Nervous and Endocrine Systems

• The body consists of trillions of cells that form organs
• Organs collaborate to create body systems for function and survival

Nervous and Endocrine Systems

• The nervous and endocrine systems both transmit messages throughout the body
• They achieve this with different methods

Message Transmission Comparison

• The nervous System transmits fast messages, while the endocrine system transmits slow messages
• The nervous system responds immediately, while the endocrine system responds usually, but slowly
• The nervous system has responses of short-term length, while the endocrine system has long-lasting responses
• The nervous system has responses that are concentrated, while the endocrine system responses that are usually but slow
• The nervous system travels along nerves (neurons) to transmit messages
• The endocrine system transmits messages through the bloodstream
• The nervous systems type of messages are electrical signals - neurons
• The type of message in the endocrine system are chemical messages - hormones

The Nervous System

• The nervous system is a communication network using neurons to send electrical messages, controlling all bodily functions, such as moving, breathing, and feeling

Nervous System Components

• Central Nervous System (CNS): Includes the brain and spinal cord, the CNS receives, processes, and sends out messages, directing the body on how to respond
• Peripheral Nervous System (PNS): Includes the nerves that carry messages to and from the CNS

Neuron Details

• Neurons are specialized cells that transmit electrical messages around the body at a very high speed

Neuron Parts

• Dendrites: receives messages from other cells and brings information to the neuron
• Cell body/soma: maintains the health of the neuron, includes the nucleus
• Axon: passes messages away from the cell body to other neurons, muscles, or glands
• Myelin Sheath: covers the axon and helps speed up neural impulses
• Axon terminal: forms junctions with other cells and takes information away from the neuron
• Neurons are bundled as nerves and are protected by the myelin sheath

Types of Neurons

• Sensory Neuron: detects the outside world and sends signals along the axon to the CNS.
• Motor Neuron: receives signals from the CNS and passes it on to effectors (muscles or glands)
• Interneuron: carries the impulse through the CNS between neurons

Neurons (Synapses)

• Synapses: the small gap between neurons that allow electrical impulses to travel to the next neuron using chemicals called neurotransmitters
• Neurotransmitters are released from the synaptic terminal of an axon and travel across the gap to the dendrite of the next neuron
• Help us understand how neurons interact

Types of Neurotransmitters

• Adrenaline (fight or flight)
• Acetylcholine (learning)
• Endorphins (euphoria)
• Noradrenaline (concentration)
• GABA (calming)
• Glutamate (memory)
• Dopamine (pleasure)
• Serotonin (mood)

Stimulus & Response

• Stimulus Response Pathway: The process of a stimulus triggering a response in the nervous system
• Reflex Arc: The simplest and quickest response form to a stimulus, used to protect the body from danger

Reflex Arc Reactions

• A reflex occurs before the message reaches the brain, a sensory neuron sends an impulse to the spinal cord, straight to the cell body of a motor neuron
• They are rapid and involve very few neurons, e.g., the knee jerk reflex test

Senses & Receptors

• There are 5 Senses & Sensory Organs
  • Sight (eye)
  • Hearing (ear)
  • Touch (skin)
  • Taste (tongue)
  • Smell (nose)
• Sensory organs enable the nervous system to gather information about the surroundings while using specific sensory receptors tailored to each sensory organ

Sensory Receptors

• Photoreceptors: sense light in the eye
• Mechanoreceptor: sense sound, pressure, and movement in the ear and skin
• Thermoreceptor: sense temperature in the skin
• Chemoreceptors: sense chemical substances on the tongue and in the nose
• Proprioceptors: sense bodily position and movement in muscles and body tissues
• Pain receptors (nociceptor): sense pain in the skin, tissues, and organs

Stimulus and Receptors

• Sight's sense organ is the eye, which detects light as a stimulus, using rods and cones in the retina as receptors
• Hearing's sense organ is the ear, which detects sound as a stimulus, using hairs in the cochlea as receptors
• Touch's sense organ is the skin, which detects heat, cold, pressure and movement as stimuli, using separate receptors for each type as receptors
• Taste's sense organ is the tongue, which detects chemical substances a stimuli, such as sweet, salty, bitter and sour using tastebuds as receptors
• Smell's sense organ is the nose, which detects chemical odours as a stimuli, using olfactory nerves inside the nose as receptors

