Fill in the blanks
Frontal Lobe function
Sense of self, associated with reasoning and higher cognition
Temporal Lobe Function
auditory system and limbic system
Parietal lobe function
processing of sensory information and spatial navigation, language processing
occipital lobe
interpreting visual stimuli (primary visual cortex)
efferent sensory axons
from brain to body
afferent motor axons
neurons from body to brain
Fill in blanks + fissures/sulcus
Forebrain parts
telencephalon + diencephalon
Midbrain parts
mesencephalon
Hindbrain parts
metencephalon + myelencephalon
telencephalon parts
cerebral cortex, olfactory system, lateral ventricle
diencephalon parts
hypothalamus, thalamus, third ventricle
mesencephalon parts
tectum, tegmentum, cerebral aquiduct
metencephalon parts
cerebellum and pons
myelencephalon
medulla oblongata
embryo development of brain
Steps of development of nervous system 1 formation of the neural groove (dent in the system) 2 walls of the groove (neural folds) come together and fuse -> neural tube formed [ENTIRE CNS DEVELOPS FROM THE NEURAL TUBE] 3 bits of neural ectoderm that are pinched off – neural crest [FROM WHICH PNS WILL DEVELOP]
Anterior/rostral
Toward the nose
Posterior
Toward the tail
Dorsal
upper surface area
Ventral
Lower surface area
Medial
Toward the midline
Lateral
Away from the midline
Ipsilateral
2 structures on the same side of the body
Contralateral
2 structures on opposite side of the body
saggital plane
midline of the braind
Coronal plane
Plan that runs ear to ear
Ventricular system function and anatomy
Creates CSF
Meninges Anatomy
Ventral Ramus
Nerves of spinal cord, collects information for the brain
Dorsal Ramus
Nerves of spinal cord, commands muscle
Cingulate Gyrus 2. thalamus 3. corpus callosum 4. pineal body 5. fornix 6. hypothalamus 7. pons 8. cerebellum 9. medulla
Corpus Callosum function
Connects communication between the two hemispheres
Pineal Body Function
Neuroendocrine organ responsible for secreting melatonin
Fornix
Part of limbic system, connects the hippocampus and hypothalamus
Hypothalamus Function
Controls homeostasis
Pons Function
Connects the cerebellum and cerebral cortex
Cerebellum Function
Important movement control center, receives input from spinal cord and pons
Medulla Function
Contains sensory and motor neurons that control respiration, cardiac function, vasodilation and several reflexes (vital function control)
What is the resting potential?
The electrical potential difference across the plasma membrane when the neuron is not in a excited stage (-65mV)
Ionic concentration (high/low) inside and outside the cell during resting potential
Inside: High potassium (K+), low sodium (Na+) and chloride (Cl-), Outside: high sodium, high chloride, low potassium
Sodium-Potassium pump
Pump involved to maintain the resting potential, lets 2 K+ in, while 3 Na+ are pumped out. Uses ATP
Ion Channels vs Ion Pumps
Ion channels facilitate ion diffusion, similar to opening a gate (no energy), whereas ion pumps actively pump out/in ions (energy)
Membrane Anatomy
Phospholipid bilayer, hydrophilic heads, hydrophobic tails + channels + pumps
Action Potential Definition
An action potential is a signal that conveys informations over distance in the nervous system
Stages of Action Potential
Threshold reaching, 2. Rising Phase 3. Overshoot (+40mV), 4. Falling phase 5. Undershoot 6. refractory period
Threshold action potential meaning
The threshold is the membrane potential at which enough voltage-gated sodium channels open so the relative ionic permeability of the membrane favors sodium over potassium (initiation of the action potential)
Rising Phase action potential meaning
When the outside of the membrane has a negative electrical potentail, there is a large driving force on Na to enter the cell. Therefore, through rapid Na movement into the cell, the membrane depolarizes
Overshoot action potentail meaning
The relative permeability of the membrane greatly favors sodium, therefore sodium enters the cell where there is already a lot of K+ making it temporarily positive (40mv)
Falling phase action potential meaning
voltage gated sodium channels are inactivated 2. voltage gated potassium channels open --> potassium leaves cell, --> depolarization of cell --> negative membrane potential
Undershoot action potential meaning
The open voltage gated potassium channels stay open a little longer than needed, creating an undershoot
Absolute refractory period
Sodium channels are still inactivated from falling phase, therefore a new action potential is impossible
Relative refractory period meaning
Part where the cell is hyperpolarizing to resting potential, action potentials are possible but the threshold is higher
Action potential transfer through myelin/schwann
Myelin sheets insulate to facilitate fast transfer, action potential occurs in nodes of ranvier between myelin sheets.
Steps of chemical neurotransmission
Small neurotransmitters
Single amino acid neurotransmitters that are able to bind to ionotropic receptors to illicit APs (e.g. glutamate)
Large neurotransmitters
Neuropeptides that bind to G-coupled receptors and manipulate a cell through second messenger systems (e.g. epinephrine)
Gap junction and
Channels between adjacent cells that mediate the transfer of small neurotransmitters and electrical transmission
Hypothalamus endocrine function
Send and regulate the pituitary gland hormone release through releasing factors
How is the anterior pituitary activated by the hypothalamus?
Hypothalamic releasing factors travel to the anterior pituitary gland through a capillary system.
Hormones released by the anterior pituitary gland
thyrotropin, growth hormone, corticotropin, FSH, LH, prolactin
How is the posterior pituitary activated by the hypothalamus
Long axises from the hypothalamus extend into the posterior pituitary which activate the gland
Hormones released by the posterior pituitary gland
ADH, oxytocin
How are sex hormones regulated?
