Test 1 Physiology

Net charge of the inside of a neuron

Negative

Net charge of the outside of a neuron

Positive

Passive channels

Always open - leak channels

Active/gated channels

Open and close in response to specific stimuli

Leak channels (passive)

Allows ions to move freely via diffusion

Active (gated) channels

Opening of these channels can change the membrane potential by a brief increase or decrease in the membrane permeability of an ion

Chemically gated ion channel

Chemical binds to a gate to open it

Voltage gated ion channel

Changes in voltage causes the gate to open by changing its structure

Mechanically gated ion channel

Pressure causes the gate to open by changing its structure

Graded potential

Small, local and temporary change in membrane potential

Depolarization

Increase in membrane potential

Hyperpolarization

Decrease in membrane potential

Action potential

Strong stimulus activated when the membrane potential becomes less than -55mV or -60mV

Unmyelinated axons

Continuous propagation

Myelinated axons

Faster propagation of an action potential

Chemical communication

An action potential passes from one neuron to a second neuron at a synapse via chemical messages called neurotransmission

Electrical synapse

Direct physical contact between two cells at a gap junction, action potential (information) is transmitted quickly and efficiently

Chemical synapse

Communication between two neurons or a neuron to another cell, information is transmitted by chemicals called neurotransmitters

Axon terminal

Presynaptic cell

Dendrite

Postsynaptic cell

Excitary neurotransmitter

Promotes the generation of an action potential in the postsynaptic cell

Inhibitory neurotransmitters

Inhibits the generation of an action potential in the postsynaptic cell

Neuromuscular junction

Transfer of information from a motor neuron to a skeletal muscle fibre

Reflex

Brief, rapid, involuntary response triggered by stimulus

Cerebrum

Controls all conscious thoughts and intellectual functions, processes sensory and motor information

Function of cerebrum

Memory, cognition, control of skeletal muscle contractions, processing/interpreting sensory information

Cerebellum

Monitors and adjust ongoing movement information

Spinal cord

Transfers information between the brain and the body

Thalamus

Filters and relays sensory information to the cerebral cortex

Hypothalamus

Major regulator of homeostasis

Midbrain

Processes visual and auditory information

Pons

Subconscious control of skeletal muscle and smooth muscle in organs

Medulla oblangata

Regulation of the cardiovascular, respiratory and digestive systems

Afferent

Sensory information travelling into the CNS through a dorsal root

Efferent

Command information travelling through out of the CNS through a ventral root

Components of the somatic nervous system

Skeletal muscles, skin and joints

Components of the autonomic nervous system

Glands, smooth muscle, cardiac muscle and adipose tissue

Sympathetic nervous system

Increase heart rate, blood rate and glucose mobilisation. Decrease digestion

Parasympathetic nervous system

Facilitates digestion, energy storage, growth and immune response

Enteric nervous system

Network of neurons in the digestive tract that operate without instructions from the CNS

How many bones in the human body?

206

Osteocytes

mature bone cell that maintains bone matrix

osteoblasts

immature bone cell that produces new bone matrix in a process called ‘ossification’ or ‘osteogenesis’. differentiates to become osteocytes.

osteoclasts

absorb and remove bone matrix. large.

osteogenic

stem cells that become osteoblasts. more rare

Osteon

Basic functional unit of mature compact bone

endochondral ossification

Formation, growth, and remodelling. Occurs in most bones. Involves replacing hyaline cartilage with bone.

endochondral ossification steps.

1. cartilage model formation

2. growth and calcification

3. blood vessel penetration and spongy bone production

4. Bone formation (osteoblasts) spreads and remodelling (osteoclasts) occurs

5. secondary ossification centre created in epiphyses.

6. epiphyses fill with spongy bone and epiphyseal plate separates epiphysis and diaphysis.

7. epiphyseal cartilage gets narrower and disappears at puberty.

How do long bones get longer?

endochondral ossification

two types of ossification

endochondral and intramembranous

difference between endochondral and intramembranous ossification

endochondral: occurs in most bones, involves replacing of hyaline cartilage with bone.

intramembranous: occurs in clavicles, mandibles, and flat bones of skull, begins when osteoblasts differentiate in mesenchymal (stem) cells or fibrous connective tissue.

What is bone made up of?

Organic collagen matrix: formed from chains, triple helices, and fibrils.

How do bones support our body weight?

Handle compressive forces via transferring force to compact bone. Tension on lateral side of bone shaft, and compression on the medial side of shaft.

How does exercise affect bone growth and maintenance?

