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Flashcards in The Brain Deck (29):
1

Human Brain size

-weight
-2 directional terms

-Weight; 1.35-1.4kg
Directional terms: Rostral (toward nose)
-Caudal (toward tail)

2

4 major regions of human brain

1. Cerebrum
2. Diencephalon
3. Brainstem (midbrain, pons, medulla oblongata)
4. Cerebellum

3

Organisation of Neural Tissue areas in brain (2)

1. Gray Matter
-houses motor neuron & interneuron cell bodies, dendrites, telodendria, unmyelinated axons
-forms cortex which overs surface of most of adult brain
-forms discrete internal clusters called cerebral nuclei
2. White matter:
-made up of myelinated axons
-lies deep to gray matter of the cortex

4

Support & Protection of brain

-4 roles of Cranial meninges

-3 layers

-Cranial Meninges are CT layers that;
-separate soft tissue of brain from bones of cranium
-enclose & protect blood vessels that supply brain
-contain & circulate cerebrospinal fluid
-form some of veins that drain blood from brain

Layers; dura mater, arachnoid mater, pia mater

5

Cranial meninges; layers (3)

1. Dura Mater
-External tough dense irregular CT
-2 layers of fibrous layers which separate to form large blood fills spaces (DURAL VENOUS SINUSES - is where deoxygenated blood leaves) connects to jugular vein to drain blood from the head
2. Arachnoid Mater
-spider web structure - collagen & elastic fibres
-subarachnoid space between AM and PM
-potential space between AM & DM = subdural space where subdural hematomas form
3. Pia Mater
-innermost cranial meningeal layer
-Thin areolar tissue, highly vascularised and adheres to the brain
-directly in contact w/ brain -> follows grooves

6

Brain Ventricles

-Ventricles = cavities or expansions w/in brain that are continuous w/ one another & central canal of spinal cord
-all contain cerebral spinal fluid
Are 4 ventricles;
-2 lateral ventricles, one in each hemispheres of cerebrum (separated by thin septum pellucidum)
-third ventricle in diencephalon
-fourth ventricle b/w pons and cerebellum

7

Cranial Dural Septa

-Dural mater creates divisions w/in brain -> creates different divisions

8

Cerebrospinal Fluid

-what it is

-3 functions

-is a clear, colourless liquid that circulates in the ventricles & subarachnoid space
FUNCTIONS
-Buoyancy: takes 95% of brain's weight (brain floats in CSF)
-Protection: provides liquid cushion from sudden movements
-Environmental stability: transports nutrients & removes waste from brain (involved in homeostatic properties)

9

Blood-Brain Barrier

-what it does
-cells that contribute to BBB
-3 locations where it is missing or reduced & why

-strictly regulates what substances can enter the interstitial fluids of brain
-Capillary endothelial cells and astrocyte perivascular feet contribute to BBB
Missing or reduced in 3 locations;
-Choroid plexus
-Hypothalamus
-pineal gland

*Choroid plexus - must be permeable to produce CSF
*other 2 = produce hormones that must have ready access to bloodstream

10

Cerebrum

-what it does

-is location of conscious thought processes & origin of intellectual functions
-large no. of neurons that needed for complex analytical & integrative functions
-left & right hemispheres
*largest part of brain

11

Cerebrum

-what formed from
-outer layer & internal layer (what matter)
-cerebral nuclei
-gyri and sulci and fissures

-Formed from telencephalon
-outer layer = cerebral cortex & is gray matter
-internal layer = white matter
-cerebral nuclei = deep to white matter are discrete regions of gray matter
-surface of cerebrum folds into elevated ridges called gyri (contours of brain)
-Adjacent gyri separated by shallow sulci or deeper grooves called fissures

12

Cerebral Hemispheres

-how many & how separated

-Corpus callosum

-cerebrum composed of 2 halves (left & right cerebral hemispheres)
-divided by a longitudinal fissure along midsaggital plane
-hemispheres separated from each other except at few locations where bundles of axons called tracts form white matter regions that allow comm. b/w them
-Corpus Callosum: largest tract & main tract that connects the two hemispheres

13

Lobes of Cerebrum (5 distinct lobes)

