Biopsychology

Central Nervous System

Consists of the brain and spinal cord.

Brain - the centre for all conscious awareness, divided into different regions for different functions (eg: the cerebral cortex for higher cognitive functions)

Spinal cord - responsible for reflex actions and the transfer of information between the brain and the PNS

Peripheral Nervous System

Transmits information between the CNS and the rest of the body

Further divided into:

• Somatic nervous system

• Autonomic nervous system

Somatic Nervous System (component of PNS)

• controls voluntary movement and transmit signals from sensory receptors to the CNS

• responsible for muscle movement

OR MARK SCHEME

• Consists of sensory and motor neurons two carry sensory and motor information to and from the CNS

• Enables reflex actions

Autonomic Nervous System (component of PNS)

Regulates involuntary functions such as heart rate, digestion, and breathing

Further divided into:

• Sympathetic nervous system

• Parasympathetic nervous system

Sympathetic Nervous System (component of ANS)

Activates the bodies fight or flight response:

• Increases heart rate

• Dilates pupils

• Inhibits digestion

• Releases adrenaline

Parasympathetic Nervous System (component of ANS)

Activates the body’s rest and digest response:

• Slows heart rate

• Constricts pupils

• Stimulates digestion

• Conserves energy and restores calm

Endocrine system

A network of glands that are hormones directly into the bloodstream to regulate bodily functions.

It works alongside the nervous system and acts slower but has widespread effects

What does endocrine system consist of?

Key glands secreting hormones. Glands are:

• Pituitary gland

• Thyroid gland

• Adrenal gland

• Pancreas

• Ovaries and testes

What is a hormone?

A chemical messenger that circulates in the blood and controls how cells/organs work/influences behaviour or mood.

Examples of hormones and functions

• melatonin: helps regulate the wake-sleep cycle

• thyroxine: increases metabolic rates and affects growth

• insulin/glucagon: help regulate blood sugar levels

• testosterone: controls the development of male physical features

• oestrogen: controls the development of female physical features.

What is a gland?

An organ in the human or animal body which secretes particular chemical substances for use in the body/discharge in surrounding.

Pituitary gland

• Master gland

• Regulates hormone release in other glands

• Releases ACTH which stimulates the adrenal glands to produce cortisol during stress

Thyroid gland

Produces thyroxine - which regulates metabolism and heart rate

Adrenal glands

Located above the kidneys

Divided into two:

• adrenal medulla - releases adrenaline and noradrenaline during stress

• adrenal cortex - releases cortisol for stress response

Pancreas

Regulates blood sugar levels with insulin and glucagon

Ovaries and testes

Produce sex hormones (oestrogen, progesterone and testosterone)

Fight or flight response

Automatic reaction to a perceived threat, triggering physiological changes to prepare the body to defend itself or escape

4 stages of flight or flight response

1) Detection of threat - The hypothalamus identifies a threat and activates the sympathetic nervous system

2) Adrenal medulla activation - Signals are sent to the adrenal medulla, releasing adrenaline into the bloodstream

3) Physiological changes:

• Increased heart rate - boosts blood flow to vital organs

• Dilated pupils - enhances vision

• Inhibited digestion - prioritises energy for emergency action

• Increased respiration rate - provide provides more oxygen for muscles

• Glucose release - boosts energy availability

4) Return to rest (parasympathetic activation):

• Once the threat is gone, the parasympathetic nervous system restores the body to a resting rate

• Slows heart rate

• Constricts pupils

• Stimulates digestion

• Promotes relaxation

Types of neurons

Sensory

Motor

Relay

Explain function and structure of sensory neuron

Function: Carry messages from PNS to CNS

Structure:

• Long dendrites to receive signals from receptors

• Short axons to transmit signal to the CNS

Pathway: receptors → sensory neuron → CNS