Year 11 Biology term 3 exam

sensory / afferent neurons

* receive signals from external environment and send to central nervous system
* dendrites receive signals
* pass through long myelinated section
* cell body is close to central nervous system
* links with associated neuron and signal travels to the brain

interneurons

* associated neurons only found in central nervous system
* function by linking sensory and motor neurons to different parts of central nervous system
* forms longitudinal tracts run length of spinal chord into the brain

motor / efferent neurons

* send signals from central nervous system to the effectors (muscles and glands)
* dendrites short and non-myelinated
* cell body within central nervous system and the myelinated axon exits via the ventral root going to organ

nerve impulses

Sodium is pumped out and potassium is pumped in

neuron

myelinated neurons

* cell membrane of the Schwann cell wraps around the axon many times (myelin sheet)

action potentials

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mitosis

process of cell division

somatic cells

body cells (non-sex cells)

IPMATC - phases of mitosis

1. Interphase
2. Prophase
3. Metaphase
4. Anaphase
5. Telophase
6. Cytokinesis

Interphase of mitosis

Growth/replication of the cell

prophase of mitosis

Prepare:

→ nuclear membrane breaks down

→ chromosomes condense

metaphase of mitosis

Middle:

→ chromosomes align on the equator

anaphase of mitosis

Pulling apart the poles

telophase of mitosis

Restoring original structure

→ nuclear membrane reform

→ cleavage of cell

cytokinesis of mitosis

Full division into 2 daughter cells

→ genetically identical to parent

types of nitrogenous waste in animals

1. Ammonia
2. Urea
3. Uric acid

Ammonia

* NH3
* Highly toxic
* Highly soluble
* Excreted by aquatic invertebrates, osteichthyes (bony fish) and tadpoles

Urea

* CO(NH2)2
* Moderately toxic
* Moderately soluble
* Excreted by chondricthyes (sharks and rays), terrestrial amphibians and mammals

Uric acid

* C5H4O3N4
* Not very toxic
* Insoluble
* Excreted by insects, most reptiles and all birds

Fat

* lipase
* Glycerol + fatty acid

Modality

Type of sensation

Common neurotransmitters

1. Acetylcholine (ACh)
2. Noradrenalin

Acetylcholine (ACh)

* used in the neuromuscular junction
* Used by motor neurons to activate muscles
* Cholinergic medications are pharmaceutical agents that mimic ACh

Noradrenalin

* mobilises the body for action
* Lowest during sleep, rises during wakefulness and reaches higher levels during situations of high stress or danger

Types of Drugs

1. Stimulants
2. Sedatives

Stimulants

1. Nicotine
2. MDMA / ecstasy

Sedatives

1. Benzodiazepines
2. THC / cannabis

Central Nervous System (CNS)

Peripheral Nervous System (PNS)

Spinal chord

Spinal Chord

Sympathetic system

Fight or flight

Parasympathetic system

Calms everything down, opposite effect of the sympathetic system

Somatic Nervous System

* part of the peripheral nervous system

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* sensory neurons

→ relay impulses to CNS from eyes, ears, olfactory organs, skin receptors, skeletal muscle and tendon

* motor neurons

→ relay impulses from CNS to the outer body tube

Visceral Nervous System

* part of the peripheral nervous system

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* sensory neurons

→ relay impulses to CNS from receptors in smooth muscle of iris, blood vessels of gut and bladder

* motor neurons

→ autonomic nervous system relays information from the CNS to viscera

—> parasympathetic system - secretes ACh

—> sympathetic system - secretes noradrenalin

Types of receptors

1. Exteroceptors
2. Interceptors
3. Proprioceptors

Types of sensory neurons

1. Nocireceptors
2. Mechanoreceptors
3. Photoreceptors
4. Chemoreceptors
5. Thermoreceptors

Nocireceptors

Type of sensory neuron that senses pain

Mechanoreceptors

Type of sensory receptor that detects pressure or distortion, eg. In the fingertips

Photoreceptors

Type of sensory neuron that detects light

Chemoreceptors

Type of sensory neuron that detects contact

→ distance chemoreceptors (smell)

→ direct chemoreceptors (direct contact)

Thermoreceptors

Type of sensory neuron that detects changes in temperature