1. Frontal lobe: concentration, communication & personality
2. Parietal lobe: sensor, texture and shape
3. Temporal lobe: hearing and smell
4. Occipital lobe: processing visual information and visual memories
5. Insula: memory and taste

14

Frontal lobe (Cerebrum)

-location
-boundaries
-precentral gyrus
-what involved in

-Located deep to frontal bone
-ends posteriorly at central sulcus - inferior border marked by lateral sulcus
-Precentral gyrus is mass of nervous tissue in frontal lobe immediately anterior to central sulcus
*involved w/ voluntary motor function, conc., verbal comm, decision making, planning & personality

15

Parietal Lobe (Cerebrum)

-Where it is
-boundaries
-what involved with

-Forms superoposterior part of each hemisphere (underlies parietal bone)
-Terminates anteriorly at central sulcus, laterally at lateral sulcus & posteriorly at parietao-occipital sulcus
-postcentral gyrus is mass of nervous tissue in parietal lobe immediately posterior to central sulcus

*involved w/ general sensory functions

16

Temporal lobe (Cerebrum)

-where located
-what involved in

-Located inferior to lateral sulcus underlying temporal bone
-Involved w/ hearing and smell

17

Occipital lobe (Cerebrum)

-where located

-what it does

-Located in posterior region of each hemisphere underlying occipital bone
-Processes incoming visual information
-Stores visual memories

18

Insula (Cerebrum)

-where located
-what involved in

-located deep to lateral sulcus
-involved in memory & interpretation of taste

19

Functional areas of cerebrum (3 areas)

-what they do

1. Motor areas: control voluntary motor functions
2. Sensory areas: provide conscious awareness of sensation
3. Association areas: integrate and store information

20

Motor Areas (3)

1. Primary Motor Cortex (somatic motor area)
-controls voluntary skeletal muscle activity; located within precentral gyrus (anterior to central sulcus)
2. Motor speech area (Broca's area)
-controls muscular movements necessary for vocalization
3. Frontal eye field
-controls and regulates eye movements and binocular vision

21

Diencephalon - 3 components

-what they do

-Components include;
Epithalamus: pineal gland involved in circadian rhythms
Thalamus: filters background info before relaying it to cerebrum
Hypothalamus: controls ANS & endocrine system; regulates body temp, emotional behaviour, food intake, water intake & sleep

22

Functions of Hypothalamus (7)

-Master control of ANS
-Master control of endocrine system
-Regulation of body temp
-Control of emotional behaviour
-control of food intake
-control of water intake
-regulation of sleep-wake (circardian) rhythms

23

Brainstem

-what it does

-connects forebrain & cerebellum to spinal cord
-is bidirectional passageway for all tracts extending between cerebrum & spinal cord
-Contains many autonomic centers and refex centers
-houses nuclei of many of cranial nerves

24

Brainstem: 3 regions

1. Mesencephaon: mid brain
2. Pons: Sensory & motor tracts connect brain to spinal cord
3. Medulla Oblongata: vital autonomic nuclei for regulating functions relating to;
-cardiac centre (heart rate)
-vasomotor centre (blood pressure)
-respiratory centre (respiratory rate)
-others (coughing, sneezing, swallowing, gagging)

25

Cerebellum

-folia

-2nd largest part of brain
-has complex, highly convoluted surface covered by layer of cerebellar cortex w/ folds called folia
-left and right cerebellar hemispheres
-each hemisphere = 2 lobes (anterior & posterior - separated by primary fissure)

26

Cerebellum - 3 regions

1. An outer gray matter layer of cortex
2. Internal region of white matter, called arbor vitae
3. Cerebellar nuclei in deepest layer

27

Cerebellar Functions - 3

-Coordinates and fine-tunes skeletal muscle movements and ensures that skeletal muscle contraction follows correct pattern leading to smooth, coordinated movement
-stores memories of previously learned movement patterns
-receives proprioceptive info from muscles and joints - uses this info to regulate body's position

28

Limbic system

-structure
-what it affects

-structures of limbic system form a ring around diencephalon
-composed of multiple cerebral and diencephalic structures that collectively process and experience emotions
-affects memory formation through integration of past memories of physical sensations w/ emotional states

29

Cranial nerves

-12 pairs
-numbered w/ roman numerals by their position (beginning w/ most anteriorly placed nerve)
-names generally related to function