Lecture 5

What is the oldest part of the brain?

brainstem

What are the 3 types of cranial nerves?

1. sensory fibres ---> sensory nerves

2. efferent fibres ---> motor nerves

3. mixed nerves mix of both

what is an example of a mixed nerve?

vagus nerve

What is reticular formation? + what does it control?

group of neurons that sends signals to the outside

CONTROLS --> arousal, sleep, muscletone, pain modulation

Where do most cranial nerves start from?

- brain stem- ( numbers 2 ---> 12 start from brain stem)

What type of nerve is the vagus nerve + what is its function?

- mixed

- sensory + efferent to many internal organs, muscles + glands

what is the function of the bratin stem and what is it composed of?

What are the 2 tracts of the medulla + their function?

1. somatosensory tract ---> sends signals to brain

2. corticospinal tracts ---> sends signals from brain to spinal cord

What is the function of the pyramids in the medulla?

- white matter ---> 90% of nerves from the right side in pyramid will cross over + go to the left side

What does the medulla control?

controls involuntary functions: blood pressure, breathing, swallowing, vomiting

What is the function of the pons?

relay station, coordinates breathing

What is the function of the midbrain?

eye movement, relay signals for hearing + seeing reflexes

What does the cerebellum coordinate?

movement

What is the function of the cerebellum?

- processes sensory info + coordinates the execution of movement

- equilibrium + balance (sensory) from somatic receptors

- motor input from cerebrum

What is the function of proprioception?

know the position of different body parts even if you can't see them

EX: your brain knows where your eyes are even if your eyes are closed

***IMPORTANT FOR BALANCE

What does the diencephalon contain?

centers for homeostasis

What is the function of the thalamus?

- relay station integrating centre ---> used for all sensory except smelling

- close to thalamus ---> no blood brain barrier

What is the function of the hypothalamus?

- control of homeostasis

- center for behavioural drives - hunger, thirst

- influences autonomic function and endocrine function

What are the 2 endocrine structures?

1. pituitary gland---> anterior, posterior

2. pineal gland ---> includes the epithalamus

What is the function of the pineal gland?

produces melatonin

Between what organs is the portal system located?

hypothalamus + pituitary ---> hormone can quickly move from 1 place to another

What is the blood flow of the portal system vs. normally?

NORMALLY : artery ---> arterioles ---> capillary ---> venule ---> vein

PORTAL SYSTEM: artery ---> arterioles ---> capillary ---> venule ---> capillary ---> venule ---> vein

What does the diencephalon consist of?

1. thalamus

2. hypothalamus

3. pineal gland

4. pituitary gland

What are the main functions of the hypothalamus?

1. maintains body temperature ---> homeostasis

2. controls body osmolarity ----> controls thirst, etc.

3. controls food intake ---> stimulates satiety etc.

4. interacts w limbic system to influence behaviour and emotions

What is the structure of the cerebrum?

- consists of 2 hemispheres connected by corpus callosum

- gray matter and white matter

What is the parts of gray matter?

1. cerebral cortex

2. basal ganglia: control of movement

3. limbic system: link between cognitive functions and emotion

What does the amygdala and cingulate gyrus control?

1. amygdala

2. hippocampus

What are the 2 parts of the limbic system?

emotion and memory

What are the parts and function of white matter?

- mostly found on the interior

- bundles of fibres connecting the different regions of the brain

What structure is the diencephalon involved in?

brainstem

What is the function of the sensory system?

- monitors internal and external environments

- initiates reflex response

What is the function of cognitive system?

- initiates voluntary response

What is the function of the behavioural state system?

governs the sleep - wake cycle and other intrinsic behaviours

How is the cerebral cortex organized?

into 3 areas:

1. sensory areas

2. motor areas

3. association areas

***also can be divided into the right and left hemisphere

What is the sensory area?

sensory input are translated into perception (awareness)

What is the motor area?

direct skeletal muscle movement

What are association areas?

- integrate information from sensory and motor areas

- can direct voluntary behaviours

What is the difference between the right and left hemisphere?

SEE GOOD NOTES

What are the 4 major motor systems that governs output from CNS?

1. skeletal muscle movement - somatic motor division

2. neuroendocrine signals - hypothalamus and adrenal medulla - involuntary actions

3. visceral responses - autonomic divisions

4. voluntary movement - primary motor cortex

- motor association areas

Where are neuroendocrine and visceral responses coordinated?

in the hypothalamus and the medulla

What does the behavioral state system modulate?

motor output

How does the behavioural state system modulate motor output?

- modulates sensory and cognitive processes

- neurons collectively known as diffuse modulatory systems ---> originate in reticular formation in brainstem

- project axons to large areas of the brain

What does the reticular activating system control?

consciousness

What measures brain activity?

Electroencephalography (EEG)

How does reticular formation in the brainstem work?

reticular formation (in brainstem) -----> have a lot of nuceli in the brainstem ----> can send signals to different parts of cerebral cortex

What is the broca area related to?

speech

what is the Wernicke area related to?

understanding of language

Why do we sleep?

- stores memories and removes waste that builds up during the day, repairs brain tissues, produces growth hormone

What are the 4 major stages of sleep?

1. N1

2. N2

3. slow - wave sleep - STAGE N3

- adjusts body without conscious command

4. rapid eye movement (REM) sleep

- brain activity inhibits motor neurons to skeletal muscle, paralyzing them

- dreaming takes place

What are the 3 sleep disorders?

1. insomnia - inability to sleep

2. sleep apnea - stopping normal breathing during sleep

3. somnambulism - sleepwalking

How does EEGs change depending on the stage of sleep you are in?

SEE GOOD NOTES

What is circadian rhythm?

- alternating daily patterns of rest and activity

- primary "clock" - suprachiasmatic nucleus (SCN) of the hypothalamus

- melatonin linked to circadian rhythms

What is learning?

the acquisition of knowledge

What are the 2 types of learning?

1. associative learning ----> linking things tog to memorize

2. nonassociative learning - straight memorizing

What is memory?

ability to retain and recall info

- stored in memory traces, cerebrum also stores memories but can't make new ones

What is anterograde amnesia?

the inability to remember new information

What is reflexive (implicit) memory vs. declarative (explicit) memory?

reflexive - knowing how to do something

declaratie - knowing something