Physiology - organisation of nervous system

Nerve

**Group of axons** from many neurons, surrounded by connective tissue

(endoneurium, perineurium, epineurium)

Organisation

• CNS: brain + spinal cord

• Ganglia / Nuclei: integration centres

• Afferent neurons: from periphery to CNS

• Efferent neurons: from CNS to periphery

Brain

**Two hemispheres** not functionally identical, for opposal sides of the body.

Left - speech; Right - perception of spatial relationships.

**Corpus callosum** - bundle of axons connecting hemispheres

Grey matter

Cell bodies + dendrites + axon terminals + most synapses

White matter

Axons connecting different parts of grey matter to each other

Cerebrum - **Cerebral cortex**

• Perception

• Sensory information integration

• Voluntary movement

• Freu Tore his Pants Off - Frontal, Temporal, Parietal, Occipital lobes

Cerebrum - **Basal nuclei**

Coordination of movement

Cerebrum - **Limbic system**

Emotional

• Amygdala - emotions: agression / fear

• Hippocampus - learning & memory (from short to long term)

• Olfactory bulb - Smell

Diencephalon - **Thalamus**

Integration & relay centre for sensory & motoric info.

All senses except smell - filter for unnecessary information.

Diencephalon - **Hypothalamus**

Control hormonal system to maintain **homeostasis**: salt/water, appetite, thirst

Diencephalon - **Pituitary gland**

Hormone secretion

Diencephalon - **Pineal gland**

Melatonin secretion

Brain stem - **Midbrain**

Eye movement control

Brain stem - **Pons**

Connects cerebrum & cerebellum;

coordination of __breating__;

origin of vestibulocochlear (__face, teeth, biting__)& trigeminal nerve (*ear*)

Brain stem - **Medulla oblongata**

Control of __involuntary functions__ (breathing, cardiovascular).

Vagus nerve origin - sensory info from important organs

**Frontal lobe**

Personality & decision making.

**Temporal lobe**

Memories, emotions, language, recognition, language, auditory.

**Parietal lobe**

filter informations, touch, body position.

**Occipital lobe**

visual information.

**Cerebellum**

Gets info from PNS - coordination of movement, organ equilibrium.

Motoric input from cerebrum - movement coordination

Learning & memory

Ventricles

Filled with **cerebrospinal fluid CFS** produced by **choroid plexus**.

Protects the brain & spinal cord from chemical/physical injuries (like pH), carries oxygen, glucose.

Glymphatic system

Astrocytes wrap around brain arteries, making a **pericapillary tunnel** for CSF.

CFS leaves generating **convective flow** to the veins - cleaning the waste at night.

Spinal nerves

**Dorosal tract -** info from PNS

**Ventral tract -** into to PNS

**Dermatome -** innervation from single dorosal room & its nerve

Patellar reflex

1. Hammer hit, tendon stretch receptors in the muscle - fire action potentials

2. Afferent - Monosynaptic pathway with motor neuron to the ventral horn of spinal cord

3. Efferent - Motor neuron fires action potential back - muscle contraction

4. Inhibition of the motor neuron for the antagonistic muscle - leg extends up

Autonomic nervous system

**Rest & digest:** pupil constriction, salivation, heathbeat slows, digestion, gonad arousal

**Fight or flight:** pupil dilatation, airways relaxed, digestion stop, bladder relax, orgasm stimmulation