ANAT215 Knowledge Block 1

L2-8, from scratch

Connective Tissue (CT) functions (5 main but go in depth)

1. structural framework for body

2. medium for transport/exchange of nutrients/waste

3. Defence - inflammation, antibodies, phages, immune response, phagocytes

4. storage - fat cells, stores electrolytes + water

5. repair - scars

Ground Substance of CT: what is it, what are its characteristics, and what is it made of

• holds things tgthr: CT with cells

• high water content, transparent, colourless, viscous

• made of glycosaminoglycans and structural glycoproteins

compare and contrast the fibres of CT

Collagen: type 1, 3 subunits, very strong, most abundant, long unbranched, tightly packed, flexible

Reticular: type 3 (reticulin), also strong but less than ^, branched network → makes it resistant to stress from multiple directions, smaller diameter

Elastic: elastin, can stretch up to 150% of resting state, complex system to form it, rubber-like

What are the fixed cells of CT and brief function description

1. fibroblasts - most common in CT, synth and maintenance of fibres in ground substance, active cell, and when its job is completed it matures in to a fibrocyte

2. fibrocytes - monitors the environment and if sm happens it can differentiate back to a fibroblast

3. macrophages - phagocytic, scattered throughout

4. mesenchymal cells - stem cells in extracellular matrix (ECM) of CT, respond to infection by dividing and specializing (mostly into fibroblasts)

5. adipocytes - stores fat

What are the wandering cells of CT and brief function description

1. free macrophages - phagocytic, derived from monocyte that has left tissue and differentiated, gets signalled when there’s an injury

2. mast cells - regulate inflammatory response (histidine)

3. plasma cells - produce antibodies

4. lymphocytes -

5. microphages - neutrophils, eosinophils, blood cells involved in immune response

What are the 3 main types of CT? (and their subcategories)

1. CT proper - loose, dense regular/irregular

2. Supportive CT - cartilage/bone

3. Special CT - fluid, adipose, elastic, reticular

What are the characteristics of loose and dense CT

Loose

• most abundant, packing material (fills space), supports epithelium, blood vessels, nerves

• ground substance is most of its volume

• looks like lots of cells, no bundles

Dense

• collagen fibre, can see bundles

• regular: fibres very tightly packed, nuclei are thin lines

• irregular: inconsistent bundles, can resist forces from all sides

What kind of CT (loose/dense/regular/irregular) are each of the special CTs, and any additional characteristics?

1. fluid - blood

2. adipose - loose CT

3. elastic - dense regular, parallel bundles of elastic fibres, fibroblasts and fibrocytes that can be stretched, walls of large blood vessels, some ligaments, under epithelium

4. reticular - loose, macrophages and fibroblasts, structure, stained with silver

What are the 3 classifications of neurons? (+ characteristics)

1. Multipolar - 3+ cell processes, most common, esp in CNS

2. Bipolar - 2 cell processes (1 axon, 1 dendrite), not common, for specialized sensory organs

3. Unipolar - 1 cell process, in PNS ganglia, pseudounipolar: short and divides to form axon

What kind of signal does a neuron send?

Electrical

Contrast the terminology used for cell body clusters and cell processes in the CNS vs PNS.

CNS: cell body clusters: nuclei; cell processes: the track

PNS: cell body clusters: ganglia (s:ganglion); cell processes: the nerve

Map out the general organization of the nervous system.

Describe the functionality of the neuron classifications.

1. Sensory/afferent neurons: unipolar with cell bodies in ganglia of PNS (think, it’s going → CNS from PNS, so cell body starts there)

2. Motor/efferent neurons: multipolar with cell bodies in CNS (going out from CNS, so starts there)

3. Interneurons: multipolar, in between afferent and efferent, in the CNS

What are the supporting cells of the CNS and PNS and their main function/characteristics?

CNS (C.AMEO):

1. Astrocytes - large, most abundant, structure of neural tissue

2. Microglia - small, not abundant, monitor health, can destroy antigens

3. Ependymal cells - cuboidal/columnar with cilia, lines cavities, CSF production/movement

4. Oligodendrocytes - myelinate (up to 60) axons by wrapping around

PNS

1. Schwann cells - myelination in PNS, only 1 portion of 1 axon per cell

2. Satellite cells - surround soma, chemical environment control

What are the hypo/epi/thalamus role and location?

• Thalamus: It is small and egg-shaped in the centre of brain, close to brain stem, its function is to recieve sensory info (except smell) and redirect that info

• Hypothalamus: Hypo=under, under and to the front of thalamus, has pituitary gland connected, endocrine system

• Epithalamus: on other side of thalamus (to back of brain), has pineal gland → melatonin, role in sleep-wake cycle

What are peduncles? And specifically what do the middle cerebellar peduncles do?

• Peduncles are thick nerve fibers (myelinated axons) that structurally + functionally connect brain parts

• The middle cerebellar peduncles connect the pons to the cerebellum

What are the components of the brain stem (in order from top to bottom) and their main role(s)?

1. Midbrain - has 4 colliculi: reflex + sensory (auditory) processing

2. Pons - 4th ventricle is behind it, also has middle cerebellar peduncles that attach to cerebellum

3. Medulla oblongata - has pyramids, olives, cardiovascular control (heart rate, blood pressure, breathing depth, coughing, sneezing, vomiting, hiccuping, etc.), foramen magnum separates medulla oblongata and spinal cord.

What are the meninges (in order from out to in), and main structure/function/characteristics?

1. Dura mater - hard, has outer periostial layer and inner meningeal layer that are almost always in contact, except for separations = dural venous sinuses, dense irregular CT

2. Arachnoid membrane - adhered to dura mater, loosely covering brain, loose collagen and elastic fibre, has subarachnoid space with CSF

3. Pia mater - tightly clings to brain/spinal cord, thin membrane, thin elastic fibres from squamous/cuboidal cells, arteries and veins to supply nutrients + O2 and take away CO2, denticulate ligaments anchor it to arachnoid membrane and stabilize horizontally

List all the parts of the ventricles (and picture where they are)

• lateral ventricles: anterior horn, body, posterior horn, inferior horn

• 3rd ventricle

• interventricular foramen

• cerebral aquaduct

• 4th ventricle

• central canal

• choroid plexus

What is the choroid plexus and what does it do?

• network of blood vessels and ependymal cells

• produces CSF

List (and visualize location) the arteries of the Circle of Willis/brain blood supply in order-ish of the direction of blood flow, including any relevant info on how they enter the skull.

• vertebral artery (enters skull from foramen magnum)

• basilar artery

• posterior cerebral artery

• posterior communicating artery

• anterior cerebral artery

• anterior communicating artery

• internal carotid artery (enters skull from carotid canal)

Falx**

What are the spinal cord englargements?

• cervical enlargement

• lumbar enlargement (from T9-T12, not actually in lumbar region of vertebrae cuz they’re not perfectly lined up)

What are the endings of the spinal cord called

1. conus medullaris

2. cauda equina

3. filum terminale

List (and visualize) the parts of the internal topography of the spinal cord.

• dorsal root

• ventral root

• dorsal root ganglion

• central canal - CSF through it

• dorsal (posterior) horn (sensory/afferent)

• ventral (anterior) horn (motor/efferent)

• lateral horn (only in thoracic and lumbar spinal cord region L1-L2/L3, autonomic functions)

• gray commissure

• anterior commissure

• anterior median fissure

• posterior median sulcus

Grey/White matter?

Grey matter: unmyelinated axons, soma, and dentrites

White matter: myelinated nerve fibres (axons?)