Neurotransmitters

Neurotransmitters
 Electrochemical messengers:
 Catecholamines, consisting of epinephrine and norepinephrine
 Dopamine, Acetycholine, and Serotonin.

The Endocrine System
 Set of glands
 Works in close association with the autonomic nervous system
 Communicates via chemical substances like hormones
 Examples are adrenaline, cortisol, somatotropic hormone, gonadotropic hormone, etc.

Endocrine and autonomic systems work together
 Connection between the hypothalamus in the brain and the pituitary gland (“master gland”)
 The pituitary gland sends out hormones that communicates with other glands to send out hormones

Adrenal gland
 Located on top of each kidney
 Comprised of the adrenal medulla and the adrenal cortex.
 Adrenal medulla secretes adrenaline (epinephrine) and noradrenaline (norepinephrine)
 Adrenal cortex secretes steroids (including mineralocorticoids and glucocorticoids, androgens, and estrogens)
Thyroid gland
 Located in the neck
 Produces hormone (thyroxin) that regulates activity level and growth.
 Hypothyroidism: Insufficient thyroid hormones (leads to low activity levels and weight gain)
 Hyperthyroidism: Over-secretion of thyroid hormones (leads to hyperactivity and weight loss, insomnia, tremors, etc.)
Pancreas
 Located below the stomach
 Regulates level of blood sugar by producing insulin which absorbs blood sugar.
 Important gland in diabetes mellitus

Fight or Flight Response

Fight or Flight Response
Increase in
 Epinephrine & norepinephrine
 Cortisol
 Heart rate & blood pressure
 Levels & mobilization of free fatty acids, cholesterol & triglycerides
 Platelet adhesiveness & aggregation
Decrease in
 Blood flow to the kidneys, skin and gut

Peripheral Nervous System ,Sympathetic nervous system

Peripheral Nervous System
Autonomic nervous system and Somatic nervous system
Somatic nervous system
Involved in both sensory and motor functions, serving mainly the skin and skeletal muscles.
Efferent impulses: carry messages from the brain to the skeletal muscles
Afferent impulses: carry messages from the sensory organs to the brain
Autonomic nervous system
Controls what is generally involuntary, automatic activity
Consists of the sympathetic and parasympathetic nervous systems.

Sympathetic nervous system
Fight of flight response
Sends out messages (neurotransmitters) to the body preparing the body for fight or flight.
Also prepares the body for strenuous activity

Parasympathetic nervous system
Restores equilibrium in the body
Decreases arousal, slows breathing and heart rate, lowers heart rate and blood pressure, etc.

Reticular Activating System and Limbic System

Reticular Activating System and Limbic System
 Reticular activating system runs from the medulla through the midbrain into the hypothalamus.
 Responsibility for activation of all areas of the brain and if damaged – coma ensues
 Limbic system controls emotion and it has three sub-circuits

Limbic System - emotions
 Amygdala and hippocampus – essential for self-preservation, includes aggression.
 Cingulate gyrus, the septum, and areas of the hypothalamus – pleasure and sexual excitement.
 Areas of the thalamus and hypothalamus – important to socially relevant behaviour

Diencephalon
Thalamus
Chief relay centre for directing sensory messages and helps regulate awareness.
Relays commands going to the skeletal muscles from the motor cortex.
Hypothalamus
Command for the control of autonomic functions such as heart rate, blood pressure, hunger, thirst.
Role in emotions and motivation (e.g., thoughts about fear get translated into arousal through hypothalamus.)

Cerebellum
 Maintains body balance and coordination of movement
 Damage to the cerebellum results motor disorders such as ataxia.
 Ataxia is a condition where our movements become jerky and uncoordinated.
Hindbrain
 Consists of:
 Pons – involved in eye movement, facial expressions and eye movement
 Medulla – controls breathing, heart rate, blood pressure
Midbrain
 Midbrain – top of brain stem, receives visual and auditory information, also important in muscle movement.
 Reticular formation – controls states of sleep, arousal, and attention.
Spinal cord
 Transmits messages from the brain to the other areas of the body.
 Efferent – away from the brain out to the body (Produces muscle action)
 Afferent – from the periphery to the brain (Relays information from the sensory organs)

Three sections of the brain

Three sections of the brain
Hindbrain
Midbrain
Forebrain
Medulla -Pathway connecting Diencephalon (Thalamus, Hypothalamus)
Pons hindbrain and Forebrain.
Telecephalon (Cerebrum, Limbic system)
cerebellum

Telencephalon
 Upper and largest portion of the brain
 Involved in higher order intelligence, memory, and personality
 Composed of two hemispheres: Left hemisphere – language processes, etc. and
Right hemisphere – visual imagery, emotions, etc.

Four lobes of the cerebral cortex
Frontal
Parietal
Temporal
Occipital
Motor activity
Bodily sensations, Hearing Primary visual
Higher level intelligence e.g., pain, heat Vision area of the brain
Planning, Problem solving Body movement Smell
Emotions, Self-awareness Memory

Three sections of the brain
Hindbrain
Midbrain
Forebrain
Medulla -Pathway connecting Diencephalon (Thalamus, Hypothalamus)
Pons hindbrain and Forebrain.
Telecephalon (Cerebrum, Limbic system)
cerebellum

Telencephalon
 Upper and largest portion of the brain
 Involved in higher order intelligence, memory, and personality
 Composed of two hemispheres: Left hemisphere – language processes, etc. and
Right hemisphere – visual imagery, emotions, etc.

Four lobes of the cerebral cortex
Frontal
Parietal
Temporal
Occipital
Motor activity
Bodily sensations, Hearing Primary visual
Higher level intelligence e.g., pain, heat Vision area of the brain
Planning, Problem solving Body movement Smell
Emotions, Self-awareness Memory

The Systems of the Body

The Systems of the Body
Neuron
 Cell body – source of life of the cell
 Dendrites – branches on the cell bodies that act as receivers of messages from adjacent neurons.
 Axon – projection through which messages travel.
 Synaptic knobs: Tips of branches at end of axon. Sends messages to adjacent neurons.
 Synapse: Fluid filled gap between neurons.