Lecture 19 Flashcards
Types of Cells - Neurons
- Can be classified according to function (sensory, motor, interneuron) or morphology (unipolar, bipolar, multipolar)
- Cell body (soma) usually bears one or more dendrites to receive information and usually one axon to transmit impulses (APs) - one-way transmission
Types of Cells – Glia (Neuroglia): For protection and support (3)
- Oligodendrocytes (CNS) and Schwann cells (PNS) - insulate axons with myelin
- Astrocytes - pass nutrients between cappillaries and neurons
- Microglia - engulf foreign material (immune cell)
Central Nervous System (CNS):
Brain and spinal cord
Peripheral Nervous System (PNS):
Nerves and ganglia outside CNS
Two Kinds of PNS Neurons:
- Afferent or sensory fibers - impulse from receptor organ to CNS
- Efferent or motor fibers - CNS to receptor organ
Somatic Nervous System:
Sensory or motor fibers to skin and voluntary skeletal muscles
Visceral Nervous System:
Sensory or motor fibers to viscera, glands and involuntary muscle
PNS: Autonomic Nervous System
- Regulates involuntary physiologic processes
- Monitor internal environment
Controls cardiac, smooth muscles, urogenital system, glands, some respiratory organs, intrinsic eye muscles
What are the Two Motor fibers in the Autonomic Nervous System:
- Sympathetic nervous system (fight or flight)
- Parasympathetic nervous system (rest and digest)
CNS: Spinal Cord and Nerves
Function: to recieve incoming impulses, integrates and coordinates them, transmits them within the CNS, and sends responses to the PNS as appropriate
CNS: Spinal Nerves (Dorsal Root):
Receive afferent fibers from sensory neurons with their soma located in dorsal root ganglion
CNS: Spinal Nerves (Ventral Root):
Contains motor neuron efferent fibers on their way to their targets
CNS: Spinal Nerve Distributions (Cervical (brachial plexus):
Neck flexors/extensors, diaphragm, shoulders/arms
CNS: Spinal Nerve Distributions (thoracacoabdominal plexus)
Intercostals and trunk muscles, abdominal muscles
CNS: Spinal Nerve Distributions (lumbar (lumbar plexus)):
Hip, thigh/legs
CNS: Spinal Nerve Distributions (Sacral (sacral plexus)):
Hip, foot/toes
CNS: Embryologic Development of the Brain (Prosencephalon):
Forebraine which is divided into two parts:
- telencephalon = cerebral hemispheres, olfactory lobes and bulbs
- Diencephalon = thalamus
CNS: Embryologic Development of the Brain (Mesencephalon):
Mindbrain - one part; optic lobes
CNS: Embryologic Development of the Brain (Rhombencephalon):
Hindbrain - two parts (balance and hearing)
- Metencephalon = cerebellum
- Myelencephalon = medulla oblongata
CNS: Functions of the Brain Regions - Forebrain (2):
- Telencephalon (cerebrum) controls all voluntary actions
- Diencephalon coordinates the endocrine system to maintain homeostasis, and relays signals to cerebrum; includes the thalamus, hypothalamus, and pituitary gland
CNS: Functions of the Brain Regions - Midbrain:
- Tectum receives sensory information
- cerebral peduncles attach cerebrum to brainstem; assist in refining motor movements, maintaining balance/posture
CNS: Functions of the Brain Regions (Hindbrain)
- Pons conveys information to the cerebellum from the cerbrum
- Medulla oblongata: regulates autonomic functions (ex. breathing, heart rate, blood pressure)
- Cerbellum: maintains equilibrium, refines motor actions
Evolution of the Brain (2):
- General trend toward enlargement of the cerbrum (‘higher functions’) and the cerebellum (regulates motor movements)
- Enlarged optic tectum in some teleost is associated with increased reliance on vision
