,LT1
Nervous System & Endocrine System
NERVOUS SYSTEM AUTONOMIC NERVOUS SYSTEM ENDOCRINE SYSTEM
- Specialised network of cells and primary 2 parts: GLANDS AND HORMONES
internal communication including the 1. Sympathetic nervous system → prepares Hormones: chemical messengers carried in by
central nervous system and peripheral body to expend energy for fight or flight blood that transmits info around the body
nervous system response affecting certain organs or cells. Produced in
FEATURES: 2. Parasympathetic nervous system → rest endocrine system (also the pancreas and
1. Collect, process and respond to info and digest → maintains and conserves hypothalamus)
2. Coordinate working of organs and cells body energy and functions Hypothalamus: pea sized structure of the brain
CENTRAL NERVOUS SYSTEM (CNS): Antagonistic actions - work oppositely integrating the nervous and endocrine systems.
- Brain + spinal cord ANS & ENDOCRINE TOGETHER Involved in homeostasis (balancing bodily
Spinal cord - ANS and endocrine usually work in processes within certain limits)
● Tube like extension connected to brain via parallel with another e.g. in a stressful - Endocrine system works alongside the
brain stem event nervous system to control vital functions
● Responsible for reflex actions - Stressor perceived (e.g. upcoming exam) in the body
● Sends messages to the brain and body = hypothalamus triggers activity in - Acts slower than NS
Brain sympathetic branch of ANS = adrenaline - Hormones are secreted into the
● Conscious awareness and decision is released from adrenal medulla into the bloodstream and affect any cell which has
making bloodstream a receptor for that hormone
● 2 hemispheres connected by corpus - Adrenaline triggers physiological changes - Thyroid gland produces hormone
callosum in the body which creates the thyroxine → increases heart rate and cells
● Contralateral control physiological arousal necessary for fight by increasing metabolic rates
● Cerebral cortex is highly developed in or flight - Major endocrine gland = pituitary gland
humans and covers subcortical parts - Happens in an instant → acute response located in the brain and produces and
PERIPHERAL NERVOUS SYSTEM (PNS): (automatic response) releases hormones e.g. produces
Transmits messages via neurons to and from CNS - Once the threat is passed, the adrenocorticotropic which stimulates
1. Autonomic nervous system (ANS) parasympathetic nervous system returns production and release of cortisol (needed
Governs vital functions e.g. breathing, heart rate, the body to resting state to control stress and healthy blood
digestion, homeostasis (involuntary actions) - The parasympathetic nervous system acts pressure) from the adrenal gland
2. Somatic nervous system (SNS) as a brake and reduces the activities of the
Controls skeletal muscles and receives info to and body that were increased by the actions of
from sensory receptors (voluntary actions) the sympathetic branch
, LT2
Neurons & Synaptic Transmission
Cell body (soma) → contains cell nucleus which houses genetic material
Dendrites → branches at the top end of a neuron which receive messages from other
neurons or sensory receptor cells to trigger an action potential (electrical impulse)
Axon → long branch of nerve fibres that connects cell body to the end of the neuron which
passes the action potential to axon terminals
Myelin sheath → fatty deposit which is a protective insulating layer and breaks along are
called nodes of Ranvier to help it travel quickly
Axon terminals → end of axon and terminal buttons which are bulb shaped containing
vesicles (tiny sacs) that store neurotransmitters for the next stage
Action potential → electrical signal which passes down the axon via the axon hillock to
stimulate the axon terminal to activate the terminal button and release neurotransmitters
due to synapse transmission
ROLE OF THE NEURON
TYPES OF NEURONS - Pass messages between neurons using neurotransmitters to enable behaviour,
1. Sensory neurons thinking and emotions
Found in receptors e.g. eyes, ears, tongue and skin and - Neuron activated = positively charged and switch from -ve → +ve ] depolarisation
carry nerve impulses to the spinal cord and brain via = creates an action potential that travels down the axon and triggers release of
PNS. neurotransmitters = released in synaptic gap and picked up by receptors
When they reach the brain they are translated into
sensations e.g. vision, hearing and taste and touch. They
do not all reach the brain and some stop at the spinal Neuron: the basic building blocks of
cord for reflex actions the nervous system and nerve cells
2. Relay neurons that process and transmit messages
Connect with other neurons, found in brain and CNS - through chemical signals
involved in analysis of the sensation, what it means and - 100 billion neurons
how to respond to it = acting between sensory and motor - 80% located in the brain
3. Motor neurons - Primary means of
Found in CNS and control muscle movement. When they communication
are stimulated, they release neurotransmitters that bind
to the receptors on muscles to trigger a response =
movement
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