More physical activity —> more applied force/stress to bones —> more bone production by osteoblasts.

Less physical activity —> less applied force/stress to bones —> bone mass loss (up to 1/3 of mass)

Factors that affect bone growth and maintenance.

Nutrition, hormones, and exercise.

Calcitriol

Regulates calcium via homeostasis.

Found in kidneys. Increases calcium and phosphate ion absorption by the intestines of the digestive tract.

Parathyroid hormone.

Regulates calcium via homeostasis. Stimulates osteoclast (and osteoblast) activity, increases the blood calcium ion level

Calcitonin

Regulates calcium via homeostasis.

In pregnant and breastfeeding women, decreases blood calcium ion level and aids calcium ion transfer to fetus.

Calcium homestasis (which hormones)

Calcitriol, parathyroid hormone, and calcitonin regulate level of calcium ions.

Why is calcium homeostasis important to be maintained?

Variations in usual calcium levels (1-2kg of calcium) affects cellular function. (eg neurons and muscle cells)

factors that decrease blood calcium ion level

Thyroid gland secretes calcitonin. triggers a bone response (osteoclast activity decreases), intestinal response (intestinal absorption of calcium decreases), and kidney response (kidneys excrete less calcium ions, leading to calcium loss in urine)

Bone blood cell production

Hemopoiesis: production of platelets, red blood cells, and white blood cells. occurs in red bone marrow.

Cartilage structure

Supportive connective tissue consiting of matrix (firm gel) and cells (chondrocytes) Avascular.

Cartilage types

Fibrocartilage, hyaline, and elastic

Fibrocartilage location and function

Location: meniscus in knee, pubic symphysis, and intervertebral discs

Function: resists compression, limits movement

Hyaline cartilage location and function

Location: synovial joints

Function: Reduces friction between articular bony surfaces, stiff yet flexible support

Ligaments structure

Dense regular connective tissue consting mostly of collagen fibres. avascular.

Examples of cells in ligaments

Fibroblasts: secrete protein subunits to form collagen.

Fibrocytes: maintain collagen fibres

Types of ligaments

Extracapsular: outside joint capsule

Intracapsular: inside joint capsule

Ligament function

Connects bone to bone, supports, strengthens and reinforces synovial joints.

Affects of aging on bones

Osteoporosis: decreased bone mass and/or density

Arthritis: joint inflammation and damage to articular cartilage.

What is the name of the process that converts DNA to mRNA?

Transcription

What is the name of the process that converts mRNA to protein?

Translation

Secretory vesicle

Fuse to membrane and empty contents into extracellular space

Membrane renewal vesicle

Add new proteins and lipids to plasma membrane

Passive transport

Requires no energy expenditure

Active transport

Requires the cell to expend energy

Diffusion

Net movement of a substance from an area of higher concentration to an area of lower concentration (passive)

Concentration gradient

Difference between high and low concentration

Down the concentration gradient

Movement of a substance from an area of higher concentration to an area of lower concentration

Osmosis

Diffusion of water across a semi-permeable membrane (passive)

Facilitated diffusion

Integral proteins bind specific ions or organic substrates and carry them across the plasma membrane via carrier-mediated/facilitated diffusion

Active transport (type of transport)

Integral proteins bind specific ions and carry them across the plasma membrane via carrier-mediated transport (active)

Exocytosis

Small membrane sac fuses with the plasma membrane to move substances out of the cell (active)

Endocytosis

Extracellular materials are packed in vesicles at the plasma membrane and transported into the cell (active)

Receptor-mediated endocytosis

Movement of hormones

Pinocytosis

Movement of nutrients

Phagocytosis

Movement of bacteria

Intercellular communication

Communication between cells

Endocrine communication

Occurs when a cell releases a chemical message into the bloodstream to affect the activity of specific cells in another part of the body

Paracrine communication

Occurs when a cell releases a chemical message into the extracellular fluid to transfer information from cell to cell, primarily with a single tissue

Autocrine communication

Occurs when the chemical messages affect the same cells that secrete them

Synaptic communication

Occurs when a neuron releases a chemical message at a chemical synapse with a target cell

Direct communication

Occurs between two cells of the same type and the cells must be in physical contact

How do somatic cells divide?

Mitosis

How do sex cells divide?

Meiosis

Tissue

A group of cells working together to perform specific functions

Connective tissue

Fills internal spaces, provides structural support, stores energy

Epithelial tissue

Covers exposed surfaces and forms glands

Nervous tissue

Carries information from one part of the body to another in the form of electrical impulses