Biopsychology - Nervous system, Endocrine System and Synaptic Transmission

What is the nervous system (what is it made of?)

A specialised neywork of cells and our main internal communication system

2 main functions of nervous system

1) Collect, process and respond to environmental info

2) Co-ordinate the workings of diff organs and cells

What 2 sub-systems is the nervous system divided into?

Central nervous system (CNS) and peripheral nervous system (PNS)

How does the nervous system communicate?

Neurons send electrical signals across body - when body receives info from environment, nerves carry data to and from the brain, allowing us to move our limbs, feel sensations etc.

What does the CNS consist of?

Brain and spinal cord

What does the brain do?

Provides conscious awareness and involved in all psych. processes - distinguishes our higher mental functions from other animals

Explain how the brain and spinal cord are connected

Connection between them allows for signals to be passed from brain to rest of body, so body can respond.

Function of cerebral cortex

Surrounds brain - related to human traits, like higher thought, language and thinking

Frontal lobe function

Higher order functions, like reasoning, planning, movement, emotions and problem solving

Parietal lobe function

Brings together info from diff senses, e.g. controls movement, orientation, recognition and perception of stimuli

Occipital lobe function

Processes visual info

Temporal lobe function

Perception and recognition of auditory stimuli, memory and speech

Cerebellum function

Coordinates voluntary movements, balance and motor skills

Brain stem function

Connected brain and spinal cord

2 functions of spinal cord

• Extension of brain - sends messages to and from brain and rest of body.

• Responsible for simple reflex actions (involuntary, almost instant movement when responding to a stimulus) - they're caused by reflex arcs (neural pathways)

Function of PNS

Uses neurons to send/ receive signals to and from CNS

State and briefly describe the 2 sub-division of the PNS

1) Somatic nervous system (SNS) - controls voluntary muscle movement and receives info from sensory receptors

2) Autonomic nervous system (ANS) - controls involuntary/ automatic functions, like breathing and heart rate

2 things the somatic nervous system has which maintains communication between CNS and environment

1) Sensory receptors - carry info to CNS

2) Motor pathways - allow the brain to control movement

State and describe the 2 subs-divisions of the autonomic nervous system

1) Sympathetic nervous system - controls body's responses during fight/ flight, e.g. dilates pupils, inhibits non-emergency processes, like digestion, & increases heart rate.

2) Parasympathetic nervous system - does rest and digest function (returns body to normal state) E.g. constricts pupils and stimulates saliva production.

What is the endocrine system?

Major info system - tells glands to release hormones into bloodstream. Hormones are carried to target organs.

2 differences between nervous and endocrine system

Endocrine is slower but has more widespread and powerful effects.

Define gland

An organ which synthesises substances, like hormones

Define hormones

Chemical substances released into bloodstream which affect target organs. Powerful effects.

How do hormones work?

They're secreted into bloodstream and affect any cell with a receptor for that hormone. Receptor binds to hormone, causing an increase/ decrease of a specific process.

What do the envious and endocrine system work together to maintain?

Homeostasis - regulate bodily processes to ensure balance

How do the PNS and CNS work together?

1) PNS collects info on state of body

2) If body is in abnormal state, PNS sends signal to CNS to make a decision

3) CNS sends signal to major endocrine glands to secrete hormones to restore homeostasis

Pituitary gland - where is it and what does it do?

In the brain; "master gland" - controls the release of hormones from other endocrine glands

Thyroxine (hormone) - where is it made and what 2 things does it do?

• Made in thyroid gland

• Affects cells in heart (increases heart rate)

• Affects other cells to increase metabolic rates (chemical processes occurring in cells), which affect growth rates.