The Brain

• The brain acts as a communication center in the Central Nervous System
• It controls and regulates body functions, composed of billions of neurons

Brain Sections

• The Cerebrum
• The Cerebellum
• The Brain Stem
• The Corpus callosum

Sections of the Brain

• Cerebrum: is the largest part of the brain, involved in conscious thoughts, voluntary movements, and receiving sensory messages from the body, mad up of 2 parts with left and right hemispheres broken up into 4 lobes
• Brain Stem: connects the brain to the spinal cord, controls vital functions like breathing, heart rate, body temperature, pain, and hunger
• Corpus Callosum: a thick bundle of nerve fibers connecting the two brain hemispheres, allowing communication between them
• Cerebellum: responsible for coordination and balance, which is essential for walking

The Cerebral Lobes

• The hemispheres consist of four lobes:
  • Frontal
  • Parietal
  • Temporal
  • Occipital

Lobe Functions

• Frontal Lobe: reasoning, planning, speech and movement (motor cortex), emotions, problem-solving
• Parietal Lobe: perception of touch, pressure, temperature, and pain stimuli, knowledge of numbers and relations, object manipulation (spatial awareness and mapping)
• Occipital Lobe: is primarily for controlling vision
• Temporal Lobe: recognition, perception of auditory stimuli (hearing) as well as vision and smell, learning and memory (hippocampus), language centre

The Endocrine System

• The endocrine system is a communication network that sends chemical messages (hormones) from glands into the bloodstream
• Functions to control and regulate bodily functions
• Changes produced by hormones are slow, long-term, and irreversible

Hormones

• Hormones control and regulate bodily functions
• Produced in small amounts in the endocrine glands
• Released directly into the bloodstream to all parts of the body
• Hormones have varied shapes to fit specific receptors on their target cells

Glands in the Endocrine System

• Hypothalamus
• Pineal gland
• Pituitary gland
• Parathyroid glands
• Thyroid glands
• Thymus
• Liver
• Adrenal gland
• Kidney
• Pancreas
• Ovary (in female)
• Placenta (in female-during pregnancy)
• Testis (in male)

Glands, hormones & their function in the Endocrine System

• Pituitary gland
  • Type of hormone(s) produced: many hormones including: follicle stimulating hormone (FSH) and luteinising hormone (LH), Growth hormone, Prolactin
  • Hormones function/effect: Stimulates ovaries to produce ova and Stimulates testes to produce sperm, Affects cell growth, Stimulates production of milk in breasts
• Hypothalamus
  • Type of hormone(s) produced: Many hormones
  • Hormones function/effect: Connects the nervous system with the endocrine system; controls body temperature, growth, sex drive, thirst, hunger and pleasure and pain sensations
• Pineal gland
  • Type of hormone(s) produced: Melatonin
  • Hormones function/effect: Controls body rhythms such as sleeping and waking
• Thyroid gland
  • Type of hormone(s) produced: Thyroxine
  • Hormones function/effect: Controls rate of chemical activity in cells and regulates growth
• Adrenal glands
  • Type of hormone(s) produced: Adrenaline and others
  • Hormones function/effect: Raises blood pressure, heart rate, breathing rate and supply of blood to muscles
• Pancreas
  • Type of hormone(s) produced: Insulin, Glucagon
  • Hormones function/effect: Decreases blood glucose level, Increases blood glucose level
• Parathyroid glands
  • Type of hormone(s) produced: Parathormone
  • Hormones function/effect: Maintains level of calcium in the blood
• Ovaries (females)
  • Type of hormone(s) produced: Oestrogen and progesterone
  • Hormones function/effect: Controls development of breasts; prepares uterus for zygote and controls menstrual cycle
• Testes (males)
  • Type of hormone(s) produced: Testosterone
  • Hormones function/effect: Controls body hair, deepening of voice and sexual urges

Homeostasis

• Homeostasis: is the process of maintaining a constant and balanced internal environment
• The body works most efficiently when it is kept stable
• Factors that impact homeostasis: Temperature, PH Levels, Water content, Oxygen, Available energy
• The stimulus-response model allows us to achieve homeostasis