Week 4 Bioscience

Question 1

Brain

Answer 1

• Receives, localises & interprets sensory input
• Generates the motor output (somatic & autonomic) that controls the activities of muscles & glands
• Is responsible for our emotions, behaviours, and personality
• Performs intellectual (cognitive) functions
• Stores memories

Question 2

Cerebrum

Answer 2

• Largest part of the brain
• Divided into two cerebral hemispheres by the longitudinal fissure (fissure = deep groove)
• Separated from the cerebellum by the transverse fissure
• Externally, each cerebral hemisphere is divided into five lobes - frontal, parietal, temporal, occipital, insula

Question 3

Cerebral Cortex (outer gray matter)

Answer 3

Contains nuclei that:
- receive, localise and interpret sensory input
- control voluntary skeletal muscle movements
- perform intellectual and language functions
- store memories
- control our emotions, behaviours and determine personality

Question 4

Primary Motor Cortex (PMC)

Answer 4

• Located in the precentral gyrus of each frontal lobe
• Generates the somatic motor output that stimulates voluntary skeletal muscle movements
• Specific areas are devoted to controlling specific body parts
  -the amount of primary motor cortex devoted to controlling a body part is proportional to the complex nature of its movements
• Damage = paralysis
  -loss of voluntary movements

Question 5

Sensory Areas of the Cerebral Cortex

Answer 5

• Are located in the insula, parietal, temporal and occipital lobes
• Allow us to become consciously aware of (perceive) sensations originating from:
  -general sensory receptors for pain, temperature, touch, vibration, pressure, proprioception
  -special sensory receptors for vision, smell, taste, hearing, balance

Question 6

Primary Somatosensory Cortex (PSC)

Answer 6

· Located in the postcentral gyrus of each parietal lobe
· Receives general sensory information
· Perceives sensations of touch, pain, vibration, pressure, temperature & proprioception
· Locates the origin of the stimulus (sensory input)
· specific areas receive sensory input from a specific part of the body
-the amount of sensory cortex devoted to a particular body part depends on the number of receptors it has

Question 7

Somatosensory Association Area

Answer 7

• Receives general sensory input from the primary somatosensory cortex
• Interprets general sensory input and compares it to stored memories of past sensory experiences so that you can recognise an object by touch alone
• Damage = failure to identify objects by touch alone

Question 8

Visual Areas

Answer 8

• Located in each occipital lobe
• Visual cortex
  -receives visual input detected by photoreceptors
  -damage = blindness
• Visual association area
  -interprets visual input - allows us to recognise what we see
  -stores memories of past visual images
  -damage = failure to recognise objects

Question 9

Auditory areas

Answer 9

• Located in each temporal lobe
• Auditory cortex
  -receives sound input detected by the hair cells in the ear to produce & locate sounds
  -damage = deafness
• Auditory association area
  -interprets auditory input - allows us to recognise sounds
  -stores memories of past sounds
  -damage = failure to recognise what is heard

Question 10

Wernicke’s Area

Answer 10

• Usually located in left temporal lobe (left hemisphere) only
  Damage = Wernicke’s aphasia
• Comprehends written and spoken language

Question 11

Prefrontal Cortex (a.k.a. anterior association area)

Answer 11

• Located in each frontal lobe
• Is responsible for our intellect, complex learning abilities (cognition), personality and behaviour
• Damage = personality changes
• responsible for intellect, cognition, personality and behaviour

Question 12

Cerebral White Matter

Answer 12

• The communication “railway” of the brain
• Composed of myelinated axons organised into tracts that:
  -conduct information between the two cerebral hemispheres
  -conduct information between cortical areas in the same hemisphere
  -conduct information between the cerebral cortex and lower parts of the CNS (e.g., thalamus, spinal cord)

Question 13

Cerebral Basal Nuclei

Answer 13

• Islands of gray matter deep within the white matter
• Communicate with the motor areas of the cerebral cortex to facilitate smooth skeletal muscle movements
• Activity is regulated by the neurotransmitter dopamine
  -Loss of dopamine = overactive basal nuclei = Parkinson’s disease

Question 14

The Cerebellum

Answer 14

• Second largest part of the brain
  -outer cortex of gray matter “cerebellar cortex”
  -inner region of white matter = “arbor vitae”
• Ensures smooth, coordinated skeletal muscle movements, and maintains posture and balance

