HL BIO - Anatomy and Physiology

Unit 5

myofibrils

repeating units of sarcomeres which contain actin and myosin proteins that slide past each other to generate muscle contraction and the protein titin, which recoils the muscles

neuromuscular junction

the synapse between a motor neuron and a muscle fiber where neurotransmitters (acetylcholine) are released to stimulate muscle contraction.

ligaments

tissue bands that connect bones to other bones at a joint, providing stability and support.

tendons

fibrous tissues that attach muscles to bones, enabling movement and force transmission.

the reflex pathway (reflex arc)

(RSIME)

Receptor detects stimuli

Sensory Neuron carries signal to CNS

Interneuron Relay processes within the spinal cord

Motor neuron carries impulse to receptor

Effector responds to stimulus

receptor nueron

carries neural impulse to the central nervous system (CNS) m

motor neuron

sends nerve impulse from CNS to effector such as muscle or gland, facilitating movement or response.

spinal cord

column of nerves that run from base of skull to reset of body

cerebrum (cerebral hemispheres)

• controls muscle function and also speech/thought/reading/writing/learning/emotions

left hemisphere controls muscles on right side of body

right hemisphere control muscles on left side of body

primary motor cortex

region of cerebrum that is responsible for voluntary movement via motor neurons sending impulses to skeletal muscle in body

• skeletal muscles are what create movement in the body by pulling at different bones

reflex

an automatic, involuntary response to stimuli which triggers an immediate action

cerebellum

modifies the commands created by the cerebral hemispheres and fine tunes muscle contractions for balance and timing

• it is located behind the brain stem below the cerebrum

functions (FMC)

• facilitates motor function

• maintenance of balance/posture

• coorination of voluntary movements

hypothalamus

• part of the nervous system

• receives information from nerves around body about internal conditions to reglate the release of hormones from the pituitary gland and other endocrine glands

• 
  

pituitary

part of the endocrine system and sends out hormones as chemical messengers

• has both posterior and anterior intended for different functions

processes monitored by the hypothalamus

• body temperature

• blood glucose

• blood osmolarity

medulla oblongata

nervous tissue in the brain that controls involuntary movement

• heart rate

• blood pressure

• breathing

• swallowing and digestion

it receives input from sensory receptors and sends signal, coordinates response with heart to change heart rate or stroke volume

sympathetic cardiac nerve and vagus nerve

• causes heart rate to increase and force of contraction

• causes heart rate to decrease and force of contraction

enteric nervous system (ENS)

mesh like system of neurons in alimentary canal that acts independent of CNS

it controls:

• vomiting reflex

• muscles containing peristalsis

• local blood flow and secretion of digestive juices

sodium-potassium pump (Na⁺/K⁺)

• a transmembrane receptor

• exchange transporter: transports ions in opposite directions across membrane

• it has binding sites for

  • three Na⁺ ions

  • two K⁺ ions

  • one inorganic phosphate group

nerve impulse

series of action potentials (movement of Na/K ions across membrane) from the tip of neuron (dendrites) to end (synaptic terminal)

neurotransmitters

chemical messengers that carry information between cells at the synapses

saltatory conduction

the process by which action potentials "jump" from one node of Ranvier to another in myelinated neurons, increasing conduction speed.

action potential

a rapid rise and fall in voltage across a cell membrane due to the movement of sodium and potassium ions, initiating the transmission of a nerve impulse.

membrane potential

the difference in electric charge across a cell membrane that results from the distribution of ions, crucial for the generation of action potentials.