Key Concepts Flashcards
What are features of the Right Hemisphere?
Non Dominant side
Non-verbal language
LH= Some still have a dominant Left Hemisphere, Few other’s have it divided between the two hemispheres
1. Non-verbal language area (body language) (90% of communication)
2. Emotional expression (language) - modulation of speech
3. Spatial skills (3D) - shape of the object
4. Conceptual understanding
5. Artistic and Musical Skills - someone who can’t talk could sing
Large extent on right hemisphere but not entirely
Dorsal column lemniscus pathway
- From the receptor it goes through the dorsal root into the spinal cord to the Gracile fasciculus or Cuneate fasciculus depending on whether it came from legs or above legs. It goes to synapse with 2’ neurons in the gracile/cuneate nucleus in the medulla.
- The axons of the second neurons cross to the opposite side of the medulla via arcuate internal fibres and enter the medial lemniscus which goes to the ventral posterior nucleus of the thalamus
- They go from ventral posterior nucleus of the thalamus through the internal capsule ot the primary somatosensory area of the cerebral cortex- cortical area of the homuncular map
Spinothalamic pathway
- The free nerve ending receptor goes through the dorsal root where it goes to through the tract of Lessauer to the posterior grey horn where it synapses with 2 order neurons
- Axons of 2 order neurons cross to the opposite side of the spinal cord through the ventral anterior white commisure and continue through the lateral spinothalamic tract (joining the medial lemniscus) which goes up to the ventral posterior nucleus of the thalamus.
- They go from ventral posterior nucleus of the thalamus through the internal capsule ot the primary somatosensory area of the cerebral cortex- cortical area of the homuncular map
Corticospinal pathway
- Upper motor neurons in the cortex go down through the internal capsule through the cerebral peduncle of the midbrain and pons. At the medulla oblongata, the axon bundles of the corticospinal tracts form ventral bulges called pyramids. This is where it starts to split up
- At medulla oblongata 85% of axons dessucate to the contralateral (opposite) side in the medulla oblongata. This is the lateral corticospinal tract.
The remaining 15% remain along the ipsilateral (same) side, and eventually dessucate at the spinal segmental level where they synapse with specific neuron- this is called the ventral/Anterior corticospinal tract.
What part of the spinal cord do the axons of the corticospinal tract form a tract in before synapsing with lower motor neuron and what type of movement is each tract responsible for
The ‘lateral corticospinal’ form the ‘latcort’ tract in the lateral white column of the spinal cord. This tract is responsible for distal parts of limbs responsible for precise agile and highly skilled movements.
The anterior corticospinal tract forms ‘antcort’ tract in the anterior white column of the spinal cord. This tract is responsible for movements of proximal parts of limbs and trunk- posture/core muscle
What 5 parts of the brain are the basal ganglia and what type of colour matter is it?
The basal ganglia are towards the bottom of the brain in the subcortical grey nuclei. It has the Caudate nucleus, the internal capsule, putamen, Globus pallidus (internal and external) sub-thalamic nucleus and the substantia nigra.
Describe the circuit starting at cerebral cortex pre motor area state the 5 steps/ pathways to a muscle movement + excite or inhib
- neurons go from the cerebral cortex to the striatum via excite
- 95% of nerves from striatum will go to substantia nigra or into the internal or external segment of the GP (inhib)
- A fibre from internal GP goes to the ventral anterior nucleus of the thalamus (inhib)
- Thalamus back to cortex (excite) which leads to the activation of upper motor neuron
- One last path which is substantia nigra to striatum by dopamine
Describe the mechanism of Action of Lipid soluble hormones
LSh diffuses through blood, interstitial fluid into the cell to the nucleus
hormone binds to receptors located within cytosol or nucleus. The activated receptor hormone complex then alters gene expression; turning genes on or off.
newly formed mRNA directs synthesis of specific proteins on ribosomes. (enzymes possibly)
New protein alters cell activity and causes response typical of that hormone.
Describe the mechanism of Action of Water soluble hormones
Hormone binds to receptor on plasma membrane of target cell which activates G protein which activates Adenyl cyclase
Activated adenyl cyclase converts ATP to cAMP which is 2nd messenger to activate protein kinases
Activated protein kinases phosphorylate other enzymes in a cascade.
Phosphorylated enzymes catalyse reactions that produce physiological response. Or phosphorylation can turn off enzymes
After a brief period phosphodiesterase inactivates cAMP which turns off cell response unless new hormone molecules come
How does hormones produced in the hypothalamus travel to the pituitary
Hypothalamic neurosecretory cells get triggered to release hormones through the termini at the end of their axons which are close to their capillary network at the base of the hypothalamus.
Hormones travel through hypophyseal portal vein through secondary plexus to capillaries sitting on the anterior pituitary to then go to target cells in the pituitary.
What are the two stages of the Stress Response
ALARM response: Sympathetic autonomic activation: mobilise resources for immediate physical activity, get more oxygen and glucose into circulation, increase alertness and activity leading to fight or flight, Followed by Sympathetic activation of the Adrenal medulla (through ACh) which secretes epinephrine and norepinephrine into the blood to supplement and prolong the alarm response
2nd stage: (Resistance reaction) Stimulation of the adrenal cortex to produce cortisol (from CRH in hypothalamus -> ACTH from anterior pituitary) that helps to dampen inflammation, depress immune response to change balance to favour immediate tissue repair to reduce tissue damage if we get damage.