Hypothalamus --> anterior pituitary gland --> fsh+lh --> gonads --> estradiol/ testosterone --> negative feedback to hypothalamus and pituitary
How does the SRY gene affect development?
The SRY gene stimulates testes development through stimulating wolfian ducts to develop and mullarian ducts to degrade. Absence of SRY does the opposite. In reality, more genes are involved
What is a steroid hormone
Steroid hormones are derived from cholesterol and can therefore travel through the membrane. Within the cell, they bind to nuclear receptor. Together with the nuclear receptor, they bind directly to DNA to alter expression. The steroid hormone does not use second messengers as opposed to other hormones
Organisational vs activational effects of hormones
Organisational hormones organise tissue in an irreversible way (testosterone, estradiol), activational hormones activate usually temporary processes like hunger
What happens when Leptin levels rise?
A rise in leptin levels stimulates the release of MSH and CART from arcuate nucleus neurons. These peptides act on the brain, in part by activating the MC4 receptor, to inhibit feeding behavior and increase metabolism.
What happens when Leptin levels fall?
A fall in leptin levels stimulates the release of NPY and AgRP from arcuate nucleus neurons (situated in the hypothalamus), and the release of MCH and orexin from neurons in the lateral hypothalamic area. These orexigenic peptides act on the brain to stimulate feeding behavior and decrease metabolism.
Insulin
Is released into the bloodstream by the β cells of the pancreas Glucose needs insulin to be transported in the other cells of the body Important during anabolism AND catabolism When the levels of glucose are high in the blood: levels of insulin decrease When levels of glucose are low in the blood: levels of insulin increase insulin acts directly on the hypothalamus
Ghrelin
Released in the stomach and small intestines Stimulates hunger through NPY neurons in the hypothalamus
MCH and food
Leptin sensitive cells in the arcuate nucleus release MCH when leptin levels drop MCH system informs the cortex of leptin levels MCH induces feeding behaviour
Orexin and food
Receive input from arcuate nucleus Stimulates feeding behavior Levels rise when leptin levels decline Orexin promotes meal initiation, MCH prolongs consumption Also a role in wakefulness
CCK and food
released with gastric distension --> satiety
Dopamine and feeding
Dopamine induces food seeking behavior, however, does not play a big role in enjoyment of food
Serotonin and feeding
Serotonin is low in postabsorptive period, rise in anticipation of food and spike during a meal especially to carbohydrates
High level motor control
Associated with strategy, involves the basal ganglia and neocortex
Mid level motor control
represented by the motor cortex and cerebellum, is concerned with tactics: the sequences of muscle contractions, arranged in space and time, required to smoothly and accurately achieve the strategic goal.
Low level motor control
The lowest level, represented by the brainstem and spinal cord, is concerned with execution: activation of the motor neuron and interneuron pools that generate the goal-directed movement and make any necessary adjustments of posture.
Lateral corticospinal tract
Distal muscle control Cortex (area 4/6) --> internal capsule between telencephalon and thalamus --> cerebral peduncle --> pons --> medulla (medullary pyramid) --> runs down the ventral surface of the medulla (pyramidal tract) --> spinal cord
Ventromedial pathways (function)
voluntary movement of proximal muscles through multiple pathways, all originate in the brain stem
vastibulospinal tract (ventromedial)
originates in vastibular nuclei of the medulla and balances the body
tectospinal tract (ventromedial)
originates in the superior colliculus and receives input from auditory and visual stimuli. Helps orient head and eyes
Pontine reticulospinal tract (ventromedial)
originate from the reticular formation of the brain stem. Enhances antigravity reflexes of the spinal cord in the lower limbs
Medullary reticulospinal tract
Liberates the antigravity muscles from reflex control Counteracts pontine tract to keep balance
Basal ganglia and movement
The basal ganglia may facilitate movement by focusing activity from widespread regions of cortex onto the SMA. Importantly, however, they also serve as a filter that keeps inappropriate movements from being expressed.
Area 4 of the cortex
Primary motor cortex (M1)
Area 6 of cortex
Higher motor control Lateral area --> premotor area (PMA) Medial region --> supplementary motor area (SMA)
a. eye lids b. pupil c. sclera d. iris e. retina f. ciliary muscle g. cornea h. iris i. fovea j. optic nerve k. lens l. conjuctiva m. sclera
optic nerve
optic chiasm
lateral geniculate nucleus (LGN)
optic tract
visual cortex
Laminar organisation of the retina
How does light get transformed into neural activity
Light enters eye --> refraction into the fovea --> passes through ganglion and horizontel cells --> hits the photoreceptors --> transformed into neural activity --> horizontal cells --> ganglion cells --> action potential
Cones
Photoreceptors responsible for more detail and help with spatial sensitivity; have different types of photo pigments that are sensitive to different wavelengths of light
Rods
contain more membranous disks; help with night vision because they are more sensitive to light; responsible for seeing contrast
LGN
Situated in the dorsal thalamus, consists of 6 layers to filter and relay visual information
non-thalamic visual targets
pineal body --> melatonin / circadian rhtyhms superior colliculus --> eye and head movement
Light, visual hemifields and optic chiasm
Light form the right hemifields, hits the left part of the eye, light from the left hits the right part of the eye. In the optic chiasm, input from the right hemifields goes to the left brain, and input from left hemifield goes to the right brain