Week 4 Bioscience Flashcards
Brain
- 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
Cerebrum
- 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
Cerebral Cortex (outer gray matter)
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
Primary Motor Cortex (PMC)
- 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
Sensory Areas of the Cerebral Cortex
- 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
Primary Somatosensory Cortex (PSC)
· 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
Somatosensory Association Area
- 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
Visual Areas
- 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
Auditory areas
- 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
Wernicke’s Area
- Usually located in left temporal lobe (left hemisphere) only
Damage = Wernicke’s aphasia - Comprehends written and spoken language
Prefrontal Cortex (a.k.a. anterior association area)
- 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
Cerebral White Matter
- 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)
Cerebral Basal Nuclei
- 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
The Cerebellum
- 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
The Diencephalon
Includes the thalamus, hypothalamus and epithalamus
The Thalamus
- 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
The Hypothalamus
- 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
The Epithalamus
Includes the pineal gland which produces melatonin - induces sleep
The Limbic System
- 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
The Brain Stem
- 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
Midbrain (a.k.a. mesencephalon)
- 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
Pons
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
Medulla Oblongata
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
Reticular Formation
- A functional system that extends through the central core of the brain stem
- Contains the reticular activating system (RAS)
-maintains consciousness
-damaged = coma