Question 15

The Diencephalon

Answer 15

Includes the thalamus, hypothalamus and epithalamus

Question 16

The Thalamus

Answer 16

• Is a relay station for information coming into the cerebral cortex - “entrance to the cerebral cortex”
• processes and integrates sensory input
• relays sensory input to the correct cerebral destination e.g. taste information to gustatory cortex
• relays the “motor adjustments” made by the basal nuclei and cerebellum to the motor areas of the cerebral cortex

Question 17

The Hypothalamus

Answer 17

• Contains nuclei that:
• control activities of the autonomic nervous system regulate:
  → body temperature - monitor body temp, initiate sweating or shivering
  → hunger, satiety and thirst
  → sleep-wake cycles
  → emotions - initiate the physical responses involved in emotions of pleasure, fear, rage, aggression, e.g. ↑ HR, respiration, sweating (part of limbic system)
  produce hormones - antidiuretic hormone (ADH), oxytocin and releasing/inhibiting hormones

Question 18

The Epithalamus

Answer 18

Includes the pineal gland which produces melatonin - induces sleep

Question 19

The Limbic System

Answer 19

• A functional system that includes specific areas of the cerebrum (e.g., prefrontal cortex & hippocampus) and diencephalon (e.g., hypothalamus)
• Establishes and controls emotions
• Involved in the formation of long-term memories
  -hippocampus - converts short-term memories into long-term memories

Question 20

The Brain Stem

Answer 20

• Includes the midbrain (mesencephalon), pons, medulla oblongata and reticular formation
• Neural tissue is organised into areas of white matter and gray matter
• white matter is composed of axon tracts - conduct sensory & motor information through the brain stem
  · gray matter contains nuclei
• some of these nuclei are associated with the cranial nerves (CN) that arise from the brain stem

Question 21

Midbrain (a.k.a. mesencephalon)

Answer 21

• Gray matter contains various nuclei:
  -visual and auditory reflex centres
  -substantia nigra - produces dopamine
  -cranial nerve nuclei that regulate eye movements via CN III and CN IV

Question 22

Pons

Answer 22

Gray matter contains:
-cranial nerve nuclei involved in taste, chewing, eye movements, hearing, balance, and facial sensations & expressions via CN V - VIII
-nuclei that regulate breathing

Question 23

Medulla Oblongata

Answer 23

Gray matter contains:
- autonomic nuclei controlled by the hypothalamus
- cardiovascular centre - controls heart rate, force of contraction and blood vessel diameter
- respiratory centres - control the rate and depth of breathing
- cranial nerve nuclei that regulate swallowing, tongue movements & digestive functions via CN IX, X and XII

Question 24

Reticular Formation

Answer 24

• A functional system that extends through the central core of the brain stem
• Contains the reticular activating system (RAS)
  -maintains consciousness
  -damaged = coma

Question 25

The Cranium

Answer 25

Cranial bones form the brain’s protective bony “helmet”. The cranium is remarkably strong and encloses the brain to protect it from mechanical forces (external impacts).

Question 26

Meninges

Answer 26

The meninges are three connective tissue membranes that cover the external surface of the brain (and spinal cord) to protect from mechanical forces.

Question 27

Dura mater - “tough mother”

Answer 27

The outer dura mater is a strong, tough, leathery protective membrane. The dura mater of the cranial meninges is a double-layered membrane; the outer periosteal layer attaches directly to the inner surface of the skull and the inner meningeal layer covers the external surface of the brain

Question 28

Arachnoid mater - “spider mother”

Answer 28

A narrow cavity called the subdural space separates the arachnoid mater from the dura mater. This cavity contains a thin film of serous fluid and veins that drain deoxygenated blood into the dural sinuses.

Question 29

Pia Mater - “tender mother”

Answer 29

The pia mater is a very thin, delicate membrane that clings tightly to the surface of the brain. It contains many small blood vessels and these blood vessels perforate through the membrane to supply the underlying neural tissue.

Question 30

Cerebrospinal Fluid (CSF)

Answer 30

CSF is produced within the brain’s four ventricles (cavities located in the cerebrum, diencephalon and brainstem

Question 31

The Blood-brain Barrier

Answer 31

The blood-brain barrier protects the neural tissue of the brain from harmful substances and pathogens (e.g., bacteria and viruses) circulating in the blood.