central nervous system- lecture 8 Flashcards
peripheral nervous system
stimulus detected by sensory receptors- stage 1 (detection) turns this into sensory info, stage 2 (recognition) sends to spinal cord, stage 3 (decision) turns into motor commands to either somatic or autonomous nervous system, stage 4 (execution) e.g. in skeletal muscles
anatomical directions
When describing the CNS we use directional terms described relative to an imaginary line drawn through the spinal cord and the front of the brain (neuraxis)
ventral
toward front of body or towards the bottom of the head
dorsal
towards the back of the body or towards top of head
anterior/rostal
nose end
prosterior/caudal
tail end
lateral
towards the sides
medial
towards the middle
bilateral
on both sides of the body or head
ipsilateral
on the same side of the body or head
contralateral
on the opposite side of the body or head
anatomical planes
- coronal (like a slice of bread)
- sagital (lik cutting a roll of a hot dog)
- horizontal (like cutting a burger bun)
resourcing the brain
the brain cannot store glucose
it relies on constant supply of blood for glucose and oxygen
interruption in supply uses all the brains resources
interruption causes consciousness
a few mins interruption can cause brain damage
blood supply to CNS
a vast circulatory system to ensure constant supply of resources
protecting the CNS
- skull and spine
- meninges
- blood-brain-barrier
- ventricular system
skull and spine
brain and spinal cord are delicate and require protection
meninges
between skull and brain/ spinal cord and spinal column, outer layer=thick tough and flexible, middle layer= web like sheet of tissue filled with cerebrospinal fluid, inner layer= thin with rich blood supply(infection in meninges is known as meningitis)
blood-brain-barrier
the CNS cant kill viruses, BBB keeps out harmful substances (viruses, bacteria), small/uncharged molecules can pass through, active transport system pumps essentials into brain (glucose/amino acids/hormones)
ventricular system
the brain floats in a bath of protective fluid (cerebrospinal fluid), CSF flows around subarachnoid space (meninges), 4 ventricles in the brain
hind brain
myelencephalon and mentecephalon
myelencephalon
medulla oblongata- control of vital functions- cardiovascular system, respiration, musce tone- through recieving info on heart rate, blood pressure, o2 and co2 levels
metencephalon
the pons (bridge) (serves as linke between hind brain and midbrain) communicates to motor cortex and sense organs, voluntary muscle movement, maintenance of balance and equilibrium, muscle tone and posture
mid brain
mesencephalon- tectum (roof) and tegmentum (covering), major pathway for sensory and motor impulses between forebrain and hindbrain- tectum- auditory and visual communication, tegmentum- sensory processes, movement, motor control (substantia nigra)
forebrain
diencephalon and telencephalon
diencephalon
thalamus (chamber) recieves sensory info and relays to sensory processing in cortex. hypothalamus- connected to pituitary gland- regulation of ANS and endocrine system
telencephalon
(the hemispheres)- the limbic system- a group of structures involved in stress and emotion, memory storage and retrieval- 1) cingulate gyrus- control of emotional behaviour, 2) fornix (arch)- links hippocampus to hypothalamus, 3) hippocampus- involved in learning and memory and also detection of threat/emotionally charged memories 4)amygdala- emotional processing and motivation
bumps and grooves
3 major grooves divide the cortex, longitudinal fissure, central sulcus, lateral fissure
the grooves form 4 major divisions (lobes)- 1) central sulcus divides frontal lobe from parietal lobe, 2) lateral fissure- divides temporall lobe from frontal, parietal and occipital lobe.
functions
medulla-brainstem and cerebllum (basic functions), limbic system (behaviours essential for surivival), cerebral cortex (higher order functions)
