticopontine fibres). They are thick white matter tracts making up the floor of the midbrain
What is found in the hindbrain?
cerebellum, pons, medulla, fourth ventricle