Describe the biology behind the fight/ flight response, after the stressor is perceived

1) Hypothalamus triggers activity in ANS's sympathetic branch (changes from parasympathetic to sympathetic state)

2) Adrenal medulla (gland) secretes adrenaline (stress hormone which affects cells of cardiovascular system)

3) Adrenaline causes physiological changes in target organs (e.g. higher heart rate) - creates physiological arousal needed for response

— happens fast - its a survival mechanism

4) When threat is gone, parasympathetic nervous system returns body to resting state - reduces activity which was increased by sympathetic branch

Define neuron

Nerve cells which use electrical and chemical signals to process and send messages, allowing nervous system to communicate

Sensory neurons - state their function, describe their dendrites/ axons and state where they're found

• Carry messages from PNS to CNS

• Long dendrites and short axons

Relay neurons - state their function, describe their dendrites/ axons and state where they're found

• Connect sensory neurons to motor/ other relay neurons

• Short dendrites and axons

• Found mostly in brain and visual system (relay = most of our neurons)

Motor neurons - state their function, describe their dendrites/ axons and state where they're found

• Connect CNS to effectors, like muscles and glands

• Short dendrites and long axons

• Their cell bodies = in brain/ spinal cord (CNS) and their axons form part of the PNS

What does the cell body of a neuron contain?

Nucleus - has cell's genetic material

What are a neuron's dendrites and what do they do?

Beanch-like structures which come out of cell body - carry nerve impulses from neighbouring neurons to cell body

What do the axons of a neuron do?

Carry impulses away from cell body down length of neuron

What is the myelin sheath of a neuron and what does it do?

Fatty layer of myelin sheath covers axon - it protects it and speeds up electrical transmission of nerve impulses

What are nodes of ranvier and what do they do?

Gaps which break up myelin sheath - speed up transmission of electrical impulse by forcing it to jump across gaps along axon

What are the terminal button and what do they do?

At end of axon - communicate with next neuron in chain across a synapse (gap)

When is the inside of a neuron negatively charged?

When neuron is in resting state

How does the inside of a neuron become positively charged (for a split sec?)

— What occurs because of this (a what potential?)

When neuron is activated by a stimulus. — Causes action potential - this is an electrical impulse which travels down axon to end of neuron.

What is the process of synaptic transmission?

Neighbouring neurons communicate by sending chemical messages across synapse that separates them

What are the groups called in which neurons communicate with each other?

Neural networks

How are the signals ____ neurons transmitted:

A) Within

B) Between

A) electrically

B) chemically (via synaptic transmission)

What do neurotransmitters do?

Brain chemicals which send signals across synapse from one neuron to another

Describe the steps of synaptic transmission - mention presynaptic terminal, neurotransmitters, synaptic vesicles and postsynaptic receptor site

1) Electrical impulse reaches presynaptic terminal (end of neuron)

2) Triggers release of neurotransmitters from synaptic vesicles (tiny sacs)

3) Neurotransmitters diffuse across synapse and are taken up by postsynaptic receptor site on the dendrites of the next neuron

4) Chemical message is converted back to electrical impulse and transmission process repeats in this neuron

Why is synaptic transmission one-way?

Neurotransmitters are released from presynaptic neuron terminal and received by postsynaptic neuron at receptor site

What are the molecular structures of neurotransmitters like? Are they the same or different?

Each has own specific molecular struc. which fits perfectly into postsynaptic receptor site, like lock and key

Neurotransmitters have specialist functions - state one and describe its function and where it's found

Acetylcholine (ACh) - found at each point where motor neuron meets a muscle — causes muscles to contract

What do neurotransmitters with an excitatory effect do? Give an example of one.

Increases postsynaptic (neighbouring) neuron's pos. charge, making it more likely to fire - e.g. adrenaline

What do neurotransmitters with an inhibitory effect do? Give an example of one.

Cause postsynaptic neuron to become more neg. charged, making it less likely to fire - e.g. serotonin

Define summation

Process which decides if a postsynaptic neuron fires.

— Add (sum) excitatory and inhibitory influences on postsynaptic neuron - if net effect is is excitatory, it's more likely to fire (more likely to trigger action potential) — if net effect is inhibitory, it's less likely to fire