What stimulates the production of glucocorticoids at the Adrenal cortex
AdrenoCorticoTropinHormone (ACTH) made from the pituitary that was released into the blood stream. The hypothalamus told the pituitary to do this by releasing Corticotropin ReleasingHormone (CRH) into the primary hypophyseal plexus and then portal vein to the anterior pituitary.
Describe the process of appositional growth 3 steps from active to inactive.
- Osteogenic cells divide, forming osteoblasts which deposit osteoid
- Some osteoblasts become trapped in the lacunae where they will eventually become osteocytes
- When growth stops, osteoblasts can convert back to osteogenic cells or die. The osteoid is fully calcified
How do long bones grow in length and why does it do that
Endochondral ossification= There is a plate of hyaline cartilage that can grow by interstitial growth underneath the epiphysis which is the epiphyseal plate. This cartilage grows, dies then is replaced by bone.
It does it this way because it can’t lay bone down on the articulate cartilage on the ends.
Describe 4 steps how a primary osteon forms from appositional growth
Osteoblasts in the active periosteum either side of the blood vessel put own new bone forming ridges
Bone continues ridges come together and fuse forming a tunnel around the blood vessel. The tunnel is now lined with endosteum.
The osteoblasts in the endosteum build concentric lamellae onto the walls of the tunnel. The tunnel fills inward toward centre
The bone continues to grow outwards as the osteoblasts in the periosteum build new circumferential lamellae.
Process repeats as new ridges fold over blood vessels
What are the 5 steps of forming a secondary osteon
Osteoclasts form and gather in an area that needs to be remodelled. They start boring its way through the existing bone.
Osteoblasts move in behind the cutting cone and line tunnel wall as new endosteum and start depositing osteoid.
Osteoid calcifies to form new lamella and a blood vessel will grow into the tunnel to supply the cells.
Osteoblasts deposit layer upon layer of new concentric lamellae on the wall of the tunnel to fill it in. Some osteoblasts get trapped and become osteocytes
When the tunnel is reduced to size of normal Haversian canal, remaining osteoblasts die or become osteogenic cells part of the resting endosteum.
Describe the 6 steps of loading cycle of articular cartilage from recently unloaded cartilage
Ion conc in the matrix increases because negative charges on disaccharide units attract positive ions into the cartilage from the joint space
Osmotic gradient is created by moving of ions causing water to move into the matrix and the cartilage to swell.
The cartilage swells until the swelling force = the tension force placed on collagen. At this point : unloaded equilibrium and the volume of cartilage doesn’t change
When a load is introduced the fluid component is squeezed out of the cartilage back to the joint space synovial fluid or other parts of uncompressed cartilage.
The volume of the cartilage decreases because the loss of fluid = creep.
Eventually the compressive load will be supported by solid component and the repulsion of negative charges and will stop shrinking= loaded equilibrium.
What is the CT, structure, and function of the synovial membrane layer of articular capsule
CT: loose CT of variable thickness
Structure: 2 layers. Can form villi which increase SA and reduce volume of synovial cavity. Lines all non articular surfaces inside the joint cavity up to the edge of articular cartilage.
Synovial subintima: highly vascularised, containing macrophages, fat cells and fibroblasts.
F: maintains and protect articular capsule during normal movement, reduces volume of joint cavity to cushion
Synovial intima: 1-3 cells thick, contains synoviocytes that F: secrete lubricating features of synovial fluid
What is the make up and function of synovial fluid
Made of
1. ultrafiltrate of blood plasma from bv in the subintima +
2. secretions of lubricating proteins eg. Hyaluronic acid from synoviocytes .
3. free cells: monocytes, lymphocytes, macrophages and synoviocytes
Function: joint lubrication, shock absorption, chondrocyte metabolism and overall joint maintenance
Describe the cells in the alveolar wall
Type 1. Squamous pneumocyte, thin bordering with capillaries for gas exchange
Type 2: Surfactant cells: secrete surfactant liquid which keeps the alveolar open
Type 3: Alveolar Macrophage: wandering cell, last line of defense against microbes
What is the mechanics of the muscles that help inspiration
In inspiration the external intercostal muscles contract and the diaphragm contracts.
External intercostal muscles causes inspiration because as they contract the ribs pivot around their joints in the vertebral column and lift the rib cage up and out.
When Diaphragm contracts, it flattens the central tendon which pulls the dome downwards and increases the volume of the thorax
What are the mechanics of the muscles that help expiration
Expiration is a passive process at rest where diaphragm passively relax and rib cage returns to resting position. In active processes the internal intercostal muscles (at right angles to external intercostal muscles) contract and drag the rib in and down.
How does the respiratory volume , intra pulmonary pressure and intra pleural pressure change during inspiration
The pleural pressure decreases from a negative pressure to an even more negative pressure. This causes the intra pulmonary pressure to go from atm down to negative pressure. This causes air to move from higher pressure (atm) to lower pressure, increasing volume of air in lungs. As volume increase to a peak the pulmonary pressure rises back up to atm (in a cup shape) .
